Longitudinal failure mechanisms and crack resistance curves of unidirectional thermoplastic composites
Federico Danzi, P.J. Silva Campos, Albertino Arteiro, Denis Dalli, Carolina Furtado, Jérémy Chevalier, Rodrigo P. Tavares, Frédéric Lani, P.P. Camanho
Abstract
This paper presents a study on the longitudinal fracture toughness, and associated crack resistance curves, of thermoplastic-based composite materials. Double-edge notched (DEN) specimens loaded in tension and compression are used to relate the size-effect laws with the crack resistance curves of unidirectional carbon-fibre reinforced PEKK. The results are corroborated with SEM and fractographic images to provide a better overview of the main failure mechanisms involved during the failure process. Moreover, tensile tests interrupted at 90% of the estimated failure load are CT-scanned to highlight the early stages of the crack propagation. This investigation confirms the suitability of the size-effect method for characterizing thermoplastic composites and it stands out as a first qualitative and quantitative analysis of their characteristic intra-laminar failure mechanisms.