Dynamic Characteristics Analysis and Optimization Design of Tractor Transmission Box
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摘要: 针对重型拖拉机液压机械无级变速器箱体的减振降噪问题,对箱体进行动态特性分析,并运用结构优化方法进行箱体的优化设计。根据箱体的初始设计几何模型,建立箱体壳单元和体单元耦合的有限元模型,进行箱体模态分析和瞬态动力学分析;基于分析结果以箱体的前六阶加权模态频率最大化为目标,运用拓扑和形貌联合优化的方法得到了箱体最优化的材料分布和加强筋分布。分析结果表明:优化后箱体的强度和刚度满足要求,质量减少8.7%,前六阶固有频率都得到提高并且避开了激励频率。该方法为同类变速器箱体的优化设计提供了参考,降低产品设计成本,缩短研发周期。Abstract: This paper focuses on the vibration and noise reduction of the transmission box for hydraulic mechanical continuous variable transmission in tractor. The dynamic characteristics of the transmission box are analyzed, and the optimum design of the box is also carried out with the structural optimization method. According to the geometric model of initial design of the transmission box, the finite element model of the box is developed via coupling between the shell and the solid elements. The modal analysis and transient dynamic analysis of the transmission box are performed. According to the analysis results, the maximization of the weighted natural frequencies of the first six modes is determined as the optimization objective. A combined topology and topography optimization scheme is employed to optimize the distribution of material and stiffener. The simulation results indicate that the strength and stiffness of the transmission box meet the design requirements and the box mass is reduced by 8.7%. Meanwhile, the natural frequencies of the first six modes are improved to avoid the excitation frequencies. This scheme provides a reference for the optimization design of the similar transmission box, which is beneficial to reduce the product design cost and shorten the design cycle.
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Key words:
- tractor /
- transmission box /
- dynamic characteristic /
- topography optimization /
- optimum design
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表 1 箱体前六阶固有频率及振型特征
阶次 固有频率/Hz 振型特征 1 279.09 右箱体底板沿Y方向的弯曲振动 2 300.35 右箱体后板沿X方向的弯曲振动 3 345.42 右箱体顶板沿Y方向的弯曲振动 4 413.03 右箱体底板和后板的弯曲振动 5 428.27 右箱体整体复杂的扭转振动 6 439.86 右箱体底板和后板的弯曲振动 表 2 中间轴输出端轴承孔激励载荷
时间/s X/N 比值 Y/N 比值 Z/N 比值 6.005 4 256 0.98 4 875 1 7 423 0.97 6.008 2 784 0.64 3 012 0.61 5 067 0.66 6.012 2 012 0.46 967 0.19 3 390 0.44 6.015 2 850 0.66 2 803 0.57 5 320 0.69 6.018 4 314 1.00 4 784 0.98 7 619 1.00 6.021 2 698 0.62 3 112 0.63 4 952 0.64 表 3 优化结果对比分析
参数 原始模型 优化后模型 质量/kg 96.6 84.4 最大应力/MPa 140.61 165.9 最大位移/mm 0.339 0.231 1阶频率/Hz 279.09 450.27 2阶频率/Hz 300.35 468.28 3阶频率/Hz 345.42 474.31 4阶频率/Hz 413.03 602.81 5阶频率/Hz 428.27 628.50 6阶频率/Hz 439.86 694.17 -
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