Crashworthiness of tapered thin-walled S-shaped structures

In a vehicular crash, a higher level of energy absorption in the frontal structures of the vehicle leads to less transferred energy to the passengers and less possibility for injury. S-shaped front rails, also known as S-rails, are one of the main structural elements and energy absorbers in the body of a vehicle. To improve the safety of passengers, the S-rail design should be optimized to absorb higher levels of energy in a frontal crash. In this study, the impact of tapering S-rails on the energy absorption is investigated. Two S-rails, one without internal diagonal reinforcement (type-A) and one with internal diagonal reinforcement (type-B), are both tapered with 20 different tapering ratios ranging from 110% to 300% in 10% increments. All of the S-rail models are subjected to static and dynamic loading conditions. Finite element analysis is used to assess the effectiveness of tapering S-rails by investigating the energy absorption (EA) and specific energy absorption (SEA) variations. An equation is developed to verify the numerical results. In this study, the reinforcing and tapering S-rails are shown to improve the EA and SEA under both static and dynamic loading conditions. By combining reinforcing and tapering techniques, S-rails showed a noticeable improvement in SEA of more than 300% in the static loading condition and an improvement of 275% in the dynamic loading condition.