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在利用盲孔法测量铸件残余应力时,有几个比较重要的试验参数:铸件材料的弹性模量、泊松比,以及应变释放系数。选择HT300灰铸铁作为试验材料,首先对其物性参数(弹性模量和泊松比)进行准确测量。在此基础上,研究HT300材料应变释放系数随拉应力的变化趋势,以及贴片和钻孔偏差对试验结果的影响。结果表明:HT300材料应变释放系数随拉应力的增加而减小,贴片和钻孔偏差引起的试验误差随拉应力的增加而不断被放大。
In the blind hole method to measure the residual stress of castings, there are several more important test parameters: the elastic modulus of castings, Poisson’s ratio, and strain release coefficient. Select HT300 gray cast iron as the test material, the first physical parameters (elastic modulus and Poisson’s ratio) for accurate measurement. Based on this, the change trend of strain relaxation coefficient of HT300 with tensile stress and the influence of deviations of patch and borehole on the test results were studied. The results show that the strain release coefficient of HT300 material decreases with the increase of tensile stress, and the experimental error caused by the deviation of the chip and the drilling hole is continuously amplified with the increase of tensile stress.