High precision stretch bending of aluminum alloy profile is the key technology for making car’s frame body. A numerical simulation study on the displacement-controlled process for a typical kind of L-section aluminum alloy profile used in high-speed rail with finite element analysis software is presented. The effect of different friction coefficients, with or without baffle and cover plate on the equivalent stress,strain and cross-sectional distortion are investigated. It is shown that the increase of the friction coefficient can increase the cross-sectional distortion, equivalent stress and strain. The installation of baffle and cover plate can significantly reduce the cross-sectional distortion in the middle section of the profile, and increase the equivalent stress and strain to some extent.

For the serious and uneven wear of the brake pad in the high-power disc brake during braking, the dynamic variation of the brake disc and the brake pad interface variable is considered, the wear calculation model is established based on the friction and wear mechanism, and the wear depth and volume of the brake pad can be calculated by equations. A finite element model of the brake disc and the brake pad is established by DEFORM software which can analyze wear of the brake pad directly. The variation trend of wear during braking is studied, and influences of braking load and initial braking speed on the wear are analyzed. The results show that the amount of the wear increases rapidly in the early wear stage of braking, and it becomes slow in the later stage; the wear of the brake pad is serious at the friction inlet and outlet, and the middle area of the brake pad is lightly worn; heavy braking load and high initial braking speed can exacerbate the wear of the brake pad.

Brake pads of disc brake play an important role in the stable braking process of a large-megawatt wind turbine. There is always vibration, screaming, and severe nonuniform wear under the effect of both retardation pressure and friction. To solve these issues, this article aims to find a new structure of the brake pads to improve brake performance. A multiobjective structure topology optimization method considering thermal-structural coupling and brake vibration is carried out in this article. Based on topology optimization method of Solid Isotropic Microstructures with Penalization (SIMP), the compromise planning theory is applied to meet the stiffness requirement and vibration performance of brake pads. Structure of brake pads is optimized, and both the stiffness and vibration performance of brake pads are also improved. The disadvantages of single-objective optimization are avoided. Thermal-structural coupling analysis is tested with the actual working conditions. The results show that the new structure meets the stiffness requirement and improves the vibration performance well for the large-megawatt wind turbine. The effectiveness of the proposed method has been proved by the whole optimization process.

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With the development of EDM technology, some multimaterial electrodes which have some special functions are regularly taking the place of traditional single material electrodes on some machining occasions and becoming widely used. In this paper, the influence of material on discharge breakdown in EDM with multimaterial electrodes is studied. A comparison model about material influence on discharge breakdown under both single discharge condition and continuous discharge condition is established, and the material property factors affecting the probability of discharge breakdown are also analyzed. Finally, a series of experiments are carried out to study the effects of different electrode materials on the discharge breakdown of EDM, a fitting formula of breakdown probability is presented, and the effectiveness of the comparison model is also verified by comparing with experimental results.