Crashworthiness optimisation of S-shape square tubes

During a car frontal crash, the front side member is expected to be folded progressively, so as to absorb more energy and to ensure enough passenger space. As the front member of a vehicle body, the crushing characteristics of an S-shape thin-walled box beam under an axial load has received crucial attention both experimentally and numerically. In this paper, the axial impact crushing behaviour of the S-shape square tube is studied by the finite element method, and effectiveness of stiffening at the curved parts and shape perturbation at two straight parts of tubes are discussed. Based on the numerical analyses, maximisation problem of the dynamic crushing energy absorption of S-shape square tubes is solved by using the crashworthiness maximisation technique for tubular structure which combines the techniques of the response surface approximation design-of-experiment as well as the usual mathematical programming.