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The Combined Effect of Fiber Distribution Irregularities and Matrix Voids on Failure Initiation in Polymer Matrix Composites



The aim of the current work is to study damage initiation and propagation in fiber- reinforced polymeric composites. A systematic analysis is carried out to analyze the effects of manufacturing induced defects such as random distribution of fibers and presence of voids in matrix on the damage initiation in unidirectional composites under transverse tension. This study focuses on the resin infusion process and the defects hence formed. Upon infusing resin, the initial fiber configuration undergoes perturbation and results in a random distribution with regions of resin rich areas and fiber clusters. In addition, micro-voids (between the fibers in a bundle) and macro- voids (between fiber bundles) are formed. Representative Volume Elements (RVEs) are constructed to capture essential fea- tures of the composite microstructure that determine the local stress fields and hence damage initiation and propagation. Stress analysis of the RVEs is conducted using Abaqus FEA software. A novel methodology is put forward to generate random dis- tributions of fibers that would simulate different levels of perturbations of the fibers from initial (dry bundle) positions during the manufacturing process resulting in dif- ferent configurations of fiber clusters. An embedded RVE approach has been adopted in a finite element model to calculate the stress fields to avoid artificial effects of the RVE boundary. Damage initiation is then monitored using a previously proposed energy based criterion for cavitation induced fiber/matrix debonding in polymers. Subsequent damage in the form of crack formation by coalescence of the debonding cracks is also analyzed by the energy based approach.

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