# Rotational Damper

Linear rotational damper

Libraries:
Simscape / Driveline / Couplings & Drives / Springs & Dampers

## Description

The Rotational Damper block models a linear rotational viscous damper. From the start of the simulation, the block uses the nominal damping coefficient. If you enable faults for the block, the damping coefficient changes in response to one or both of these triggers:

• Simulation time — A fault occurs at a specified time.

• Simulation behavior — If the magnitude of the rotational acceleration exceeds a specified maximum value, the block increments the number of shocks by one. A fault occurs if the number of shocks exceeds a specified maximum number of shocks.

If a fault trigger event occurs, the block uses the faulted damping coefficient for the remainder of the simulation. You can program the block to issue a fault report as a warning or error message.

The defining equations are

`$T=D\omega$`

and

`$\omega ={\omega }_{R}-{\omega }_{C},$`

where

• T is the torque transmitted through the damper.

• D is the damping (viscous friction) coefficient.

• ω is the relative velocity.

• ωR and ωC are the absolute velocities of terminals R and C, respectively.

The positive block direction is from port R to port C. Therefore, the torque is positive if it acts in the direction from R to C.

### Thermal Modelling

You can model the effects of heat flow and temperature change by enabling the optional thermal port. To enable the port, set Thermal port to `Model`.

Enabling thermal modelling exposes the Thermal mass parameter.

### 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.

## Ports

### Conserving

expand all

Mechanical rotational conserving port associated with the rod interface.

Mechanical rotational conserving port associated with the case interface.

Thermal conserving port associated with heat flow. Heat flow affects damper temperature, and therefore, power transmission efficiency.

#### Dependencies

To enable this port, set Thermal port to `Model`.

## Parameters

expand all

Main

The oscillation-reducing torque due to viscous friction that the block applies if no trigger event occurs. Specify a value that is greater than or equal to zero.

Faults

To enable the block to use a different damping coefficient based on the simulation time or when the magnitude of the rotational acceleration exceeds the specified number of shocks, select `On`.

#### Dependencies

Selecting `On` makes these parameters visible:

• Faulted damping coefficient

• Enable temporal fault trigger

• Enable behavioral fault trigger

• Reporting when fault occurs

The oscillation-reducing torque due to viscous friction that the block applies if a trigger event occurs. Specify a value that is greater than or equal to zero.

#### Dependencies

This parameter is only visible if you select `On` for the Enable faults parameter.

To enable the block to use the faulted damping coefficient starting at a specified time in the simulation, select `On`.

#### Dependencies

This parameter is only visible if you select `On` for the Enable faults parameter.

Selecting `On` makes the Simulation time for fault event parameter visible.

Specify the time during the simulation that you want the block to start using the faulted damping coefficient.

#### Dependencies

This parameter is only visible if you select `On` for the Enable faults parameter and `On` for the Enable temporal fault trigger parameter.

To use the faulted damping coefficient when the number of sustained shocks exceeds a specified maximum number of shocks, select `On`.

#### Dependencies

This parameter is only visible if you select `On` for the Enable faults parameter.

Selecting `On` makes these parameters visible:

• Maximum permissible acceleration

• Maximum number of shocks

The maximum value that the magnitude of the rotational acceleration can reach without causing the block to increment the number of sustained shocks.

#### Dependencies

This parameter is only visible if you select `On` for the Enable faults parameter and `On` for the Enable behavioral fault trigger parameter.

The maximum number of shocks that can be sustained without triggering the block to use the faulted damping coefficient.

#### Dependencies

This parameter is only visible if you select `On` for the Enable faults parameter and `On` for the Enable behavioral fault trigger parameter.

Select your reporting preference for the fault condition.

#### Dependencies

This parameter is only visible if you select `On` for the Enable faults parameter.

Thermal port

Option to model effects of heat flow and temperature change.

Thermal energy required to change the component temperature by a unit increase. The thermal mass represents the ability of the damper to absorb and retain heat energy.

## Version History

Introduced in R2016b