An empirical fatigue-life model for high-performance fibre composites with and without impact damage

This article follows earlier work on the development of a life-prediction method for carbon-fibre/epoxy laminates. For comparison with the behaviour of a number of different CFRP laminates already studied, further constant-life fatigue data have now been obtained for a further CFRP composite and a GRP laminate of similar construction - a 16-ply [(+/-45,O-2)(2)](S) lay-up. Fatigue tests have been carried out on these materials in both the Virgin condition and after damage by low-velocity impacts. Following analysis of these new data and a re-examination of the older data base, the constant-life model has been appropriately modified. It now offers a prediction procedure for the fatigue response of composite materials in the virgin and impact-damaged conditions which requires, in the first instance, only the tensile and compressive strengths of the composite in question. The model is equally applicable to both GRP and CFRP, despite the fact that the fatigue response of a GRP laminate is different from that of an equivalent CFRP material. (C) 1999 Elsevier Science Ltd. All rights reserved.