基于齿根动应力的船用人字齿轮疲劳分析与优化

为了合理预估人字齿轮齿根动应力疲劳寿命,利用考虑啮合刚度激励、啮合冲击激励和齿面摩擦激励的十二自由度人字齿轮弯-扭-轴耦合动力学模型,同时考虑了参与啮合齿对之间的齿根应力关联性,并由此合理有效地计算出了人字齿轮齿根受拉侧的动应力变化趋势。通过对轮齿疲劳寿命机理分析,选取三种常用载荷工况下小轮齿根中点受拉侧动应力作为疲劳寿命计算对象,采用考虑应力幅值和应力均值双参数的雨流计数法,结合Miner线性累积损伤理论对人字齿轮受拉侧齿根弯曲疲劳寿命进行了预估。同时比较了考察啮合轮齿在进入啮合前其它齿对产生的反向压缩应力对疲劳寿命的影响。通过三维修形技术,对人字齿轮齿面进行了以综合载荷工况下齿根动应力疲劳寿命为目标的优化设计,优化结果表明修形后齿根动应力变化趋势平缓,疲劳寿命增加25%。

FATIGUE ANALYSIS AND OPTIMIZATION OF MARINE HERRINGBONE GEAR BASED ON TOOTH ROOT DYNAMIC STRESS

In order reasonably to estimate herringbone gear fatigue life through the dynamic stress of tooth root, a gear vibration model of 12-degree freedom of herringbone is established, considering meshing stiffness, corner mesh impact, and tooth surface contact friction. Meanwhile, the tooth-root-stress relevance between other meshing teeth is also considered, and the dynamic stress trend of herringbone gear tooth root of the tension side is calculated. The dynamic stress at the mid-point of the pinion tooth root of the tension side under three commonly used load conditions is selected as the fatigue life calculation object by analyzing the theory of tooth fatigue life mechanism. The dynamic stress fatigue life of herringbone gear teeth root is calculated by Miner linear cumulative damage theory and the counting method of two-parameter rain flow, considering stress amplitude and mean stress. The influence is discussed on the fatigue life of the tooth root reverse compressive stress between other meshing teeth. Herringbone gear tooth surface is optimized under tooth dynamic stress fatigue life to the consolidated load conditions by three-dimensional modification technology. The results show that the tooth root dynamic stress trend flattens after modification, and the fatigue life is increased by 25%.