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Automobile crash test facility and preliminary analysis of low speed crush characteristics Miyasaki, Grant W. 1987

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AUTOMOBILE  CRASH TEST FACILITY AND PRELIMINARY ANALYSIS OF LOW SPEED CRUSH  CHARACTERISTICS by  GRANT W. MIYASAKl B.A.Sc, The University of Toronto  A THESIS SUBMITTED IN THE  PARTIAL FULFILMENT OF  REQUIREMENTS FOR THE DECREE OF MASTER OF APPLIED SCIENCE  in THE  FACULTY OF GRADUATE STUDIES  DEPARTMENT OF CIVIL ENGINEERING  We accept this thesis as conforming to the required standard  THE  UNIVERSITY OF BRITISH COLUMBIA September,  1987  © Grant W. Miyasaki,  1987  In  presenting  degree  at  this  the  thesis  in  University of  partial  fulfilment  of  of  department  this or  publication of  thesis for by  his  or  her  representatives.  £t\«JI*.€tfi\4  The University of British Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 Date  DE-6(3/81)  OcJoljlr'  f  /?^7  for  an advanced  Library shall make  it  agree that permission for extensive  It  this thesis for financial gain shall not  Cli/ll  that the  scholarly purposes may be  permission.  Department of  requirements  British Columbia, I agree  freely available for reference and study. I further copying  the  is  granted  by the  understood  that  head of copying  my or  be allowed without my written  ABSTRACT  A  large percentage  of automobile  accidents in city traffic occur  below 15 mph. Unfortunately there is a scarcity of experimental low  speeds  to help  vehicle crush  experimental mentioned  crash  crash data at these  investigators to reconstruct accidents. Accident reconstruction  experts have consequently from  at speeds  attached  a low level of confidence  at the low end of the speed data,  by  accident  Research  Croup  has  Insurance  Corporation  especially  in a  investigators.  constructed of British  low  The  a  to speed predictions  spectrum. The need  speed  range,  has repeatedly  University of British  crash  Columbia  test  facility  to address  for more  Columbia  in conjunction this  need.  been  Accident with  The  the  lCBC-UBC  barrier is a low speed crash test facility.  A techniques impacts  on  accumulated  description of the ICBC-UBC crash barrier, its systems and crash testing at the ICBC-UBC the same  facility  crush data that reproduced  subsequent  in this  thesis.  vehicle are investigated to see if this  preliminary findings are presented and  are presented  known  vehicle  range.  ii  technique  multiple provided  high speed crashes. In addition, the  on the impact  implications toward  Also  speed  crush  to initiate permanent crush  characteristics  in a  low  speed  TABLE OF CONTENTS ABSTRACT  ii  LIST OF TABLES  v  LIST OF FIGURES  vi  ACKNOWLEDGEMENT  ix  1. INTRODUCTION  1  2. LITERATURE REVIEW 2.1. 2.2. 2.3. 2.4. 2.5. 2.6. 2.7. 2.8. 2.9.  4  First Full Frontal Barrier Impact Test UCLA-ITTE Crash Test Facility Ford Motor Company Test Facility Road Research Laboratory Test Facility General Motors Corporation Automotive Crash Test Facility Crash Test Techniques at Fiat Transport Canada Motor Vehicle Test Centre A Few Other Crash Test Techniques Conclusion  4 5 6 10 11 12 13 14 14  3. ICBC-UBC CRASH TESTING FACILITY DESIGN AND CONSTRUCTION 3.1. Introduction 3.2. Overview of the Crash Testing Facility 3.3. Test Site 3.4. Crash Barrier 3.5. Propulsion System 3.6. Speed Measurement 3.7. Recording of the Impact Event 3.8. Release Mechanisms 3.8.1. Main release mechanism 3.8.2. Redundant release mechanism 3.9. Data Collection 3.10. Safety Considerations ,  15 15 16 18 20 24 26 29 29 30 34 39 41  4. VALIDATION OF ICBC-UBC CRASH TESTING FACILITY 4.1. ICBC-UBC Crash Testing Facility and SAE Recommendations 4.2. Validation of ICBC-UBC Crash Test Facility Results  42 42 43  5. HIGH SPEED CRASH DATA FROM REPEATED IMPACTS 5.1. Introduction 5.2. Campbell's Derivation of Energy Absorbed in Residual Crush 5.3. Absorbed Energy in Crush from Multiple Impacts 5.3.1. Force-residual crush response of multiple impacts 5.3.2. Quantification of crush energy from multiple impacts 5.4. Repeated Crash Tests  53 53 54 60 62 64 68  iii  6. BUMPER PERFORMANCE LEVEL AND LOW SPEED ENERGY ABSORPTION CHARACTERISTICS 6.1. Low Speed Bumper Tests 6.2. Graphical Interpretation of Crush Energy in the Low Speed Range 6.3. Crush Energy of the Two Regime Model 6.4. Three Regime Model of Vehicle Crush Characteristics  73 74 .... 75 83 84  7. APPLICATIONS T O THE CRASH3 PROGRAM  88  8. CONCLUSION  98  9. FURTHER AND FUTURE RESEARCH 9.1. Further Research  101 101  9.2. Future Research  103  BIBLIOGRAPHY  105  APPENDIX I  109  APPENDIX II  115  APPENDIX III  119  APPENDIX IV  123  APPENDIX V  126  iv  LIST O F  TABLES  Table 4.1  : Errors of fit/prediction  48  Table 4.2  : Honda test data  52  Table 5.1  : Double impact results  68  Table 5.2  : Double impact equivalent  Table 6.1  : Bumper tests  74  Table 7.1  : Speed-residual crush coefficients  91  Table 7.2  : Force-residual crush coefficients  91  Table 7.3  : Energy of deformation  94  speed  across the residual crush profile  v  69  LIST  Figure 2.1  OF  FIGURES  7  : UCLA-ITTE test setup  Figure 2.2 : Ford Motor Company crash barrier construction  9  Figure 2.3  : Towing arrangement  9  Figure 2.4  : Fiat catapult  12  Figure 3.1  : Towing arrangement  17  Figure 3.2  : Site plan view - original and prepared site  19  Figure 3.3  : Acceleration-speed-distance relationship  21  Figure 3.4  : Crash barrier  23  Figure 3.5  : Speed trap-remote unit  Figure 3.6  : Main release mechanism  electronics unit & sensor  27  31  Figure 3.7 : Main release dynamic load test results  33  Figure 3.8 : Main release static load test results  35  Figure 3.9 : Main release calculated static release force maximum spring travel/spring constant/ static release force  36  Figure 3.10  : Main release calculated static release force incline angle/friction coefficient/ static release force  Figure 3.11  : Redundant release mechanism vi  37  38  Figure 3.12  : Redundant release dynamic load test results  to 1981  Honda Civics  40  Figure 4.1  : Crash test results of 1975  Figure 4.2  : Residual plot of lCBC-UBC, Transport Canada, and Strother et al data  Figure 4.3  : Frequency distribution of errors of fit/pred. (Honda Civics)  47  Figure 4.4  : Crash test results of 1971-1972 full size C M . cars  49  Figure 4.5  : Residual plot of ICBC-UBC and Campbell data  50  Figure 4.6  : Frequency distribution of errors of fit/pred. (Full size C M . cars)  51  Figure 5.1  : Force-residual crush response  56  Figure 5.2  : Measured force-crush responses  58  Figure 5.3  : Impact speed-residual crush curve 1971-1972 C M . vehicles  61  Figure 5.4  : Crush energy of a vehicle repeatedly  Figure 5.5  : Possible deviation of multiple  impacted  impact data from single impact data  45  46  63 67  Figure 5.6 -. Multiple  impact test results-1977  Honda Civic  70  Figure 5.7  : Multiple  impact test results-1971 C M . Cutlass  72  Figure 6.1  : Single regime force per unit width-residual crush model  Figure 6.2  : Two regime speed-residual crush model  vii  77  78  Figure 6.3  : Two regime force-residual crush model  80  Figure 6.4  : Higher order force-residual crush function  81  Figure 6.5  : Two regime energy plot  82  Figure 6.6  : Impact speed vs residual crush for full frontal barrier tests for C M . Citations 1979-1982  85  Figure 6.7  : Three regime speed-residual crush model  87  Figure 7.1  : Impact speed vs residual crush 1975-1981 Honda Civic  90  Figure 7.2  : Force per unit width vs residual crush 1975-1981 Honda Civic  92  Figure 7.3  : Damage pattern  93  Figure 1-1 : Triangular deceleration pulse  112  Figure I-2  : Effect of wall movement  112  Figure I-3  : Crash barrier free body diagram  Figure IV-1  on earth pressure  : Force response for elastic and plastic crushing  viii  113  124  ACKNOWLEDGEMENT  This thesis would people.  1 would  preparation thank  Mike  of  like  to  not thank  this thesis, and  MacNabb  have  for  Dr.  been Francis  for the  possible without the Navin  for  coordination  his contributions  to  the  assistance of  his advice  of  the  and  guidance  crash barrier  design and  many in  project.  coordination  of  I  the  facility. His assistance was responsible for much of the success of the test facility.  Thanks  are  extended  to  the  staff  at  the  Insurance  Corporation  of  British  Columbia - Material Damage Center. The assistance of John Gane, Bob Wilson, Larry Kenmare, and lain Saville in the construction and preparation help in testing of vehicles is greatly  I  would  like  to  thank  of the test facility and  appreciated.  Rod  Nussbaumer  for  designing  the  speed  trap  electronics and also John Nepomuceno for building the speed trap switch box.  In  addition,  I  would  Richard Postgate and Max  like  to  acknowledge  the  work  and  assistance  of  Nazar in building the release mechanisms.  Financial assistance came from the Council.  ix  Natural  Science and Engineering Research  INTRODUCTION  1.  At the scene of an automobile of information vehicle  since  residual  to  the  this  crush  collision. More  accident, one of the most important  accident reconstruction  provides  profile  a vital  provides  clue  a  to  expert  is the  the  speed  of  the  measure  precisely, it indicates the quantity  damage  change  energy  pieces  pattern on  the  during  impact.  The  dissipated  during  the  of the vehicle's kinetic energy that  is absorbed in residual crush. The energy absorbed in residual crush is necessary for predicting speed changes of the vehicles involved in the the permanent  In  like  crush on the vehicle or plastic deformation.  order  characteristics  of  a plastic  to the  determine vehicle  and the  parameters  define  permanent  crushing and the  the  characteristics  front  quantities  structure  describe the  of  be  known.  the  quantity  in  crush  of  energy  characteristics increase the  absorbs a greater  energy  of energy absorbed to  of  of  a  the  (spring  vehicle.  structure.  the  front structure  spring.  with further  front  per unit of  crush,  pre-compression force  in force  vehicle's  residual  The vehicle's  characteristics  (force  behaves to  constant)  Similary, The  residual Different  force  crush  begin  are  these to  crushing vehicles  the two  initiate define absorb  residual crush. A vehicle that has a stiff per  with a soft front structure. In summary, the the  absorbed  increase in force with displacement  that  different  energy  a collision. The  parameters  crush  the  must  spring during  displacement)  accident. Residual crush is  unit of  residual  crush than  a vehicle  crush characteristics of a vehicle enable  be calculated from which the speed change of  the vehicle is determined.  1  2 The full frontal residual  crush characteristics  barrier  crush  consumed vehicle  From the  easily  determined  deforming  model,  the  vehicle's  collisions. In a full frontal  is  in  of  many  impact  the  full  speed  frontal  barrier  since  structure.  and  residual  most  crash  all  To  barrier  front  of  impact, the the  determine  impacts  are  crush data  structure  vehicle's the  derived  kinetic  stiffness  these  from  energy absorbed in  conducted  of  are  at  tests,  energy  of  a  is  specific  different speeds. the  vehicle crush  characteristics are derived.  The Canadian frontal  source  and  U.S.  Federal  Motor  data  at  the  estimates  is in this narrow  low  from  and  the  high  residual  is  Vehicle  barrier collisions in a medium  most crash data data  of  impact  the  Safety  compliance  tests  Standards.  These  conducted  for  tests  full  speed range of 48 to 56  speed range,  end  of  the  crush  in  a .low  km/hr. Since  there is a scarcity of  speed  spectrum.  speed  range  are  experimental  Consequently, are  being  speed  challenged  because of this lack of data. In response to this need for crash data, a test facility was  constructed  by the  University  of  British Columbia Accident  Research Group  in  conjunction with the Insurance Corporation of British Columbia (ICBC).  The research for this thesis consists of two design and calibration  construction of  the  barrier  of  a reliable,  was  done  by  low  major topics. The first topic is  cost, low  speed crash test facility.  collecting impact  speed  and  The  residual crush  for a few different vehicles and compare them to known results.  The second part of the the  facility.  A program  of  research involves the  crash tests were  analysis of data produced at  conducted to  investigate  the  following  3 two topics:  •Determination  of  frontal  crush  characteristics  from  repeated impacts on the same vehicle - To reduce the cost  of data collection, one  method  suggested  is to  use the same cars in multiple impacts. This technique was  investigated  research  because  money. The  of  its potential  theory behind  to  repeated  save  impacts  will be presented and crash tests performed to evaluate this theory. •Examine systems  the -  energy  Tests  absorption  were  conducted  capacity to  of  determine  energy absorbing capacity of the Honda Civic system  and/or  impact  speed  bumper  required  the  bumper  to  initiate  permanent crush.  Chapter 2  is a literature  review of the systems and  techniques used to  conduct vehicle crash tests. In Chapter 3 is a full documentation of the design and construction of the ICBC-UBC test facility, and Chapter 4 has the validation data of the  ICBC-UBC test facility. A preliminary analysis of the multiple impact technique is  presented  in  Chapter  5.  An  investigation  of  the  threshold  speed  and  crush  characteristics at the low end of the speed spectrum is presented in Chapter 6. An application  of the proposed  crush behaviour model  of Chapter 6  is outlined in  Chapter 7 where an equivalent barrier speed is predicted from a example accident case. Chapter 8 is the conclusion and Chapter 9 identifies areas of further research.  2. LITERATURE  Vehicle  impact testing  has been  variety  of  different  crash  struck.  In  addition,  impact  testing  vehicles. This  review  is  scale  configurations  REVIEW  quite as  extensive and  well  as  many  includes individual  confined  to  full  scale  encompasses a wide  different  objects  components as well barrier  impact  being as full  testing.  The  evolution of barrier impact testing is sketched from the early primitive, yet effective techniques test  of  facilities  the in  1950's,  North  to  the  present  America and  sophisticated procedures. Different  Europe  are  described with  a  crash  focus on  the  following topics:  •Crash barrier design  '•Propulsion of the test vehicle  •Directional control of the test vehicle  •Speed control of the test vehicle  •Instrumentation  In  addition, the  and data acquisition  motivation  behind undertaking the  full scale barrier testing will be  outlined.  2.1.  FIRST FULL  Barrier retaining wall.  FRONTAL  BARRIER I M P A C T TEST  impact testing began in 1934 In  that test  the  vehicle was  4  when driven  C M . crashed a vehicle into a at  a low  speed to  allow  the  5 driver to jump out just prior to impact.  This technique was very simple since the  driver controlled the vehicle. The  vehicle's own  engine was used for propulsion and a driver steered the vehicle and  controlled the  speed. However,  the  technique was limited to very low speeds, and  the safety of the driver remained a problem.  2.2. UCLA-ITTE CRASH TEST FACILITY  An California  automobile  in  restraining  crash  the  1950's.  features  of  addition, the specificially,  The  the  test  facility  purpose  chest-type,  of  was  constructed  the  crash  lap-type  and  tests  by  the  were  to  shoulder-type  University  of  compare  the  safety  belt.  collapse characteristics of automobile structures were investigated. the  deceleration  pulse was  examined  and  the  causes for  In  More  departure  of  this deceleration pulse from the ideal uniform deceleration pulse were investigated.  This crash barrier consisted of the  ground and supported by cross  by earth and 4.3  fill to  provide  test  vehicle  another vehicle (control  the  members  and  resistance. The  utility poles sunk 2.4  braces. The impact  barrier  surface was  m into  was backed 2.4  m high  m wide.  The  was 30  additional  large diameter  m  barrier.  from  the  was  propelled  car). The  barrier  then  control break  toward  the  car would away,  barrier push the  decelerate  by test  and stop  pushing vehicle 12  it  with  until  it  m short of  6 Directional control was selsyn motor. A the  identical The  selsyn motor is held  control car. Movement  motor which  changes the  motor  maintained  in the  of  by  remote control steering that utilizes a  in contact  with an  this steering wheel  output from  the  test car which  auxiliary steering wheel in  rotates  the  shaft  of  the  selsyn. This output is transmitted  is held  in contact  output produces a similar movement of the  with  selsyn to  an  its steering wheel.  selsyn shaft and  steering wheel. A  person in the control car steers the test vehicle with the auxiliary steering wheel.  Trial runs were conducted Trial runs showed that by barrier  it would  km/hr. Figure 2.1  The placed and  test  in the  so  the  pushing the  decelerate,  while  impact speed  test vehicle to 48  coasting,  to  the  could  be  achieved.  km/hr at 30  m  from  desired  impact  speed  the  of  40  is a diagram of the test arrangement.  vehicle  was  driver seat  and  fully  instrumented.  instrumented with  head. Strain guages were  mounted  rest, seat and  chest level safety belt. The  the  equipment  recording  desired  on  the  to  An  anthropometric  accelerometers in the  record  the  impact  forces  dummy  was  chest cavity on  the  foot  signals from these detectors were sent to  control vehicle  by  an  30  m  cable.  High  speed  cameras were used to record the impact event.  2.3.  FORD M O T O R COMPANY TEST FACILITY  A collisions  crash during  test facility the  of the  1950's and  happens to occupants during  Ford  Motor  1960's. Tests  a collision. The  Company  were  has  conducted  dynamics of the  provided to  full  scale  determine what  dummies and  injury  7  Source : Severy, D.M. and Mathewson, J.H. "Automobile-Barrier Impacts"  Figure 2.1  UCLA-ITTE test setup  8 mechanisms  were  investigated by  observing  the  damage  sustained  by  the  dummy  from striking the interior of the passenger compartment.  The 1.8  m  sand  crash barrier is constructed of 0.6  into a trench that is packed with pile and  wide, 1.8  m  4.5  m  test vehicle is displaced 3.3  determine the  just  by m  a tow laterally  prior  established when  impact. The  the  planks. The  provides  tow  towing  a cable toward  m  behind  car is operating  the  on  accurate  is actuated  distances  barrier is 5.5  m  2.2.  car with 10  barrier is backed by a  in Figure 2.3. Trial runs are performed  release mechanism which  to  oak  and  steering wheel position which  impact direction. A cable  with  long as shown in Figure  test vehicle is towed  arrangement is shown  diameter logs embedded vertically  a concrete fill. The  impact surface is faced  high and  The The  the  m  an  the barrier.  tow  car. This  open  area to  tracking and  correct  manually, releases the  for various  tow  impact  speeds  are  towing  a 1800  kg  at full throttle while  car. Setting these towing distances allows control of impact speed.  The and  floor  test vehicle is instrumented pan  impact, and  of  the  tensiometers  impact. Dummies with the  front  electric  and  cable  High speed speed  passenger are  to  an  accelerometers  compartment  mounted  accelerometers  rear seats. The  with  on  the  in the  signals from  instrumentation  van  to seat  head these  which  mounted  measure belt  and  to  the frame  decelerations measure  during  loads  during  stomach cavity are placed in  transducers  follows  on  are sent  alongside  the  through  test vehicle.  cameras placed at the side of the barrier record the impact, and  cameras  mounted  on  the  the  test  vehicle record  the  an  movements  of  high the  P L A N  L O G S 2 It. DIA. 12 ft. O IN G  OAK P A IN K H IG  D R IE C T O I N OF U l PACTsOf)  6  h . H I G H  R O A D S U R F A C E  |.  ;~  P A C K E D Fill C O N C R E T E  \\WM'  E L E V A T O IN  Source : Fredericks, A.L. "Automobile Crash Research" Figure 2.2 : Ford Motor Company crash barrier construction  N IS T R U M E N T A T O IN VAN T O W B R ID  C R A S H N IG CAR  Source : Haynes, A.L. Fredericks, R.H. and Ruby, W.J, "Automotive C o l l i s i o n Impact Phenomena" Figure 2.3  Towing arrangement  10 dummies.  2.4.  ROAD  RESEARCH LABORATORY TEST FACILITY  A England crash  crash  test facility at the  built in the  1960's has  barrier is constructed  rods. The  Road  Research  provided  of 56  crash  concrete  barrier weighs 91,000 kg  and  Laboratory  track in Crowthorne,  information on  blocks  is 1.8  European  that are held  m  high, 3.7  cars.  together  m  wide  The  with tie  and  6.4  m  long.  The gear  crash car has  engaged.  A  control  its ignition switched car  pushes  the  on,  crash  car  thereafter the crash car accelerates under its own short distance  behind  since the  selsyn motor. A  person  crash  car from  the  until  vehicles are connected  in the  control car  desired speed at impact is achieved the  the  by  barrier and  clutch and  appropriate  its engine  starts,  power. The  the instrumentation. Directional control is maintained a  and  by  by  and  control car follows 'a  the  electrical cables of  remote control steering with  remotely  steers the  crash  car.  The  setting the throttle opening, the distance of  the  speed  to which  the  crash  car is pushed.  Trial runs are conducted to determine these settings for the desired impact speed.  The  crash  car  displacement  meters and  to  decelerations  measure  contact  strips  which  are  is  instrumented  strain guages. The of  the  placed  with  acclerometers  passenger on  impact. They are also placed behind  the  accelerometers,  are mounted  compartment.  front  bumper  event  to  The  on  event  record  the  markers, the floor  markers  are  instant of  the engine block to record the time from first  11 impact  and  the  passenger  Displacement  meters  movement  the  of  compartment  are  placed  steering  wheel  in  moving  the  forward  passenger  column. The  to  the  engine  compartment  strain  guages  to  block. measure  are clamped  to the  seat belts to measure the loads during impact. Dummies with accelerometers in the chest cavity are placed in the front seats. High speed  motion  cameras are used to  record the deformation of the car and movement of the dummies.  2.5.  GENERAL  MOTORS  General  CORPORATION  Motors  Corporation built  provide data for development to  a  crash  test  U.S. Federal Motor Vehicle Safety Standards. The  tow  system  cable passes through  and  tensioners.  position  by  drive-drum  guide with  a  with sand with a subgrade  a friction  cable pulleys. shaft  drive  is wrapped A  around  vehicle  connecting  system  the  rear  of the test vehicles are maintained  vehicle  is chained  Speed  control  the  is acheived  against the system measurement and  m  in the  1%0's  to  testing for compliance  foundation. The  high and  speed. A  dolly by  which  3 m  mass of  wide.  manually  and  ground  stands  the  drive-drum.  to  a dolly  along the  balancing the  of pulleys, drive-drum  drive-drum  on  axle  with  slides  composed the  mounted  control  to  facility  FACILITY  consists of an endless cable that forms a continuous loop.  The  The  TEST  barrier at this facility consists of  barrier is 64,000 kg and the impact face is 2.1  The  CRASH  of crashworthy automobiles and  a formation of concrete packed the  AUTOMOTIVE  and  guide  flange  power  maintained in powers  the  Directional  rail. The  test  of the guide  rail.  input  to the  system  tach generator connected to the drive-drum provides a  display of speed  for the person controlling the speed.  12  1.6. CRASH TEST TECHNIQUES AT FIAT  Fiat cars.  One  has  of  at speeds up  tried  a  number  these  techniques  to  km/hr.  40  is  of  different  a  catapult  This test  and which  techniques  launches  rig is shown in Figure  Barrier  dampers  unique  a vehicle  for with  crashing springs  2.4.  Release  t r a v e l 2 . 3 m max  Source : Franchini, E. "Crash Testing Evolution at F i a t " Figure 2.4 : Fiat catapult  Another vehicle.  The  test  technique  attempted  vehicle was  steered  was  to  push the  test  vehicle with  by a long steering column which  another extended  through the rear window to a person in the pushing car. As the vehicle nears the barrier,  the pushing car brakes and the steering column slides off so the test car  travels freely to the barrier.  A  more  elaborate  method  of  conducting crash tests was to radio control  13 the to  whole steer,  vehicle shift  operation.  gears  and  The  test vehicles were  actuate  the  clutch,  equiped  accelerator  and  with  pneumatic  brake.  jacks  Radio signals  sent to the test vehicle actuated the various actions of the vehicle.  Fiat's new  Safety Center built in the  1970's is a versatile  crash test facility  capable of staging many different collision configurations. It has a 2 million kg solid concrete  block for  testing  trucks  concrete  block. Vehicles are  of  up  propelled  culvert below the surface. The trolley  to  by  18,000  a two  kg  ton  and  a smaller  trolley  TRANSPORT  CANADA  MOTOR  on  rails  V E H I C L E TEST  kg  in a  is driven by a closed loop cable powered  an electric motor. The motor speed is controlled by a central  2.7.  rolling  320,000  by  computer.  CENTRE  A crash test facility in Blainville, Quebec was built for compliance testing of vehicles to in 1979  Canadian Federal Motor  Vehicle  Safety  Standards. Vehicle  m  began  and to date over one hundred vehicles have been tested.  The crash barrier is a solid 180 metric tonne is 4  testing  high,  5.8  m  long  and  3.4  m wide.  It  reinforced concrete block that  rests on  a concrete  pad that is  supported by piles.  The  test  vehicle  is  powered by an electric motor.  propelled Directional  by  a  cable  that  is  control is maintained  driven  by  a  winch  by a guide rail. The  test vehicle is chained to a dolly which slides along the guide rail.  14 Test  vehicles  are  High  speed  accelerometers.  fully  instrumented  cameras  are  with  mounted  anthropometric overhead,  dummies  below  and  at  and both  sides of the vehicle.  2.8. A FEW OTHER CRASH TEST TECHNIQUES Daimler  Benz  has  rocket which  staged  collisions  pushes the vehicle. The  propulsion and  guidance  by  propelling present test  the  test  rig that Daimler  Swedish State Power Board  used  test vehicles. In this technique, vehicles were dropped from gravity  to  propel  with  a  steam  Benz uses for  of test vehicles is a linear motor drive which accelerates a  trolley along a channel. The  used  vehicle  vehicles  wherein  test  vehicles  gravity to propel the  a crane. Volvo has also  descended  down  a  sloping  track.  2.9. CONCLUSION 1. There are as many different methods used  2. Most  barriers are becoming  to run the tests as facilities.  progressively more costly  operate.  3. Proprietory data limited the availability of the results.  to build  and  complex  to  3. ICBC-UBC CRASH TESTING FACILITY DESIGN AND  CONSTRUCTION  3.1. INTRODUCTION  A  need  UBC-Accident  for  low  Research  speed  Croup  to  automobile  design  and  crash  data  construct  a  had  crash  motivated test  the  facility.  The  whole facility is comprised of six different design components. The components are: Site Layout Barrier design Propulsion system Speed measurement High speed video camera Release mechanisms Data collection Safety considerations Many of the components had, a number of alternatives the  final design. In this section the  considered before  arriving at  design and construction of each of the  facility  components will be described.  The facilities, and  low  the  control  information  cost  of  the  ICBC-UBC facility systems  because  facility was  not  impact  should  be  intended speed  to  and  sought. Simplicity was sought throughout  The  design  between  the  and the  Insurance  and  University  of  construction British  of  the  Columbia  -  emphasized. have  Unlike  expensive  residual  crush  the  testing  facility  Accident  and  supply  vehicles. 15  Personell  instrumentation is  was  Research  Corporation of British Columbia (ICBC).  facility,  test  the  primary  the design and construction.  from  a  joint  Croup  The role of the  was to design and construct the testing facility while ICBC would maintain  other  both  project  (UBC-ARC) UBC-ARC  provide the  the  UBC-ARC  site, and  16 ICBC conduct the crash tests.  3.2. OVERVIEW OF THE  The positioned  CRASH TESTING FACILITY  configuration directly  of  behind  the  test vehicle is positioned impact surface  of the  with  rope  a  wire  mechanism and  the  on  crash  testing  barrier on an  a  that  is  attached  attached to the  roadway  approach way  barrier. Connection  facility  at an  of the  to  the  as  consists  of  shown  The  distance  from  the  having  The  test facility is configured  the  such that the  tow  test site as well as being the  since it obviates pulleys or snatch blocks as required  The facility  actual crash  checks  vehicle from  have  stops accelerating  tow  performed  consists  its position immediately behind  from its position on  release  testing procedure once the  been  and  the  approach way.  of  the  vehicle then deccelerates  tow  Once the  cable  to a stop.  from  by  and  towing arrangement  other towing arrangements.  pre-test vehicle preparation  the  driver  accelerating  towing the  until impact. At tow  and  the  tow  test vehicle  test speed is attained, the  the  barrier  found most suitable  simplest  barrier and  maintains a constant speed  mechanism detaches the  release  of the barrier.  roadway, approach way,  along a straight path. This arrangement was  geometry of the  main  test vehicle through a redundant release mechanism.  wire rope is threaded through a conduit that extends the length  for  test vehicle is  a  The  location are aligned  vehicle 3.1.  vehicle to the  tow-vehicle  tow  in Figure  acceleration  tow  a  driver  impact the  vehicle. The  driver of  main the  REDUNDANT RELEASE MECHANISM MAIN RELEASE MECHANISM  CRASH BARRIER  TOW CABLE  / -fyTOW-VEHICLE  /  SAND FILL  (  CONCRETE BLOCKS  Figure 3.1 : Towing arrangement  \^  TEST VEHICLE  18 3.3.  TEST SITE  A  plan view of the ICBC Surrey test site is shown in Figure 3.2. It is 195  metres long and west end, on  30.5  metres wide and  is bounded  a residential lot at the east end  the north  and  occupies  93  m  building  is  the  south  sides. An  existing  of the west portion of the testing  area  which  and  the  tow  road.  A  15  cm  barrier placement, see Figure  The the  back  away. The road  lot. The  face  of  the  102  m  long  levelling, and  "approach"  building and  from the m.  The  and  30.5  spreading  depression  was  m  this wide.  a gravel surface  excavated  for  the  3.2.  barrier extends 9 m  continues  residential lots  section of the lot behind  testing site arrangement has the approach way  distance of 65.5 fence  both commercial and  measures  deep  King George Highway at the  building that is used for vehicle repairs  Preparation of the site involved clearing and for  by  ending  from the end  back of the approach way  which provides a secure  at the  impact  surface  of the approach way  barrier to the and  barrier  to the barrier starting at  , and  east property  barrier lie within an  area from unauthorized  27.5 the  m tow  line which is a  existing chain link  personell entering the testing  area.  At accelerate  the the  approach way way,  the  test  outset it was test  and  vehicle at tow  decided 0.10  road. At an  vehicle can  attain  C  that the . This  tow  system would  acceleration governed  acceleration of 0.10  a velocity  of  be  26  C  km/h.  sufficient for our earlier tests which will run at less than 26  the  over a 27.5 This km/h.  designed length  to of  m  approach  approach  length is  For later tests at  K i n g George  Hwy.  30.5m  TJ  O  n>  TJ  0) n rt) Cb  0)  in rr 01  rr  lO C  n>  a c  LO rt)  3  D  rt)  H  o  »-  3  3 o  id 3  PJ 0) If  n x  MM  %  TJ  •-1 rt)  TJ  0J  rt) a  It  a  cn  rt 03  Residential 6L  Lots  H y,  x'  20 speeds  between  opening two  26  km/h  and  40  garage doors on  km/h,  the  the east and  approach  way  can  be  extended  west sides of the building and  by  towing  the test vehicle through the building.  The  65.5  accelerate to 40 a  margin  m  tow  road  km/hr then  of safety. The  allows  enough  decelerate at 0.5  curves  C  of Figure 3.3  relationship used in determining  distance  tow  vehicle to  to a stop with excess  roadway as  shows the  for  the  acceleration-speed-distance  the roadway lengths.  3.4. CRASH BARRIER  The 40  km/h  earth  low  impact  fill. The  speed of  a  blocks  crash 1820  are  barrier is a rigid kg  solid  vehicle. It is constructed concrete  which  retaining wall systems. Each block measures 0.75 high, and  weighs 1995  matching slots on  the  kg. The  reasons: the  is much  less than  one  of  interlock and m  wide, 1.5  concrete  for a  blocks  and  are typically used for m  long and  blocks interlock with a set of keys on  0.75  the top  m and  underside.  Interlocking concrete for two  non-moveable wall designed  blocks were chosen instead of a poured  material and of poured  construction cost of an concrete. Also the  interlocking  blocks  may  be  concrete wall block barrier easily moved  if necessary.  3  A total of 30 blocks and 23 m of earth fill are used in the barrier pictured in Figure 3.4. Eighteen blocks are stacked to form the barrier wall that is  Figure 3.3  : Acceleration-speed-distance  relationship  22 3.0 m block  wide, 2.3 m walls  that  high  and 2.3 m  are 2.3 m  high  thick. Behind  and 3.0 m  the barrier wall  long. The side walls  are two side  contain  the 23  3  m  of earth  fill as well as providing  set in a 15 cm  deep excavation for increased  dimensions of the barrier are 9.1 m  The inch  impact  plywood  resistance to movement. The whole barrier is  surface  in length, 2.1 m  is 3.0 m  in accordance  with  resistance to movement. The overall  wide  SAE  high and 3.0 m  and 2.1 m  Recommended  high  tow  cable  and faced  Practice  were specially cast with a hole for placement of the 8 cm  wide.  with 3/4  J850a. Two  blocks  pipe through which the  passes. The pipe is flared at both ends to reduce abrasion  of the tow  cable.  The  total  mass  and  configuration  the  barrier  was  designed  by  consideration  of the applied  deceleration  pulse was used to approximate the vehicle deceleration on impact. The  applied force during  forces during  of  impact and resistance forces. A triangular  impact was then calculated utilizing Newton's second law:  Force = The  resistance forces  and  the passive  mass * acceleration  come  pressure  from  friction  of the earth  between the concrete blocks fill.  A  net force  during  and ground,  the impact  event  imparts a velocity to the barrier and as the impact force subsides a net resistance force  deccelerates  the barrier. Appendix  I shows  the calculations  of the barrier  movement.  According to  less  than  1%  to these calculations, the barrier is sufficient of the permanent  crush  of the vehicle  to limit  movement  as specified  in SAE  Figure  3.4 : C r a s h  barrier  24 Recommendations (J850a). The meets the  total mass of the  recommendations of approximately 98,000 kgs  equivalent which is stated in an  Although the will  still  barrier is 100,000 kgs  require  barriers. This  a  barrier validation  involves  of compacted  earlier version of the SAE  barrier meets SAE  comparing  ensure  ICBC-UBC  compatibility  of  results to  those  crush  earth fill or  Recommendations (J850).  Recommendations the crush to  which also  results obtained results to of  other  other crash  barriers under similar test conditions.  3.5.  PROPULSION  As wire  rope.  SYSTEM  previously mentioned, the test vehicle is pulled by a tow The  tow  vehicle  is a  Chevrolet  pickup  sufficient power to accelerate a test vehicle at 0.10 tow  road surface  The  acceleration of the tow  the  main release mechanism.  The rope  was  tow  cable  that is 45.7  required  rather  m  than  found  to provide  truck  G.  From  long. A  12  flexibilty.  x  The  24 6.4  capable  of  by  tonnes  was  gravel  at 0.10  G.  the withdrawal force of  inch) diameter, 12 construction  providing  initial tests, the  sufficient traction to accelerate  vehicle is actually governed  is a 9.5mm (3/8  vehicle with a  x 24 chosen  breaking  strength  construction wire since is  strength is more  than  adequate to sustain the towing force.  Initially means.  guidance  of  the  test  vehicle  was  to  be  accomplished  by  two  25 1. The steering is locked with the wheels directed travel.  along the line of  2. The tow cable pulls the test vehicle in the direction of travel. The tow cable pull is maintained along the approach way centerline by the guidance conduit in the barrier.  However, inadequate. and  a trial  test  It is difficult  at a low speed  indicated  to set the wheels  these  two  precisely  guidance  directed  methods  in the test vehicle wandering  at the  off the approach  the start of its acceleration. The simple solution was to have a person  alongside  the test  vehicle  vehicle reaches a speed  with  one hand  of approximately  on the steering wheel. 20 km/hr the person  lets the vehicle travel the remaining distance on its own  were  towards the barrier  the cable pull does not keep the test vehicle aimed  barrier. These problems resulted at  that  When  way  running the test  guiding the vehicle  accord. At speeds  higher  than approximately 20 km/hr and the shorter length of tow cable, the test vehicle maintains  better  directional  stability  than  at lower  speeds  and thus the directional  pull of the tow cable is sufficient to keep the vehicle on course for the remaining distance. This guidance  method  has produced  mixed success because  of the gravel  approaches.  A and beam  guide  rail  reliability when will  wheels will  be  laid  system  will  be  installed  a concrete approach along  be guided  to improve  is built. In this system  the length of the approach  in the trough  the directional  way  of the U-channel.  been used successfully by most facilities in North  America.  a steel  accuracy U-channel  and the test vehicle's  This type  of system  has  26 3.6.  SPEED MEASUREMENT  Impact primary  speed  speed  measurement  was  measurement is obtained  made  from  with  three  a speed  different  devices. The  trap. The speed  trap has a  sensor unit and a remote electronics unit. The sensor unit is housed in a box that is 1 metre in length and width spaced  30.58 cm apart. The unit is set flush to the approach way surface 3 metres  back from tire  and 10 cm deep with three switch levers on top  the barrier face, and positioned to one side of centerline for the front  of the test vehicle to pass over. A  picture of the speed  trap is shown in  Figure 3.5 .  The  remote  electronics  unit  interpreting the signals sent from digital  display giving  accurate  to within  contains  the sensor  an immediate  reading  the timer  microprocessor for  unit via wires. It is equipped of speed  one percent. The speed  and  trap  in miles  is powered  with a  per hour  and is  by 12v DC  current  provided by a 12v car battery.  When  the test  counter  starts,  tripping  tripping  of the third  obtained  which  vehicle's front of the second switch  stops  provides two speed  tire  trips  switch  the first  records  the counter.  switch  an  the counter  Thus,  two  measurements. Comparison  timer  electronic  reading, and readings are  of the two speed  measurements indicates whether the vehicle was accelerating or decelerating prior to impact. and  If the two measurements differ significantly the vehicle's speed  therefore the actual speed  the speed trap. It is important  at impact  is somewhat different than  to have an accurate speed  is changing indicated by  measurement since even  Figure  3.5  : Speed un 11  trap-remote  electronics  unit  &  senso  28 a small difference in speed  results in a substantial difference in the vehicle's kinetic  energy.  Two  redundant  camera and from  impact  speed  measurements  are available  from  a video  a fifth wheel attached to the tow vehicle . The video camera is  located on one side of the crash site perpendicular to the vehicle path at impact. The  camera has an internal timer to record the time to 1/100 of a second.  speed of  is determined  from  playback of the video showing  the time and movement  the vehicle past markers on the approach way.  The  fifth wheel looks much like a bicycle wheel. It is attached to the tow  vehicle by an arm extending from a set of wheel forks and is rolled tow  Impact  vehicle.  An  optical  sensor  sends  a  pulse  signal  - which  alongside the  has a frequency  proportional to the angular velocity of the wheel - to an electronics unit on board the on  tow vehicle. The signal is processed and the tow vehicle's speed tape. The tow vehicle's speed  vehicle. Since the fifth  wheel  is recorded  should be very close to the velocity of the test  measurement  gives  an indirect  measurement  of the  test vehicle's speed, it is the least accurate, however the measurement is valuable if the  other measurement methods fail.  Both  the  speed  measurement  while  the  trap speed  and  fifth  measurement  obtainable after playback of the video.  wheel from  give  an  the  high  immediate speed  velocity camera is  29 3.7.  RECORDING  Crash  OF  THE  IMPACT  EVENT  testing facilities typically capture the  cameras that have a resolution of 200 SAE  recommendation  professional  camera  J850a. operator.  rental rate is $300 per day Such equipment was  Standard site perpendicular  too  video  cameras  3.8.  frames per  second  cameras  are  very  expensive  These  cameras  cost  approximately day  high  speed  as specified and  require  $12,000  and  by a the  for a camera operator.  costly for this project.  video  cameras  are  on are  a boom used  frames per  for  positioned  on  both  sides  instant of barrier contact. An  directly above the visual  second is not  recording  barrier contact of  the  impact  of  the  overhead point.  The  only.  The  sufficient for micromotion analysis of  impact.  RELEASE  Two the  impact with  These  to the vehicle path at the  scanning rate of 30 the  1000  plus approximately $300 per  commercial  video camera is mounted standard  to  vehicle  towing  MECHANISMS  release  mechanisms were designed  vehicle. The  main  release  mechanism  to  separate on  the  tow  release with each test, however if it fails a redundant release the tow  cable from the test vehicle.  the  test vehicle vehicle  will  from usually  mechanism will detach  30 3.8.1. Main release mechanism  The  main  vehicle and  release  mechanism  is bolted  is designed to release the  cable release from the tow it through the  cable  to  the  upon  rear  bumper  after each test. The  the  tow  test vehicle impact. Having  vehicle prevents a whipping cable and  barrier conduit  of  need to  the  rethread  main release is shown in Figure  3.6 .  The second  main release has  roller is free to  rotate. The  roller that  springs  that  push  pushed  between  notches on the  outward  rollers two  the  wedge  to  slide  down  slide  up A  into  tow  cable  static  load  at a  incline  high  to  with apart.  rollers  is spring notches The  are  loaded on  free with  each  rollers  force of the springs on  seat  to two  side is into  the  the rollers resists  notches when a withdrawal force is  of  minimal  the  slot. Both  down  them  angle  the  wedge  force. The  wedge  steep  outward with  is shallow incline  allowing angle  movement of the  cable  clamps.  At  in  the the  wedge.  impact  the  cable pulls the wedge from the roller assembly.  characteristics of  before  and  resistance force against  is connected  required  in a  rollers from the  position with  tension generated in the tow  Two  roller is fixed in position while the  wedge  rollers' forcing  wedge. The  notches produces a high  Retension  and  together.  movement of the  to  high  up  rollers: one  each side of the wedge. The  applied  The  slide  is free to  the the  two  releasing  static load  and  the yet  is required  cable while the test vehicle is accelerated. A  release release to low  mechanism with  prevent  low  are  to  energy  withstand  a  expended.  premature releasing of  the  release energy is desirable so that  Figure  3.6  : Main  release  mechanism  32 a  minimal  amount  of  energy  is added  by  the  release  mechanism  to  vehicle's kinetic energy at impact . These two  properties of the mechanism  controlled  of the springs, the incline  by  the altering the pre-compression  the test can  be  angle in  the notch and the spring stiffness.  An involved The  impact test apparatus was  mounting  impact  the  loading  mechanism  system  set up  on  consisted  to determine the release energy. This  a test stand and of a round  wedge with a stopper plate at the bottom end weights dropped loads  and  at different heights  energy applications. The  applying  an  impact  load.  steel guide bar hanging from the of the bar. Different sizes of steel  along the guide bar produced potential energy  in the drop  different impact  height  and  weight  is converted to kinetic energy which is applied to the release mechanism.  The  wedge  stiffness of 1750 1.3  cm,  has  N/cm  a  incline  (1000  angle  lb/inch). When  the release energy is 90  ft-lb) kinetic energy represents  only  an  of a 1400 1.9%  of  N*m  kg  increase.  40  degrees  and  the maximum  spring  (66 ft-lbs). Compared  car travelling  Results  at 25  the  springs  have  a  travel is set to  to 4700 N*m  (3500  km/hr, the release  energy  of the release energy  tests is shown in  Figure 3.7 .  A  2000 N  test vehicle slack  in the  at 0.10 cable  force is the calculated static tension G,  however , a substantially greater  is taken  up.  Towing  tests  were  in the cable force  to pull the  is generated when  conducted  and  the  release  mechanism settings sufficient to prevent premature releasing were determined to be: •1750 N/cm (1000 lb/in) spring constant *1.3 cm (0.5 in) maximum spring travel  Figure 3.7 : Main release dynamic load test  results  Ul  34 *40 degree incline in the wedge notches Static load of 4000 N/cm  tests conducted with the above release settings gave a withdrawal force  N  (9001b). Figure  spring. Figure  3.8 displays the results of static load  3.9 is a plot of the calculated relationship between  spring travel, spring constant calculated force.  mechanism  latter  The the tow  release  two  plots  settings during  3.8.2. Redundant  of  and static release force. Figure  relationship between  These  release  mechanism  and  incline were  the design  angle, used  friction  as  a  3.10  coefficient  guide  a 530  maximum  is a plot of the and  for selecting  static  release  the  release  stage.  mechanism  redundant release cable  tests using  mechanism  acts  the test vehicle. Two  are hooked  as a link between chains  connected  the trailing  to the redundant  to the underside of the test vehicle and  rope is engaged into the release mechanism. A  end  the wire  picture of the release mechanism is  shown is Figure 3.11 .  The principle behind the  release  mechanism  The release mechanism  which will  held  in place  through 9.5 mm  swaged  the brass  shear on  impact  pin holding only  the tow cable to  if the main  socket  is crimped  release  fails. socket  to one end of the tow  between the plates by a shear pin. The brass  cable  shear pin is slid  (3/8 inch) holes in one plate, the swage and the other plate, thus  securing the swage and tow cable of  is a brass  has two steel plates between which a closed swaged  is positioned. The closed and  its operation  pin at the two  in place. The tow cable  interfaces between  is released  by  shearing  the plates and swage. The  brass  Figure 3.8  : Main release s t a t i c load test  results  on  Figure 3.9 : Main release calculated static release force maximum spring travel/spring constant/static release force  Figure 3.10 : Main release calculated static release force incline angle/friction c o e f f i c i e n t / s t a t i c release force  Figure  3.11  Redundant  r e l e a s e m e c h a n i sm  39 shear pin is 9.5  mm  in diameter and  a smaller diameter. The  at the shear locations the pin is notched to  pin diameter at the notches is machined to 6.75  will not shear at impact unless the main release fails. The 11/16  inch  at its widest  point  which  will  mm  and  closed swage socket is 1  allow it to  pass  through  the  3  inch  diameter conduit in the barrier.  Both static and  dynamic load tests were performed  the same testing apparatus as the main release. The which  is 10,000  energy required  N  greater than  to shear the pin is 156 by  the  main  cable during towing car  the  when  the  relationship  main  between  N*m  release. The  and  withdrawal which  shear  does not add  release shear  and  pin size  of  the  N*m  main  release.  greater than the  is sufficient  to retain  a significant amount of energy  mechanism area  shear pin can resist 14,000 N  force  is 66  on the shear pins using  fails  energy  to  operate. Figure  to  shear  the  pin  The  energy  the  tow  to the test  3.12 derived  shows  the  from  the  dynamic load tests.  3.9. DATA  COLLECTION  The  raw  data collected from the tests are impact speed  The  residual  and  after the collision. Prior to testing, the vehicle's dimensions  dimensions width,  and  crush  measurements  recorded front  or  recorded from which  are front rear  or  vehicle  are accomplished  rear  overhang,  width.  After  by  taking  wheelbase,  impact,  the residual crush is determined. The  shows the additional vehicle information recorded.  the  and  residual crush.  measurements before are measured. The  front same  and  rear  dimensions  track are  data form in Appendix II  160  0.8  Shear p i n a r e a  Figure 3.12 : Redundant release dynamic load test  results  41 Measurement the  video  maximum dynamic  cameras.  of elastic During  deformation just  rebound  and rebound  the impact,  prior  four  to elastic  crush, and the difference  between  velocity  images  rebound  will  be made with  are recorded  from  is determined. This  the dynamic  which  gives the  and residual crush  is  the  elastic rebound.  SAFETY CONSIDERATIONS  3.10.  2.5  m  The  test facility was designed with a number of safety features such as a  high  chain  redundant followed  release  link fence mechanism.  and safety equipment  encompassing A  the barrier  recommendation  and approach  of all safety  way, and a  procedures to be  required are outlined in the manual of Appendix III.  4.  4.1.  VALIDATION OF  ICBC-UBC CRASH TESTING FACILITY AND  Systems accordance to  ICBC-UBC CRASH TESTING FACILITY  to  "establish  and  SAE  components Recommendation  should crush  be of  specification  for  be  the  crash  J850a. The  sufficient standardization  tests at different facilities may  The  of  SAE  of  RECOMMENDATIONS  test  facility  purpose of  barrier  collision  the  vehicle".  The  following  the  barrier  Theoretically,  factors  states  the  "The  barrier  were identified as  •Speed measurement not •Accelerating •Vehicle degrees  results  of  barrier  size  mass  and of the  is sufficient  possible  construction  to  permanent meet  this  actual movement.  reasons  for  data that  is  exactly  90  concrete blocks  of  barrier  accurate  test vehicle at impact  does  not  strike  the  extent of these factors were investigated  Trial the  that  comparable. •Excessive movement of the  The  in  compared".  sufficient to limit barrier face motion to less than 1% the  designed  recommendation is  methods  specification, however trial tests were required to determine the  not  were  barrier  at  in trial tests.  tests have shown a slight movement between the  barrier. The  whole  barrier  is not  sliding on  42  its foundation  and  there  is  no  43 permanent shifting the  kinetic  of the blocks. However, any  energy  of the vehicle  movement  is expended  indicates  in movement  that some of  rather  than  dynamic  crush of the vehicle.  from 0.5  Speed  measurement  the speed  trap and  mph  of  each  other  accuracy was  high speed (note:  checked  by  video. These  Imperial  units  comparing  two  are  the measurements  measurements were within  used  from  here  on  since  speed-crush data has traditionally been presented in these units).  An which  accelerating vehicle at impact will have inertial forces from  may  increase  the  amount  of  crush. The  speed  trap  gives  the  wheels  two  speed  measurements from which acceleration at impact can be determined. i  A barrier  vehicle was  face.  degrees  The  directed  average  into  residual  the barrier at a twenty crush  to the barrier surface. Thus,  was  much  directional  less  degree  than  accuracy is an  a  angle to the  collision  at  90  important factor in  full frontal barrier crash testing. If collisions occur at less than a 90  degree angle,  then the test falls into the category of an angled barrier impact. From testing experience, I estimate that an impact angle between 90°±5°  past crash  is equivalent to  a full frontal impact.  4.2. VALIDATION OF ICBC-UBC  Validation data  of  CRASH TEST FACILITY  of the results from  other test  facilities.  A  1975  the test and  1977  facility  RESULTS  involves  Honda  Civic  comparison and  a  1971  to the CM.  44 Cutlass station wagon were chosen for validation purposes  since abundant test data  is available on these vehicles over a wide range of impact  speeds.  plot  of impact  speed  barrier impacts  1975  to 1981  Honda  versus  residual crush  Civics. The  data  of full frontal  is from  three  Figure 4.1 is a involving  sources: Transport  Canada,  Strother et al, and the ICBC-UBC test facility. The ICBC-UBC data is not in range of the Transport Canada and Strother et al data therefore direct comparison be  performed.  Instead the ICBC-UBC data data can be compared  or predicted speed squares  fit of a  at the same linear  model  crush  estimated relationship between impact V  =  4.4 +  speed  Canada  relationship Strother  close indicates  et al and  ICBC-UBC  data  proximity that  values  a least  Strother data. This  1.5C  of  the  the results  Transport  and  being  and residual crush is:  where C is residual crush in inches and V is impact  The  to the estimated  levels. The predicted speed  to the Transport  cannot  ICBC-UBC  data  in miles per hour.  points  to  this  are acceptable. The  errors  data,  of prediction  Canada  are shown  speed  and  in Figure  the error  4.2. The  ICBC-UBC  estimated  of fit of the  values  of the have  a  noticeably smaller error. In Table 4.1 are the errors of fit of the Transport Canada and  Strother data and the errors of prediction of the ICBC-UBC data.  The  quality  of  the  ICBC-UBC  results  distribution, as shown in Figure 4.3. The frequency and The  is portrayed distribution  with  a  frequency  of the errors of  fit  predictions is plotted along with a Normal distribution with the same variance. distribution  appears  to  deviations of the ICBC-UBC  be  normally  results from  distributed.  The  the predicted impact  number speed  of  standard  are shown in  Figure 4.1  : Crash test results of 1975  to 1981  Honda Civics  a 6  A ICBC-UBC  c o  •  Transport Canada  O Strother et a l TJ OJ  u  \  a  4J  J-l  o u  a  V-Impact speed (mph)  Figure 4.2 : Residual plot of ICBC-UBC, Transport Canada, and Strother  et a l data ^  0.4  -n  0.35  -  0.3  H  Error  4.3  : Frequency (Honda  of  fit/prediction  distribution  Civics)  of  (mph)  errors  of  fit/pred.  48 Table 4.1.  Figure 4.4 is a plot of impact speed size  CM.  impact outside  vehicles from  result  Campbell. A  of the C M .  of the speed  Cutlass  range  relationship is valid to a crush point to the line data  of  and residual crush  regression  line  is drawn  of 1971-1972 full  and the ICBC-UBC  is also plotted. The ICBC-UBC the data,  however  assuming  data the  level of four inches then the closeness  point  lies  estimated  of the data  indicates that it is also valid. The error of fit of the Campbell  and the error of prediction of the ICBC-UBC value  At a crush level of 3.8 inches, the estimated  is plotted in Figure 4.5.  relationship over-predicts speed by 0.8  mph. The distribution of the errors of fit and the Normal distribution are shown in Figure  4.6. The  ICBC-UBC  result  is 0.4  standard  deviations  from  the expected  impact speed.  Table 4.1 : Errors of fit/prediction DATA SOURCE  IMPACT SPEED (mph)  ERROR OF FIT OR PREDICTION (mph)  Transp. Canada Transp. Canada Transp. Canada Transp. Canada Transp. Canada Strother Strother Strother Strother Strother ICBC-UBC ICBC-UBC ICBC-UBC ICBC-UBC  28.7 29.7 29.2 34.9 29.3 8.9 13.9 27.1 27.1 40.0 19.7 19.2 18.3 17.3  1.5 -0.4 4.9 2.7 -2.4 -0.6 -0.8 -2.1 -3.7 0.8 0.3 0.6 0.7 1.2  STANDARD DEVIATION  0.1 0.2 0.3 0.5  C-Residual crush  Figure 4.4  (inches)  : Crash test results of 1971-1972 f u l l size G.M.  cars  • ICBC-UBC Q Campbell  • •  rP. -TJB•  I 20  1  1  I  40  60  Predicted speed (mph)  Figure 4.5 : Residual plot of ICBC-UBC and Campbell data (1971-1972 f u l l size G.M. cars) o  Error of f i t / p r e d i c t i o n  Figure 4.6  (mph)  : Frequency d i s t r i b u t i o n of errors of (Full size G.M. cars)  fit/pred.  52  Repeatability damage for the the mph,  is the  ability  as shown in Figure 4.1. slight differences  the test facility. Table 4.2  TABLE 4.2  the  same test variables. To  Honda Civics were tested  with the  of  testing facility  check the  to  reproduce the  repeatability of the  same  test facility,  at impact speeds within a narrow range of 17 to The  slight differences  in residual crush is  in impact speeds. These tests confirm the  20  consistent  repeatabilty  of  contains the Honda test data.  : Honda test data  The with predicted  speed and  Impact Speed (mph)  Residual Crush (inches)  19.7 19.2 18.3 17.3  10.0 9.5 8.8 7.8  crush data from the  values of Transport Canada and  test facility produces results that can  be  ICBC-UBC test facility are Strother  data. Thus, the  compared with other test facilities.  consistent ICBC-UBC  5.  5.1.  HIGH  SPEED  CRASH  DATA  FROM  REPEATED  IMPACTS  INTRODUCTION  There speeds.  is a  Multiple  equivalent  scarcity  low  to a single  inexpensive low speed  of barrier  speed  impacts  higher speed  crash  data  performed  at either  on  the  low  same  and  vehicle  impact. If a equivalence exists then  crash tests can be performed  very high may  be  relatively  to generate high speed  crash  data. This chapter will quantify the speed-residual crush relationship of repeated low speed  impacts and attempt to verify the the relationship by conducting a series of  repeated low speed crash tests.  Conducting high speed testing in a 40 to 60 mph costly  undertaking than  high speed  low speed  testing.  First,  a testing  speed  range is a more  facility  to accomodate  crashes requires substantially larger components and systems. The barrier  must  be considerably more  solid  reinforced  concrete  massive, usually requiring block. A  more  powerful  a subgrade and  foundation and a  sophisticated  propulsion  system is required or alternatively a longer approach and guidance track is required.  Producing the damage speed  impacts  speeds  from  and  has the added  pattern of a high speed benefit  of providing  a single vehicle. After each  equivalent  barrier  speed  gives  a  impact  crash  data  from over  repeated low a range of  low speed  collision, the progressive crush  new  value  data  further  along  on  the  speed-residual crush curve. Three or four speed-residual crush values obtainable from a single vehicle drastically reduces the cost of test vehicles.  53  54 A  high  applicable  speed  when  crash  damage  interest. Obviously safety  derived  pattern  from  and  information  repeated  impact  such  speed  low speed  crashes may  is the only  as occupant  dynamics  information of and deceleration  histories during a high speed collision cannot be derived from repeated impacts.  5.2.  CAMPBELL'S  DERIVATION  O F ENERGY  ABSORBED  IN  RESIDUAL  The following list defines the variables used in this chapter.  C  a  0  a  x  =  Plastic deformation (referred to as residual crush)  Force per unit width to initiate residual crushing  =  =  The increase in force per unit width with residual crush  f =  Force per unit width  W  1  =  Width of residual crush  W  0  =  Vehicle width  b„  =  Impact speed to initiate residual crushing  bi  =  Slope of impact speed-residual crush line  V  E  =  =  Impact speed  Absorbed  energy  Equivalent kinetic  energy  which  multiple impacts.  speed:  the vehicle  equals the total  speed kinetic  be  which  has a  energy  of the  CRUSH  55 Campbell's pioneering work in quantifying the energy absorbed  in residual  crush provides the foundation to derive an equivalence between multiple low speed impacts  and a single high speed  impact  (Campbell,1974).  Campbell's crush  model is based on residual crush, or plastic crush, which is the crush after the impact.  In this model, force per unit width  is assumed  energy  remaining  to be  linearly  related to residual crush as depicted in Figure 5.1.  (1)  f • a, + a C x  The parameters a  0  and a  x  define the force-residual crush response  force at which residual crushing begins and a deformation. The force response  x  where a  0  is the  is the increase in force with plastic  cannot be fully defined in terms of residual crush  alone and as such it is not an entirely correct representation of the force response during plastic deformation. However, the force response effective relationship of the energy absorbed a more accurate force response  of equation (1) provides an  in residual crush. Appendix IV describes  in terms of elastic and plastic crush which would  more closely emulate the true force response.  Integrating the force per unit width (equation (1) ) with respect to residual crush and width gives the energy absorbed  E  = a  The  J  /  0  0  in residual crush.  (ao+axOdC dw + c o n s t a n t  constant represents the energy stored in the initial elastic range. This is the  fundamental model for crush energy adopted by accident reconstructionists and has been incorporated into the CRASH3 program. The accuracy of this model has been tested extensively and has shown to yield acceptable results when correct stiffness  i Residual  Figure 5.1  r  1 crush  : Force-residual crush response  57 parameters  are specified  (Woolley et al,1986). This model  represents the current  'state-of-the-art' in determining the absorbed energy from vehicle damage.  ln Figure 5.2 is the measured force response in terms of elastic and plastic crush of Torinos (McHenry,1987). function  in both  response  chosen  elastic by  and  Force is shown to be  plastic  Campbell  may  approximated  crushing. This indicates be  a valid  assumption  that  a  by a linear linear  in his crush  force energy  model.  Campbell derived the a  and a  0  was selected between impact speed (V)  V = b A  linear  relationship  0  parameters as follows. A linear relationship  x  and residual crush (C).  + b C  (2)  x  is assumed  for the force  per  unit width (f) of the  front  structure as a function of residual crush.  f  = a  0  + a C  (3)  x  In a barrier impact all the vehicle's kinetic vehicle's front structure. The  energy  is absorbed  in crush of the  integral of the force per unit width with respect to  crush and width is the energy absorbed in residual crush, and the kinetic energy at impact is fmV . Equating the vehicle's kinetic energy at impact to absorbed energy 2  in crush gives:  W. £mV  2  =  C  ;  /  0  0  x  f dC dw  Substituting equations (2) and (3) gives:  + constant  Crush(inches)  Source : McHenry, R.R. McHenry, B.C. 'A Revised Damage Analysis Procedure for the CRASH3 Computer Program'.  Figure 5.2 : Measured force-crush responses  59  W /  C, / ( a + C ) d C dw + c o n s t a n t  0  0  0  tmCbo+biC) = J  0  (4)  a i  The constant term is required to account for some initial energy absorbed in elastic deformation  with  no residual crush. In equation (2) an impact  speed  of b  0  is  required to initiate residual crushing of the vehicle. This impact speed is the kinetic energy  absorbed  in the initial  comprised  of deflection  structure.  When  elastic  deformation. The  in the bumper system  the input  energy  exceeds  elastic  deformation is  and elastic bending the  energy  of the front  absorbed  by  elastic  deformation, the front structure undergoes plastic deformation.  The  parameters a  and a  0  1  can be related to the coefficients b  0  and b  x  by integrating equation (4) and solving by comparison of like terms.  a  =  ^  S  (5)  mb?  a, -  (6,  constant=tmbo  (7)  Thus, the force per unit width can be expressed in terms of the coefficients b  0  and  x  b  L  which  are derived  from  full  frontal barrier  collisions.  The b  0  and  b  coefficients are unique to each vehicle model or category of vehicles.  f = a„ +  a i  C = J  (b b + bjc) 0  x  (8)  "0  The  integral of equation (8) with  respect to residual  crush and width gives the  60  absorbed energy  mb?C  +  )dC dW + tmbo  W  0  where Cj equation  is the residual crush allows  the  W  and  absorbed  is the width of residual crush. This general  x  energy  to  be  determined  for  are:  is  different  damage  patterns.  The  major  residual crush and  assumptions  of  this  model  the stiffness is constant  residual crush must be  force  linearly  related  to  across the front of the vehicle. Also the  across the full height of the vehicle's front structure for the  model to be applicable.  5.3. ABSORBED ENERGY IN  As model from and  shown  are full  the b  previously the  expressed frontal x  CRUSH FROM MULTIPLE IMPACTS  in terms  of  barrier impacts.  coefficient  is the  key  parameters a  the  The  coefficients b„  coefficient  slope of the  and  0  b„  a  and  is the  of the  t  b  crush  energy  are  derived  which  x  impact  speed intercept  impact impact speed-residual  crush  line.  These coefficients are derived from a least squares fit of a linear model to impact speed-residual category  of  crush  vehicles, many  speed-residual 1971-1972 G.M. impact  data. To  speed  established by  crush  derive the  coefficients of a specific vehicle model or  vehicles must  function. In Figure  5.3  vehicles are plotted which and  residual crush  repeatedly impacting  be the  crash  tested  impact  to  establish the  speed-residual  crush  impact data of  exemplifies a linear relationship between  (Campbell,1974).  If this  same  function  can  be  the same vehicle then the cost for test vehicles  Source : "Energy basis for collision severity", Campbell,K.L, 1974.  Figure 5.3 : Impact speed-residual crush 1971-1972 C M . vehicles  curve  62 can be reduced.  The crash  impact  testing  repeatedly  speed-residual  many  vehicles  impacted  will  function derived from then on  be  determined  as  few  repeatedly impact  as  once  produce  only.  impact  single impacts on  two  impacted  vehicles.  A  vehicle will  speed-residual  crush function  be  5.3  was  possible  established  that  one  vehicles. The model  b  by  0  and  of singly  will  impacted  help in identifying  b  coefficient  x  conducting multiple  force-residual  presented which  vehicle  crush  produce vehicles.  response  could impacts of  a  the same linear The  assumptions  possible reasons for deviations from  impact speed-residual crush function of single impacts.  5.3.1. Force-residual crush response of  Figure impacts. The  5.4  depicts  multiple impacts  the postulated  energy absorbed  force-residual crush response  of multiple  in the initial elastic crush plus area 1 represents the  energy absorbed in the first impact. The energy absorbed in the second impact third  by  speed-residual crush data that follows the  postulated  be  of Figure  It may  for a particular vehicle  inherent in this model will the  crush function  impact  is represented  by  areas  2  and  3  respectively.  The  total  and  energy  absorbed in the three repeated impacts is the initial elastic crush of the first impact plus areas 1, 2 and  3. Thus for the second  impact, the same force-residual crush  response is assumed to continue beyond the residual crush, d ,  The crushing.  For  of the first impact.  force-residual crush response models the energy absorbed during plastic a  single  impact,  the  energy  absorbed  in the  elastic  range  is the  Figure 5.4 : Crush energy of a vehicle repeatedly impacted OJ  64 energy required  to initiate residual crushing  or plastic deformation. This energy is  accounted for by the constant term in equation (1). In the multiple impact model the  same force-residual  crush response is assumed, however for the second and  subsequent impacts the energy absorbed in the initial elastic crush is neglected. The validity of this  model and the associated  assumptions is tested with experimental  data. The next section will derive the impact speed-residual crush relationship that is generated from the force-residual crush response of Figure 5.4.  5.3.2. Quantification  of crush energy from multiple  impacts  Using Campbell's force-crush model a relationship for crush energy will be derived in terms of the residual crush from the first impact, C , and the residual x  crush from the second impact, C 2  The energy absorbed in two full frontal impacts on the same vehicle is  E  3  J  /  0  0  ( a + C ) d C dw + tmbo 0  (9)  a i  where Ci+Cj is the total residual crush from both impacts and ^mbj is the energy absorbed in the elastic range of the first impact. Substituting equations (5) and (6) for a  0  and a  gives  x  W  0  E  a  -  /  0  Ci+Cj jab  jfoiQ  b  J 0  ( - ^ "0  +  , "0  )dC dW  +  *mb  0  Integrating the above equation.  a  mb?(C,+C,) 2  2  2  65 It can be shown that the relationship between and  cumulative  residual  crush  is the same  as  the equivalent speed  the impact  function of single impacts. Equating the total absorbed  energy  (E  speed-residual of both  )  crush  impacts to  the equivalent kinetic energy of both impacts (£mV^) yields  tmv^ =  ttb.MCx+0  +  mb?(C,+C,) I V  l  2  + tmb,  l )  2  ,  After some rearranging, this reduces to  V  e q  = b  0  (10)  + MCj+C,)  The above equation can be generalized as follows  V  e q  = b  e  + b  n  x  I C i=l  (11)  1  where n is the number of impacts and  is the residual crush of the ith impact.  In this model, the total residual crush from has  an equivalent  same  residual  repeated  speed  equal to the impact  crush. The  cumulative  residual  crashes should lie on the impact  multiple impacts on a vehicle  speed  of a single  crush  and  impact  equivalent  speed-residual crush line  with the  speed  from  of full frontal  barrier impacts.  Multiple  impacts  on  speed-residual crush function and  b  theory  x  can  be  from  determined.  is the total  energy  the  vehicle  which  The  absorbed  will  give  a  trace  of  the  impact  the crush characteristics or parameters  underlying  assumption  in residual  crush  of the multiple  is the same  b  0  impact  regardless of  66 whether that residual crush level is produced this  major  assumption  in one impact or many impacts. For  to be valid, a number of other assumptions  were  made  relating to the force-residual crush behaviour of the vehicle. The above force-residual crush model and assumptions will help in identifying possible reasons for deviations of the multiple impact results from the speed-crush function. The assumptions made in the model are: 1. The energy absorbed in the elastic subsequent impacts is negligible  crush for the second  and  2. The force versus residual crush is a linear relationship.  If the first assumption the  elastic crush of the second  is not valid and significant energy and subsequent  is absorbed in  impacts then the multiple impact  data may show a significant deviation from the impacts speed-residual crush line of single impacts. This deviation is depicted in Figure 5.5 where in multiple impacts a higher equivalent speed is required to produce the same crush as a single impact. This deviation  results from  the greater quantity  of elastic  energy  absorbed  from  repeated impacts.  Experimental tests on vehicles were conducted  to determine whether the  equivalent barrier speed versus cumulative crush will trace the impact speed-residual crush line of single impacts and provide the same b„ and b section presents the result of the tests.  x  coefficients. The next  multiple  impacts  Residual  crush  Figure 5.5 : Possible deviation of mu.tip.e impact data from singie impact data  68  R E P E A T E D C R A S H T E S T S  5.4.  To crush from 1974  verify  the relationship  between  the equivalent  speed  repeated impacts, repeated crash tests were conducted  Honda  Civic,  and a  1971  CM.  Cutlass  station  and cumulative on a 1977 and  wagon. All of the vehicles  underwent two full frontal barrier impacts test; the results of these tests are given in Table 5.1.  Table 5.1 : Double impact results MAKE/MODEL  IMPACT No.  ACTUAL IMPACT SPEED(mph)  RESIDUAL CRUSH (in)  Honda Civic  1 2  19.2 18.8  9.5 4.3  1974 Honda Civic  1 2  18.3 15.2  8.8 4.6  CM.  1 2  9.4 14.5  3.8 10.0  1977  Cutlass SA/V  The  impact speed  For  two impacts, the equivalent speed  equal to the total the  and residual crush for the first impact is as shown in the table.  kinetic  energy  is the speed such that the kinetic energy is  of both  impacts. Thus, the equivalent  speed of  two impacts is calculated as follows:  eq where V the  x  is the impact speed  in the first impact and V  second test. This reduces to  v„  = <v* + v ) 2  2  *  2  is the impact speed in  69 or can be be written in a more general form as  V  n = ( I  ^  i  =  V?)  j, 2  i '  1  The residual crush of both impacts is the total residual crush. n  C = Z C. i-l 1  The  equivalent  speed  and total  residual  crush  for two impacts  are presented in  Table 5.2.  Table 5.2 : Double impact equivalent speed MAKE/MODEL  EQUIVALENT SPEED (mph)  1977 Honda Civic 1974 Honda Civic C M . Cutlass SAW  TOTAL RESIDUAL CRUSH (in)  26.9 23.8 17.3  Figure 5.6 is a plot of impact speed Honda Civics and the ICBC-UBC  13.8 13.5 13.8  and residual crush for 1975 to 1981  multiple impact test results. The impact speed and  residual crush of the first impact  on the 1977 Honda  is designated with an 'AT  and  total  of the double  the equivalent  speed  and  residual  crush  impact is  designated with a 'A2'. The single and double impact result on the 1974 Honda is designated with 'B1' and 'B2'. The double impact  data values for both Hondas lie  very close to the speed-residual crush relationship for single impacts. The predicted equivalent  speed  for the 1977  under-prediction. The predicted  Honda  equivalent  is 25.1 speed  mph  which  is an  for the 1974 Honda  1.8  mph  is 24.7 mph  50  -Residual crush (inches)  Figure 5.6  : Multiple impact test results - 1977 Honda Civic  VI  o  71 which is a 0.9 mph distribution  over-prediction. Refering once again to Figure 4.3 depicting the  in the errors  of fit and  prediction,  1977 Honda has an error of 1.8 mph. The  impact  is 19 mph  equivalent speed  The relationship  which  repeated  test data of 1971-1972 full size  is an 1.7 mph  of the double  experimental  the estimated or predicted value.  impact  values  A  more  vehicle  can  to the derived  impacts  up to 27 mph.  the same  data  speed-residual crush data of single impacts. The theory is valid for repeated  should be undertaken  on  of the  impact  an equivalent speed  impacts  over-prediction. The  CM.  produce  with  indicates  proximity  of the  deviation of 0.7.  test results. The predicted equivalent speed  is 1.0 standard deviation from  close  result  which is a standard deviation of 0.4.  Figure 5.7 is a plot of single impact  second  impact  This error has a standard  1974 Honda has an error of -0.9 mph  vehicles and the multiple impact  the double  extensive crash testing program  to conclusively validate this theory.  Figure 5.7 : Multiple impact test result - 1971  CM.  Cutlass ro  6. BUMPER PERFORMANCE LEVEL AND LOW SPEED ENERGY ABSORPTION CHARACTERISTICS  The (threshold  barrier  impact  speed) is one  speed  to initiate  of two  parameters  residual  crushing  in the linear  of the vehicle  relationship  between  impact speed and residual crush. Past experimental data suggests that this parameter is approximately 5 mph. That is extrapolation of the linear relationship gives a 5 mph  intercept. If a 5 mph  data will  intercept, b„ parameter, is accepted then collection of  be greatly simplified  single variable b  x  since the speed-crush  function  will  depend  (Navin,1986). Only one valid test point is necessary to derive the  parameter b . Tests were conducted to investigate the threshold speed 2  the  on a  and assess  validity of assuming a 5 mph intercept.  Before presenting the results of the tests, it is important that a few issues on the b  0  parameter is understood. The 5 mph  intercept is derived from a linear  regression process utilizing  data from crash tests in a medium speed range. It is a  "best fit" parameter from  the regression process and as such may  not have any  physical significance. At very low speeds the crush characteristics of vehicles may be different  from  those  in  a  medium  speed  range,  consequently  the  linear  speed-residual crush function may not be valid at very low speeds. In summary, the 5 mph  value for b„ may be a valid parameter in defining the crush characteristics  in a medium speed range however may have no physical significance for low speed impacts.  If this  is the case  then  the b„  bumper tests.  73  parameter  cannot  be  validated  from  74  6.1. LOW SPEED BUMPER TESTS  Bumper  tests  were  residual crush. A 1977 propelled  into  the  conducted to  determine  the  Honda Civic with an energy  barrier  three  times  at  impact  speed  absorbing bumper  progressively  higher  to  initiate  system was  speeds. The  impact  speed and damage sustained are shown in Table 6.1 .  Table 6.1  : Bumper tests  Test No.  After  Impact speed (mph)  Damage observed  1  4.4  None  2  7.2  3  10.8  Slight superficial damage to bumper Dents on exterior body panels  the  impact  first 7.2  was  the  system. The second  vehicle overhang.  no  measurable  threshold greater  bumper contacted the  left and right  shortening  speed at which  than  10.8  superficial  bumper  the  at the  slight  to  bumper fully rebounded and there was no residual crush of impact, the  only  damage  the  small dents  produced  no  to  third  mph  there  damage  In the  at  impact  of  exterior  bumper,  the  body panels producing two  side. The bumper fully recovered and there was  the  the  permanent  overhang.  These  crush or shortening  mph. A data value in Figure 5.6  tests of  indicate  the  shows four  that  the  vehicle  begins is  inches of  crush at  10 mph. This value from a paper by Strother et al contradicts our findings.  The  b„  parameter  which  is approximately  5  mph  is much  threshold speed which has been shown to be greater than 10.8  less than  mph. Thus, the  the b„  75 parameter defines the crush characteristics in a medium threshold  speed. The limited  Civics,  an  extrapolated  impact  speed  when  number  linear  range and is not the  of tests indicate that for early model Honda  speed-residual  the speed  speed  crush  relationship  is low. Since there is a lack  will  underestimate  of low speed  crash  data on most vehicle models, the linear speed-residual crush function is assumed to extend back to b - Consequently, for most vehicle collisions impact speed may 0  underestimated  for low speed  changes.  Vehicle  manufacturers  are likely  to design  bumper systems to protect the vehicle in collisions at somewhat higher than 5 to  surpass Federal safety standards. It can therefore be argued  will exhibit threshold that more  speeds  greater than the 5 mph  parameters are required  to characterize  b  0  be  mph  that most vehicles  parameter. This suggests  a vehicle's stiffness from  low to  high residual crush levels.  6.2.  GRAPHICAL  INTERPRETATION  OF  CRUSH  ENERGY  IN  THE  L O W SPEED  RANGE  Since the threshold speed energy is being absorbed  is greater than 5 mph  or dissipated  Campbell's work. In Campbell's  by the bumper  for Honda Civics, more  system  than considered in  derivation of energy absorbed in residual crush, the  force per unit width increases linearly with residual crush.  f = a„ + a C x  The  area  under  this  (Campbell, 1974). The £mb§  where b  e  linear energy  function arbsorbed  is the threshold  is the  energy  in the elastic  absorbed range  speed. Graphically, this  in residual  or bumper  energy  crush  system is  is represented by  76 the  area  under  Appendix  V  the  for  extension  a  full  regime the  regime  linear The  function  C  dimension  g  force-residual  end  of  the  is  a  Figure 6.1  hypothetical  higher absorption characteristics of crush  model  is  proposed  speed-residual crush function. Figure 6.2  lower  as shown in  (See elastic  bo/b^  To account for the two  the  derivation).  deflection and is equal to  a  of  speed  spectrum  is  and  illustrates  the a  bumper system,  corresponding  this model. In  characterized  by  a  two  Figure  6.2  flatter speed-crush  function which is valid from a residual crush of zero to the  intersection point C j .  This  b  linear  function  is  defined  by  threshold speed derived  from  possible explaination  quantify  levels.  linear  criterion.  which  bumper the  parameters  b  tests. A two absorption  and  2  regime  where  3  force  characteristics at  b  is  2  the  response is one low  residual crush  '  The two  to  the  force-residual crush function selected for  First, in  represents  tmbi/W,,. Second,  the the  Figure 6.3b energy  the  absorbed  area under  the  regime  area under this function by  the  function  bumper from  C  x  from  system to  I should satisfy  -  to  C„ -  should  equal  C  x  should equal  the  area under the single regime force-residual crush function over the same range. That is the  energy absorbed for a residual crush of  regime  model  speed  predictions  and single  regime  consistent  with  is the  same for both  model. This is a necessary condition to the  original  least  square  the  two  produce  speed-residual  crush  function. A force-residual crush function for regime I that has a higher crush energy than the single regime model will over-predict speeds.  Figure 6.1  : Single regime force per unit width-residual crush model  •vl "vl  Figure 6.2 : Two regime speed-residual crush model  vi 03  79 In Figure 6.3a is a depiction of the force-residual crush function that meets the  above  two  conventional function and  criterions. The  force-residual  defined  by  parameters  attached  The  crush  by  parameters  function  that is assumed  a  a  this  and  2  function  a  and  0  in Campbell's  corresponds to the low  3  from  C  to C  levels of  be considered  a  x  is the  work. The  speed  regime  accounts for the higher  0  - where regime II  in the function. At present a physical  to this step, however it may  more complex  derived  defined  in the bumper system. At crush  begins there is a step be  crush  the larger area under  energy absorbed  function  interpretation  cannot  as an approximation to a  non-linear function as shown in Figure 6.4 .  crush characteristics of vehicles can be represented by energy plots as  in a paper energy  E  by has  Strother et aKStrother et al.,1986). The a  linear  relationship  to  residual  square root  crush.  of the  The  mathematical  a  of regime II,  ct expression for this relationship is: 2E )t„  (  A  /(B)  +  t  (B)*C  "0  where A and  corresponds to the force intercepts a  B corresponds to the slopes a  3  of regime  2  of regime  I and  I and  0  a,, of regime  II. E  is the  crush energy which is  W j  C / (A+BC)dC dw  0  0  0  E  = £mV*  «  a  + A /2B 2  Figure 6.5 depicts the energy plot for the single regime model and the two model.  At  the  low  higher for the two  end  of the energy  regime  model  than  plot  (Regime  the single  I), the  regime  energy  model  regime  absorbed is  for crush  levels  Figure 6.3a  4J TJ •H  C  a  <u o o  c. Residual  crush  x: 4-1 TJ  c a Ul OJ  a  a> u o  X  Residual  crush  F i g u r e 6.3 : Two regime f o r c e - c r u s h model  Figure 6.4 : Higher order force-residual crush function  00  O  \ 63  o  CM  U  <U  c  a> JC in D  Li  O  a,/(a,) a /(aj) 0  Residual Source  crush  : "Crush Energy i n A c c i d e n t Reconstruction". S t r o t h e r e t a l ( 1 9 8 6 ) , SAE 860371  Figure  6.5  : Two  regime  energy  plot  00  83 less than Cj.  However, at a crush level of C j , the two models converge and the  energy absorption characteristics are the same.  The above very  the threshold low speeds,  regime the  advantage  model  range  by making  crush  energy  model  speed. Since a high  there  cannot  whole speed  of a two regime  is a definite  percentage  need  effectively replicate  is more  spectrum. Adaptation of a single large  shifts in the b  characteristics  and b  0  improvement. absorption  Also  a single  characteristics  over  regime model to the low speed x  parameters  at higher speeds. Quality  medium speeds for better prediction  just  of collisions occur at these  for this  the energy  accuracy at speeds  can adversely  of prediction  at lower speeds. On  affect  is sacrificed at  the other hand  adding a  third parameter to the model substantially increases complexity.  6.3.  CRUSH  The  ENERGY  OF THE T W O REGIME  parameters a  2  and a  terms of the coefficient b  2  and b .  a2  MODEL  in the two regime model can be expressed in  3  3  _ mbiba  _ mxb b  =  B  =  WQ  3  WQ  mbj a  where  x=^*- . The solution b  '  =  w  0  for these two parameters  are shown  in Appendix  V.  0  The force per unit width in the low speed regime is:  f  _ nixboba W#)  In  frontal  collisions, the energy  mb C 2  +  WQ  absorbed  in crush  at crush  levels  less  than  84  Cj  is:  E  =  a  For crush levels  =  a  one  low  crush energy is:  tmbf  3  C / (ao+axOdC dw C  I  threshold  of  the  2  coefficient  2  crash  limit  3  0 0  a  valid  lower the  With  2  J  °  tests.  0  o  W /  b  0  Cj / (a +a C)dC dw +  +  The  C / (a + a C)dC dw + $m b f  exceeding Cj,  W° E  W, J  test  the  or  threshold  speed, the at  a  speed  medium  speed  speed regime  with this  b  speed  is  coefficient  3  just  above  regime  lower  easily  or  the  can  determined  slope  can  threshold  be  assumed  be  limit will establish the  b  bumper  established  speed. and  from  the  from  Alternatively intersection  a of  coefficient.  3  6.4. THREE REGIME MODEL OF VEHICLE CRUSH CHARACTERISTICS  A  paper  suggests  a  saturation  level.  wherein  by  two  Strother  regime  Such a model high  speed  speed-residual  crush  function  two  regime  al(1986)  model  the  the  et  in  at  the  high  speed  for  crush energy the  force  identified  data  crush  speed-crush function  Combining  which  has been  crash  on  for  indicates  levels  above  G.M.  regime  in  per 1979  a  accident unit to  22.5  width  1982  flattening inches.  reconstruction reaches  G.M.  of  the  Figure  6.6  a  Citations impact shows  Citations.  suggested  by  Strother  et  al(1986)  and  85  C-RESIDUAL CRUSH (in.) A  Strother et ol.( 1986 ), Figure 5  •  Hight «t o l . ( 1 9 8 5 ) , Figure 4  *  Transport Conodo data  Source : "CRASH3 and Canadian data". Navin, F (1986) Figure 6.6 : Impact speed vs Residual crush for f u l l f r o n t a l barrier tests for G.M. C i t a t i o n s 1979-1982  86 the low speed regime proposed in this research produces a three regime model, ln this model the vehicle exhibits three different crush characteristics which are obeyed for  a  specific  function  crush  range.  Figure  6.7  depicts  the  impact  speed-residual  crush  of the three regime model. Regime II reflects the crush characteristics of  Campbell's original single regime  A absorption  two  regime  characteristics  force at  model.  response  low  residual  is a  proposed  crush  levels.  model Other  of factors  the  energy  may  also  significantly affect the amount of residual crush and energy absorbed. At low impact speeds, the energy level is relatively low and pitch  during  impact  may  represent  absorbed in residual crushing.  a  as a result the vehicle  significant quantity of energy  rotation  or  that is not  Residual crush  Figure 6.7 : Three regime speed-residual crush model  03 VI  7. APPLICATIONS TO THE CRASH3 PROGRAM  CRASH 3 accidents.  is a widely  Contained  within  speeds:  reconstruction  vehicle  trajectories  used  it are two  based  on  the lack  of vehicle  methods  for reconstruction  for determination  and reconstruction  of linear  momentum.  crush  speed  of vehicle of  accident  based  on the  Reconstruction  for its large errors in speed  specific  capability in a low and high  program  the damage  and conservation  damage basis has been criticized to  computer  on  a  prediction due partly  characteristics. In addition,  range has been challenged  the predictive  due to the lack of  crash data in these ranges.  The  CRASH3 program  categorizes  of a lack of vehicle specific crush assumed errors  to have  have  al,1986).  been  Some  the crush  characteristics assigned  according  to wheelbase  characteristics. All vehicles within  characteristics of the overall  demonstrated  vehicles  vehicles  exhibit  and attributed markedly  a category are However,  to this categorization  different  to its size category which  errors. As a result it has been  group.  crush  speed  to  stiff, normal  crush  than the prediction  suggested that vehicles be further stratified  relative stiffness (Navin,1986). Within each size category, vehicles would and soft categories. One step  further would  large  (Woolley et  characteristics  results in large  because  by their  be assigned  be to determine the  characteristics of each vehicle model, however the data requirements and cost  may not be commensurate with the improved accuracy.  A promise  multiple  impact  as a method  technique,  of producing  as presented  inexpensive crash  88  in Chapter data. This  5  shows  technique  much can be  89 of great benefit for producing the data requirements to further stratify vehicle crush characteristics according to relative stiffness.  Presently, the CRASH3 program  predicts accident speeds on  a damage basis  with a single regime force-residual crush model. Crash data from tests in a medium speed  range  however  these  consequence speed  are used  characteristics  Preliminary  definable low speed  will be  the crush characteristics  may  not  the accuracy of the CRASH3  range.  The  to define  two  utilized  tests  at the  be  valid  program  ICBC-UBC  at can  facility  (a„  and  low be  a  parameters),  x  speeds  and  challenged in the  indicates  that  there  regime  equivalent  its application  to the CRASH3  of a two barrier  the CRASH3  regime  speed  will  program. The  the " vehicle velocity at which energy which was  force-residual  crush function  will  be  for a  Civic  predicted  Honda  be  equivalent barrier speed  is defined  ICBC-UBC,  derived,  involved  in an  prediction  by Campbell  the kinetic energy of the vehicle would  and  as  equal the  absorbed in plastic deformation."  Figure 7.1 Honda Civics. A  is a  program. Using the  accident. This prediction will be compared to the equivalent barrier speed from  low  model for the crush characteristics presented in Chapter 6  test data on the Honda Civics from Strother et al, Transport Canada and  an  a  regime.  to demonstrate  the parameters  as  shows the two  regime speed-residual crush model for 1975-1981  least squares fit to the data determined  regime  II. The  ICBC-UBC  data suggests that a residual crush of 8 inches is the lower limit to regime II. The y-intercept  or threshold  speed  of regime  I was  determined  from  crash  tests.  The  91 y-intercept and slope of regime I and regime II is tabulated in Table 7.1.  Table 7.1 : Speed-residual  crush coefficients  Regime I  Y-intercept (b ) Slope (bj)  10.8 mph 0.7 mph/in  Regime II  Y-intercept (b )  4.4 mph  2  0  Slope (b )  1.5 mph/in  x  The  parameters for the two regime force-residual crush  using equations  function were calculated  (1) to (4) in Appendix V which are tabulated in Table 7.2. The  mass (m) is 5.7 lb*sec /in and the vehicle width 2  is 58.5 inches. Figure 7.2 shows  the force-residual crush function of 1975-1981 Honda Civics. Table 7.2 : Force-residual crush parameters  Regime I  Y-intercept ( a ) Slope ( a )  227.8 lb/in 14.7 Ib/in*in  Y-intercept (a„) Slope ( )  199.1 lb/in 67.9 lb/in*in  2  3  Regime II  a i  In Figure 7.3 is the residual crush profile of a Honda Civic involved in a frontal collision with a rigid immovable object such as a bridge abutement. The six residual  crush  dimensions  in inches  are C^O.O, C2=2.3, C3=6.2, C =8.0, 4  C =9.3, C,=14.8. Using a trapezoidal approximation 5  the  residual crush  for the first  interval  to the area within the profile,  is (C +c )/2. Since 1  2  the crush  for this  interval lies within the range of regime I, the force-crush parameters are a and 2  a . The energy of deformation is: 3  Figure 7 . 3  : Damage pattern  is U)  94  E = / /  (a +a C)dC dw + 3  o o  ^ 2a 3  3  r / „ aC _ aJW = / (a,C + ~Z— )dw +-*— o 2 2a, W  2  3  where W is the width of residual crush. Substituting the crush of interval 1 ((C +C,)/2 ) for C gives x  W l E  =  ;  (  o  c  a (C C ,) a ^ C ^ C , * Cf) 2 8 2  1+  7  a|W. 2a  +  +  1  3  where W is the width of residual crush interval 1. Integrating over the width of x  interval 1 gives: . c  (  a.CC.+C,)^ a(C?+2C,C,+ Cj) 2 2 3  a]j^ 2a  + 1  3  Ec = 22081 lb*in These calculations are repeated for intervals 2 and 3. For intervals 4 and 5 which has crush levels in regime II, the a  0  and a  x  parameters are utilized for calculating  the energy of deformation. Table 7.3 summarizes the crush energy for each interval. Table 7.3 : Energy of deformation across the residual crush profile  Interval  Residual Crush (in)  Width of Crush (in)  Crush Energy (lb • in)  1 2 3 4 5  1.2 4.3 7.1 8.7 12.1  10 10 10 10 10  22081 29581 39291 45539 76209  Total  -  W= 50  E=212700 N  95 The  crush  energy  in Table 7.3 assumes the forces producing  the deformation  acts  normal to the edge of the vehicle. If the principle direction of force is inclined to the  edge  of the vehicle  the following  correction  factor must  be  applied to  (Smith, R.A. and Noga, J.T., 1982).  Correction factor =  (1 +  tan a) J  where a is indicated on Figure 7.3. Thus, the corrected  E • (1 +  tan*a)E  energy of deformation is:  N  = (1 + tan*(15°))(212700)  =  227972 lb-in  The  line of action of the force vector does not pass through the center of mass.  The  non-central  impact  factor (7) used  is 0.97. This  factor is determined  by the  relationship  7  =  K*/(K*+H ) 2  where K is the radius of gyration about a vertical axis through the center of mass and  H  is the moment  arm  of the line-of-action of the average  force  about  a  vertical axis through the center of mass (Smith, R.A. and Noga, J.T., 1982).  The  delta-V  CRASH3 algorithm  for a  vehicle  by the relation:  in a  two-vehicle  crash  is computed  in the  96 Since the Honda Civic struck a rigid immovable object, the energy absorbed by the object (E ) is zero and its mass (m ) can be considered 2  2  infinite. Therefore  delta-V  for the vehicle is:  where E  x  is the energy absorbed by the vehicle in crush. Delta-V  for the Honda  Civic is:  AV  X  = 279 i n / s e c • 15.8 mph  Using the CRASH3 computer program, the delta-V for the Honda Civic is: AV The  X  = 16.1 mph  CRASH 3 computation  of delta-V  utilizes  a single regime  force-residual crush  model with average stiffness parameters of vehicles in the "micro"  category. There  is a small difference in the delta-V prediction which is largely due to the difference in crush coefficients utilized by CRASH3 and those tests. When the same the  Honda Civic crush  calculations are repeated  derived from Honda Civic crash  using a single regime model with  coefficients, the delta-V is 14.5 mph.  This is a 1.3  mph  difference between the two regime model and single regime model.  The Honda Civic crush is a hypothetical accident case created to exemplify the  application of the two  regime  delta-V  is not known, the accuracy  staged  collisions  should  be  model  in computing  of this model  conducted  to determine  delta-V.  Since  the true  cannot be judged. Full scale the accuracy  of the speed  97 predictions.  8. CONCLUSION  A which verified the  very inexpensive and reliable low speed crash test facility has been  has proven  successful for controlled  indicating  the facility  does  replicate  crash  tests. The test  results from  results have  built been  other barriers. At present,  facility has the following capabilities:  •The tow system can accelerate the test vehicle to 30 km/h.  •the  crash  1800  kg car at 40 km/h.  •The  barrier  speed  has been  trap  provides  designed  a  speed  for an  impact  measurement  of an  with  an  rear impacts can be performed  on  accuracy of ± 1 % .  •Impact  •Both  speed can be controlled to within  full frontal  and full  ± 2 km/h.  vehicles.  •Data  derived  from  each  test  crush. At present the facility camera for making dynamic  •A  high  test  rate  is impact does  speed  not have  and residual a  high  speed  crush measurements.  of one crash  test  per hour  can easily be  achieved.  There  has not been  any known  98  experimental investigations  of repeated  99 impact this  tests on  technique  the same vehicle. Repeated of  generating impact  impact  speed-residual  tests were conducted crush  data. The  to verify  findings  from  these test are:  •A  second  low  speed  impact  on  the same vehicle  produces  speed-crush data (ie. crush characteristics) that is comparable to a single equivalent higher speed impact.  •The that  standard the  double  higher speed  Low residual  speed  deviation impact  of  the  results  errors are  of  prediction  equivalent  to  indicate a  single  impact.  crash tests were conducted  crush of vehicles with an  energy  to determine  absorbing bumper  the speed system. The  conclusions were drawn.  •The  threshold  absorbing mph).  bumper  This  absorbing  speed  is  speeds above 8  •A a  system  an  bumper  of  Civics  with  is much  higher  than  indication system  that  vehicles  (ie. isolators) will  an 8  with  energy km/h  an  exhibit  (5  energy threshold  km/h.  least squares fit of a linear model to speed-crush data in medium  speed  range  speeds below 20 to 25  •At  Honda  the  low  end  (48-55  km/h)  may  not  be  valid  at  km/h.  of  the  speed  spectrum,  a  second  to initiate following  speed-crush  regime exists for specific vehicle models. The  characteristics  at  low  crush  levels  is different  than  at  crush higher  crush levels.  •The may  accuracy  of  delta-V  predictions  be improved when a two  in low  speed  collisions  regime model is utilized.  9. FURTHER  The further other  crash  research  testing  to be  areas of future  facility  AND  opens up  pursued  on  research  FUTURE  on  many different organizations can  be  many  the topics low  RESEARCH  speed  pursued  areas for research. There  covered  in this  collisions. The  through  low  thesis,  crash  University community, insurance industry, accident investigators, and manufacturers can benefit from  ICBC  and  UBC  interests of testing.  Accident  Research  Group  will  The  small automobile  the test facility. In this chapter, further research  the topics covered in this thesis will be identified and of  as well as  research  speed  is still  on  the future research interests  be  outlined.  In  addition,  the  research interests of private firms will be outlined.  9.1.  FURTHER  RESEARCH  Further tests should be conducted same  vehicle.  complement be  comprehensive  testing  program  should  be  established  the tests already completed. In particular repeated impact  conducted  program. The provide  A  into full frontal repeated impacts on the  on  a  number  equivalent  vehicle  of  of impacts  speeds  that  each  size  category  and  impact  speed  cover  the  whole  as  defined  by  of each vehicle  speed  spectrum.  to  tests should the  CRASH 3  tested should The  equivalent  speed has been defined as  n V  where at an  =  (  is the impact speed impact  speed  of 32  Z  x  V?)  2  of the  km/h  impact. For example, four impacts each  (20mph) is equivalent to four impacts  101  at impact  102 speeds of 32 km/h, 45 km/h, and  40  impact  mph). This  program  55 km/h of tests  is needed  speed  of the speed-crush  to further validate  to determine the crush  different bumper systems should  ,34  mph  the multiple  characteristics in the  speeds,  consequently  the  some  would  be established. The slope  function for different vehicle models is also needed, ln addition,  the accuracy of prediction over the low speed  which  28 mph  regime for different vehicle models. The threshold speed for vehicles of  different mass and with  impact  (20 mph,  technique.  More crash tests are needed low  and 64 km/h  kinetic  energy  of the assumptions  otherwise  be  insignificant  and  regime should  crush  may  energy  produce  at high  be evaluated. At low  is  significant  impact  relatively  low  and  errors in prediction  speeds. For example, it  is  assumed that the force-crush characteristics does not vary across the vehicle width. In  an  offset  low speed  impact  stiffness across the vehicle width By  setting  up  the ICBC-UBC  with may facility  an  immovable  object, a slight  have a significant effect on speed for pole  impacts,  the variation  variation in prediction. in stiffness  across the front of the vehicle can be tested.  At  low  considering both By  determining  vehicle models from based  speeds  more  consistent  static and dynamic crush the percentage  speed  rather than  of total crush  and at different crush  predictions may  be  derived  only static or residual crush.  that is dynamic crush  levels - the total  crush  - for different  can be  determined  the level of static crush. Prediction of equivalent barrier speeds can then on both  static and dynamic crush. Crash  by  tests recorded  with  a high  camera would provide dynamic crush data from which the dynamic crush  be  speed  percentage  103 as a function of the static crush  9.2. FUTURE  level can  be  determined.  RESEARCH  The  future  research  interests of  ICBC  and  UBC  Accident  Research  Group  are:  •  •  Repair  Strengths  impact  can  be  - Damage  to  repaired  vehicles  investigated  to  assess how  the  in  characteristics of the vehicle during  direct bearing  the risk of injury to the occupants.  Repairability and and  models  Damagability - The  can  be  evaluated  controlled barrier  repaired  energy absorption on  a  area  alters  collision. This has  the a  repair costs of different vehicle makes  to  assess  premiums  for  the  different  vehicles.  •  Side Impacts - In a low subjected can  •  to some intrusion. Conducting side impact tests at low  provide information  Effect  of  Corrosion  on  on  structural frame rails of  •  speed side impact the passenger compartment is  Seat  tests  undertaken on  -  Integrity  older vehicles can  vehicle stiffness.  belt  injury risks to occupants for different vehicles.  Structural  effects on  Once  speeds  a  suitable  be  dummy  Corrosion investigated  is obtained,  degradation to  assess  tests  will  four point seat belts to assess their effectiveness on  reduction. Three point seat belts will also be  tested.  in the  be  injury  104 Private firms have expressed an interest in conducting test for the following research:  •  Accident reconstruction  experts  have  involving collisions at less than 5 mph. in the elastic deflection  a  significant  percentage  of  cases  Consequently, they are interested  of the energy absorbing bumper system  and its  relation to impact speed.  •  An mph  automobile  manufacturer  crash test on  has  expressed  a  need  prototype vehicles to gain  prior  for conducting knowledge  ability to pass Canadian Motor Vehicle Safety Standards.  on  30  their  BIBLIOGRAPHY  Appleby, M.R. and Morris, A.G.R. "Automobile Damageability and Insurance Costs", SAE paper 740305, 1974.  Bartee, E.M. Engineering Experimental Design Fundamentals. Prentice-Hall lnc.,Englewood Cliffs, N.J., 1968.  Bigg, G.W. "Uses and Abuses of Speed Change Results from Crush Analysis", Proc. of the Canadian Multidisciplinary Road Safety Conference IV, May 26-28, 1985.  Bleckert, H. and Mack, G. "Linear Drive for Crash Test Facility", Siemens Review, No. 7, 1977.  Campbell, K.L. "Energy Basis for Collision Severity", SAE paper 740565, 1974.  Franchini, E. "Crash Testing Evolution at Fiat", SAE paper 660165, 1966.  Fredericks, R.H. "Automobile Crash Research", SAE paper S363, 1962.  Guenther, D.A., Goodwin, L.G. and Bookwalter, J.C. "Barrier Equivalent Impacts Speeds: An Analytical Review With Some Experimental Validation", Proc. of the Canadian Multidisciplinary Road Safey Conference III, May 27-30, 1984.  Haynes, A.L., Fredericks, R.H. and Ruby, W.J. "Automotive Collision Impact Phenomena", Highway Research Board Bulletin V. 142, 1956.  Hight, P.V. and Lent-Koop, D.B. "Correlation Between Delta V, Barrier Equivalent Velocity and Crush in Automobile Collisions", Proc. of the Canadian Multidisciplinary Road Safety Conference III, May 27-30, 1984.  Jones,!.S. and Jennings, P.W. "Development and Evaluation of the CRASH2 Program for Use Under European Conditions", 105  106 SAE paper 810473, 1981.  Lundstrom, LC. "The Safety Factor in Automotive Design", SAE paper 660539, 1967.  Macmillan, R.H. "Vehicle Impact Testing", SAE paper 700404, 1970.  Macaulay, M.A.  "Vehicle Frontal Barrier Impacts", TRRL Report LR 481, 1972.  McHenry, R.R. "A Comparison of Results Obtained With Different Analytical Techniques for Reconstruction of Highway Accidents", SAE paper 740565, 1974.  McHenry, R.R. and McHenry, B.C. "A Revised Damage Analysis Procedure for the CRASH Computer Program", SAE paper 861894, 1987.  Meriam, J.L. Dynamics. 2d ed. John Wiley, 1975.  Miller, P.M., Ryder M.O., and Shoemaker, N.E. "Crash Energy Management in Subcompact Automobiles", SAE paper 740572, 1974.  Myers,R.H. Classical and Modern Regression With Applications. Boston Massachusetts: Duxbury, 1986.  Navin, F., Navin N., and MacNabb M. "CRASH 111 and Canadian Data", SAE paper 870499, 1987.  O'Neill, B. "Bumper Perfomance Level and Insurance Loss Experience", SAE paper 840224, 1985.  Scott, D. "Versatile Crash Test Facility has Cable Drive", Automotive Engineering, V.85 No. 7, July 1977.  Severy, D.M. and Mathewson, J.H. "Automobile-Barrier Impacts", Highway Research Board Bulletin 91, 1953.  107 Severy, D.M. "Automobile Collisions on Purpose", Human Factors V. 2 No. 4, Nov. 1960.  Sinke, R.A. and Prevost, T.C. "An Automotive Crash Test Facility", SAE paper 700527, 1970.  Smith, R.A. and Noga, J.T. "Accuracy and Sensitivy of Crash", National Highway Traffic Safety Adminstration Technical Report No. DOT-HS-806152, March 1982.  Snider, H.P. "Vehicle Instrumentation for Crash Testing", IEEE Transactions on Industrial Electronics and Control Instrumentation, V. IECI-11, 1964.  Stonex, K.A. "Single-Car Accident Problem", SAE paper 811 A, 1965.  Strother, C.E., Woolley, R.L., James, M.B. and Warner, CY. "Crush Energy in Accident Reconstruction" SAE paper 860371, 1986.  Wilson, R.A. "A Review of Vehicle Impact Testing: How Done", SAE paper 700403, 1970.  it Began and What is Being  Woolley R.L., Warner, CY. and Tagg, M.D. "Inaccuracies in the CRASH3 Program",SAE paper 850255, 1986.  A Review of Canadian Bumper Standards, of British Columbia, 1986.  Insurance  Corporation  Research Trends, Cornell Aeronautical Laboratory Inc., Summer-Autumn 1972.  Society of Automotive Engineers Tests", SAE J850a, 1986.  Foundation  "Crash  Handbook, "Barrier Collision  Engineering. 1974.  Testing at Fiat", Engineering, Aug 1966  "Controlled Vehicle Impacts-Instrumentation Test Procedure", RRL Report LR92, 1967.  APPENDIX  I  Crash Barrier Calculations  109  110 Crash Barrier Calculations  The  barrier movement was calculated by considering  the vehicle and the resistive forces from the passive  earth  the impact force of pressures and friction  between the concrete blocks and foundation. During impact, the deceleration vehicle is assumed to increase  of the  to a peak then decrease to zero. The deceleration  of the vehicle multiplied by its mass is the force applied to the barrier according to Newton's second law. The deceleration pulse with a peak deceleration  history is approximated by a triangular  of 40g as shown in Figure  1-1. The passive  pressure generated by the gravel fill behind the barrier wall increases movement of the wall increases. This is shown in Figure horizontal to vertical stress (K) increases  earth  as the  I-2 where the ratio of  with horizontal movement. The friction force  between between the concrete blocks and foundation is assumed to be fully developed with the slightest movement.  Since the impact force and passive  resistance are a function of time and  barrier displacement, the net force, barrier velocity, and acceleration were calculated at time steps of 0.01 seconds. A net force is calculated which accelerates the barrier. Ti:e velocity and displacement of the barrier at the end of the time step is then calculated from the acceleration which is assumed to be constant over the time step. The displacement allows calculation of a new net force and subsequently acceleration in the next time step. These calculations are repeated until the barrier velocity reaches zero. Table 1-1 show the calculations of the barrier movement.  111  Figure  I-3 shows a diagram of the barrier and  a free body diagram.  friction force is:  F. = M(Mass of blocks)a  = 0.5 * 30 blocks * 1995 kg/block * 9.81 m/sec  a  where F  The  294  =  friction force between barrier and  f  u a  =  =  passive  F  foundation  coefficient of friction =  g  KN  gravitational acceleration  earth force is:  - (7HiW + i-7H2W}K(d)  p  = (18(0.74)*(1.5) + i(18)(1.6)*(1.5)}K(d) = 48-K(d) where W j  = =  H H, W  K(d) d  =  width of gravel fill  (m)  unit weight of gravel fill (KN/m ) J  =  height of fill  =  ratio of horizontal to vertical stress displacement  (m)  (m)  The  10.0  *  1  I-.  »  8.0  1  i  — —  2.0 _  H  /  •  /  •  ^  L  O  O  S  E  —  1 •  o  //  1.0  "••*".  0.8  O  -  112  >  2  i—r  11I  3.0  ' ec  i  ^ • ^ ^ D E N S E  4.0  < u  i  0.6 0.5 0.4  ACTIVE  STATE  0.3  o x  0.2  T  LOOSE  >  —  ^ /  <  PASSIVE  STATE  -  :  0.1  J  —  —  COMPACT  »v  DENSE >^  0£  P  —  N CM:  K  . .  ,  I  !  L__  1  l  |  WALL ROTATION , — . H  Source Figure  : Foundation Engineering  1-2  : Effect  o f w a l l movement on  ,1974. earth pressure  70 60 -4  so H  40 -4  30 -J 20  H  10 H  20  40 Time a f t e r  Figure  1-1  :  60  80  collision  onset  Triangular  100 (msec)  deceleration pulse  120  Elevation view  Figure 1-3 : Crash barrier free body diagram  114  Table I - l : B a r r i e r  TlK  Tlas lncrcaeot.  l«c)  calculations  DUUoct  (see) 0.00  Velocity l«/J)  0.0  0.0  0.0  0.0  0.0  0.0  0.0  0.0  ao  0.0  4.202-05  0.00M  4.202-05  O.0OH  3.022-01  0.043  3.022-04  0.043  1.042-03  0.105  1.042-03  0.105  I.21E-03  0.135  1.212-03  0.135  2.502-03  ft 123  2.508-03  0.123  3.402-03  0.064  3.402-03  0.064  3.152-03  0.005  3.152-03  0.005  3.152-03  0.00  lipact force IB]  0.01  0.01 0.01 0.01 0.02 0.02 0.01 0.03 0.03 • 0.01 0.04 0.04 0.01 0.05 0.05 0.01 0.06 0.06 0.01  0.01 0.01 0.01 0.06 0.1)9 0.01 0.09 0.09 0.01 0.10  Movement of Static  barrier  c r u s h of  Movement of  -  a t 40  lei force |U)  Accelerilloo  lit  1.0  -46  -130  0  0.0  249  1.0  -46  -201  0  0.0  392  1.0  -48  -294  50  0.14  552  1.0  -48  -294  210  3.51  113  1.0  -41  -294  311  6.20  534  1.1  -53  -294  161  3.12  261  1.1  -53  -294  -60  -1.34  0  (.2  -56  -294  -352  -5.M  0  1.2  -56  -294  -352  -5.U  0  1.2  -56  -294  -352  -S.U  0 . 0 ' 0 3 8 m » 3 . 8 mm « 0 . 1 5  a vehicle  barrier  FujlTt resist Frlclioa force (III force (•)  I  km/hr »  as a % o f c r u s h  «  inches  5 0 8 mm • 20  inches  ( 0 . 1 5 / 2 0 ) * 100 - 0 . 7 5 %  APPENDIX  II  Data Collection Form  i  115  116  ICBC-UBC  TEST  FACILITY  Date:  Ambient Temp. :  Times  Impact  VEHICLE IXFORHATIOK  Ho.:  VEHICLE DESCRIPTION  V e n u l e Hake:  Frame Type:  VIM :  E n f l n e Displacement:  unlbody  Date of K a n u f a c . :  Test Weight:  Vehicle Hodel:  H a n u f a c . Weight:  K l l e a f e:  CRASH TEST  Location of Impact i  Front Q  Rear F r o n t end  Q Rear end  Total tt of p r e v i o u s lmnaets  * of p r e v i o u s Impacts it  ICBC teat f a c i l i t y  VEHICLE DIHENSIOHS  Before F r o n t Overhang  L e f t Side  _______  After  R i g h t Side Before After  _____  Wheel Base Rear Overhang  _ _ _ _ _ _ Front  width Track Width  Rear . _ _ _ _ _ _ _  ladder frame  117  SPEED HEASUREHENTS  Video  Speed T r a p  ftverall SDeed :  First  F i r s t Time  Second M a r k e r S o a c l n f :  Interval:  Second Time Difference  Interval:  ln Time:  O t h e r Hethod Specify: Speed  Measurement:  COMMENTS  M a r k e r Soaclna::  F i r s t Time second Time  Interval: Interval:  Replay  11 8  APPENDIX  III  Recommended Safety Procedures  119  120 RECOMMENDED SAFETY PROCEDURES  To  FOR CRASH TESTING  ensure the safety of all on-site personnel during testing, the following  safety procedures  and equipment are recommended.  Test Vehicle Preparation  •Completely  drain fuel tank, lines and carburator of gasoline  •Remove battery  •Put maximum  allowable air pressure in test vehicle tires  Site Preparation  •Close and lock all gates and garage doors during testing to prevent  people  •Line both  wandering onto the test area.  sides of the approach road to the barrier with guard  rails to prevent  runaway test vehicles from leaving the site.  •Erect appropriate fencing around the tow road to keep unauthorized  •A  people  away from the test area.  guide rail for directional control of the test vehicle is strongly  recommended.  Equipment Check  •Check that the gap between the rollers of the main release is  121 not less than  1.1  cm  (0.45 in).  •Check that the rollers are clean of debris, free to rotate, and well greased.  •Check that the redundant release has the correct shear pin (Only the designated brass shear pin is to be used)  •Inspect the entire length of the tow  cable prior to each test for  frays, kinks and/or broken strands.  •Inspect the wire rope  •Do  not proceed  clamps to ensure they are firmly in place.  with testing if there are deficiencies in any of  the above.  •The cab of the tow  vehicle should be  protected with a wire  cage.  Personnel Safety  •During testing all personnel except the tow test controller are to stay at least 15 tow  lanes and  the tow  (50 feet) back from  the  barrier.  •The driver of the tow helmet and  m  vehicle driver and  vehicle shall wear an approved  motorcycle  a properly adjusted 3 point seat belt while operating  vehicle.  •Heavy gloves on  personnel handling test vehicles especially after  122  barrier impact. •No  smoking around test vehicles.  Test Procedure  •During the testing only two personnel are to be in the test area: the tow vehicle  driver and the test controller. All other  personnel are to stay out of the designated test area.  •Radio communication shall be set up between the driver of the tow vehicle and the test controller.  •The test controller is responsible for ensuring that are  all personnel  in the safe location during testing.  •The tow vehicle  driver shall watch for unauthorized people  entering the site behind the the barrier just prior to testing.  •The test controller shall stand a safe distance to one side of the approach and tow roads.  •The tow vehicle  driver must wait for clearance from the test  controller before commencing  the test.  •Once the test has commenced there is only limited abort capabilities. Should the test controller notice an unsafe situation he must immediately signal the tow vehicle driver to halt  acceleration.  APPENDIX IV  Force response during elastic and  123  plastic  deformation  124 Force response during elastic and plastic deformation  McHenry and in plastic intercept  has  suggested that a force  deformation,  would  be  more  response, in accurately  the  initial elastic  range  emulated  with a zero  force  as shown in Figure 1V-1.  Elastic and plastic crush  Figure IV-1 : Force response for elastic and plastic crushing  In this force response, the applied force increases linearly from zero as the vehicle  deforms  elastically.  The  deforms plastically. At maximum zero  for  a  corresponding maximum  barrier  impact.  velocity  the  continues  to  increase  linearly  elastic and plastic crushing, the  This  change  crush is attained,  force  the is  approach  called  vehicle  the  period  of  approach  begins to  rebound  the  as  the  vehicle  vehicle's velocity is collision  velocity  and  change.  away from  the  the Once  barrier.  125 The applied force drops sharply as the elastic crush is restored. The restoration of elastic crush produces a rebound velocity change.  The total change in velocity is the sum of the approach velocity change and rebound velocity change. During the approach period, the energy stored and absorbed in elastic and plastic crush is the area under the force response from zero to maximum elastic and plastic crush.  This force response proposed by McHenry is more realistic than Campbell's force response based on residual crush, however it is less practical since the maximum elastic and plastic crush is not easily obtained. Following an automobile collision, residual crush is the only measurement available. A force response in terms of residual crush provides a practical and robust model of the energy absorbed per unit of residual crush. Wx E  = a  Cx  J  J  0  0  (a +axC)dC dw + 0  constant  McHenry pointed out that Campbell's crush energy model neglects the restored energy during the rebound period and only considers the energy absorbed and stored during the approach period. Consequently, the approach velocity change is determined in this model.  APPENDIX  V  Solutions for Crush Parameters  b  Solutions for Crush Parameters  a  126  127 Solution for the linear extension of the force-crush function  The  area  under  shown  to represent  energy  absorbed  C  e  extension  the energy absorption  in the elastic  range  of the force-crush  parameters a„  and  ^  =  e  a  i  before  permanent  ^ a, are equal to:  _ mbub! Wo  ^  function can be  capacity of the bumper crushing  dimension in the above figure will be established as follows: C  The  the linear  _ mbf Wp  which can be substituted into the above expression.  system  occurs.  or the  First, the  The  area under the linear extension  E  Substituting for C  g  b  -  and a  0  frC a e  of the force-crush function  0  gives:  This is the energy absorbed per unit width in the elastic range.  129  Solution for crush parameters a , a,, a c  7 >  a  3  Solution for Regime I parameters:  W  t *K„=  '  mV  j-mCbj+bjC) =  C  0  / (f)dC dw  W„ C J J (aj, + a C)dC dw + constant 3  tmbl+mbjbjC + i-mbJC = a W C + JajC'W,, + constant 1  2  0  Comparison of like terms gives: constant = fmb? a, =  mb bi W. 2  (1)  130 mbj,  (2)  Solution for Regime II parameters: W„ C ; ; (f)dc dw  i-mv* =  0  w  imCV.+biCC-C.))'-  /  0  0  c  / (f_+ a C)dC dw + E. x  o  0  i-mVj+mV.bxCC-C.)* imb?(C-C.) = f_W (C-C_)+ta W 2  0  1  0  (C-C_)  2  + E, Comparison of like terms gives: E.-i-mVj  ^ 0  1  mb?  The intersection values f ^ and V_ are equal to: f_ = a, + a C_ x  V. = b  0  + bxCj  which can be substituted into equation (3). Solving for a„ gives: a. =  (5)  


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