Abstract:
The strain release coefficients in classical ring-core residual stress measurement formula were obtained by numerical calibration or experimental calibration, and these release coefficients in the existing standard were determined only at a specific Poisson′s ratio. To expand the applicable range of measuring residual stress by ring-core method, the effects of Poisson′s ratio of different materials on release coefficients were evaluated by theoretical analysis and finite element simulation. Finite element model was established to calibrate the strain release coefficients, and a functional relationship between the release coefficients and Poisson′s ratio and groove depth was established. It is found that Poisson′s ratio with a relatively big deviation from 0.3 could cause significant error in the measured residual stress, and the error was systematic in nature. A modified residual stress formula including Poisson′s ratio was obtained, and the formula was verified through an experiment. The modified formula was not limited by Poisson′s ratio.