基于蒙特卡洛法的曲轴结构优化分析

目的:为减轻曲轴质量,对16缸V型柴油机的曲轴进行结构优化。方法:首先,按照柴油机真实的工作环境对曲轴单个曲柄的有限元模型进行边界条件和力的加载,求解获得最大应力及最大位移的数值及位置;然后,建立垂直曲柄中心截面的2D有限元模型,在等效加载的情况下应用ANSYS计算最大应力及位移,计算结果同三维模型进行比较,证明2D截面网格的计算合理性;最后,运用ANSYS PDS模块,基于蒙特卡洛抽样方法,对单位曲柄进行主要尺寸优化。结果:主轴颈直径150 mm、曲柄销直径125 mm、圆角半径4.5 mm时单曲柄质量降低3.37 kg,整个曲轴质量降低26.99 kg,到达优化的目的。结论:证明了二维模型替代三维模型的合理性以及运用蒙特卡洛法进行结构优化的可行性,为今后的曲轴优化提供了参考。

Optimization of Crankshaft Structure based on Monte-Carlo Method

Objective To reduce crankshaft mass and optimize the crankshaft of a V-type 16-cylinder diesel engine. Method First, the load was applied to the finite element model of the single crank and boundary conditions according to the actual working environment of the diesel engine to obtain the value and position of maximum stress and displacement. Second, a 2D finite element model of the vertical interface of the crankshaft center was established; and then the maximum stress and displacement were calculated with ANSYS under equivalent loading conditions. The results were compared with the 3D model to verify that the 2D mesh model was reliable. Finally, based on Monte-Carlo sampling method, main dimension of the unit crankshaft was optimized with ANSYS PDS module. Results When the main journal radius was 150mm, the crankpin radius was 125mm, and the fillet radius was 4.5 mm; the unit crankshaft mass was reduced by 3.37 kg and the entire crankshaft mass was reduced by 26.99 kg. The purpose of optimization was achieved. Conclusion The rationality of replacing 3D model with 2D model instead and the feasibility of using Monte Carlo method to optimize the structure are proved, providing guidance for the future crankshaft optimization.