Mode-II interlaminar fracture and crack-jump phenomenon in CFRP composite laminate materials

An interlaminar crack-jump event is one of the complex failure phenomena in laminated composite structures. This paper examines the mechanics of the interlaminar damage process leading to crack-jump event in CFRP composites under mode-II loading condition. A series of end-notched flexure tests of CFRP composite were conducted to create a standard interface failure, and an unstable interface fracture that led to crack-jump event. FE simulation of the composite tests was created using a new FE model-based construction and CZM theory in combination with a hybrid experimental-computational approach to assess the interface damage and crack-jump events. The FE model of the standard test predicted a short range crack-jump event instead of a gradual interface crack growth, coincided with the load drop in the structural response. A constant value of interface damage dissipation was predicted at the time of fracture for all composite cases. The unstable crack-jump event occurred due to the release of high strain energy in the composite structure while the interface underwent cracking process.