Study on intralaminar crack propagation mechanisms in single- and multi-layer 2D woven composite laminate

The intralaminar crack propagation of the carbon/epoxy two-dimensional plain woven composite material has been experimentally investigated. It was found that the propagation direction is insensitive to pre-crack tip locations. The propagation path direction is aligned along the intersecting position of warp fibers and weft fibers weaving, and the extends forward along the crack tip until the final fracture failure. The crack propagation process has two major stages, the maximum energy accumulation stage (stage A) and the gradual release of energy stage (stage B). In stage B, there are many single or several fiber bundles breakage during these stages due to the characteristics of reinforcing fibers woven from multiple fiber bundles. The warp fiber bundles gradually break under the axial tensile loading. Analysis of the images obtained by the optical microscope and scanning electron microscope, the fracture surfaces of the specimens are all sawtoothed, the fracture damage of the plain woven single-layer laminate is mainly fiber bundles separation, breakage of the fiber, and debonding of the fiber and the matrix. In addition, the validity of the intralaminar crack propagation mechanisms is further verified by multi-layer laminate experiments.

Automated summary

The experimental investigation focused on the intralaminar crack propagation of the carbon/epoxy two-dimensional plain woven composite material. Findings showed that the crack propagation direction is aligned along the intersecting position of warp and weft fibers. The process involves two major stages and was further verified by analysis of optical and scanning electron microscope images.