Slow-growth damage tolerance for fatigue after impact in FRP composites: Why current research won't get us there

Using the slow-growth certification approach for damage tolerance of composite aircraft structures has the potential to reduce their weight. Applying this approach requires that damage growth is slow, stable, and predictable. However, currently available methods do not allow for sufficiently accurate predictions, due to knowledge gaps related to damage characterisation, prediction of damage growth, and prediction of final failure. This article highlights these knowledge gaps, discusses the limitations of the current state of the art and research approaches, and identifies possible ways forward.