PhD Track Co-Supervision Research

Experimental Study and Micromechanical Modeling of Compression Failure of a Unidirectional Composite Laminate

Project Details

Abstract

Carbon fiber reinforced polymer composites are widely used in aerospace structures because of their high stiffness-to-weight ratio. However, their mechanical behavior strongly depends on manufacturing quality and the presence of defects such as fiber waviness, ply overlaps, or orientation misalignment. These defects significantly affect compressive strength, which is one of the most critical loading conditions for unidirectional composite laminates. Under longitudinal compression, failure often occurs through the formation of a localized shear band, known as a “kink band,” involving fiber instability, matrix cracking, and possible delamination. The objective of this PhD research is to improve the understanding and prediction of compressive failure in unidirectional composite laminates through micromechanical modeling and dedicated experiments. A finite element micromechanical model will be developed at the fiber scale to simulate compressive fiber failure and the formation of kink bands. The model will account for manufacturing defects such as fiber waviness and misalignment, and will aim to predict both compressive strength and the critical energy release rate associated with fiber failure. In parallel, experimental investigations will be conducted at different scales to validate and improve the numerical model. Advanced in-situ testing techniques, including microscopic observations during loading, will be used to better capture damage initiation and propagation mechanisms. The final goal is to develop a reliable micromechanical framework capable of predicting compressive failure and fracture toughness without relying solely on complex experimental procedures. This work will contribute to more accurate design and reduced over-dimensioning of aerospace composite structures. This PhD research is conducted in international co-supervision between the ISAE-Supaero, Institut Clément Ader (France) and the Lebanese American University (Lebanon).