Stress-life prediction of 25°C polypropylene materials based on calibration of Zhurkov fatigue life model

In this study, to evaluate the chemical and mechanical properties of polypropylene (PP), activation-energy and tensile tests were performed at room temperature (25°C) on pure PP and PP reinforced with glass fibre (GF). To improve the prediction accuracy of the fatigue life, three models based on the calibration of the Zhurkov model were proposed: a regression model, modified strain-rate model and lethargy coefficient-based model. Based on the experimental data analysis and statistical assessment results, we proposed a modified strain-rate model that satisfies the dependency of the physical parameters and is congruent with the predicted fatigue life data. The experimental data and modified strain-rate model were compared with the direct cyclic analysis results. The tendency of the frequency factor as a correction parameter in the modified strain-rate model corresponded to the experimental activation energy and the increasing GF content.