Manufacture of Al/CF/PEEK curved beams by hot stamping forming process

Abstract

ABSTRACT Due to their unlimited shelf life, high impact resistance, recyclability, and fast processing time, the use of carbon fibers in combination with a thermoplastic matrix promises a fiber metal laminate (FML) with improved properties and potentially automated series production. Accordingly, the formability and performance of fast forming technologies, i.e., the hot stamping of thermoplastic FMLs, are increasingly attracting research interest. In this study, a new one-step hot stamping process is first proposed to produce curved thermoplastic FML beams fabricated by Al sheets, PEEK films, and CF/PEEK prepregs (Al/CF/PEEK). Then, the effects of the forming temperature and punching speed on the formability, as well as on the performances of the curved beams, i.e., their macro- and micro-defects, interlaminate strength and failure, thickness distribution, and spring-back, are experimentally investigated via SEM observations, four-point bending tests, and digital image correlations. It is found that curved Al/CF/PEEK laminate beams with the least spring-back (<0.2°) and thickness reduction (<0.2 mm), the fewest defects, the highest curved beam strength (195 N·mm/mm), and the highest interlaminate strength (16.5 MPa) can be produced under the forming temperature of 380°C and punching speed of 10 mm/s.