一个基于塑性的损伤本构模型的参数辨识

研究了一个用于混凝土的基于塑性的损伤模型本构参数辨识问题。把从实验获得的应力-应变曲线与数值计算中获得的应力-应变曲线的差别,作为局部水平上最小二乘法的目标函数。为了求解这个反问题,局部水平上求解损伤弹塑性正问题的子程序被嵌入到本文的反问题的迭代格式之中。灵敏度系数矩阵是通过有限差分方法近似计算得到的。给出的数值计算例子计算了单轴压缩试验结果的参数辨识问题。采用反分析得到的模型参数值,对单向拉伸及三种不同侧压作用下的压缩试验进行了数值模拟。数值结果表明:本文采用的应力反分析计算格式稳定,且具有合理的准确性,数值计算得到的应力-应变结果可以较准确地拟合实验曲线。

Parameter Identification of a Plasticity-based Damage Model

Studies on parameter identification of a plasticity-based damage constitutive model for concrete are presented in this paper.Differences between the stress-strain curves experimentally obtained and the ones numerically obtained at local level were used as the objective function of a regularized least square method.For solving the inverse problem,the solution of the direct problem at local level obtained by a driver subroutine was embedded in the iterative solution procedure for the inverse problem proposed in this paper.The sensitivity matrix was calculated numerically by the finite difference method.Numerical examples are given for fitting the numerically obtained stress-strain curves to a set of experimental results.Parameter identifications under uniaxial compression were performed.The values of parameters obtained by inverse analysis were used to simulate numerically the stress-strain behaviors under various loading cases,which include uniaxial extension and triaxial compression with different confining stresses.Results indicate that the numerical scheme is stable and has reasonable accuracy.