Non-linear mechanical response of triaxial braided composites under tension

The presented work investigates the non-linear mechanical response of different 2×2 triaxial braided composites under multi-axial loading. Straight-sided specimens were subjected to incremental tensile load cycles, which included loading, unloading and reloading up to final failure. This procedure allows characterizing the evolution of plastic strain and damage and hence provides an insight into the physical phenomena acting within the material. A total of three braid architectures were investigated, comprising braiding angles of 30°, 45° and 60° loaded in the axial and transverse direction. Digital image correlation (DIC) was used to identify and locate constituent failure mechanisms and investigate surface crack propagation. Micro-sections of the specimen were analysed for the purpose of geometrical material characterization and assessment of failure mechanisms in the thickness direction.