Reliability Analysis Of The Large Parallel Shaft Helical Gear Reducer

The reliability of the gear transmission largely determined the life and performance of the machinery equipment, so analyzing the reliability of the large gear transmission is essential to the safe use of large machinery. In addition, because there are uncertainties in all aspects of structural engineering, whether material or load and size, etc. so, considering the uncertainty in the finite element calculation has become an inevitable trend. By using the reliability analysis method of single components which basing on the stochastic finite element method and the RD new theory,every important component and the whole transmission’s reliability are analyzed here, and the methods have important guiding significance for the reliability analysis of other large-scale transmission. In this paper, strength of the components in a large gear transmission are analyzed firstly in ANSYS, then on the basis of the strength analysis, we analyzed the reliability of the parts and the whole system of this gear transmission, the details are as follows:(1) Describes research status of the large gears, gear research and reliability analysis basing on stochastic finite element method; Then introduced some general content for structural reliability analysis, and summarized the basic theory of reliability analysis basing on the stochastic finite element method, which include four kinds of stochastic finite element method, five kinds of reliability analysis method which basing on the stochastic finite element method for the single components and the new RD theory for the system reliability analysis.(2) Taking the lift system of the offshore oil platform as a example, we analyzed the strength of the components which comprised the gear transmission in ANSYS, among this, the contact strength analysis results of the gears show that whether the double or single tooth meshing engagement, the contact strength are all meeting the design requirements. Besides, according to the results of calculation, The strength of other components are also meeting the design requirements.(3) Analyzed the reliability of the single components in the transmission. Except the contact stress of the first helical gears and the bend stress of the first big gear reliability are relatively small, the rest of the parts is reliable in principle in its lifetime. By calculating, the contact stress reliability of the first helical gears is 83.6%, we can see that, even the strength is meeting the design requirements, the parts is not necessarily entirely reliable in its lifetime, This shows that in the design process, only considering the safety factor in calculation formula is not enough, there is a need for structural reliability design.(4) On the basis of the reliability calculation of the individual components, we analyzed the reliability of the entire system by using the RD new theory, including system analysis and simplified, single component reliability calculation, calculation of primary and secondary correlation coefficient and the reliability calculation of system; By calculation,the reliability of the system is 73.2%.