Fatigue life prediction under complex loading for XAS/914 CFRP incorporating a mechanical fastener

A method of predicting lifetime to failure for a carbon fibre reinforced composite system subjected to a complex load-time history has been developed. The prediction first requires the generation of a model to characterize the general fatigue response of the particular composite system. Once the models are derived they can be used to predict lifetimes to failure for a load-time history using a modified Miner's damage summation rule and rainflow analysis. Variable amplitude fatigue testing of XAS/914 CFRP incorporating a mechanical fastener and use of the FALSTAFF load sequence allowed comparisons between predicted and actual lifetimes to failure and was useful in verifying the accuracy of the life prediction methodology employed. Two multidirectional CFRP laminates were studied, possessing matrix and fibre dominated properties respectively. The results from the life prediction models showed them to be accurate predictors of fatigue behaviour where matrix properties dominate but less so where fibre properties are the major influence on fatigue response.