Damage Analysis of CFRP under Impact Fatigue

In recent years carbon fibre reinforced polymers (CFRPs) have become some of the most important structural materials in the aerospace industry due to their excellent stiffness and strength to weight ratios. The real-life loading histories of aerospace composite components and structures involve the generation of transient loads that can propagate as cyclic impacts. This phenomenon is known as impact fatigue (IF). Such loads can cause various types of damage in composites, including fibre breakage, transverse matrix cracking, de-bonding between fibres and matrix and delamination, resulting in a reduction of residual stiffness and a loss of functionality. The effects of IF are of major importance due its detrimental effect on the performance and reliability of components and structures after relatively few impacts and low force levels compared to those in a standard fatigue regime. This study employs a unique testing system with the capability of subjecting specimens to fully instrumented repetitive impact loading. The main aim of this paper is to provide results elucidating the effect of IF on the damage behaviour of CFRP specimens. A detailed damage analysis is implemented utilising an X-ray micro computed tomography (CT) system.