Effect of frequency on the fatigue crack propagation of a polyamide 6/layered-silicate nanocomposite

In this work, the effect of the frequency of a sinusoidal applied load on the fatigue crack propagation (FCP) behaviour of a polyamide 6 (PA6)/organo-clay nanocomposite, and its corresponding neat PA6, was investigated via FCP tests carried out at a non-zero mean stress. An attempt at elucidating the role played by the mean stress (creep) in the fatigue fracture process of the two materials was done. In particular, from FCP data obtained at the various frequencies, a creep contribution to the fatigue fracture propagation was indirectly evaluated and compared with that experimentally measured in creep crack propagation (CCP) experiments.