MotionView User's Guide

Spring Dampers Panel - Properties Tab

Spring Dampers Panel - Properties Tab

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Spring Dampers Panel - Properties Tab

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The Properties tab on the Spring Dampers panel allows you to define the translational or rotational stiffness and damping properties of coil or torsion springs respectively.

coil_spring_properties

Spring Dampers panel - Properties tab

The spring force can be represented through a linear stiffness, a curve based function, a 3D spline, or an expression based function.

For Coil Springs:

Enter:

K Linear

linear stiffness coefficient of the coil spring.  The value entered must be real and positive.

K Curve

spring force transmitted through the spring-damper, expressed in the form of a curve which is a function of an independent variable.

spring_damper_fk_curve

Select AKIMA, CUBIC, LINEAR, or QUINTIC under Interpolation and resolve the curve by clicking on the Curve collector and selecting a 2-D Cartesian curve from the Select a Curve dialog.

Specify an expression under Independent variable.  By default, the independent variable is filled with the expression {sd.DM}, where sd is the variable name of the Spring Damper.

K Spline3D

spring force transmitted through the spring-damper, expressed in the form of a 3D spline which is a function of two independent variables.

spring_damper_k_3dspline_mv

Select AKIMA, CUBIC, LINEAR, or QUINTIC under Interpolation and resolve the 3D spline by clicking on the Spline3D collector and selecting a Spline3D entity from the Select a Spline3D dialog.

Specify an expression each under Independent variable X and Independent variable Z.  By default, the Independent variable X is filled with the expression {sd.DM}, where sd is the variable name of the Spring Damper.

K Expression

spring force transmitted through the spring-damper, expressed in the form of a solver function.

spring_damper_fk_expression

The above panel image shows an example expression where the spring force is a cubic polynomial function depending on distance between the two ends of the spring.

Similarly, the damping force can be represented through a linear damping coefficient, a curve based function, or an expression based function.

C Linear

liner damping coefficient of the coil spring.  The value entered must be real and positive.

C Curve

damping force, expressed in the form of a curve which is a function of an independent variable.

spring_damper_fc_curve

Select AKIMA, CUBIC, LINEAR, or QUINTIC under Interpolation and resolve the curve by clicking on the Curve collector and selecting a 2-D Cartesian curve from the Select a Curve dialog.

Specify an expression under Independent variable.  By default, the independent variable is filled with the expression {sd.VR}, where sd is the variable name of the Spring Damper.

C Spline3D

damping force transmitted through the spring-damper, expressed in the form of a 3D spline which is a function of two independent variables.

spring_damper_c_3dspline_mv

Select AKIMA, CUBIC, LINEAR, or QUINTIC under Interpolation and resolve the 3D spline by clicking on the Spline3D collector and selecting a Spline3D entity from the Select a Spline3D dialog.

Specify an expression each under Independent variable X and Independent variable Z.  By default, the Independent variable X is filled with the expression {sd.VR}, where sd is the variable name of the Spring Damper.

C Expression

damping force transmitted through the coil spring, expressed in the form of a solver function.

spring_damper_fc_expression

In the example shown above, a STEP function is used to vary the damping force with respect to the relative velocity.

For Torsion
Springs:

Enter:

KT Linear

linear rotational stiffness coefficient of a linear torsion spring.  The value entered must be real and positive.

KT Curve

spring torque transmitted through the torsion spring, expressed in the form of a curve which is a function of an independent variable.

Select AKIMA, CUBIC, LINEAR, or QUINTIC under Interpolation and resolve the curve by clicking on the Curve collector and selecting a 2-D Cartesian curve from the Select a Curve dialog.

spring_damper_torsion_prop_tab_kt_curve_mv

Specify an expression under Independent variable.  By default, the independent variable is filled with the expression {sd.AZ}, where sd is the variable name of the Spring Damper.

KT Spline3D

spring force transmitted through the spring-damper, expressed in the form of a 3D spline which is a function of two independent variables.

spring_damper_torsion_prop_tab_kt_spline3d_mv

Select AKIMA, CUBIC, LINEAR, or QUINTIC under Interpolation and resolve the 3D spline by clicking on the Spline3D collector and selecting a Spline3D entity from the Select a Spline3D dialog.

Specify an expression each under Independent variable X and Independent variable Z.  By default, the Independent variable X is filled with the expression {sd.AZ}, where sd is the variable name of the Spring Damper.

KT Expression

spring torque transmitted through the spring, expressed in the form of a solver function.

 

 

CT Linear

linear damping coefficient of the torsion spring.  The value entered must be real and positive.

CT Curve

damping torque, expressed in the form of a curve which is a function of an independent variable.

Select AKIMA, CUBIC, LINEAR, or QUINTIC under Interpolation and resolve the curve by clicking on the Curve collector and selecting a 2-D Cartesian curve from the Select a Curve dialog.

spring_damper_torsion_prop_tab_ct_curve_mv

Specify an expression under Independent variable.  By default, the independent variable is filled with the expression {sd.WZ}, where sd is the variable name of the Spring Damper.

CT Spline3D

damping force transmitted through the spring-damper, expressed in the form of a 3D spline which is a function of two independent variables.

spring_damper_torsion_prop_tab_ct_spline3d_mv

Select AKIMA, CUBIC, LINEAR, or QUINTIC under Interpolation and resolve the 3D spline by clicking on the Spline3D collector and selecting a Spline3D entity from the Select a Spline3D dialog.

Specify an expression each under Independent variable X and Independent variable Z.  By default, the Independent variable X is filled with the expression {sd.WZ}, where sd is the variable name of the Spring Damper.

CT Expression

damping force transmitted through the torsion spring, expressed in the form of a solver function.

Notes:

1.For spring dampers with Linear properties, a Force_SpringDamper statement is written in MotionSolve xml.
2.Use the Curve or Expression type to define a non-linear spring or damper.
3.If a Curve or Expression type is specified for either the spring or damper property, a Force_Scalar_TwoBody statement is written to the MotionSolve xml.  Any Preload specified using the PreLoad tab is not considered.
4.{sd.DM} (where sd is the variable name of the spring damper) traces the distance magnitude of the two spring end points.  The expression is evaluated as DM(i,j), where i is the spring damper marker on Body 1 at Point 1 and j is the spring damper marker on Body 2 at Point 2.
5.{sd.VR} traces the relative radial velocity between the two end points.  The expression is evaluated as VR(i,j).
6.{sd.AZ} traces the relative rotation between the two end points of the spring.  The expression is evaluated as AZ(i,j).
7.{sd.WZ} traces the relative rotational velocity between two end points of the spring.  The expression is evaluated as WZ(i,j).

 

How do I...

Create a 2D Cartesian Curve

Define non-linear properties

Define non-linear properties using expressions

Defining Non-linear Properties Using Curves