Research On The Elastic-plastic Contact Calculation Model Of Rough Surface Asperities For Spur Gear

Gear is the basis of the important transmission parts, with the development of high efficiency and power density, high precision, low noise, micromation and so on. It’s also widely pay attention to the research on the effects of friction on the transmission performance. The micro contact problem is a priority for all problems of friction on gear tooth profiles, it has important significance to explore the failure mechanism of gear contact, such as frictional wear, gear scuffing, crack and so on. So it is necessary to study the contact characteristics from the micro level. Taking the spur gear as the research object, this paper analyzes the contact effect of single and multiple asperities on microscopic state of gear tooth surface. This paper presents a continuous elastic-plastic asperity contact model with or without the consideration of friction to investigate the micro-contact properties of gear tooth profiles. The model for normal or side contact analysis is established according to Hertz contact theory and the asperity morphology feature, which yields to similar results as obtained from the CEB model and the KE model. More importantly, this model avoids the constant average contact stress as predicted by the CEB model, and the noncontinuous contact stress and deformation within the ultimate strength as given by the KE model. As a application of the present theoretical model in micro-contact analysis of rough tooth profiles, a finite element model(FE model) for elastic–plastic asperity in normal or side contact is established according to the measured surface parameters of a spur gear pair. Compared with CEB model, KE model, and FE model, the consistent results are attained by the present theoretical model in elastic–plastic asperity contact analysis. The results indicate that the theoretical model is applicable to the elastic–plastic asperity contact analysis on the rough surface of a spur gear drive. Using CATIA reverse tools and based on the measured gear rough surface morphology parameters to build a 3D model, according to the characters of gear tooth surface morphology the micro gear rough surface contact were equivalent to the contact of a rigid plate and multiple cylinder asperities. Taking three asperities contact as a example, the paper emphatically analyzes the contact properties with different separation distances and different relative height, when three asperities under four conditions. Respectively to explore the contact properties from five aspects such as the distribution of Von Mise stress and relative deformation on contact surface, the distribution of Von Mise stress and relative deformation along normal direction and the total contact area, the results show that the higher peak has a great influence on the contact effect of intermediate asperity, moreover along with the increase of the spacing between asperities the increase of total contact area is nearly linear.