Development of a hygrothermal constitutive model for epoxy resin considering the glass transition temperature and its applications

Abstract

Epoxy resin, as a crucial constituent of aerospace-grade composites, is an important consideration in designing composites for severing service conditions in terms of the hygrothermal environment (i.e. contains both temperature and moisture). In this work, a state-of-art elastoplastic-damage constitutive model is expanded to include the hygrothermal effects which are characterized by employing a glass transition temperature Tg as a bridge. The formulation of yield and fracture strengths with respect to hygrothermal effects demonstrates a high level of mathematical consistency. The model correctly captures the plastic flow and fracture initiation behavior with hygrothermal effects, as validated through quasi-static experiments. Subsequently, the application of this hygrothermal constitutive model for an epoxy resin on micro-mechanical analysis of carbon polymer composite materials is implemented. A representative volume element (RVE) is established with a random placement of fibers. Based on the commercial software ABAQUS, different loading scenarios are applied to evaluate the mechanical response and damage evolution of the composite in different hygrothermal conditions, enabling an initial understanding of the hygrothermal effects of epoxy resins on the mechanical performance of composite materials.