Transient thermomechanical deformation of point contacts sliding with dry friction
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The non-linear finite element program Abaqus will be used to simulate transient contact of a steel sphere sliding with friction against a rigid plane. The contact conditions include elastic and elastic/plastic deformation of the sphere. Both isothermal and thermomechanical conditions, i.e. with and without frictional heating are included. The contact radius, pressure distribution and temperature are tracked. From parametric studies, varying load, friction coefficient and material properties, dimensionless relationships will be developed. Comparison between the numerical studies and theoretical work under stricter conditions are made, where possible. Elastic and thermoelastic simulations agree with theory, although thermoelastic instabilities are found under conditions, where they are not normally expected. Under isothermal elastic/plastic conditions, the contact area during static load and sliding is larger than in the elastic case. Under thermoelasto-plastic sliding, we find interactions between thermomechanical instabilities (shrinking of the contact patch), thermal softening and plastic deformation, generally yielding contact sizes that may be somewhat larger than either the thermoelastic or the isothermal elastoplastic cases. We also find unexpected pressure and temperature distributions, even where contact sizes and pressure are close to the Hertzian, thermoelastic or elasto-plastic conditions. The thermomechanical elastic-plastic results can only be obtained by computational approach.