A versatile method of discrete convolution and FFT (DC-FFT) for contact analyses

A numerical method for solving rough contact problems based on the multi-level multi-summation and conjugate gradient techniques

Contact modeling of two rough surfaces under normal approach and with relative motion is carried out to predict real area of contact and surface and subsurface stresses affecting friction and wear of an interface. When two macroscopically flat bodies with microroughness come in contact, the contact occurs at multiple asperities of arbitrary shapes, and varying sizes and heights. Deformation at the asperity contacts can be either elastic and/or elastic-plastic. If a thin liquid film is present at the interface, attractive meniscus forces may affect friction and wear. Historically, statistical models have been used to predict contact parameters, and these generally require many assumptions about asperity geometry and height distributions. With the advent of computer technology, numerical contact models of 3-D rough surfaces have been developed, particularly in the past decade, which can simulate digitized rough surfaces with no assumptions concerning the roughness distribution. In this article, a comprehensive review of modeling of multiple-asperity contacts in dry and wet conditions is presented. Contact models for homogeneous and layered, elastic and elastic-plastic solids with and without tangential loading are presented. The models reviewed in this paper fall into two groups: (a) analytical solutions for surfaces with well-defined height distributions and asperity geometry and (b) numerical solutions for real surfaces with asperities of arbitrary shape and varying size and height distributions. Implications of these models in friction and wear studies are discussed.

Contact mechanics of rough surfaces in tribology: multiple asperity contact

This paper present a micro-contact model incorporating asperity interactions in elastic-plastic contact of rough surfaces. The effect of the asperity interactions on the local deformation behavior of a given micro-contact is first modeled based on the Saint-Venant's Principle and Love's Formula. The local contact interference is related in closed form to the local contact load, the global mean pressure and material parameters. This micro-contact model equation is then integrated into the elastic-plastic contact model developed in Zhao et al. (2000) to allow the asperity interactions and plastic deformation to be considered simultaneously. The effects of the asperity interactions on the mean surface separation, the real area of contact and the redistribution of the contact load among contacting asperities of different heights are studied. The results show that the asperity interactions can significantly affect the mean surface separation and microcontact load redistribution. The results also reveal that the effect of asperity interactions can be largely cancelled out by the effect of asperity plastic deformation.

A model of asperity interactions in elastic-plastic contact of rough surfaces

/pdf/quantitative-characterization-of-micro-topography-a-2kb6z20ran.pdf

Quantitative characterization of micro-topography a bibliography of industrial surface metrology

Surface roughness plays an important role in affecting friction, wear, and lubrication of contacting bodies. A small change in the distribution of the asperity heights and widths can have a significant effect on the performance variables which include the real area of contact, the average gap, and the average asperity contact pressure. A series of contact simulations were conducted in order to investigate the effects of the surface topography, material hardness and load on the deformation behavior of the rough surfaces. These surfaces were numerically generated by computer and varied widely in statistical roughness properties, ranging from isotropic to strongly anisotropic. The current simulations took into account the elastic-plastic deformation behavior of the asperities. Using the contact simulation results, the performance variables were curve-fitted to convenient analytical formulas as functions of the surface roughness parameters, material hardness, and load. Presented at the 49th Annual Meeting in ...

Behavior of Elastic-Plastic Rough Surface Contacts as Affected by Surface Topography, Load, and Material Hardness

A series of experiments was conducted for validating a newly developed theory of scuffing. The Critical Temperature-Pressure (CTP) theory is based on the physisorption behavior of lubricants and is capable of predicting the onset of scuffing failures over a wide range of operating conditions, including the contacts operating in the boundary lubrication and in the partial elastohydrodynamic lubrication (EHL) regimes. According to the CTP theory, failures occur when the contact temperature exceeds a certain critical value which is a function of the lubricant pressure generated by the hydrodynamic action of the EHL contact. A special device capable of simulating the ambient conditions of the partial EHL conjunctions (of contact temperature, pressure, and the lubricant pressure) was constructed. A ball-on-flat type wear tester was put inside a pressure vessel, completely immersed in a highly pressurized bath of mineral oil. The temperature on the flat specimen was gradually increased while the ball was slowly...

Si C. Lee

Papers

Behavior of Elastic-Plastic Rough Surface Contacts as Affected by Surface Topography, Load, and Material Hardness

Experimental validation of critical temperature-pressure theory of scuffing