Torsional Spring-Damper
Rotational spring and damper coupling with Coulomb friction, locking, and hard stops
Libraries:
Simscape /
Driveline /
Couplings & Drives
Description
The Torsional Spring-Damper block represents a rotational spring and damper that imposes a combination of internally generated torques between the two connected driveshaft axes, the rod and the case. The block defines the torque using the following behaviors:
Linear damped spring
Coulomb friction (including locking static friction)
Hard-stop compliance
This block is a composite component that consists of these blocks:
Block | Contribution | Library |
---|---|---|
Loaded-Contact Rotational Friction | Coulomb friction | Simscape / Driveline / Brakes & Detents / Rotational |
Rotational Damper | Damping | Simscape / Foundation Library / Mechanical / Rotational Elements |
Rotational Spring | Spring | |
Rotational Hard Stop | Hard stop |
For more information, see Composite Components.
Assumptions and Limitations
Including hard-stop and Coulomb friction enhances model fidelity, but reduces simulation speed. For more information, see Driveline Simulation Performance.
Ports
Conserving
C — Follower port
mechanical rotational
Mechanical rotational port associated with the slider that travels between the stops installed on the case.
R — Base port
mechanical rotational
Mechanical rotational port associated with the rod.
Parameters
Spring-Damper
Spring stiffness — Torsional spring stiffness
1000
N*m/rad
(default) | nonnegative scalar
Torsional spring stiffness that acts on connected driveshafts.
Viscous friction coefficient — Torsional viscous friction
10
N*m/(rad/s)
(default) | nonnegative scalar
Torsional friction that acts on the connected driveshafts.
Coulomb friction torque — Kinetic friction torque
0
N*m
(default) | nonnegative scalar
Constant kinetic friction torque that acts on the connected driveshafts. This constant torque opposes rotation at any velocity.
Ratio of static to kinetic friction — Static friction with respect to kinetic friction
1.1
(default) | positive scalar
Constant ratio of static Coulomb friction torque to kinetic Coulomb friction torque that acts on connected driveshafts. The value must be greater than or equal to one.
Velocity tolerance — Mating driveshaft differential speed tolerance
0.001
rad/s
(default) | positive scalar
Minimum relative angular speed below which the two connected driveshafts can lock and rotate together.
Hard Stops
Hard stop — Simulate boundary hard stops
No hard stops - Suitable for HIL
simulation
(default) | Compliant hard stops
Include or exclude hard-stop torque by selecting one of these options:
No hard stops - Suitable for HIL simulation
— Select this option to enhance simulation speed by excluding the hard-stop torque contribution.Compliant hard stops
— Select this option to enhance model fidelity by including the hard stop torque contribution.
Upper bound — Location of upper hard stop
10
deg
(default) | scalar
Upper hard-stop angular displacement from the zero-torque reference angle. The value must be greater than the Lower bound parameter.
Dependencies
To enable this parameter, set Hard stop to
Compliant hard stops
.
Lower bound — Location of lower hard stop
-10
deg
(default) | scalar
Lower hard-stop angular displacement from the zero spring force reference angle. The value must be less than the Upper bound parameter.
Dependencies
To enable this parameter, set Hard stop to
Compliant hard stops
.
Contact stiffness — Hard stop proportional spring constant
1e6
N*m/(rad/s)
(default) | nonnegative scalar
Hard-stop stiffness. This value only applies if the relative angle moves into the hard-stop region.
Dependencies
To enable this parameter, set Hard stop to
Compliant hard stops
.
Contact damping — Hard stop proportional damping
10
(N*m)/(rad/s)
(default) | positive scalar
Hard-stop damping. This value only applies if the relative angle moves into the hard-stop region. The value must be greater than zero.
Dependencies
To enable this parameter, set Hard stop to
Compliant hard stops
.
Hard stop model — Hard stop transition behavior
Stiffness and damping applied smoothly
through transition region, damped rebound
(default) | ...
Stiffness and rebound options for the hard stop model. The block uses a composite implementation of the Rotational Hard Stop block. You can choose from the following options:
Stiffness and damping applied smoothly through transition region, damped rebound
Full stiffness and damping applied at bounds, undamped rebound
Full stiffness and damping applied at bounds, damped rebound
Based on coefficient of restitution
Dependencies
To enable this parameter, set Hard stop to
Compliant hard stops
.
Transition region — Region of partial hard stop effects
0.001
rad
(default) | positive scalar
Distance from full compression or full extension where the effects of stiffness and
damping are partially applied. When you set Hard stop
model to Stiffness and damping applied
smoothly through transition region, damped rebound
,
the block smoothly transitions the onset of stiffness and damping as the
spring approaches full extension or full compression.
Dependencies
To enable this parameter, set Hard stop to Compliant
hard stops
and Hard stop
model to Stiffness and damping applied
smoothly through transition region, damped
rebound
.
Coefficient of restitution — Ratio of final-to-initial relative speed between slider and stop after collision
0.7
(default) | unitless value between 0 and 1
Ratio of the final to the initial relative speed between the slider and the stop after the slider bounces.
Dependencies
To enable this parameter, set Hard stop to
Compliant hard stops
and
Hard stop model to Based on
coefficient of restitution
.
Static contact speed threshold — Threshold relative speed between slider and stop before collision
0.1
rad/s
(default) | nonnegative scalar
Threshold relative speed between the slider and the stop before
collision. When the slider hits the case with speed less than the value
of this parameter, they stay in contact. Otherwise, the slider bounces.
To avoid modeling static contact between the slider and the case, set
this parameter to 0
.
Dependencies
To enable this parameter, set Hard stop to
Compliant hard stops
and
Hard stop model to Based on
coefficient of restitution
.
Static contact release torque threshold — Threshold force needed to transition from contact mode to free mode
0.001
N*m
(default)
Minimum force needed to release the slider from a static contact mode.
Dependencies
To enable this parameter, set Hard stop to
Compliant hard stops
and
Hard stop model to Based on
coefficient of restitution
.
Initial Conditions
Initial deformation — Starting deformation value
0
deg
(default) | scalar
Initial deformation of the torsional spring relative to the zero-torque reference angle.
More About
Hardware-in-the-Loop Simulation
For the best simulation performance, use the Hard Stops > Hard stop parameter default setting, No hard stops - Suitable for
HIL simulation
.
Extended Capabilities
C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.
Version History
Introduced in R2011aR2023a: Composite Hard Stop Updates
Due to updates in the Rotational Hard Stop block, the Hard stop
model parameter now features the Coefficient of
restitution
option.
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