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Jinhua Liu,Liang Luo,Xuewen Xiao,Chen Zhang,Ling Zhang,Chengji Mi 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.6
In order to optimize the stiffness and strength and modal characteristics of frame in an electric mining dump truck determined by experiential design, the multi-objectives topology optimization is the most frequently used method. However, each single objective satisfaction degree has fuzziness when it comes to solve engineering problems. In this paper, a novel fuzzy multi-objective topology optimization method based on fuzzy satisfaction variable weight coefficients was presented. Based on the variable density method and SIMP interpolation model, the single objective topology optimization design under different conditions was performed. The fuzzy membership function was utilized to measure the sub-objective fuzzy satisfaction degree of frame. The weight factor of each single objective was dynamically assigned through variable weight approach. In consideration of fatigue stress constraint, the fuzzy multi-objectives topology optimization of frame was conducted through OptiStruct solver. The results showed that the stiffness of optimized frame under forward torsion and post torsion and full torsion conditions was improved by 4.7 %, 7.4 % and 5.4 %, respectively, while the stiffness of optimized frame under bending condition was worsened by 2.7 %. The first order natural frequency of optimized frame was improved by 5.6 %.
Chengji Mi,Jidong Liu,Xuewen Xiao,Wentai Li,Xiao Sun,Xingzu Ming,Changyan Tao,Ziyi Ren 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.3
The traditional fatigue design of accessories attached to a train body does not consider welding residual stress for fatigue life prediction of welded structures during the design stage, thereby resulting in insufficient fatigue strength for local welded parts. The power spectral density of random excitation caused by rail irregularity from American six-level spectrums was obtained in this paper. Through welding thermal elastoplastic theory combined with ellipsoid heat source model, a numerical simulation for welding residual stress production and distribution of a train buffer beam was conducted. In accordance with the coupling stress component, the fatigue performance of a train buffer beam under random loads was evaluated by the AA6082 welded joint S–N curve, whose lifetime did not satisfy design requirements. Then, the surrogate model of a train buffer beam for anti-fatigue optimization design was constructed based on the response surface method. The fatigue life of the optimized train buffer beam increased by two orders with the use of the genetic algorithm to find the optimal solution in global variables.