# Frictional behavior

 When surfaces are in contact they usually transmit shear as well as normal forces across their interface. There is generally a relationship between these two force components. The relationship, known as the friction between the contacting bodies, is usually expressed in terms of the stresses at the interface of the bodies. The friction models available in Abaqus: include the classical isotropic Coulomb friction model (see Coulomb friction), which in Abaqus: in its general form allows the friction coefficient to be defined in terms of slip rate, contact pressure, average surface temperature at the contact point, and field variables; and provides the option for you to define a static and a kinetic friction coefficient with a smooth transition zone defined by an exponential curve; allow the introduction of a shear stress limit, $τm⁢a⁢x$, which is the maximum value of shear stress that can be carried by the interface before the surfaces begin to slide; include an anisotropic extension of the basic Coulomb friction model; include a model that eliminates frictional slip when surfaces are in contact; include a “softened” interface model for sticking friction in Abaqus/Explicit in which the shear stress is a function of elastic slip; can be implemented with a stiffness (penalty) method, a kinematic method (in Abaqus/Explicit), or a Lagrange multiplier method (in Abaqus/Standard), depending on the contact algorithm used; and can be defined in user subroutines FRIC or FRIC_COEF (in Abaqus/Standard) or VFRIC, VFRICTION, or VFRIC_COEF (in Abaqus/Explicit). In Abaqus/Standard tangential damping forces can be introduced proportional to the relative tangential velocity, while in Abaqus/Explicit tangential damping forces can be introduced proportional to the rate of relative elastic slip between the contacting surfaces (see Contact damping for more information). The following topics are discussed:
 Related Topics About mechanical contact properties In Other Guides FRIC FRIC_COEF VFRIC VFRIC_COEF VFRICTION *FRICTION *CHANGE FRICTION Creating interaction properties

ProductsAbaqus/StandardAbaqus/ExplicitAbaqus/CAE