Thermoelastic constitutive modeling of irradiated polymer composites with matrix property change and fiber/matrix debonding

Abstract

In this paper, thermoelastic models are presented for the evaluation of the constitutive response of irradiated fiber-reinforced polymer composites with change in the fiber and matrix properties and fiber/matrix interfacial debonding. These models are based upon thermodynamic considerations involving Helmholtz and Gibbs free energies and micromechanical stress and strain fields associated with the fiber and matrix materials. The proposed union between the energy functions and micromechanics provides a unifying framework that can deal with the potential property changes in the fibers and matrix and at the fibre/matrix interface. The results for a typical graphite/epoxy polymer composite system show reasonable trends when compared with the available experimental data for primary elastic constants. The parametric study for all the principal elastic constants involving matrix stiffening, softening and fiber/matrix interfacial debonding exhibit a number of interesting results. A significant influence of interfacial fiber/matrix debonding on the matrix-dominated material properties, such as (E 2) c r and (G 66) c r, has also been noted.