Micromechanical effect of pores on elastic properties of polymer matrix composites

Advanced composite polymer matrix and their different manufacturing processes tend to develop pores of varying size and play a major limiting role in residual stress, damage initiation, matrix cracking, strength, and durability. Direct imaging or simulations to understand the pore formation mechanism in the viscous polymer is difficult. Ultimately, the mechanical performance of the solidified matrix needs better prediction. This paper presents a stochastic micromechanical model, including the effect of pores' formation on the polymer matrix's elastic properties. Theoretical homogenization based micromechanical models for polymer composites is reviewed in the first part. Later, a micromechanical model is proposed considering the different stages of pore formation in a polymer matrix. Polymer samples are fabricated for determining the pore distribution parameters and used appropriately in the proposed model to estimate the elastic properties for a given distribution and volume fraction of the pores. A modified Mori-Tanaka homogenization approach and a differential scheme of inclusion of pores are incorporated in the model. Results obtained from the proposed model are compared with the experimental measurements, and a significant correlation is found.