BALL_RADIUS=Rb

Defines the radius of the ball in a spherical joint for use in friction-force and torque calculations.

Range: BALL_RADIUS > 0

STICTION_TRANSITION_VELOCITY=r

Defines the absolute velocity threshold for the transition from dynamic friction to static friction. If the absolute relative velocity of the joint marker is below STICTION_TRANSITION_VELOCITY, then static friction or stiction acts to make the joint stick.

Range: STICTION_TRANSITION_VELOCITY > 0

EFFECT={ALL[[STICTION, SLIDING]]}

Defines the frictional effects included in the friction model. Stiction is static-friction effect, while sliding is dynamic-friction effect. Excluding stiction in simulations that don’t require it can greatly improve simulation speed.

FRICTION_FORCE_PRELOAD=r

Defines the joint’s preload frictional force, which is usually caused by mechanical interference in the assembly of the joint.

Range: FRICTION_FORCE_PRELOAD > 0

FRICTION_ARM=Rn,

Defines the effective moment arm used to compute the axial component of the friction torque in revolute, Hooke, and universal joints.

Range: FRICTION_ARM > 0

INACTIVE=STATIC

Specifies that frictional forces not be calculated for a static or quasi-static solution.

Range: STATIC

INITIAL_OVERLAP=Xs0

Defines the initial overlap of the sliding parts in either a translational or cylindrical joint. The joint's bending moment is divided by overlap to compute the bending moment's contribution to frictional forces.

Range: INITIAL_OVERLAP > 0

Defines the input forces to the friction model. By default, all user-defined preloads and joint-reaction force and moments are included. You can customize the friction-force model by limiting the input forces you list in the statement.

Joint type: (Available inputs:)
Translational (PRELOAD, REACTION_FORCE, BENDING_MOMENT, TORSIONAL_MOMENT)
Cylindrical, Revolute, Universal, Hooke (PRELOAD, REACTION_FORCE, BENDING_MOMENT)
Spherical (PRELOAD, REACTION_FORCE)

Identifies the JOINT to which frictional forces apply.

Defines the maximum creep that can occur in a joint during the stiction regime. The creep allows Adams Solver (C++) to impose the Coulomb conditions for stiction or static friction, for example:

Friction force magnitude < µstatic * normal force

Therefore, even at zero velocity, a finite stiction force is applied if your system dynamics requires it.

Range: MAX_STICTION_DEFORMATION > 0

Defines the coefficient of dynamic friction during the sliding regime. The magnitude of the frictional force is the product of MU_DYN and the magnitude of the normal force in the joint, for example:

Friction force magnitude, F = µN

where µ = MU_DYNAMIC and N = normal force

The dynamic frictional force acts in the opposite direction of the velocity of the joint.

Range: MU_DYNAMIC > 0

Lists the current values of the FRICTION statement.

Defines the coefficient of static friction in the joint. The magnitude of the frictional force is the product of a function of MU_STATIC, MU_DYNAMIC, and the creep, times the magnitude of the normal force in the joint, for example:

Friction Force Magnitude, F = µN

where µ = ƒ(MU_STATIC, MU_DYNAMIC, creep) and N = normal force

The static frictional force acts to oppose the net force or torque along the degrees of freedom of the joint.

Range: MU_STATIC > 0

To define friction in a sliding joint (either a translational or a cylindrical joint), Adams Solver (C++) computes the overlap of the joint. As the joint slides, the overlap can increase, decrease, or remain constant. OVERLAP_DELTA is used to define any change in overlap.

BENDING_FACTOR = r

Defines the coefficient that multiplies the term Tm/Xs when the BENDING_MOMENT input is used for the friction force computation. This coefficient was hardcoded to 1.0 in releases previous to 2016.

Range: BENDING_FACTOR>0.

Defines the radius of the pin for a revolute, cylindrical, Hooke, or universal joint.

Range: PIN_RADIUS > 0

Defines the effective moment arm of the joint-reaction torque about the translational joint’s axial axis (the z-direction of the joint’s J marker). This value is used to compute the contribution of the torsional moment to the net frictional force.

Range: REACTION_ARM > 0

Defines the preload friction torque in the joint, which is usually caused by mechanical interference in the assembly of the joint.

Range: FRICTION_TORQUE_PRELOAD > 0

I_YOKE and J_YOKE define the rotational constraint on which the FRICTION statement acts. I_YOKE identifies the yoke to the I marker’s rotational constraint. Likewise, J_YOKE identifies the yoke to the J marker’s rotational constraint. These keywords are used with only Hooke and UNIVERSAL joints.

BRISTLE_STIFFNESS_COEFFICIENT = r

Defines the stiffness coefficient of the bristle and is the coefficient in the LuGre formulation.

Default: 1e4

Range: BRISTLE_STIFFNESS_COEFFICIENT > 0

DAMPING_COEFFICIENT = r

Defines the damping coefficient in the rate of microscopic deflection and is the coefficient in the LuGre formulation

Default: 1e2

Range: DAMPING_COEFFICIENT >= 0

VISCOUS_FRICTION_COEFFICIENT = r

Defines the damping coefficient of the viscous component of the friction force and is the coefficient in the LuGre formulation

Default: 0

Range: VISCOUS_FRICTION_COEFFICIENT >= 0

VELOCITY_THRESHOLD_STRIBECK = r

Defines the threshold of the Stribeck velocity and is the vs component in the LuGre formulation

Default: 1e-3

Range: VELOCITY_THRESHOLD_STRIBECK > 0

DECAY_EXPONENT_STRIBECK = r

Defines the exponent of the Stribeck friction decay and is the component in the LuGre formulation

Default: 2

Range: DECAY_EXPONENT_STRIBECK > 0