复合材料粘弹性本构关系与热应力松弛规律研究Ⅱ:数值分析

给出了预测复合材料粘弹性松弛模量、等效热应力松弛系数和等效时变热膨胀系数的均匀化方法的有限元数值实现步骤, 研究了单向纤维复合材料随温度变化的粘弹性本构关系, 以及热应力松弛规律和热膨胀系数的时变特征。单向纤维复合材料的一维热变形分析数据显示了热应变对时间的强烈依赖关系;以数值形式给出的等效热应力松弛模量对时间的依赖关系表明, 等效的热应力松弛模量对时间的依赖性较弱, 其冲击模量和渐近模量只相差0.4 %。

STUDY ON THE THERMAL STRESS RELAXATION AND CONSTITUTIVE EQUATIONS OFVISCOELASTIC COMPOSITE MATERIALS, PART II : NUMERICAL SIMULATION

The finite element processes for predicting the effective viscoelastic relaxation modulus, the effective thermal stress relaxation modulus and the effective time-dependent thermal expansion coefficient are given. The thermal viscoelastic constitutive equations including temperature change, the effective thermal stress relaxation laws and the time-dependent character of the thermal expansion coefficients of unidirectional fiber reinforced composite materials are studied. The deformation analysis of a one-dimensional structure of unidirectional fiber reinforced composites shows that the thermal strain depends on time intensively. The numerical results illustrate that the time-dependency of the effective thermal stress relaxation modulus of unidirectional fiber reinforced composites is slight; its impact modulus is only 0.4% more than its asymptotic modulus.