6.3.2.4. Rotational Spring
A rotational spring represents a physical torsional spring that acts at a point between two different bodies, generating a torque about a rotational axis.
Figure 6.257 RSDA system
6.3.2.4.1. Modeling Options
The user can create a force entity as follows.
Joint
Joint: Selects a revolute joint or a cylindrical joint.
Point, Direction
Point: Selects a point on two bodies to define the location of rotational spring force.
Direction: Defines the direction of z-axis of rotational spring force.
Body, Body, Point, Direction
Body: Selects a base body of rotational spring force.
Body: Selects an action body of rotational spring force.
Point: Selects a point on two bodies to define the location of rotational spring force.
Direction: Defines the direction of z-axis of rotational spring force.
6.3.2.4.2. Properties
Figure 6.258 Rotational Spring property page
The magnitude of the rotational spring force is calculated according to the following equations:
\({{T}_{RS}}=-{{K}_{R}}{{(\theta -{{\theta }_{f}})}^{m}}-{{C}_{R}}{{\dot{\theta }}^{n}}+{{T}_{i}},\text{ }{{T}_{b}}=-{{T}_{a}}\)
Where, the inputs into the equation are defined in the following table:
Stiffness Coefficient (FL/R) |
\({{K}_{R}}\) |
Enter the coefficient that determines spring stiffness, namely the change in the spring force given a change in length (units are force-length/radian). |
Stiffness Spline |
Fill in values of spring rotations and spring torques that cover the range of rotation of the spring. For more information, click here. |
|
Damping Coefficient (FLT/R) |
\({{C}_{R}}\) |
Enter the coefficient that determines the damping force given the rotational velocity of the spring (units are force-length-time/radian) |
Damping Spline |
Fill in values of spring rotational velocities and damping torques that covers the range of positive and negative velocities in the spring. For more information, click here. |
|
Stiffness Exponent |
\({{m}}\) |
Specify an exponent that is applied to the change in angle from the free angle. |
Damping Exponent |
\({{n}}\) |
Specify an exponent that is applied to rotational velocity of the spring (spring velocity). |
Free Angle(PV:R) |
\({{\theta}_{f}}\) |
Enter zero (0) if the rotational spring is defined at its free angle. If the rotational spring is defined with an initial rotation then enter the angle of that rotation. In case of using Parametric Value, the unit of this value is only Radian regardless of the global unit. |
Current Length |
\({{\theta}}\) |
The current angle of rotational spring. |
Pre Torque |
\({{T}_{i}}\) |
Specify the force in the spring at its free angle. |
Angle between Two Markers: Displays the angle between the base marker and action marker.
Force Display: Displays the resultant force vector graphically on Working Window.