An Orthotropic Integrated Flow-Stress Model for Process Simulation of Composite Materials—Part II: Three-Phase Systems

Abstract

In this paper, the two-phase orthotropic integrated flow-stress (IFS) process model presented in Part I is extended to a three-phase model where the third-phase accounts for the presence of gas in the composite material system. The gas flow and its compressibility are taken into account, while the seamless transformation of the resin material from its initially liquid stage to a cured solid material is incorporated within the previously developed IFS framework. A three-phase orthotropic flow model is employed to describe the behavior of the composite material during the pregelation stage of the process cycle which transforms continuously to a solid mechanics model using a stepwise three-phase micromechanics. The model is implemented in a u–v–P plane strain finite element code similar to that presented in Part I but with extended degrees-of-freedom accounting for the velocity and pressure of the gas phase. The numerical model is applied to the debulking and curing process of an L-shaped unidirectional composite laminate. Performance of the model is assessed through evaluating the process-induced deformations and residual porosity distribution over the spatial domain of the laminate.