Suchao Xie

Crashworthiness analysis and structural optimisation of multi-cell square tubes under axial and oblique loads

ABSTRACT Square tubes have been widely used as energy absorption components. To investigate the influences of multi-cell configuration and loading arrangement on the crashworthiness of square tubes, eight kinds of multi-cell square tubes were numerically analysed under axial and oblique loads. Validation was performed against experimental data. According to the complex proportional assessment method, the T5-1 tube is found to have the best crashworthiness performance. Next, a parameter study was performed to analyse the effect of geometric parameters of the T5-1 tube on the crashworthiness. It was found that the s/b ratio and thickness have a significant influence on the energy absorption. The critical loading angle lies in the range of 10°–11°. Finally, a structural improvement design, with the straight tube changed to the taper tube, was implemented and the taper T5-1 tube was proposed. The results show that the taper T5-1 tube has better crashworthiness performance, compared with the original T5-1 tube.

Impact characteristics and crashworthiness of multi-cell, square, thin-walled, structures under axial loads

ABSTRACT To study the crashworthiness of single- and multi-cell, square structures under axial loads, the response surface models of these structures were established separately by using the polynomial response surface method (PRSM). The models describe the response surfaces of specific energy absorption (SEA), peak crushing force Fmax and mean crushing force Favg under the variation of the side-length a, wall thickness t and number of cells N in the structure. The results showed that for the square thin-walled structures with the same N, the SEA basically increases with wall thickness t and decreases with side-length a; Fmax increases with t and a, while Favg increases with t but remained unchanged with a. Besides, under the same dimensional parameters (identical a and t), the larger the value of N, the larger the values of SEA, Fmax and Favg. When other parameters are the same, with the progress of the crushing distance in a collision, structures with large side-length a, wall thickness t and number of cells N are subjected to large crushing forces and therefore the kinetic energy generated in the collision, and absorbed by these structures, is large; however, for parameters t and N, the crushing force and absorption energy change only slightly with a.

Design and analysis of a composite energy-absorbing structure for use on railway vehicles

Safety during railway vehicle collisions requires an excellent energy-absorbing ability of the structures of trains. In this paper, a new composite energy-absorbing structure is designed by combining the characteristics of a thin-walled metal structure and an aluminum honeycomb structure. A finite element model of the energy-absorbing structure is created using mechanical properties of the honeycomb structures simulated using material equivalent models. Structures with three types of aluminum honeycomb (honeycombs 1, 2 and 3, respectively) and without a honeycomb are numerically assessed. The results indicate that the entire structure generates an orderly deformation of the structure using the designed energy-absorbing system. The larger the extent of the plateau stress of the honeycomb, the greater is its contribution to the total energy dissipation of the entire structure. For the three energy-absorbing structures, honeycombs 1, 2 and 3, the energy absorbed by the honeycomb structure accounts for 18.03, 19.86 and 27.40 % of the total energy dissipation, respectively. The total energy dissipation of the energy-absorbing structure is also improved with an increase of the plateau stress of the honeycomb structure.

Optimization of the target profile for asymmetrical rail grinding in sharp-radius curves for high-speed railways

Asymmetrical rail grinding in sharp-radius curves could reduce the side wear of railheads and enhance curve capacity of rail vehicles. The wheel/rail contact performance and curve capacity could be further improved by the optimization of the asymmetrical rail grinding target profile. In order to modify the target profile smoothly, the nonuniform rational B-spline curve with adjustable weight factors is used to establish a parameterized model of railhead curves in the asymmetrical grinding region. The indices of contact performance and curve capacity for different weight factors are obtained using experiment design and service performance simulation. Two Kriging surrogate models are proposed, in which the design variables are the adjustable weight factors, and the response parameters are the indices of contact performance and curve capacity, respectively. The multi-objective optimization model of the target profile is established, in which the objective functions are the two Kriging surrogate models of contact performance and curve capacity. The optimized weight factors are sought using a nondominated sorting genetic algorithm II, and the corresponding optimal target profile is obtained. The wheel/rail service performance simulation before and after optimization indicates that the contact performance and curve capacity are improved significantly.