Application of sandwich beam in automobile front bumper for frontal crash analysis

Abstract

The study of energy-absorbing behavior in sandwich beams under static loading has become the basis for the design of crashworthy structure in automobile applications. Unlike metals, composite sandwich materials display little or no plastic deformation. Research has shown that foam-cored sandwich beam has significantly higher energy absorption than low carbon/high carbon steel used in automobiles.This thesis is aimed at developing a structural component that provides better kinetic energy absorption, than the existing car front bumper. Occupants of motor vehicles are injured or killed in several different types of crash situations. These are frontal, side, rear, and rollover. The most severe accident situations are frontal impact. The car front bumper is a major structural component, and it carries most of the impact load in crash events. Therefore, in order to improve the front bumper performance, an attempt is made in this study to use sandwich material in the front bumper. And for that, a study is carried out to arrive at a combination of core and face sheet that offers maximum energy absorption. A Finite Element (FE) model of a Ford Taurus is first utilized and validated, using the LS-Dyna FE software. Frontal crash analysis is then performed on the car with sandwich bumper model according to the Federal Motor Vehicle Safety Standard 208 (FMVSS 208) and the New Car Assessment Program (NCAP). The vehicle displacements, energy absorption, and deceleration levels are compared for both the steel and sandwich models. Occupant injuries are then evaluated for frontal impact sled test at 35 mph, using the LS-Dyna, for both steeel and the new composite models. The injury levels including, head, neck and chest injuries are evaluated and compared for the both models. It is demonstrated that foam-cored sandwich beam with carbon/epoxy face sheet is more effective than the present steel car bumper.