Investigation of the correlation between fatigue behavior and fatigue crack growth in short fiber reinforced polymers

The aim of this study is to investigate potential correlations between the fatigue behavior and the fracture mechanical behavior of short fiber-reinforced polymers. Specifically, fatigue and fracture mechanics tests were conducted on polypropylene reinforced with 20% and 40% short glass fibers by weight. These tests were performed under controlled conditions at room temperature and using a stress ratio of R = 0.1. Both fatigue and fracture mechanics tests were carried out in two different material orientations to better understand the influence of fiber reinforcement on the mechanical properties of the polymer. The two orientations were chosen to capture the anisotropic effects introduced by the fiber alignment within the polymer matrix, as this factor can significantly impact both fatigue resistance and fracture toughness. Additionally, two distinct models were employed to analyze the results. The first model was used to construct S-N curves from the fracture mechanics data, providing insight into the material’s fatigue life. The second model focused on calculating the permissible stress amplitude for the very high cycle fatigue regime, also based on the fracture mechanical properties of the material. The combination of these approaches aims to offer a deeper understanding of the possible correlation between fatigue and fracture mechanics of short fiber reinforced polymers.