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Vaidyanathan, Sidhant Sunder

University of British Columbia

Residual stresses are stresses that are “locked-in” within a material, existing independently of external loads. Measuring residual stresses accurately can be beneficial for a wide range of engineering applications. The indentation method to determine residual stress is an attractive choice over current methods like Hole-Drilling due to simplicity of instrumentation and less damage to the specimen. The currently used procedure is the Force-Depth method where the indentation force is measured for constant depth of indentation on a stress-relaxed specimen vs. a specimen with residual stress. Though convenient, this method cannot distinguish the directions and separate sizes of the in-plane residual stresses. In this thesis, a novel approach is proposed using full-field optical techniques to capture rich surface displacement data from millions of pixels, in contrast to a single data source from an indentation force measurement. These data are used to determine the magnitude of residual stresses on metal surfaces for an isotropic residual stress distribution case. In this approach, finite element simulations are used to study the relationship between surface displacement and in-plane residual stresses. The studied characteristics are used to create a quantitative relationship between surface displacement and residual stress. These calibration values correlate well with corresponding experiments on steel specimens and serve as proof of concept for the proposed method to measure residual stress. Further avenues to improve the method are discussed in conclusion.

Text

2023-12-21

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/87004

Mechanical Engineering

University of British Columbia

UBCV

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