Contacts

The Contacts component is required to define the options in the Contact Properties section for inter-leaf contacts. METAL_METAL is the default contact. You can add any number of contacts based on the requirement.

The contact force is modeled as an Impact function:

Note: For more information about impact, see the MotionSolve documentation on the IMPACT function.

Contact Properties

The following section explains the options used in Contact Properties.

Clearance: Minimum distance above which no contact force will be applied. It is used to define spacer thickness.
Stiffness: Defines the stiffness of the contact force.
Exponent: Defines the exponent of the force deformation characteristic.
Max. Damping: Defines the maximum damping coefficient.
Max. Penetration Depth: Penetration at which the full damping coefficient is applied.

Friction

Friction data is required only if you select the friction option. It is used for the contact forces in constructing the leaves. The Coulomb model of friction calculates the friction force as the normal force multiplied by the coefficient of friction. This coefficient is calculated as a function of the slip velocity. It does not support stiction. The following explains the parameters used in the Friction option:

Dynamic Friction Coefficient: Defines the coefficient of friction when the slip velocity is greater than the dynamic friction slip speed.
Static Friction Coefficient: Defines the coefficient of friction when the slip velocity is less than the stiction transition slip speed.
Stiction to Transition Slip Speed: Defines the value at which full value of static friction coefficient is used as coefficient of friction.
Dynamic Friction Slip Speed: Defines the value at which full value of dynamic friction coefficient is used as coefficient of friction.

Contact Properties for Leaf Property File (*lpf)

In the Contact Properties block of Leaf Property file, the attribute, type, and valid value that has to be entered in TiemOrbit file format are displayed. This table also provides information about the mandatory requirements for attributes.

An example of how an Contact Properties block is represented in a TiemOrbit file format is shown below:

$-------------------------------------CONTACT_PROPERTIES
[CONTACT_PROPERTIES]
(METAL_METAL)
DYNAMICFRICSLIPSPEED = 0.2
DYNAMICFRICTIONCOEFFICIENT = 0.15
FRICTIONSWITCH = 'OFF'
IMPACTCLEARANCE = 0.0
IMPACTDAMPMAX = 50.0
IMPACTEXPONENT = 2.1
IMPACTPENETRATIONMAX = 0.05
IMPACTSTIFFNESS = 100000.0
STATICFRICTIONCOEFFICIENT = 0.2
STICTIONTRANSITIONSLIPSPEED = 0.1
(METAL_PLASTIC)
DYNAMICFRICSLIPSPEED = 0.2
DYNAMICFRICTIONCOEFFICIENT = 0.15
FRICTIONSWITCH = 'OFF'
IMPACTCLEARANCE = 2.42
IMPACTDAMPMAX = 1.0
IMPACTEXPONENT = 2.1
IMPACTPENETRATIONMAX = 0.005
IMPACTSTIFFNESS = 600.0
STATICFRICTIONCOEFFICIENT = 0.2
STICTIONTRANSITIONSLIPSPEED = 0.1

Block Name = ‘CONTACT_PROPERTIES’ (Required)

Sub-block Name = ‘METAL_METAL’ (Default)

Attributes	Type	Valid Value	Required
impactStiffness	Real	> 0	Yes
impactExponent	Real	> 0	Yes
impactDampMax	Real	> 0	Yes
impactPenetrationMax	Real	> 0	Yes
frictionSwitch	String	'On','OFF'	Optional
dynamicFrictionCoefficient	Real	< 0	Yes
statisFrictionCoefficient	Real	< 0	Yes
stictionTransitionSlipSpeed	Real	-	Yes
dynamicFricSlipSpeed	Real	-	Yes