Investigation of the Effect of Impact Velocity on the Energy Absorption Characteristics of Crash Boxes

Abstract

The automotive industry has implored the use of thin walled structure known as the crash box to increase the level of safety of passenger vehicles in the event of frontal collision. The crash box is characterized by its progressive folding which absorbs the energy of the collision through its plastic deformation by converting the kinetic energy to plastic strain energy. In this study, the effect of impact velocity on the energy absorption characteristic of four thin-walled square frusta steel specimen used as energy absorbing elements was numerically analyzed. For each specimen, four quasi-static analyses were conducted using LS-Dyna with four different impact velocities from about 10 to 40 m/s. The specimens were impacted axially with a striking mass of 60 kg. Assessment of the performance of these specimens were carried out using metrics like energy absorption, specific energy absorption, initial peak force, mean load and crush force efficiency. The results revealed that as the velocity increased the initial peak force and the energy absorption also increased while the crush force efficiency decreased at higher impact velocities.