Crashworthiness of Tapered Beams in Automotive Application

Abstract

In a car crash, the higher level of energy absorption in the frontal structures leads to less transferred energy to the passengers and hence a safer car. S-shaped front rails, also known as S-rails, are one of the main structural elements and energy absorbers in a car body. Energy absorption in the S-rails happens through local buckling. In order to improve the passenger safety in a frontal crash, S-rails design should be optimized to absorb higher level of energy while crushing. In this study, we investigate the crashworthiness impact of tapering S-rails. Two S-rails, one without internal diagonal reinforcement (type-A) and one with this reinforcement (type-B), both are tapered with 20 different tapering ratios ranging from 110 % to 300 % in 10 % increments. All S-rail models are subjected to static and also dynamic loading conditions. The effectiveness of tapering S-rails is assessed through investigating the energy absorption (EA) and specific energy absorption (SEA) variations using finite element method. An equation is developed to verify the numerical results. In this study, we showed the reinforcing and tapering S-rails both could improve the EA and SEA in both static and dynamic loading conditions. Combining reinforcing and tapering the S-rails showed a noticeable improvement in SEA of more than 300 % in static loading condition as well as 275 % SEA increase in dynamic loading condition.