Investigation of mechanical behavior of energy absorbers in expansion and folding modes under axial quasi-static loading in both experimental and numerical methods

Abstract

In this paper, a new form of energy absorbing structures has been introduced which energy absorbing is occurred during a combined process. The structure consists of a thin-walled aluminum matrix and a thin-walled steel punch. Energy is absorbed as the matrix gets expanded followed by simultaneous matrix and punch folding. In order to demonstrate the effectiveness of absorbent introduced, many samples of each type were fabricated and tested. In one case, it was found that, the new structure tends to absorb up to 32% more energy than sum of the energy absorbed by its individual parts. Also, the energy absorption properties and the parametric study were simulated using finite element code LS-Dyna. The results showed that among different section geometries, structures with rectangular section have the lowest energy absorption and the highest crush force efficiency; by increasing the number of sides of the cross section the absorbed energy increased and crush force efficiency is decreased. In addition, increasing the thickness of the punch leads to increased energy absorption. Also, it was found that, selecting an appropriate thickness for the punch, one can predict overall shape of load-displacement curve and maximum force location for the combined structure.