预应力下实验标定的盲孔法测试技术

Blind Hole-Drilling by Calibration Experiment under Pre-stress

分析了盲孔法测量构件残余应力的理论基础,利用实验标定法确定材料在不同预应力下的应变释放系数A′和B′,并在理论释放系数A和B的基础上进行修正。施加预应力-400～400 MPa后,通过盲孔法测量得到了应变值,并根据所得的A′和B′计算获得了残余应力。研究结果表明:A′和B′与应力水平有关,采用预应力下实验标定法进行盲孔法测试,计算所得残余应力值与实际的预应力值吻合程度较高,但它们之间有一定的误差,其相对偏差范围在2.2%～10.1%。研究结果可作为压入响应实验结果比较对象,促进压入响应下的残余应力测试应用研究。

The theoretical method of the blind hole-drilling method is analyzed for calculating residual stress.Strain releasing coefficients A′ and B′ of the materials under pre-stress are determined in a calibration experiment.They are revised based on A and B obtained with the theoretical formula.Strains around the blind hole are measured for materials in which pre-stresses ranged from-400MPa to ＋400MPa.The residual stresses are obtained based on the strain releasing coefficients A′ and B′.The results show that the strain releasing coefficients are related to the level of residual stresses.The residual stresses calculated from A′ and B′ using the blind-hole-drilling method agree with the pre-stresses set purposely for the materials.Errors range from 2.2% to 10.1%.These results may be used as a reference in the study of residual stresses evaluation with the indentation method.