Multi-cornered thin-walled sheet metal members for enhanced crashworthiness and occupant protection

• Several profiles of multi-corner thin-walled columns of square, hexagonal, octagonal, and newly introduced 12-edge cross-sections were presented and their crashworthiness capacities under axial crush loading were investigated analytically, experimentally, and numerically.
• Explicit formulations for predicting the mean crushing force of multi-corner thin-walled columns were derived using the theory of super folding element (SFE).
• Newly introduced 12-edge section with high energy absorption capacity was developed and its dominance was established through the responses in quasi-static experiments and CAE simulations.
• The foundational dominance of the 12-edge section was extended to the dynamic environment through a full vehicle crash test simulation to evaluate overall reduction in crashworthiness parameters which reflected occupant safety.

Crash energy management in frontal crumple zone of the automotive body is one of the key elements for the design of automotive structure. Improving energy absorption characteristics reduces the magnitude of forces transferred to the occupant compartments. Here, a new strategy has been proposed to improve energy absorption efficiency of thin-walled columns by introducing extra stable corners in the cross-section. Several profiles of multi-corner thin-walled columns obtained through this strategy were presented and their crashworthiness capacities under axial crush loading were investigated analytically, experimentally, and numerically. First, explicit formulations for predicting the mean crushing force of multi-corner thin-walled columns were derived using the theory of super folding element (SFE). Predicted results of these formulations showed a good agreement with the results of quasi-static experiments and CAE simulations, which were performed by explicit non-linear finite element code through LS-DYNA. Based on this agreement, other significant crashworthiness assessment parameters were then investigated experimentally and numerically. Newly introduced 12-edge section with high energy absorption capacity was developed and its dominance was established through the responses in quasi-static experiments and CAE simulations. Finally, the foundational dominance of the 12-edge section was extended to the dynamic environment through a full vehicle crash test simulation to evaluate overall reduction in crashworthiness parameters which reflected occupant safety. Interestingly, in the case of using 12-edge section as crush absorbers, specific energy absorption (SEA), dash intrusion and maximum occupant’s chest deceleration showed significant improvement, compared to the baseline design which used a rectangular section.