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contact stiffness

Dr. Hanaor - Department of Ceramic Materials - TU Berlin's picture

Contact stiffness of rough surfaces

Contact stiffness of multiscale surfaces by truncation analysis

 

In this concise piece of work, an effective method is shown to gain new understandings into the role of surface structure in the field of contact mechanics. In particular, normal contact stiffness is correlated to parameters of surfaces' fractal dimension and amplitude. 

Nonlinear stiffness for cohesive behaviour

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Hi all,

 Does anyone know how to define nonliner (or exponential) stiffness for cohesive behaviour (for ascending branch before damage)? In CAE it's only allowed to enter one value

 Thanks

 Mo

Surface Roughness and Electrical Contact Resistance

J.R.Barber The contact of rough surfaces Surfaces are rough on the microscopic scale, so contact is restricted to a few `actual contact areas'. If a current flows between two contacting bodies, it has to pass through these areas, causing an electrical contact resistance. The problem can be seen as analogous to a large number of people trying to get out of a hall through a small number of doors.

Classical treatments of the problem are mostly based on the approximation of the surfaces as a set of `asperities' of idealized shape. The real surfaces are represented as a statistical distribution of such asperities with height above some datum surface. However, modern measurement techniques have shown surfaces have multiscale, quasi-fractal characteristics over a wide range of length scales. This makes it difficult to decide on what scale to define the asperities.

Yanfei Gao's picture

Nanoscale incipient asperity sliding and interface micro-slip assessed by the measurement of tangential contact stiffness

Experiments with a multidimensional nano-contact system (Lucas, Hay, and Oliver, J. Mater. Res. 2004) have shown that, prior to kinetic frictional sliding, there is a significant reduction of the tangential contact stiffness relative to the elastic prediction. The reduction occurs at contact sizes below about 50~200nm for aluminum single crystals and several other materials. Using a cohesive interface model, we find that this reduction corresponds to a transition from a small-scale-slip to large-scale-slip condition of the interface.

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