Effect of Defects on the Mechanical Properties of Virtually Cured Composite Structures

摘要

This paper addresses the effects of defects occurring during the manufacturingprocess on mechanical performance of Polymer Matrix Composites (PMCs). Damageaccumulation during cure and subsequent in-service performance are studied by usingrandomly packed Repeating Unit Cell (RUC) representative of unidirectional fiber plymaterial or a textile fiber tow, at the microstructural level. Computations are carried outusing the Finite Element (FE) method within the commercial code ABAQUS in whichconstitutive models are implemented via user-written subroutines. The transition froma continuum to damage and failure is determined by using the Bažant-Oh crack bandmodel. Results are presented for RUCs that are first subjected to curing andsubsequently to mechanical loading in the transverse direction. The analysis shows thedifferences in both the cured RUC transverse strength, S_(22)~+, and stiffness, E_(22), whencure induced damage and imperfections such as presence of voids, fiber contact,imperfect fiber/matrix bonding and presence of matrix pockets are considered.