Progressive failure analysis of 2 × 2 braided composites exhibiting multiscale heterogeneity

Periodic analysis is generally used in the modeling of textile composites, which are usually idealized to possess perfectly uniform periodic microstructures. However, the as-manufactured textile composites generally do not have perfectly uniform microstructures due to variations in tow geometric properties such as waviness, cross-section shape, and fiber volume fractions. Therefore, their behavior cannot be fully characterized by conducting periodic analysis on a single unit cell model. This paper focuses on the effect of variation in braid parameters on the progressive failure behavior of a 2 × 2 braided composite laminate. The laminate consists of stacked 2 × 2 braid mats. Each mat is made of interlaced tows and matrix pockets, and the tow contains fibers and matrix. A bottom-up multi-scale finite element modeling approach was employed that sequentially considered the fiber/matrix scale, the tow architecture scale and the laminate scale. The details of the analysis approach, the multiscale finite element models, and the numerical results are described and the analysis results are presented and discussed.