Delamination growth in curved composite beam at elevated temperatures

Abstract

Delamination failure commonly appears in composite structures, especially those with curved regions, where a relatively high through-thickness stress is generally created. This study examined the delamination growth behavior of curved composite laminates at elevated temperatures. A four-point bending test was performed at room temperature, 100°C, and 125°C, where 125°C exceeds the epoxy glass transition temperature. We found that the failure load at 100°C was 32.5% lower than that at room temperature, whereas at 125°C, the failure load decreased by 64.5%. Additionally, the delamination growth process, that is, delamination propagation, varied significantly with temperature. Finite element analyses using cohesive elements were performed to determine reasonable sets of cohesive parameters that accurately represent the delamination behavior of the beam at high temperatures. The values of the cohesive parameters were identified considering the degradation owing to high temperature. A comparison of the numerical and experimental results revealed good agreement in terms of the failure load and modes. The effect of temperature on the failure mechanism was thoroughly discussed.