Role of temperature in the development of micro-scale damage in CFRP laminates through interrupted high-rate loading and synchrotron phase-contrast µ-CT

Abstract

Understanding the evolution of damage in aerospace-grade CFRP composites after high-speed impact events is crucial for the safe design of components that can withstand dynamic loads. In this study, the temperature-dependent mechanisms of micro-scale damage in angle-ply CFRP were studied through a combination of interrupted high-rate compression experiments and synchrotron X-ray phase-contrast micro-tomography employing deep-learning-aided image analysis. Despite the earlier damage onset at low temperatures, all specimens tested have similar apparent-yield strains. The mechanisms responsible for the early damage, namely mode-II-dominant fracture in surface and subsurface plies, are observed to be similar at both low and room temperature, with the surface ply cracks the first to develop into opened damage. After the occurrence of the middle-ply opened damage, while the room-temperature specimens dissipate energy through deformation and cracking originating from the specimen loading ends, glassy inter-ply fractures propagating from the surface towards the middle plies are the root of the rapid drop in specimen strength at low temperatures after the apparent-yield point.