Experimental study on failure behavior of thick anisotropic CFRP laminate and bolted joint

This study investigates the failure behavior of thick anisotropic carbon fiber reinforced polymer (CFRP) laminate through orientation-dependent tensile, compressive, and in-plane shear tests, alongside single-lap bolted joint performance to examine thickness induced failure mechanisms relevant to structural applications. A 20.4 mm of thick CFRP laminate, featuring an anisotropic stacking sequence dominant in 0° direction, was fabricated. The experimental results reveal that mechanical performance and failure modes are highly sensitive to the loading direction. However, damage consistently initiated and propagated along the interfaces between unidirectional and multidirectional plies. Under tensile, compressive, and in-plane shear loads, interfacial delamination was observed in conjunction with fiber fracture, local buckling, and through-thickness shear failure. In the bolted joint test, a combined failure mode involving shear failure and splitting was identified. These findings underscore that the structural integrity of thick anisotropic CFRPs cannot be accurately characterized by a single material property or failure mode. This work provides critical experimental benchmarks for the analysis and design of thick section composites, highlighting limitations of existing design assumptions developed for thin laminates and the necessity of frameworks that explicitly account for interlaminar behavior in thick sections.