环芯法测定残余应力适用范围的拓展

摘要

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.%传统的采用环芯法测定残余应力公式中的应变释放系数公式是通过数值标定或试验标定得到的，而且现有标准中释放系数的确定只是针对特定泊松比的材料.为了拓展环芯法测定残余应力的适用范围，采用理论分析及有限元模拟的方法评估了不同材料的泊松比对释放系数的影响，建立了标定应变释放系数的有限元模型及其释放系数与泊松比、槽深的函数关系.结果表明：泊松比偏离0．3较大时，传统环芯残余应力测定方法会有明显的误差，而此误差本质上是系统误差；得到了考虑泊松比的残余应力修正公式，并用试验验证了该公式的正确性；修正公式不受泊松比的限制.