Effect of Fiber Characteristics on the Mechanical Properties and Failure Modes of CFRTP with Thin-ply Prepreg

This study presents the effects of fiber characteristics of carbon fiber diameter and surface sizing agents, etc. on the mechanical properties and failure modes of carbon fiber reinforced thermoplastic (CFRTP) laminates. In the study, 90° tensile tests of unidirectional laminates, 3-point bending tests, and CAI tests of quasi-isotropic laminates employing three types of carbon fibers were carried out. Furthermore, the correlation between the failure modes of the laminates under both static and impact loading was also investigated. The 3-point bending tests clarified that increasing the fiber diameter suppressed buckling on the compressive side and improved the flexural properties of the laminates. However, in the case of thick fiber, the interfacial adhesion was decreased and the extent of damage caused by impact loading was larger than that in the case of static loading due to reduction in the number of filaments per unit cross-sectional area. Even when the fiber diameter was increased, the interfacial adhesion, and hence the CFRTP failure modes, were found to be dependent on the sizing agent. Moreover, the failure modes were independent of the loading modes (static or impact) in each carbon fiber/PA6 combination.