Lightweight Aluminum–FRP Crash Management System Developed Using a Novel Hybrid Forming Technology

The one-step hybrid forming process is a novel process to fabricate a metal fiber-reinforced plastic (FRP) structure with reduced cycle time and cost compared to classical multi-step methods. It is realized by a combined forming tool for both sheet metal and FRP forming to create a hybrid part in only one step. During the forming process, sheet metal pre-coated with an adhesion promoter is joined with the FRP simultaneously. In this work, the crashworthiness and lightweight potential of a hybrid crash management system manufactured with a hybrid forming process were investigated. It includes the experimental behaviors and finite element analysis of glass mat thermoplastics (GMT), as well as aluminum–GMT hybrid structures, under dynamic axial crushing loadings. Beginning with the original geometry of a series aluminum crash management system, the design was optimized for a hybrid forming process, where an aluminum sheet metal part is reinforced by a GMT structure with a ground layer and additional ribs. The forming behavior and fiber filling of the GMT crash box were determined and analyzed as well. Finite element method optimization was used to obtain the optimal geometry of the hybrid crash box with the highest possible specific energy absorption and the utmost homogeneous force level over displacement. A hybrid bumper beam was also developed, along with other necessary connection parts, to join the beam with the crash box and the entire crash management system (CMS) to the vehicle body. The joining technique was determined to be a key factor restricting the lightweight potential of the hybrid CMS.