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Variable Rotational Damper

Rotational damper with variable damping coefficient


Couplings & Drives/Springs & Dampers

  • Variable Rotational Damper block


The block represents a rotational viscous damper with a variable damping coefficient. A physical signal input port provides the magnitude of the damping coefficient. The magnitude of the damping torque is equal to the product of the physical signal input and the relative angular velocity between the two rotational conserving ports, R and C. A minimum damping coefficient prevents non-physical negative damping values.

The damping torque satisfies the following expression:


The parameters are:

  • T — Torque transmitted through damper

  • B — Viscous damping coefficient

  • ω — Relative angular velocity measured between the two rotational conserving ports according to ω=ωRωC

  • ωR — Angular velocity of rotational conserving port R

  • ωC — Angular velocity of rotational conserving port C

The block applies equal and opposite damping torques on the rotational conserving ports. The sign of the damping torque acting on port R is equal to the sign of the relative angular velocity. A positive relative angular velocity corresponds to a positive damping torque acting on port R, and a negative damping torque of equal magnitude acting on port C.

Assumptions and Limitations

  • The block represents only viscous damping

  • The value of the damping coefficient must be equal to or greater than zero.



Physical signal input port representing the variable damping coefficient.


Rotational conserving port.


Rotational conserving port.


Minimum damping coefficient

Minimum value allowed for the damping coefficient. The physical signal input saturates below this level. The parameter must be greater than or equal to zero. The default value is 0 N*m/(rad/s).

Extended Capabilities

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

Introduced in R2013a