3-D X-ray Tomography for In-Situ Characterization of Progressive Damage Response of Carbon Fiber Laminates Subject to Mechanical Loadings

Abstract

Composite laminates possess heterogeneous microstructures which make characterization and modeling a great challenge, particularly in their failure response to different loadings. One of the most emerging research areas involves the development of a robust, high-fidelity, physics-based model to predict the progressive damage response of composites under mechanical loading. In the literature, many failure models have been developed with a view to predicting various failure modes observed in composites, including fiber breakage, fiber kinking, matrix cracking, and delamination between plies. Digital image correlation (DIC) techniques have been widely used to identify hot spots and failure evolution by tracking the surface strain histories. Although this method can capture crack propagation, the application is limited to determining surface intra-ply damage, and the resolution is generally not fine enough to capture the failure at the fiber level. The most viable approach to produce data of value for the formulation and validation of composite material models would need to be fully 3-D and in-situ. In this experiment, a proof of concept approach to study carbon fiber laminates with 3-D X-ray tomography and in-situ tensile loading is proposed and developed. Test results revealed information regarding through-ply cracking and its impact on catastrophic failure of the specimen. Based on the results of this experiment, the implementation of 3-D data correlation (digital volume correlation) can be evaluated as a way to quantify the load- and time-based material changes that lead to failure. Additionally, other types of loadings including temperature, compressive loading, and 3-point/4-point bending can be considered for future studies.