齿轮弯曲疲劳强度及疲劳裂纹扩展研究

发布时间：2018-01-24 11:47

本文关键词： 弯曲疲劳强度疲劳裂纹扩展断面分析分形维数　出处：《河南工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：本课题所研究的大模数齿轮齿条为三峡大坝升船机所用的大模数产品,缺少相关可参考的标准和资料,为突破大模数齿轮齿条设计相关标准及文献资料的局限性,本文主要针对三峡升船机模数为62.7mm的大模数齿条材料35CrNiMo的弯曲疲劳强度和裂纹扩展等进行了相关研究,主要包括以下方面。首先本文进行齿轮弯曲疲劳强度试验研究。采用单齿加载法和成组法试验方案进行试验,对所得的数据进行拟合处理。最终得到齿轮的弯曲疲劳的极限应力值,以及各个应力与循环寿命的关系即P-S-N曲线。其次本文在齿轮弯曲疲劳极限理论的基础上利用断裂力学的理论,着重研究当齿轮出现微小裂纹后其剩余寿命。利用有限元软件和Franc3D进行仿真分析,获得强度应力因子等相关参数,根据仿真所获得的参数预测下一步裂纹的扩展情况,并生成下一步扩展的裂纹,循环迭代直至完全断裂。再次本文对弯曲疲劳强度试验中所产生的弯曲疲劳断齿先做宏观断口分析,然后再对样本做扫描电镜分析,着重研究其裂纹源,以求找到导致该型号齿轮的断裂原因,为预防该裂纹的产生提供依据。最后本文基于分形理论对裂纹扩展的路径进行维数计算,寻找裂纹扩展路径与维数之间的关系。首先利用相机采集整个裂纹扩展的图像,然后利用Matlab软件对所采集到的图像进行处理,把RGB格式的图像处理为二值图。用计盒维数法对二值图进行维数计算,最终得到相应的裂纹分形维数。
[Abstract]:The large modulus gear rack studied in this paper is the large modulus product used in the three Gorges Dam ship lift, and lacks the relevant standards and data. In order to break through the limitation of design standards and literature of large modulus gear rack. In this paper, the bending fatigue strength and crack propagation of 35CrNiMo, a large modulus rack material with a modulus of 62.7 mm for the three Gorges ship lift, are studied. The main contents are as follows. Firstly, the bending fatigue strength of gears is studied in this paper. The single-tooth loading method and group method are used to test the fatigue strength. Finally, the ultimate stress value of gear bending fatigue is obtained by fitting the obtained data. The relationship between each stress and cyclic life is P-S-N curve. Secondly, the theory of fracture mechanics is used on the basis of the bending fatigue limit theory of gear. The residual life of gear with tiny crack is studied emphatically. Using finite element software and Franc3D to simulate and analyze, the relevant parameters such as intensity stress factor are obtained. According to the parameters obtained by simulation, the next crack propagation is predicted, and the crack of the next step propagation is generated. Cycle iteration until complete fracture. Again, the bending fatigue fracture of teeth produced in the bending fatigue strength test is analyzed first, then the sample is analyzed by scanning electron microscope, and the crack source is studied emphatically. In order to find out the cause of the fracture of the gear, and to provide a basis for the prevention of the crack. Finally, based on the fractal theory, the path dimension of the crack propagation is calculated. In order to find the relationship between the crack propagation path and the dimension, the image of the whole crack propagation is collected by the camera, and then the image is processed by the Matlab software. The image of RGB format is processed as a binary graph, and the dimension of the binary graph is calculated by box-counting dimension method, and the corresponding fractal dimension of crack is obtained.
【学位授予单位】：河南工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U642

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