Q235钢应变释放系数塑性修正问题的研究

Research on plasticity modification of strain relief coefficients in Q235 steel

针对盲孔法测量高残余应力时因塑性效应引入的测量误差问题,对Q235钢应变释放系数的塑性修正问题进行研究.通过分析应变释放系数标定的原理及Q235钢的本构关系模型,采用有限元法仿真计算Q235钢在弹性阶段和塑性阶段的应变释放系数,指出塑性阶段的应变释放系数需要修正;给出基于参量S的修正公式,用于修正高残余应力引起的测量误差,并应用于高残余应力焊接件的测量试验中.结果表明,在弹性阶段,有限元仿真计算与实验结果一致性较好;在塑性阶段,给出的修正公式对于高残余应力的测量有着较好的修正效果,从而拓展盲孔法残余应力测量装置的应用范围.

Considering that measuring errors caused by the plasticity effect when measuring high residual stresses in Q235 steel,the plasticity modification of the strain relief coefficients was investigated.After analyzing the calibration of the strain relief coefficients and the constitutive model of Q235 steel,the strain relief coefficients in the elasticity and the plasticity conditions were calculated based on the finite element analysis （FEA）.And the conclusion was obtained that the strain relief coefficients in the plasticity condition should be modified.Then a modification formula was presented based on the parameter S.It was used for modifying the measuring errors of plasticity deformation due to high residual stress,and applied to measure high residual stress in the welding specimen.The results show that the solutions of FEA calculation exactly agree with the experimental results in the elasticity condition and the modification formula has better modifying effects for measuring high residual stresses in the plasticity condition.Therefore,the application of instruments for measuring residual stress based on the blind-hole method is extended.