Damage tolerance of carbon and Kevlar based hybrid composites against quasi-static indentation

Abstract

The presence of dent in composites causes a reduction in its compressive strength. To understand the effect of a dent in hybrid composites with the inter-ply approach of Carbon and Kevlar reinforcements in an epoxy matrix, the damage tolerance estimated by applying a compression load in compression after impact test to the samples having with indentation produced in quasi-static apparatus using a conical-shaped penetrator. It was observed that the place and content of Kevlar layers directly effect on the toughness of composites which steered to the enhancement of the penetration resistance. The compression loading was given to the penetrated samples and then compressive residual strength calculated. The results revealed that the test sample of Kevlar reinforced epoxy composite presented a reduction of 32% in compression strength after quasi-static indentation and hence is more damage tolerant against indentation compared to other carbon-Kevlar/epoxy hybrid and carbon-reinforced epoxy composites. The samples submitted to compression after tests were photographed revealing typical crack aspects. The quasi-static indentation process and key findings can help as a design guideline for dynamic application, predominantly, velocity impact loading.