Crashworthiness design of novel CFRP functionally-graded conical square structures with variable circumscribed diameters

Abstract

Carbon fiber reinforced plastic (CFRP) thin-walled structures have been widely acknowledged as superior energy absorbers due to comprehensive advantages on crashworthiness and light weight. However, few studies have been reported concerning CFRP thin-walled structures with nonlinearly variable sectional dimensions along the longitudinal direction. Hence, in the present study, a novel CFRP functionally-graded conical square thin-walled structure with variable circumscribed diameter (functionally-graded conical square tube, FGCST) is proposed and comprehensively investigated. Specifically, finite element (FE) models of FGCST under multi-angle crushing loading are first built and validated. Second, a comprehensive crashworthiness comparison among the FGCST, the conventional CFRP conical square tube (CST) and the CFRP straight square tube (SST) under multi-angle crushing loading is executed to explore the relative merits of FGCST over others. Third, a parameter study is implemented on FGCST to explore the action laws of its structural parameters on its overall crashworthiness under multi-angle crushing loading. Finally, the FGCST is multi-objective crashworthiness optimized for maximizing overall specific energy absorption (SEAθ) and minimizing overall peak crushing force (PCF0) simultaneously through Taguchi method coupled with grey relational analysis (GRA). The optimized FGCST obtains 6.06% higher of SEAθ and meanwhile 40.58% lower of PCF0 compared with the baseline design, thus demonstrating good potential as a superior candidate for vehicle collision energy absorbers.