Modelling of residual stress during curing of a polymer under autoclave conditions and experimental validation

This study develops a multi -scale predictive framework to study the cure kinetics of a polymeric resin under autoclave conditions. The novelty of the study includes evaluation of the cure performance such that the influence of porosity on the residual stress can be interpreted. A representative volume element based finite element model is developed which captures the cure rate and degree of cure under periodic boundary conditions. Resin cure kinetics and heat generation are coded in Fortran via user defined subroutines to capture the nonlinear cure response. The autoclave system is simulated as a pressure and thermal load on the resin domain. It is found that an increase of porosity by up to 5%, decreases the level of residual stress by 35% when compared to an ideal configuration, i.e., a no porosity content. The magnitude of residual stress is further validated with XRD results and found to lie within 8%. The proposed model is robust to capture the cure phenomenon of a given thermoset polymer, given the cure kinetic parameters.