当钻孔位置不在应变花中心或者应变片任意排布时,联系松驰应变与残余应力之间足够简单的一般关系式至今还没见到。Sandifer和Hsin—PangWang都推导过这方面的关系式,但相当复杂,很难在一般钻孔位置的情况下求解。且Sandifer提出的用二条迭代法术解主应力与主方向,由于没有判别第一主应力方向的条件,迭代很麻烦且极易出错。关于钻孔法中第一主应力的判别问题,Gupta首先注意并对此进行了讨论,但他提出的 The general relationship between simple strain relaxation and residual stress has not been seen so far, when the drilling position is not centered at the center of the strain or when the strain gage is randomly arranged. Both Sandifer and Hsin-Pang Wang deduced this relation, but it is quite complex and difficult to solve in the general drilling position. And Sandifer proposed by two iterative method to solve the main stress and the main direction, because there is no condition to determine the direction of the first principal stress, iteration is very troublesome and error-prone. Gupta first noticed and discussed the issue of discrimination of the first principal stress in the drilling method, but he proposed