Study Of Viscoelastic Properties For Polymer Matrix Composites

As a kind of engineering material, polymer matrix composite has been widespread used in aerospace and other high-tech industries due to its high specific stiffness, high specific strength, good corrosion resistance, good fatigue resistance, good designability and other excellent properties. Thanks to the use of polymer and other viscoelastic material, the viscoelastic characteristics become an important property of composite materials. The macroscopic properties and equivalent constitutive relationship of viscoelastic composite materials can be obtained by a large number of material characteristics experimental means, but there are many difficulties and very inconvenient for the material design. In this paper, the effective properties of viscoelastic composite materials are predicted based on the asymptotic homogenization method and finite element theory.In this paper, the viscoelastic constitutive equation is simplified through elastic- viscoelastic correspondence principle and Laplace transformation. Based on homogenization theory to solve elastic problems, the expression of effective relaxation modulus of composites which both matrix and inclusions are isotropic is discussed. The finite element software ANSYS is used to establish the composite unit cell model. The FORTRAN language is used to write the application program that solves the effective relaxation modulus. Finally, the MATLAB software is used to post-process the results.The influence of the volume fraction of inclusion and the relaxation parameters on effective relaxation modulus of isotropic composite is studied. Specific examples are given and compared with other methods to show that this method is effective.The transversely isotropic of unidirectional fiber composite materials is discussed based on the study of isotropic composites, and concrete expression is given. The effective relaxation modulus of unidirectional fiber composite materials is predicted based on the homogenization theory. And the influence of volume fraction on effective relaxation modulus is studied. The effect of circular fibers and rectangular fiber on enhance of the composite material is discussed with the same parameters.This study can play a guiding role to the viscoelastic composites design and application.