The governing equations together with a solution methodology are given which enables one to effectively handle an EHL line contact problem with simple non-Newtonian fluids including thermal effects. A computational algorithm is proposed that determines the equivalent viscosity as a function of shear strain rate for a specified constitutive equation. It is shown that the method effectively handles Bair-Winer’s rheological equation in its original form and without the need for an approximate perturbation analysis. Among the performance parameters presented are the local behavior of the shear stress as predicted by the Bair-Winer’s model and its comparison to that of the Ree-Eyrings constitutive equation. It is shown that these rheological equations predict a qualitatively similar trend for the traction coefficient. Nevertheless, depending on the operating conditions, the local shear stress as predicted by the Ree-Eyring equation may exceed the material limiting shear stress. A comparison study of the traction coefficient as predicted by the Bair-Winer’s fluid model and actual experimental measurements is also presented. The results are found to be in good quantitative agreement.

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Marine transmission gears usually have large size, and often experience severe working conditions, such as heavy load, large transmission power and high speed ratio, together with the effect of surface asperities, which cause coexisting lubrication-contact state and seriously stress concentration, and further may lead to micro-pitting and fatigue failure. In this paper, the subsurface stress prediction model of the timing transmission spur gears of marine engine is developed, together with considering real 3D machined surface roughness and mixed lubrication-contact state. Results show, when the contact bodies with perfect elastic behavior,the maximum von Mises stress appears on the surface and no longer shows regular distributions along the line of action because of the 3D roughness.The transverse turned surface can reduce the subsurface stress greatly, the shaved and ground surfaces cause large subsurface stress and high-pressure area on the surface. The influence of surface roughness on the stress state is increased under the special conditions of low velocity and high power density, and the contact state is greatly improved by optimizing the parameters of tooth width. Effects of different materials indicate nylon-nylon contact surfaces has the smallest maximum stress compared with that in other four pairs. However, nylon-nylon contact surfaces have the highest friction coefficients, which can easily lead to severe wear or scuffing failures.

The rheological effects of lubricants and the surface deformation of disks are considered in the lubrication of line contacts. The lubrication equation for fluids obeying power law model has been derived. The lubrication equation and the elastic equation have been solved simultaneously within the contact zone by means of the Newton-tangent method. Pressure distributions and film profiles are obtained. The results of this paper show that with the increase of the power law exponent n, the oil film becomes thicker and the position of the cavitation point moves closer to the center of contact.