盲孔法中应变释放系数的有限元模拟标定

FEM simulation of calibration on strain release coefficients in blind hole method

盲孔法测量焊接残余应力时,孔周围材料超过屈服状态,产生塑性变形而引入塑性附加应变,使得测量结果产生较大误差.根据应变释放系数A,B试验标定原理,对Q345R钢进行试验标定.以一定应力状态下形状改变比能系数S作为判据,对应变释放系数A,B进行修正,使得焊接等高残余应力的测量结果更为精确.基于强度理论,应用有限元软件,对Q345R钢的应变释放系数A,B进行三维有限元数值计算.结果表明,用有限元进行应变释放系数的塑性修正是可行的.

The significant error of the measuring result may arise when measuring welding residual stress by means of the blind hole method.Because the stress around the hole exceed the yield limit,the plastic deformation induces plastic strain.Therefore,based on the principle of the calibration experiment,the strain release coefficients A and B of the steel Q345R are determined.According to the energy parameter S,the strain release coefficient A and B can be revised by the variation formulas;by this method,the result of measuring high residual stress can be more accurate.Based on the strength theory,the strain release coefficients A and B of steel Q345R,which were numerically calculated by the finite element method(FEM),coincide well with the calibration experiment results.So the FEM determination of the strain release coefficients A and B is viable.