Elasticity limits structural superlubricity in large contacts

TA Sharp and L Pastewka and MO Robbins, PHYSICAL REVIEW B, 93, 121402 (2016).

DOI: 10.1103/PhysRevB.93.121402

Geometrically imposed force cancellations lead to ultralow friction between rigid incommensurate crystalline asperities. Elastic deformations may avert this cancellation but are difficult to treat analytically in finite and three-dimensional systems. We use atomic- scale simulations to show that elasticity affects the friction only after the contact radius a exceeds a characteristic length set by the core width of interfacial dislocations b(core). As a increases past b(core), the frictional stress for both incommensurate and commensurate surfaces decreases to a constant value. This plateau corresponds to a Peierls stress that drops exponentially with increasing b(core) but remains finite.

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