| Abstract: | A relationship of the form  developed for the evaluation of cyclic crack propagation in tensile/tensile fatigue was used to investigate the effects of frequency on fatigue crack growth. In order to establish the correlation between stress intensity K and dK/dt at 21°C, dynamic fracture toughness tests were performed on a range of polymers. It was shown that, in general, fracture toughness increased with the strain rate applied. Consequently, a decreasing trend in the crack growth rate was observed in the fatigue tests performed at higher frequencies. The occurrence of other localized peaks of fracture toughness recorded at various temperatures and strain rates is described. The fractography of fatigue surfaces is also discussed. |
