A multiphysics numerical simulation of the curing process of a thermosetting polymer resin

Abstract

Quality issues represent a great deal of interest in the field of fibre-reinforced composites with thermosetting polymer matrix, where such concerns are derived from matrix heterogeneity, defects (bubbles and cracks, for instance) and fibre microbuckling. These group of composite materials undergoes a complex coupled thermal, chemical and mechanical phenomenon during curing of the polymer, enhanced by the exothermal behaviour of the thermosetting chemical reaction, which can lead to important gradients of degree of cure and change of properties in the materials, more specifically in thick composites. Numerical simulations were carried out on the commercial software COMSOL Multiphysics®, based on the Finite Element Method, for the investigation of the curing process of a thick LY 556 epoxy system by considering the chemical, thermal and mechanical couplings. The curing parameters and material properties, which evolve with the curing, were thus evaluated. Experimental tests were also performed in order to obtain epoxies with different levels and degree of cure gradients, by varying the temperature and the curing time for each sample. Agreements between numerical predictions, experimental data and previous numerical results reinforce the presented model and the promising capacity of the multiphysics simulation of the epoxies curing process.