| Generally speaking, tooth failure is the main failure forms of the gear transmission system, and the failure form of the tooth is varied. Fatigue broken teeth occupies the largest percentage in all kinds of failure forms, followed by surface contact fatigue, in a word, fatigue failure is one of the main failure form of the teeth. Therefore, it is necessary to research the fatigue reliability of the gear transmission system. By using analysis method of fatigue reliability that based on stochastic finite element method, the fatigue reliability for the planetary gear transmission system of the offshore oil platformis researched in this paper. During the research, the uncertainty of load, size and material performance parameters is considered. Take the ANSYS finite element software as platform, bending fatigue reliability and contact fatigue reliability for key components of the planetary gear transmission system are calculated in this paper. On this basis, this paper calculated the fatigue reliability of the whole planetary gear transmission system. The details are as follows:(1)The research status of domestic and overseas for the offshore oil platform, large transmission device, fatigue analysis and fatigue reliability analysis are summarized in this paper. At the same time, theory of the mechanical fatigue reliability is described. Then, the research method of fatigue reliability for mechanical products is presented.(2) Taking the planetary gear transmission of the offshore oil platform lift system as example, this paper analyzed its working condition, then, we calculated the speed, power and torque of each component when the transmission is working. At last, we described the research idea and process of the fatigue reliability for planetary gear transmission.(3)Take the ANSYS finite element software as platform, this paper introduced the basic theory knowledge of the finite element static analysis, and provided the process of taking finite element method to analysis issue at the same time. Then, we calculated the static strength for each componentby taking finite element method and traditional method respectively, on this basis, we did comparison and analysis for the finite element result and the traditional result. The result shows that: the static strength of all the part meets the design requirements, but the finite element result is more accurate relatively. This is because the traditional theoretical calculation doesn’t consider the influence of the gear contact ratio.(4)This paper did fatigue reliability analysis for each component on the basis of its static strength analysis. Result shows that: the bending fatigue reliability of the first sun gear, second sun gear and second gear ring is lower than its corresponding contact fatigue reliability when the transmission system is within the design life. Result also shows that: in spite of the bending stress and the contact stress is far less than its allowable stress, its reliability has not reached 100% within the design life. This phenomenon shows that: only static strength analysis for the component is not enough, even though the static strength meets the design requirements, the component may also be failure within its design life. In order to improve the safety and reliability of the component within design life,it is necessary to calculate the reliability of the component. Finally, based on the analysis of fatigue reliability for individual component, this paper calculated the fatigue reliability of the whole planetary gear transmission system during its design life and the whole fatigue reliability is 88.25%. |
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