Micromechanical damage behavior of fiber-reinforced composites under transverse loading including fiber-matrix debonding and matrix cracks

This paper examines the micromechanical damage behavior of carbon-epoxy composite using representative volume elements (RVEs). An algorithm is developed to generate random distributions of fibers in the RVE, and it is possible to create a fiber distribution with high fiber volume fractions. Fiber-matrix debonding and matrix crack are considered as the dominant damage modes. The fiber material is considered linear elastic and Drucker-Prager's plastic criterion coupled with progressive damage behavior is assumed for matrix material. Moreover, cohesive elements are considered to model fiber-matrix debonding. The effects of different parameters such as fiber volume fraction, random fiber distribution, normal radii distribution, various cohesive parameters, and minimum fiber neighboring spacing on the overall damage behavior of the RVE, mostly the regime beyond the peak stress, are described in detail. It is concluded that due to the high-stress concentration regions, smaller elements are needed to analyze the high fiber volume fractions RVEs accurately. The peak stress and the corresponding strain are insensitive to microstructural randomness. Furthermore, the RVEs' final failure strain is highly dependent on different fiber arrangements layouts. Since the RVEs are under transverse strain, normal cohesive strength is the dominant cohesive zone parameter that has a significant role in the damage behavior of RVEs. It is shown that minimum fiber neighboring spacing affects the strain in which matrix crack initiates.