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Study On Improved Algorithm Of The Time-varying Meshing Stiffness Of Gear And Stiffness Excitation

Posted on:2010-05-14Degree:MasterType:Thesis
Country:ChinaCandidate:Y P LiFull Text:PDF
GTID:2132360302460898Subject:Mechanical design and theory
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The gear transmission system is an important part of the mechanical transmission. With the application field extending, more requirements are put forward to the gear system. Further research on the gear dynamics is the necessary way to improve the performance of the transmission system. If we want to get more characteristic of the gear dynamics in the globe aspect and improve the performance of the gear system, we must pay more attention on the parameter of the gear dynamics, especially the parameter of time-varying mesh stiffness is necessary.In this thesis, planetary gear system was studied. Differential equation of planetary gear system was established, according to theory of material mechanics, theory of finite element and theory of gear's time-varying meshing stiffness and the Ishikawa formula, more detail of the parameters were introduced which were refer to in the Ishikawa formula, e.g. effective root diameter, the distance of load. What's more, this paper proposed an improved formula which was used to calculation displace of gear tooth when gears are meshing. And a comparison between the Ishikawa formula result and the improved formula result was show in this paper. CAE was used in order to get the value of displace of gear tooth when gears are meshing. The CAE result is also compared with the result of improved formula. At last, this paper studies on the effect of the stiffness excitation when the gears are meshing.Firstly, this paper set up the lumped parameter physical model of planetary gear according to the theory of the gear dynamics. Then differential equation of planetary was established in accord with physical model. And the significance of time-varying mesh stiffness was pointed out when it take place in the gear dynamics equation.Secondly, this paper introduced the Ishikawa formula concretely, and then this paper gives the solving steps of effective root diameter and the distance of load in detail. A improved formula was give by the paper, this improved formula make up the deficiency of Ishikawa formula. What's more, this paper also introduces the principle of composite stiffness, and the compare was taken between the result of Ishikawa formula and the result of improved formula by an example of the planetary gear system.Thirdly, the explicit dynamic analysis procedure was adopted. According to the planetary gear system which was mentioned above, we simulate the meshing process by the computer. And then we can get the displace curve of one node which was in the mating surface and near by the pitch circle. The node displace curve can be used to instead of the gear tooth displace curve. At last, this paper compares the FEA curve with the improved formula curve.Fourth, this paper introduces a new way which was used to simplify the time-varying mesh stiffness formula. The Fourier decomposition was be used to change the type of the simplify stiffness formula. In the new type of the stiffness formula, we can get the frequency of the sine wave easily, all the sine wave compose the stiffness excitation. this paper analyzes the effect of the stiffness excitation when the gears are meshing. In the process of analysis, this paper use the application of ANSYS and the technology of condition combination, the analysis type is harmonic. The aim of the result analysis focuses on fatigue of the gear tooth.At last, this paper also study on the effect of gear basic parameters on the time-varying gear mesh stiffness. Thought the numerical experiment, this paper have proofed that the stiffness excitation and the gear tooth root stress can be reduced by selecting the suitable gear basic parameters.
Keywords/Search Tags:Planetary transmission system, Ishikawa formula, Effective root diameter, Time-varying mesh stiffness, Stiffness excitation
PDF Full Text Request
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