Redesign of Crash-Box for Enhanced Energy Absorption in Low Velocity Impact

Design of vehicle structure to provide safe structural environment for occupants of vehicles involved in high speed (> 15 km/h) collisions has drawn considerable resources as safety of humans is at stake. Low speed impacts, since these do not cause severe injuries to the occupants, do not generate much concern. However, structural design for this situation has generated a lot of interest among insurance companies as the structural damage caused by these types of collisions is substantial, requiring significant payments by the insurance companies. In this work alternative designs for crash-box have been assessed for RCAR (Research Council of Automotive Repairs) requirement for frontal crash. Using structural details of an existing sedan, various designs of crash-box that can be fitted within the packaging space have been assessed for low speed impact. Geometric parameters like length, wall thickness, cross-section shapes (rectangle hexagon and octagon), number of buckle initiators (2 to 7) for steel and aluminium have been altered to generate different designs. Through use of thinner walls in steel tube of rectangular cross-section an, increased number of buckle initiators, it was possible to limit major deformation to the crash-box. Use of this crash-box reduced permanent deformation in S-rails to a level where their replacement after low speed impact was not necessary.