Study of transverse cracking in aero-engine grade polymer composite under quasi static loading

This work aims to contribute to the development of a damage prediction model for cross-ply laminates subjected to realistic use conditions of commercial aero-engine composite materials, including isothermal cycling and aging at 150 °C and quasi-static load. The implementation of high-temperature polymer composites in aero-engines offers significant weight reduction, leading to reduced fuel consumption and environmental impact. The development of a damage prediction model is crucial to analyze the material's behavior avoiding the need for expensive and time-consuming tests under various conditions. In this study, a composite laminate with a cross-ply configuration was utilized, and samples were subjected to isothermal cycling and aging at 150 °C, followed by quasi-static loading to investigate the evolution and behavior of intralaminar cracks, in terms of crack density. The crack density was then modeled using a statistical approach based on the Weibull distribution. This model enables the prediction of crack density evolution in the 90° layers of the cross-ply during quasi-static loading under different conditions, including as-built, cycled, and aged materials at both room temperature and elevated temperature of 150°C. Experimental data obtained from quasi-static loading, degradation of the longitudinal elastic modulus after each load stage, and microscopic analysis of the microstructure of the cross- ply sample edges will contribute to the development of the damage prediction model. By integrating these findings, a comprehensive understanding of the material's damage evolution and its corresponding mechanical response can be achieved, facilitating more accurate predictions of the life and performance of fiber-reinforced composite materials in aero-engine applications.