The optimum profile modification curve of a gear pair is usually determined according to the fluctuation minimization of static transmission error (STE). For the calculation of STE, the potential energy method dismisses the correlative tooth deflection induced by gear body elastic coupling effects, and the finite element method requires high calculation cost. In order to simultaneously obtain high calculation accuracy and efficiency, the single tooth deflection is calculated through analytical integration about the Hertz contact pressure based on the conformal map method. The correlative tooth deflection is calculated based on the power series solution of the mixed boundary problem of an elastic annulus. Via combination of deflection compatibility and the force equilibrium condition, a contact analysis model of a spur gear pair is built. Based on the model, the STE is first calculated and compared with the finite element analysis result to verify the model rationality. Then, the optimum profile modification curve which renders constant STE is calculated. For a gear pair with the obtained modification curve, fluctuation of dynamic transmission error also decreases and the optimization effect is verified.
A certain type of gearbox is investigated for the problem that the stiffness and damping of bearings are difficult to be accurately determined and then affect the analysis of vibration and noise of gearbox. Firstly, a coupled dynamic lumped parameter model of three-stage helical gear system with consideration of bearing stiffness, bearing damping, and transmission error is established. The modal parameters of gear system are obtained by using the experimental modal analysis method with single-input and multiple-output. The equation for joint parameter identification of gearbox is established which is based on the experimental modal analysis theory and the dynamic lumped parameter model, and subsequently the parameters of the joint are obtained by the least square method. Then, a gear-shaft-bearing-housing coupled dynamic finite element model is developed on the basis of the identified parameters, and after that the dynamic response results of gearbox are solved by using the modal superposition method and compared with the vibration test results. Finally, an acoustic boundary element model of gearbox is established by taking the dynamic response results as the acoustic boundary condition, and the surface sound pressure and radiation noise of gearbox are solved by the boundary element method (BEM), and then the results are compared with the noise test. The results show that the simulation laws and test laws are in good agreement, and thus the method of joint parameter identification, vibration and noise analysis of gearbox is feasible.
The research about internal flowpath optimization of wet friction clutch has significant effect on the reduce of heat generating. Taking the diameter and position of nozzle as design parameters, the maximum and minimum lubricant pressure as constraint conditions, and the RMS of lubricant pressure applied on friction disc and dual plate as objective function, the parametric FEM optimum model of flowpath about clutch is established. Based on the method of second order response surface, the paper sets up the response surface function of objective function by structure parameter, and optimizes the objective function through quadratic programming. The optimized structure of flowpath is obtained, and the rationality of optimization result is verified.
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