Browsing by Subject "Sliding friction"

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Open Access
Sliding friction across the scales: Thermomechanical interactions and dissipation partitioning
(Elsevier Ltd, 2016) Temizer, İ.
A homogenization framework is developed for determining the complete macroscopic thermomechanical sliding contact response of soft interfaces with microscopic roughness. To this end, a micro-macro mechanical dissipation equality is first established which enables defining a macroscopic frictional traction. The derivation allows both contacting bodies to be deformable, thereby extending the commonly adopted setting where one of the bodies is rigid. Moreover, it forms a basis for the second step, where a novel micro-macro thermal dissipation equality is established which enables defining partitioning coefficients that are associated with the frictional dissipation as it is perceived on the macroscale. Finally, a comparison of the temperature fields from the original heterogeneous thermomechanical contact problem and an idealized homogeneous one reveals an identification of the macroscopic temperature jump. The computational implementation of the framework is carried out within an incrementally two-phase micromechanical test which delivers a well-defined macroscopic response that is not influenced by purely algorithmic choices such as the duration of sliding. Two-dimensional numerical investigations on periodic and random samples from thermo-viscoelastic boundary layers with unilateral and bilateral roughness demonstrate the temperature-velocity-pressure dependence of the macroscopic contact response. © 2016 Elsevier Ltd. All rights reserved.
Open Access
Tuning macroscopic sliding friction at soft contact interfaces: interaction of bulk and surface heterogeneities
(Elsevier Ltd, 2016) Kılıç, K. İ.; Temizer, İ.
Macroscopic frictional response of soft interfaces is strongly governed by the interaction of surface heterogeneities such as micro-texture features with bulk heterogeneities such as voids or inclusions beneath the highly deformable surface. This microscopic interaction manifests itself on the macroscale as an interface response that is reminiscent of stick-slip. Consequently, the accompanying macroscopic friction signal exhibits strong oscillations around a mean value, which itself significantly differs from its microscopic value due to finite deformations. In this work, a mechanism is proposed which enables the tuning of the macroscopic friction signal of soft interfaces. Specifically, it is demonstrated that optimally positioning subsurface particles in the vicinity of micro-texture features can significantly reduce observed oscillations, thereby allowing control of macroscopic sliding friction. © 2016 Elsevier Ltd