Modeling and optimization of foam-filled thin-walled columns for crashworthiness designs

Thin-walled columns play an important role on passenger safety in vehicular collisions for their progressive deformation patterns and large energy absorptions. A thin-walled column with a large specific energy, i.e., the ratio of energy absorption to its mass, is often desirable to the automotive industry, because such designs could enhance safety and reduce manufacturing cost. Due to the complexity of crash mechanism, obtaining such designs has been a challenge to the trial-and-error approach using physical prototype testing. To this end, combining finite element simulations with optimization methodologies has become the viable means to meet the challenge. In this paper, single- and triple-cell hexagonal columns filled with aluminum foams were optimized for maximum specific energy with simultaneous consideration of section geometry, tube thickness, and foam density. The effects of crushing forces on column designs were analyzed by comparing optimum solutions with and without constraints on the mean crushing forces. The interaction effects between the tube and foam of composite columns and the relative advantages of single- and triple-cell structures were investigated and discussed.