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Sunday, February 17, 2013
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Contact Mechanics And Friction
While Classical Mechanics deals solely with bulk material properties Contact Mechanics deals with bulk properties that consider surface and geometrical constraints. It is in the nature of many rheological tools to probe the materials from "outside". For instance,a probe in the form of a pin in a pin-on-disk tester is brought into contact with the material of interest, measuring properties such as hardness, wear rates, etc. Geometrical effects on local elastic deformation properties have been considered as early as 1880 with the Hertzian Theory of Elastic Deformation.1 This theory relates the circular contact area of a sphere with a plane (or more general between two spheres) to the elastic deformation properties of the materials. In the theory any surface interactions such as near contact Van der Waals interactions, or contact Adhesive interactions are neglected. An improvement over the Hertzian theory was provided by Johnson et al. (around 1970) with the JKR (Johnson, Kendall, Roberts) Theory.1 In the JKR-Theory the contact is considered to be adhesive. Hence the theory correlates the contact area to the elastic material properties plus the interfacial interaction strength. Due to the adhesive contact, contacts can be formed during the unloading cycle also in the negative loading (pulling) regime. Such as the Hertzian theory, the JKR solution is also restricted to elastic sphere- sphere contacts.This seminar kit consist of
¡What is Contact Mechanics?
¡The two different kind of contacts.
¡Boussinesq
and Cerruti
Potential Functions
¡The specific case of an Applied Normal
Force
¡Hertz Equations- Derivation, Assumptions
¡Rigid Sphere Contacting a Deformable
Plate
¡Deformable Sphere Contacting a Rigid
Plate
Click Here To Download Full Seminar Kit
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