Loaded-contact friction between two sliding bodies
Brakes & Detents/Translational
The Loaded-Contact Translational Friction block simulates friction between two sliding bodies loaded with a normal force.
The block is implemented as a structural component based on the Fundamental Friction Clutch block. From the locked state, the clutch unlocks if the friction force exceeds the static friction, as defined by the static coefficient of friction and current normal force. For details on how the locking and unlocking are modeled, see the Fundamental Friction Clutch block reference page.
Friction force is transmitted for normal forces larger than the Threshold force parameter.
B and F are translational conserving ports associated with the base and follower, respectively. N is the physical signal terminal through which you import the normal force.
Select how to specify the kinetic friction coefficient. The
Fixed kinetic friction coefficient.
Fixed kinetic friction coefficient —
Provide a fixed value for the kinetic friction coefficient.
The kinetic, or Coulomb, friction coefficient. Must be greater
than zero. The default is
Table lookup kinetic friction coefficient —
Define the kinetic friction coefficient by one-dimensional table lookup
based on the relative angular velocity between disks. If you select
this option, the panel changes from its default.
The static, or peak, value of the friction coefficient. Must
be greater than the kinetic friction coefficient. The default is
Relative velocity below which the two surfaces can lock. For
the surfaces to lock, the force across the B and F translational ports
must be less than the product of the static friction coefficient and
the applied normal force. The default is
From the drop-down list, choose units. The default is meters/second
The normal force applied to the physical signal port N must
exceed the Threshold force parameter value to
be applied to the contact. Forces below the Threshold force are
not applied, and there is consequently no transmitted frictional torque.
The default is
From the drop-down list, choose units. The default is newton
Viscous drag coefficient μvisc for
computing the drag force. The coefficient depends on the type of operating
fluid, fluid temperature, and the maximum distance between the sliding
bodies. The default is
From the drop-down list, choose units. The default is newton/(meters/second)
Select the initial condition applied to the Fundamental Friction Clutch state inside the block:
Locked — Translational
ports B and F are initially locked together. This is the default.
Unlocked — Translational
ports B and F are initially sliding relative to each other.
The block simulates friction between two sliding bodies loaded with a normal force. When the two sliding bodies are not locked, the friction force is determined with the following equations:
Ffr = N · μ· sign(vrel) + Fvisc ,
Fvisc = μvisc · vrel ,
|Fvisc||Viscous drag force|
|μvisc||Viscous drag force coefficient|
The model does not account for body mass. Add mass terms externally to the B and F ports as required.
The model computes the friction force assuming a uniform distribution of the normal force.