复合材料蠕变本构关系及实验测定 Ⅱ实验测定

CREEP CONSTITUTIVE EQUATION AND EXPERIMENTAL DETERMINATION OF COMPOSITE MATERIALS PartⅡ: Experimental Determination

在前一部分,本文得到复合材料蠕变的本构关系,在此基础上,本文进一步分析了复合材料蠕变本构关系的具体形式,实验测得了长纤维增强复合材料在蠕变、恢复两个阶段的应变,以用来确定本构关系中的待定参数,考虑到本构关系为复杂的非线性方程,本文提出了用离散变量和最小二乘法联合的方法确定参数,进而拟合蠕变本构关系的理论公式,分离出了蠕变过程中的弹性变形、粘弹性变形和粘塑性变形,对本构关系中的几个参函数,本文根据有限的实验数据拟合了其函数.

The constitutive equations of composite materials have been obtained in the first part of this paper.Based on the previous study, the modified form of constitutive equation of creep deformation is given in this part. The strain in two stages of creep and recovery are experimentally recorded,which is used to determine the parameters of the constitutive equation, In view of the complexity of the nonlinear equation, this paper proposed a method to determine the parameters,in which the least-square-error method is used in conjunction with the discreteness of variables. Then the theoretical formulas are modelled by data fitting and each kind of strains is separated. Finally, based on a few of available experimental data, the three parametric functions of stress in the constitutive relationship are obtained.