基于应力不确定性最小化法的7075铝合金板内部残余应力检测
Determination of Residual Stresses in Aluminum Alloy Plate 7075 Based on Minimizing Stress Uncertainty
阿咖尼·克瑞思, 吴运新, 龚 海
点击：3268次 下载：0次
作者单位：中南大学 机电工程学院, 湖南 长沙 410083
中文关键字：残余应力； 淬火铝合金板； 裂纹柔度法； 不确定度
英文关键字：residual stress; quenched aluminum alloy plate; crack compliance method; uncertainty
中文摘要：采用裂纹柔度法测试残余应力时，柔度函数的计算和插值函数阶数的选择对计算结果的精确性有较大影响。采用有限元法计算得到测试试样的裂纹柔度函数，考虑应力计算不确定度的两个主要来源: 应变测量数据的随机误差和模型误差；基于应力总不确定度的最小化目标，确定最优的插值函数阶数，进而计算得到7075铝合金淬火板内部残余应力的分布。结果表明：分别采用11阶和9阶勒让德多项式能较好地拟合铝合金板材内部轧向和横向残余应力的分布，不确定度的均方根值分别为2.9015MPa和4.7558 MPa。轧向或横向残余应力都呈明显的外压内拉的分布规律，且在板厚度的中面出现局部的残余拉应力的最小值。
英文摘要：In evaluation of residual stresses by crack compliance method, the calculation of compliance function and the choice of the order of interpolation function are important factors that influence the accuracy of calculation results. The compliance functions were calculated using finite element analysis. Considering first the major sources (propagated uncertainty and model uncertainty) in residual stress calculation by crack compliance method using Legendre Polynomials, and then the optimal number of terms for a quenched aluminum alloy plate 7075 was determined based on minimizing stress uncertainty. The results show that Legendre polynomial of order 11 and 9 can evaluate accurately through-thickness residual stress in the rolling and transverse direction, and the root-mean-square average of the uncertainty is respectively 2.9015 MPa and 4.7558 MPa. It is also shown that the residual stresses are compressive below the surface and tensile in the center, and the minimum of local residual tensile stress occurs at the midplane of the plate thickness.