Mixed Mode I/III fatigue fracture characterization of Polyoxymethylene

The crack growth behaviour of thermoplastic polymers is a relevant topic in current research. While a dominant portion of studies in fracture mechanics investigates Mode I loading situations, very little is done to better understand Mixed Mode crack growth, which can be equally important to accurate live time predictions of polymer parts. In this research, fatigue tests on cylindrically notched specimens were performed in Mixed Mode I/III loading and compared via the so called equivalent stress intensity factor. Under these loading conditions, a significant reduction of the cycles to fracture occurred compared to pure Mode I.