Residual strength of a damaged laminated CFRP under compressive fatigue stresses

Laminated composite plates are extensively used in the construction of aerospace, civil, marine, automotive and other high performance structures due to their high specific stiffness and strength, compared to the conventional metallic materials. In general, these structures require high reliability assurance for which, the prediction of the maximum load that the structure can withstand as well as the failure process is very crucial. Compressive fatigue tests on damaged specimens of laminated CFRP’s showed that the failure is dependent of a minimum delaminated area – allowable delaminated area. There is a correlation between the size of the allowable delaminated area, the critical number of cycles, and the critical fatigue stress. Monitoring the damage propagation by C-scan, different delaminated area growth ratios were defined for the test specimens. Correlating different data, a delamination growth relation was established that enables the evaluation of the residual strength of the CFRP.