Abstract

It is essential to understand the behavior of composite laminates against fatigue crack initiation and growth in order to accurately predict component service life and to establish safe maintenance periods.

In this work, an extrapolation procedure to characterize the mode II fatigue behavior based on the J_0i-C_0i and Δ_0i-C_0i master curves is presented and validated.

The extrapolation procedure, based on the compliance variation, assumes that all effects associated with damage are included in the equivalent crack length. In this method, new factored expressions for flexibility (C_0i), Integral-J (J_0i) and crack tip displacement (Δ_0i) are defined and according to their polynomial expressions with respect to the equivalent crack length, invariant relationships between J_0i-C_0i and Δ_0i-C_0i are obtained for a given material system and test configuration.

Once the master curves have been calibrated, the extrapolation procedure allows characterizing the fatigue behavior of a material system by determining the Paris law during the fatigue test, monitoring only the test flexibility and the maximum load with respect to the number of cycles.