Design and Development of Automotive Bumper Subsystem for Light Weight and Vehicular Crashworthiness

Reducing fuel consumption, satisfying current regulation and legislation regarding GHG emission and customer safety requirements are the main concerns for automotive industries. Today, Scholars and research and development department of car industries are trying to address such issue trough substitution the traditional steel by lightweight advanced composite materials. However, the complex composite failure behavior particularly under certain sever conditions like crash and trade-off between light vehicles and vehicle crashworthiness, makes the substitution of metallic to composite materials very difficult and remains the main obstacle for their rapid development. The current development in die forming manufacturing and injection over-molding technologies makes the production of open composite beam shells with the desired end profile and structurally integrating crash box with beam as a single unit possible. Therefore, if the strength/stiffness of an open structure is maintained, the capability of component integration will offer part reduction, increase production rate and reduce mechanical joints. The fact is, an open-channel thin-wall beam component is structurally weak and can readily buckle under lateral and compressive loads. However, with very little lateral support, provided by a thin-wall rib-like injection-molded plastic subcomponent, the buckling resistance (and the stiffness) of the component can be greatly increased. In the current study, three composite materials considered for automotive bumper beam for light weight and better crashworthiness. Rib pattern selection and beam end section and rib geometry optimization are conducted numerically. Low velocity impact test were conducted and parameters, such as impact energy, peak load, crash resistance and energy absorption have been taken as evaluation criteria to compare the proposed materials solutions with steel solutions. The result shows that with a proper end section and ribs geometry optimization and reinforcing ribs, selection an open section beam can yield a structural performance comparable with that of the close section beam.