Evaluation on Damage Behavior under Bending and Lateral Compressive Load of CF/PEEK Round Rod Manufactured by Prepreg Tape Thermal Pultrusion Process

Abstract

This study focuses on the pultrusion process and mechanical properties of unidirectional carbon fiber reinforced poly-ether-ether-ketone (CF/PEEK) round rods. A laboratory-scale thermal pultrusion machine with a compressive insert mold was developed to manufacture thermoplastic CFRP round rods. The round rods manufactured using CF/PEEK prepreg tape exhibited high density without visible voids or fiber bundle layers. To investigate the effects of fiber orientation on the mechanical properties of CF/PEEK round rods, the prepreg tapes were pultruded in a twisted state. The mechanical properties of the CF/PEEK round rods were evaluated by a three-point bending test and a lateral compression test, and the damage behavior was investigated by cross-sectional observations after the test. CF/PEEK round rods with twisted fiber orientation exhibited lower elastic modulus and reduced maximum load in the three-point bending tests, but fiber twisting has a significant effect on resistance to lateral compressive loads and stress redistribution. It was confirmed that the complex fiber orientation obtained by twisting the prepreg tape suppresses the straight propagation of transverse cracks in the longitudinal direction of CF/PEEK round rod. The thermal pultrusion process developed in this study was realized as an effective reinforcing method against lateral compressive loads by adding tape twisting.