Fatigue behavior and modeling of thermoplastics including temperature and mean stress effects

An experimental investigation was conducted to evaluate fatigue behaviors of two thermoplastics. The effects considered include mold flow direction, thickness, mean stress, temperature, and frequency. Tension-compression as well as tension-tension load-controlled fatigue tests were performed at room temperature, -40 degrees C and 85 degrees C. Incremental step cyclic deformation tests were also performed to generate cyclic stress-strain curves to determine strain-life fatigue properties. The effect of mean stress was modeled using various parameters. The Walker mean stress model and a simple model with a mean stress sensitivity factor proved to be the most effective models to correlate the wide range of experimental data generated. POLYM. ENG. SCI., 54:725-738, 2014. (c) 2013 Society of Plastics Engineers