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To, Hoang Luc

University of British Columbia

The Hole-Drilling method is a popular technique for measuring residual stresses. It involves measuring the deformations around a drilled hole to determine the residual stresses originally within the cut hole. Because the hole drilling only partially relieves the stresses at the hole location, calibration is needed to know the correct fraction of the strain relief. The hole-drilling method is typically applied to a case where the test material is much bigger than the drilled hole, thus the area of interest conceptually has “infinite” boundaries. A conventional finite element method for hole-drilling calibration must have quasi-infinite boundaries and such a model usually becomes very large and numerically inefficient. An idea of using a more compact finite element model with a closer boundary coupled to a special ring to simulate the compliance stiffness of the far-field material is proposed here. Analytical procedures are described to specify the material properties for the needed outer ring. These are demonstrated for both hole loading and thermal loading methods. The calibration results from the simulated compact models demonstrate that the procedures work effectively for the isotropic stress state and reproduce good correspondences between the calculated deformations and the theoretical expectations. For the deviatoric stress state, some adjustments are required to create comparable matches. A procedure of forming a general stress state using the thermal loading method is also introduced with outcome performances similar to the ones in the deviatoric stress state. The research work confirms the ability to create similar “infinite” boundary responses of a special outer ring coupled to a small compact hole-drilling model. This method is useful for significantly reducing the calculation effort for hole-drilling calibration processes.

Text

2022-12-22

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/83473

Mechanical Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/