Torsional Spring-Damper

R2026b

Rotational spring and damper coupling with Coulomb friction, locking, and hard stops

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  • Torsional Spring-Damper block

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:

BlockContributionLibrary
Loaded-Contact Rotational FrictionCoulomb frictionSimscape / Driveline / Brakes & Detents / Rotational
Rotational DamperDampingSimscape / Foundation Library / Mechanical / Rotational Elements
Rotational SpringSpring
Rotational Hard StopHard stop

For more information, see Composite Components.

Assumptions and Limitations

Ports

Conserving

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Mechanical rotational port associated with the slider that travels between the stops installed on the case.

Programmatic Use

Port: C

Mechanical rotational port associated with the rod.

Programmatic Use

Port: R

Parameters

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Spring-Damper

Torsional spring stiffness that acts on connected driveshafts.

Programmatic Use

Parameter: k

Torsional friction that acts on the connected driveshafts.

Programmatic Use

Parameter: mu_visc

Constant kinetic friction torque that acts on the connected driveshafts. This constant torque opposes rotation at any velocity.

Programmatic Use

Parameter: trq_coulomb

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.

Programmatic Use

Parameter: static_kinetic_ratio

Minimum relative angular speed below which the two connected driveshafts can lock and rotate together.

Programmatic Use

Parameter: w_tol

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.

Programmatic Use

Parameter: model_hardstop
Values: "sdl.enum.hardStopOffOn.off" | "sdl.enum.hardStopOffOn.on"

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.

Programmatic Use

Parameter: upper_bound

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.

Programmatic Use

Parameter: lower_bound

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.

Programmatic Use

Parameter: k_endstop

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.

Programmatic Use

Parameter: D_endstop

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.

Programmatic Use

Parameter: hardstop_model
Values: "simscape.enum.hardstop.smooth" | "simscape.enum.hardstop.fullundamped" | "simscape.enum.hardstop.fulldamped" | "simscape.enum.hardstop.modechart"

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.

Programmatic Use

Parameter: transition

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.

Programmatic Use

Parameter: coeff_rest

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.

Programmatic Use

Parameter: w_tol_hardstop

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.

Programmatic Use

Parameter: trq_tol

Initial Conditions

Initial deformation of the torsional spring relative to the zero-torque reference angle.

Programmatic Use

Parameter: x0

Programmatic Use: Add Block

To add the block programmatically, use the add_block function with one of these library block paths as the source.

"sdl_lib/Couplings & Drives/Torsional Spring-Damper"

Example: add_block("sdl_lib/Couplings & Drives/Torsional Spring-Damper","myModel/myBlock",MakeNameUnique="on")

For information about programmatic access to individual block parameters, see the Programmatic Use section of parameter descriptions on this page.

More About

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Extended Capabilities

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C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2011a

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See Also

Topics