Impact performance of unconventional trigger holes

Abstract

Crash boxes in vehicles are one of the passive safety measures that aim to reduce injury to passengers and damage to the vehicle during a collision. Their function is to absorb the mechanical energy resulting from a collision by deforming plastically. Considering human safety, not only the energy must be damped, but also the forces acting on the passengers must be controlled. This force control can be adjusted to some extent using trigger mechanisms. There is a wide variety of research on hole type triggers, but they concentrated on traditional shapes; unique or hybrid shapes have not been sufficiently tested. This study examined the effects of various hole profiles with equal areas on dynamic mechanical performances of Al 6063-T6 rectangular crash boxes. Four types of trigger shapes were formed: upward keyhole, downward keyhole, U-shaped, and S-shaped. The dynamic performance evaluation was carried out experimentally by testing five types of geometries, the fifth one being the geometry without any trigger. In addition, dynamic Finite element analyses were conducted and validated using the experimental data, with the aim of employing the Finite element models in future geometry improvement studies. The experimental results were interpreted with some common evaluation parameters: peak force, crash force efficiency, mean crash force, and total energy absorption. The downward keyhole profile generally gave the best results, while the lowest peak force was observed in the U-shaped profile.