Finite element simulation of energy absorption devices under axial static compressive and impact loading

The behaviour of energy absorption devices is studied using the Finite Elem ent Method. The ABAQUS standard code is used to simulate quasi-static loadi ng and the ABAQUS explicit code is employed in dynamic impact simulations. Our study examines the response of thin square section columns to axial imp act loading so that fracture propagates along the corner edges as the tube inverts, as observed and reported in the literature [1]. The plastic deform ation process is assisted by forcing the tube downwards onto a rigid die of finite radius - tube inversion occurs for small die radii whereas larger r adii produce curling. The methodology examines the features of the passive crashworthiness system that dissipate impact energy by plastic deformation, friction and the spread of the fracture. The force-displacement characteri stics are examined and it is shown that the nature of the contact between t he deforming tube and the rigid surface depends upon the tube thickness and die radius. The analysis is also extended to examine the axial force-displacement chara cteristics of metal tubes with thin walls that have a thickness that varies in a parabolic manner. The results from quasi-static and-dynamic axial loa ding cases are compared with reported experimental results [2]. In this cas e, the approximate theoretical derivation developed by others [1,2] (i.e. c ontinuous contact between tube and die and the retention of a uniform wall thickness) appear to be valid. If full contact between tube and die is main tained, more energy can be absorbed.