用逐层钻孔的小孔法测量非均匀残余应力

Abstract

针对传统的小孔法只能测量试件内沿深度方向均匀分布的残余应力,采用逐层钻孔的小孔法测量试件中的非均匀残余应力,通过有限元法标定计算校准系数矩阵,构建了一种实用的非均匀应力测试技术。首先,用AnSyS软件构造试件和应变花粘贴的三维有限元模型,采用分层加载的办法实现各层校准系数的仿真计算,标定计算出钻孔深度达到H=0.5d使应力完全释放时,用5步逐层钻孔法构造5层不均匀应力所需的校准系数矩阵;然后,利用标定出的校准系数矩阵,采用5步逐层钻孔的实验方法,测量构建Cr12MOV淬火件的5层非均匀残余应力,并与传统的小孔法进行测试比对。结果表明:用有限元仿真的方法可以模拟试件中的非均匀残余应力场,用于标定计算测量所需的校准系数矩阵;通过5步逐层钻孔实验测量,可以构建出Cr12MOV淬火件的5层不均匀残余应力。

While conventional hole-drilling methods can only measure uniform residual stresses along a specimen′s depth,an incremental hole-drilling method is used to measure non-uniform residual stresses inside a specimen.The calibration constants matrix is calculated using the finite element calibration method,and a practical measurement technology of non-uniform stress is established.An agglutinate 3-D finite element model of a specimen with rosette is built using ANSYS software,and the calibration constants in each layer are calculated with a dividing-layer loading method.The calibration constants matrix is obtained when the hole depth reaches h=0.5 Dto completely release residual stresses,and is used to form the fivelayer non-uniform stresses with the five-step hole-drilling method.Then,the five-step incremental holedrilling method and the calculated calibration constants matrix are used to experimentally measure the nonuniform residual stresses within the Cr12 MoV quenching specimens.Comparing these measurements with the results of conventional hole-drilling methods shows that the finite element calibration method can simulate non-uniform residual stresses field inner specimen to calculate the calibration constants matrix.In addition,the five-step incremental hole-drilling results show that the five-layer non-uniform residual stresses can be built up in Cr12 MoV quenching specimens.