Meaning
Localized tangential displacement between two contacting surfaces under loads that are insufficient to cause macro-slip defines the partial sliding behavior at a clamped boundary. This phenomenon, known as interface micro-slip, occurs at the microscopic level due to surface roughness. It leads to energy dissipation and mechanical hysteresis in precision joints.
Mechanical Cause
When external forces act on a bolted assembly, the distribution of contact pressure across the joint is never completely uniform. As a result, localized regions of the contact area experience tangential stresses that exceed the local static friction limit while the rest of the joint remains locked. This localized sliding in interface micro-slip areas absorbs mechanical energy and contributes to the damping capacity of assembled structures.
Friction Regime
Fretting wear and localized corrosion often result from sustained small-scale cyclic displacements. As the contact points slide over one another, they wear away protective oxide layers on metal surfaces. To analyze interface micro-slip, engineers use finite element analysis models that calculate local contact stress and tangential compliance.
These calculations assist in optimizing bolt torque and surface finishes to restrict sliding to acceptable limits.
Structural Compliance
Reducing the amplitude of these localized displacements prevents the loss of joint clamp load. Stiffness optimization across the mating surfaces remains the primary method to control interface micro-slip in precision positioning stages.
