# 4.17.3. Velocity and Normal Force Dependent Friction¶

frictionModel('VelNormalFrcDep', frnTag, aSlow, nSlow, aFast, nFast, alpha0, alpha1, alpha2, maxMuFact)

This command is used to construct a VelNormalFrcDep friction model object.

 frnTag (int) unique friction model tag aSlow (float) constant for coefficient of friction at low velocity nSlow (float) exponent for coefficient of friction at low velocity aFast (float) constant for coefficient of friction at high velocity nFast (float) exponent for coefficient of friction at high velocity alpha0 (float) constant rate parameter coefficient alpha1 (float) linear rate parameter coefficient alpha2 (float) quadratic rate parameter coefficient maxMuFact (float) factor for determining the maximum coefficient of friction. This value prevents the friction coefficient from exceeding an unrealistic maximum value when the normal force becomes very small. The maximum friction coefficient is determined from μFast, for example $$\mu \leq maxMuFac*μFast$$.