A continuum damage model for composite laminates: Part IV- Experimental and numerical tests. (March 2021) - Llobet, J.
Abstract: This paper follows on from part III (Llobet et al., 2020) where a mesoscale continuum damage mechanics (CDM) model for composite laminates under static and fatigue loads has been presented. An experimental investigation on the damage occurrence and the strength of carbon/epoxy notched laminates subjected to static, tension-tension fatigue and residual strength tests is provided. X-ray inspections reveal that matrix cracking, longitudinal splitting and delamination control the fatigue degradation process. This paper presents a coupled computational model to account for intralaminar damage using the CDM model and interlaminar damage using a cohesive zone model (CZM). The capability of the computational model to capture the main fatigue degradation mechanisms and the residual strength is examined by simulating open-hole and double-edge notched specimens. The numerical predictions show that the main fatigue degradation mechanisms are well captured as well as the post-fatigue residual strengths except for the open-hole specimen. Further experimental and modelling work are required to develop a more reliable computational tool for quantitative evaluation of fatigue and damage tolerance of composite structures. Highlights: Fatigue damage reduces the notch sensitivity and increases the post-fatigue residual strength in tension. Matrix Longitudinal splitting and delamination control the fatigue degradation process of carbon/epoxy notched laminates. The model is capable of predicting the split direction provided that the mesh is oriented in the fibre direction. The fatigue damage predictions show an underestimation of the split length and delamination area after fatigue. Excessive distortion issues occur when the most damaged finite elements undergo large strains.