What happens at the microscopic level when two surfaces begin to slide? The transition from static to dynamic friction plays a crucial role in everything from earthquake dynamics to the stability and wear of mechanical systems.
Yet a fundamental question remains: why is the force needed to initiate sliding often greater than the force required to keep surfaces moving? Our research investigates the microscopic contact mechanisms behind this transition.
Using high-resolution fluorescence microscopy, we observed that the real contact area between surfaces can grow during sliding. Since friction nevertheless decreases, this reveals a reduction in the average interfacial shear strength, challenging the idea of a constant friction force per unit contact area.
Understanding frictional interfaces
Stationary interfaces evolve over time, changing the friction force needed to initiate sliding. This behaviour connects frictional contacts to the physics of glassy and jammed materials.
By combining surface profilometry, contact imaging and friction measurements, we investigate how microscopic asperities deform and evolve during sliding.
Explore the research
Discover the experimental findings and underlying physics in our publication.
SCIENCE ADVANCES · 2019 Frictional weakening of slip interfaces Weber et al. Read publication ↗Research contact: Kasra Farain · k.farain@uva.nl