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 thermalstress 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-dependentcharacter 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 straindepends 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.