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Translational Spring (PB)

Ideal spring in position-based mechanical translational systems

Since R2024b

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  • Translational Spring (PB) block

Libraries:
Simscape / Foundation Library / Translational / Elements

Description

The Translational Spring (PB) block represents an ideal translational spring. Spring deformation is the difference between length and rest length. Positive deformation increases length.

f=−K⋅δ

δ=length−lengthrest

length=xF−xB

where:

  • f is force transmitted through the spring.

  • K is the spring stiffness.

  • δ is the spring deformation.

  • length is the spring length.

  • lengthrest is the spring rest length.

  • xB and xF are the absolute positions of ports B and F, respectively.

  • power_dissipated is the power dissipated through the damper.

Connections B and F are position-based mechanical translational conserving ports. The spring force acts from port B on port F. Positive spring force drives port F in the positive direction. Positive spring force corresponds to the spring in a state of compression, if length is positive. For more information, see Two-Port Block Orientation and Force Flow Conventions.

Variables

To set the priority and initial target values for the block variables prior to simulation, use the Initial Targets section in the block dialog box or Property Inspector. For more information, see Set Priority and Initial Target for Block Variables.

Nominal values provide a way to specify the expected magnitude of a variable in a model. Using system scaling based on nominal values increases the simulation robustness. Nominal values can come from different sources, one of which is the Nominal Values section in the block dialog box or Property Inspector. For more information, see Modify Nominal Values for a Block Variable.

The correct way to initialize the block depends on its placement in the block diagram:

  • In general, specify any two variables as high-priority targets, for example, Force and Length, or Rest length and Deformation. The exception is Force and Deformation, because these two variables are proportional to each other.

  • If the spring is in series with a known force, specify only Length or Rest length as a high-priority target.

  • If the spring is in parallel with a known length, specify only Force, Deformation, or Rest length as a high-priority target.

  • If the spring is in series with a known force and in parallel with a known length, do not specify any high-priority targets.

Examples

Force Flow in the Position-Based Translational Domain

Force Flow in the Position-Based Translational Domain

Describes how to interpret forces in a Simscape™ position-based mechanical translational network. The example summarizes rules for interpreting the signs of logged forces and then considers forces in three types of systems: springs being pulled or pushed from different ends, simple systems with external forces applied at a mid-point, and a more complex system with an external force applied at the mid-point.

Ports

Conserving

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Position-based mechanical translational conserving port that represents the base connection.

Position-based mechanical translational conserving port that represents the follower connection. For positive length, port F has a more positive position than port B.

Parameters

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Spring rate.

Extended Capabilities

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

Version History

Introduced in R2024b

See Also

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