Finite Element Simulation of Energy Absorption Devices under Axial Static Compressive and Impact Loading

Abstract

The behaviour of energy absorption devices is studied using the Finite Element Method. The ABAQUS standard code is used to simulate quasi-static loading and the ABAQUS explicit code is employed in dynamic impact simulations. Our study examines the response of thin square section columns to axial impact loading so that fracture propagates along the comer edges as the tube inverts, as observed and reported in the literature [1]. The plastic deformation process is assisted by forcing the tube downwards onto a rigid die of finite radius - tube inversion occurs for small die radii whereas larger radii 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 characteristics are examined and it is shown that the nature of the contact between the 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 characteristics of metal tubes with thin walls that have a thickness that varies in a parabolic manner. The results from quasi-static and dynamic axial loading cases are compared with reported experimental results [2]. In this case, the approximate theoretical derivation developed by others [1,2] (i.e. continuous 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 maintained, more energy can be absorbed.