An improved model for meshing characteristics analysis of spur gears considering fractal surface contact and friction

Considering the influence of roughness on the normal contact stiffness of gears, a fractal contact model suited for gear pair contact has been established. On the basis of modified fractal contact model, the asperity contact stiffness is calculated, thus the fractal contact compliance can be obtained. By substituting the nonlinear Hertz contact compliance with the fractal contact compliance, the effects of roughness on the time-varying mesh characteristics (including mesh stiffness (TVMS), loaded static transmission error (STE), load sharing ratio (LSR) and contact stress (CS)) of gears then can be discussed. The numerical simulation results show that the contact stiffness increases with the increment of the fractal dimension and the reduction of the fractal scale characteristic coefficient. In addition, the effect of friction on the mesh characteristics has also been investigated. As the coefficient of friction increases, the variation of the mesh characteristics in the single-tooth engagement region will increase correspondingly. Besides, the influence of multi-parameters on the mesh characteristics of gear pairs has been conducted. It can be found from the parametric studies that the amplitudes of gear mesh stiffness and contact stress are nonlinear with the changes of fractal parameter and friction coefficient.