AmontonsCoulombReibung

AmontonsCoulombReibung refers to the classical Amontons–Coulomb model of dry friction, a widely used framework for describing friction between rough surfaces. The model assumes that the friction force is proportional to the normal contact force and is characterized by two coefficients depending on whether the contact is stationary or sliding.

In its simplest form, the tangential friction force Ff satisfies Ff ≤ μN, where N is the normal force and μ is the friction coefficient. When the contact is at rest, the friction can take any value up to μsN, with μs the static friction coefficient. If the tangential forcing exceeds μsN, motion starts and the system enters the sliding regime, where the friction force is approximately μkN opposing the motion, with μk the kinetic friction coefficient. Thus, μ is μs for v = 0 and μk for v ≠ 0.

Historical context: Guillaume Amontons proposed the proportionality of friction to normal load and the independence from apparent contact area in the late 17th century, while Charles-Augustin de Coulomb distinguished static and kinetic friction in the 18th century. The combined Amontons–Coulomb formulation became a standard first-order approximation in engineering and physics.

Assumptions and limitations: The model describes dry, rough contacts and neglects velocity dependence beyond the static/sliding distinction. It treats friction as independent of contact area and surface history, ignoring pre-sliding micro-slip, lubrication, temperature, humidity, and aging effects. The abrupt transition between static and kinetic regimes can produce stick-slip phenomena in some systems.

Applications: It is used in mechanical design, control, and simulations where a simple, robust friction estimate suffices. More advanced models (rate-and-state, velocity-dependent laws) are employed when higher fidelity is required.

---