【作者】 何晓华；

【导师】 陈兵奎；

【作者基本信息】 重庆大学 ， 机械设计及理论， 2011， 硕士

【摘要】 20CrMoH渗碳齿轮由于加入了Mo元素而显著提高了材料的淬透性和心部硬度,因而具有较好的工艺性能和传动性能。这种齿轮广泛应用于中、重型汽车传动装置中。齿轮在工作过程中承受较大的载荷,齿轮的弯曲疲劳强度往往是其传动性能的关键技术指标。目前关于20CrMoH渗碳齿轮弯曲疲劳强度的研究尚未见报道。本文的研究主要包括以下几个方面:①针对20CrMoH渗碳齿轮开展单齿弯曲疲劳强度试验。试验采用脉动加载法和成组试验方案,在电磁谐振疲劳试验机上对齿轮轮齿进行了5个应力级的疲劳强度试验。②依据平截面法和折截面法对不同载荷级下的齿根应力进行了计算,并对齿轮试样疲劳断口的宏观形貌进行了分析。③应用概率论与数理统计理论对试验数据进行对数正态分布、二参数威布尔分布和三参数三种概率分布类型的假设检验,分析定应力下20CrMoH渗碳齿轮弯曲疲劳寿命的概率分布形式。④对20CrMoH渗碳齿轮的弯曲疲劳寿命进行可靠性分析,拟合出该齿轮的P - S - N曲线以及不同可靠度下的弯曲疲劳极限应力。⑤结合APDL与齿廓方程,建立了20CrMoH渗碳齿轮参数化的有限元分析模型;基于ANSYS/FE—SAFE、以齿轮的计算齿根应力为基础,进行了齿轮弯曲疲劳强度分析,为齿轮弯曲疲劳强度研究提供了一种新的思路。更多还原

【Abstract】 Because of the chemical element with the symbol Mo can remarkable raise the hardenability of steel, 20CrMoH carburized gear have great processability and transmission performance. This kind of gear is widely used in driving device of medium and heavy vehicle. The gear undertake relatively large load during the working time, so the bending fatigue strength is always the key indicator for the transmission performance. There is no relative research about the bending fatigue strength of 20CrMoH carburized gear so far. Major contents of the thesis as follows:①The test of the single-tooth bending fatigue strength of 20CrMoH carburized gear have been discussed. The test method of pulse load in single-tooth and the group method have been used in the experiment, the bending fatigue strength test of tooth of the gear at 5 classes of constant stress levels was carried out on the electromagnetic resonance testing machine.②By employing planar section method and broken-line method, the root stress of gear teeth under different load levers have been calculated. The macro morphology of fatigue fracture of gear test specimens have been analyzed.③By making use of the probability theory and the principle of statistics, through hypothesis test to the test data in three different forms of probability distribution like log-normal distribution, two-parameter Weibull distribution and three-parameter Weibull distribution, the form of the probability distribution of gear bending fatigue life of 20CrMoH carburized gear have been analyzed under constant stress.④Analyzed the reliability of the bending fatigue strength of 20CrMoH carburized gear. The P - S - N curves of the gear and the limiting bending fatigue stress of gear teeth under different reliability have been achieved.⑤Combined with the equation of tooth profile and Ansys parametric design language(APDL), the parametrized finite element model of gear test specimens was presented. Then on the basis of the tooth root stress of the gear test specimen, the bending fatigue strength of gear have been analyzed based on ANSYS/FE-SAFE. It’s a new approach to evaluate the bending fatigue strength of gear teeth.更多还原