DESIGN OF BUMPERS OF LIGHT COMMERCIAL VEHICLES FOR EFFECTIVE ENERGY ABSORPTION DURING THE FRONTAL IMPACT

Abstract

The box tubular structures are among the energy absorbing devices which can be newlineused in many applications such as cars, ships, and aircrafts and so on. newlineCrashworthiness studies have attracted much attention in recent years particularly to newlineanalyse the deformation characteristics and determining the energy absorbing newlineefficiency of various thin walled crashworthy components of different materials. With newlinethe increase in number of vehicles every year, there is increase in number of accidental newlinedeaths also. newlineFrom the extensive literature review it is observed that most of the researchers have newlinedone study of square tube of aluminium or aluminium alloy whereas rectangular tubes newlineare used in many light commercial vehicles like jeep and others. Also compared to newlinealuminium material, steel is having more energy absorption for a given volume of newlinematerial which is important in case of vehicle structure. Thus the need is to concentrate newlinemore research on energy absorption capability of rectangular steel tubes. In past, the newlineresearch was mostly related to axial loading whereas oblique loading are realistic newlinesituations. Also very few researchers have done study of behavior of the tubes in newlineassembly. newlineThe aim of the research work was to study the behavior of rectangular steel tube under newlineoblique loading. Improve its energy absorption capacity by using buckling initiators. newlineThen study the behavior of bumper of light commercial vehicle during oblique impacts. newlineThen improve energy absorption by bumper for oblique impact loading using improved newlineenergy absorber. newlineThe analysis was done using the finite element method based software LS-DYNA. newlineInitially axial quasi-static analysis of the tube was done and mean crushing load was newlinecalculated. This mean load was compared with the estimated value of mean load of a newlinesquare tube of same perimeter. Then dynamic analysis was done using the Cowper newlineSymonds equation for strain hardening and considering inertia. The angle of impact was varied from 0o to 30o in steps of 5o. Use of buckling initiators was done newlinesuccessfully to increase the energy absorption capacity of the rectangular tube. Out of newlinethe tried three tubes with different arrangement of buckling initiators, the best one was newlinefinalized for use in bumper of the vehicle. newline