Fatigue Crack Growth Curves for Material Selection, Design and Service-Life Studies of Carbon-Fibre Reinforced-Plastic Composites: Effect of Test Temperature and R-ratio

The growth of cracks between plies, i.e. delaminations, in continuous fibre polymer matrix composites under cyclic-fatigue loading in operational aircraft structures has always been a very important factor, which has the potential to significantly decrease the service life of such structures. Whilst current designs are based on a ‘no growth’ design philosophy, delamination growth can nevertheless arise in operational aircraft and compromise structural integrity. Therefore, the present paper addresses the problem of fatigue crack growth in composite structures, with special relevance to composite airframes. An immediate challenge facing the composites community is to extend the ‘no-growth’ design philosophy to allow for the nucleation and growth of small, naturally-occurring delaminations in composite structures. The main aim of the present paper is, therefore, to investigate the robustness of the Hartman-Schijve methodology to meet this challenge when the effects of test temperature, together with the R-ratio, on the fatigue behaviour are considered.