Residual Compressive Characteristics of Hybrid Composites with Non-Woven Tissue after Static Indentation Damage

The residual strengths of hybrid composites with non-woven carbon tissue (NWCT) are investigated under in-plane compressive static and fatigue loading conditions after contact loading with a steel ball as the indentor. The hybrid composites are made by interleaving the NWCT layer between the CFRP layer interfaces. Four kinds of angle-ply laminates are studied; i.e., CFRP laminates ([45₅/-45₅/45₅] and [45₃/-45 ₃/45₃/-45₃/45₃]), and hybrid laminates ([45₅//-45₅//45₅] and [45 ₃//-45₃//45₃//-45₃//45 ₃]). The symbol "//" means that the NWCT layer is located at an interface between CFRP layers. In the previous study, the delamination areas of the hybrid composites were reduced to about a half of the CFRP's by the indentation loading. Based on this result, in this report, the residual compressive strengths of the hybrid composites are expected to be improved by the interaction between the indentation damage and in-plane compressive loading conditions. Fatigue lives of the hybrid composites under compression-compression fatigue loading were significantly extended in all stress ranges. The compressive static and fatigue failure processes are discussed from observation of the fracture surfaces of damaged parts and failed specimens' appearances when subjected to compression after the damaged.