盲孔法测量非均匀残余应力时的释放系数  

Release coefficients during measuring non-uniform residual stress with blind-hole method

作　　者：李昊[1] 李华[1] 

机构地区：[1]合肥工业大学土木与水利工程学院,合肥230009

出　　处：《焊接学报》2013年第6期85-88,117,共4页Transactions of The China Welding Institution

摘　　要：盲孔法测量沿深度非均匀的残余应力时,积分法是最常用的计算方法,其释放系数矩阵[a],[b]对计算精度有很大影响.由于在标定释放系数矩阵时假定各层上的残余应力均匀分布,当应力梯度变化较大时会引起较大的计算误差.文中首先建立了标定释放系数矩阵的三维有限元模型,并通过模拟均匀残余应力场验证了其有效性.在此基础上分析了积分法标定的释放系数矩阵用于计算沿深度非均匀残余应力时的误差,并提出了二次标定的修正方法.结果表明,采用二次标定的释放系数矩阵计算得到的残余应力值更接近于真实应力.Integral method is widely used in calculating the non-uniform residual stresses from the measured relaxed strains using the blind-hole method,in which the release coefficients have great influence on the measurement accuracy.As the residual stresses in each layer are assumed to be uniform when calibrating the coefficients,the calculated results are considerably different from the real stresses if the residual stresses vary rapidly along the depth.In this paper,a three-dimensional FEM model was established for the release coefficients,and verified by a simulated test on a uniform loaded plate.The errors in the calculation of the non-uniform residual stress field were studied using the release coefficients calibrated by the integral method,and then an improved technique was proposed to recalibrate the release coefficients.The results show that the calculated residual stresses using the recalibrated coefficients are closer to the real ones.

关 键 词：盲孔法 非均匀残余应力 积分法 释放系数 二次标定 

分 类 号：TG404[金属学及工艺—焊接]