Dynamic plastic behavior of single and nested rings under lateral impact

Abstract

This paper aims to investigate the dynamic plastic behavior of single and nested circular rings traditionally used as energy absorbers. The response characteristics of these structures are experimentally and numerically determined when they are subjected to high rate lateral impacts. It should be emphasized that a gas gun is employed in order to conduct experimental tests in which a load cell is utilized to measure the force-time response at the distal end. Furthermore, the finite element software LS-Dyna is employed to obtain numerical results in which the Johnson-Cook constitutive equation is used to take into account the strain rate and hardening effects. It is revealed that employed single rings as energy absorbers are absorbing input energies while transmitting small amounts of forces particularly peak loads to protected specimens or occupants. Moreover, it is determined that circular rings having smaller thicknesses and greater inner diameters are much more efficient energy absorbers. However, it is found that single rings have low energy absorption capacity leading to high peak loads for high input energies. It is shown in the presented paper that nested rings can be used as suitablealternatives since they can absorb much more energy and transmit much fewer forces compared to single rings.