The influence of triggers geometry upon the stiffness of cylindrical thin walled tubes

Abstract

Today's automobile manufacturers are increasingly using lightweight materials to reduce weight; these include plastics, composites, aluminium, magnesium alloys, and also new types of high strength steels. Many of these materials have limited strength or ductility, therefore in many cases the rupture being serious consequences during crashes, underscore Picketta et al. in their studies. Automotive structures must deform plastically in a short period of time, a few milliseconds, to absorb the crash energy in a controllable manner. It must be light and enable economically mass-production [1]. FE models rapidly gained acceptance among engineers. Many other factors facilitated the development of vehicle models by shell finite elements since most of the geometry of the structural surfaces was already on computer graphic files. Kee Poong Kim and Hoon Huh emphasize that the crashworthiness of each vehicle part needs to be evaluated at the initial stage of design for good performance of an assembled vehicle. As the dynamic behaviour of structural members is different from the static one, the crashworthiness of the vehicle structures has to be assessed by impact analysis. The paper analyzes the influence of trigger geometry upon the compression of thin-walled cylindrical tubes. Simulations performed on a simple model showed the dependence between triggers area and deformation times as well as the maximum deformations obtained for various speeds at which the simulations ware carried out. Likewise, the geometry of trigger leads to different results.

Analysis of the Deformation Mode and Determination of the Energy Dissipated by the Resistance Structure of the Vehicles

“…On the tube generator we used deformation triggers, like in [3,5,6]. Deformation triggers allow for a better and faster energy absorption as well as for a stable deformation and yet, having various deformation modes, depending on trigger geometry [13]. The triggers were positioned in series of 4 along the tube diameter and in series of 5 along the tube generator, figure 4.…”

“…Experimental studies, simulations with FEM and mathematical models on the vehicle deformation are to be found in [1,3,4], [6,7,8,9], [10,11,12,13]. There are two major considerations in the design of automotive structures for crash energy management: absorption of the kinetic energy of the vehicle and the crash resistance or strength to sustain the crush process and/or maintain passenger compartment integrity.…”

A Theoretical Approach upon the Stiffness of Vehicle Resistance Structure Submitted to an Axial Impact

“…In order to determine the compression stress occurring in the tube, it is necessary to determine the minimum cross section of the tube as it is at this very point that the compressive strain exceeds the yield strength of the material and plastic deformations occur, σco > σc. The compression stress σco in case of an impact has been determined in [13] and depends on the cross section of the tube subject to impact.…”