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Shock Absorber

Spring and damper system that absorbs translational shocks

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  • Shock Absorber block

Libraries:
Simscape / Driveline / Couplings & Drives

Description

The Shock Absorber block represents a spring-damper system that absorbs vibrations. An internal force acts between ports R and C. This force is the sum of spring stiffness, damping, Coulomb friction, and hard-stop contributions. All force contributions are optional.

Diagram of a shock absorber with port R at the opposite end of port C.

The block is a composite of these blocks:

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

Assumptions and Limitations

  • Setting Hard stop to Compliant hard stop or setting Coulomb friction force to a nonzero value enhances model fidelity, but reduces simulation speed. For more information, see Driveline Simulation Performance.

Ports

Conserving

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Mechanical translational conserving port associated with one end of the shock absorber. Positive force acts from port R to port C.

Mechanical translational conserving port associated with one end of the shock absorber. Positive force acts from port R to port C.

Parameters

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Spring-Damper

Value of the spring stiffness constant, k.

Value of the viscous damping constant, b.

Value of the Coulomb friction force. Setting the value to 0 eliminates the Coulomb friction force contribution, which enhances simulation speed and makes the model more suitable for HIL testing.

Value of the ratio of static friction to kinetic friction, Fs/Fk.

Value of the relative velocity below which ports R and C lock and translate together. When the relative velocity is greater than this value, the ports slide relative to one another.

Hard Stops

Whether to model translational hard stops. Select from these options:

  • No hard stops — Suitable for HIL simulation — Enhance simulation speed by excluding the hard-stop force contribution.

  • Compliant hard stops — Enhance model fidelity by including the hard-stop force contribution.

Upper hard-stop position, UB. Positive displacement beyond the upper bound activates the hard-stop contact force. The value must be greater than the Lower bound parameter.

Dependencies

To enable this parameter, set Hard Stop to Compliant hard stops.

Lower hard-stop position, LB. Negative displacement beyond the lower bound activates the hard-stop contact force. The value must be smaller than the Upper bound parameter.

Dependencies

To enable this parameter, set Hard Stop to Compliant hard stops.

Value of the hard-stop stiffness constant, kHS.

Dependencies

To enable this parameter, set Hard Stop to Compliant hard stops.

Value of the hard stop damping constant, bHS. This parameter specifies a dissipating property of colliding bodies. The greater the value of the parameter, the more energy the hard stop dissipates during an interaction.

Dependencies

To enable this parameter, set Hard Stop to Compliant hard stops.

Stiffness and rebound options for the hard stop model. The block uses a composite implementation of the Translational 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

Region where the force ramps up from zero to the full value. At the end of the transition region, the block applies full stiffness and damping.

Dependencies

To enable this parameter, set Hard Stop to Stiffness and damping applied smoothly through transition region, damped rebound.

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.

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.

Minimum torque 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.

Extended Capabilities

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

Version History

Introduced in R2013a

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See Also

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