Engee documentation

Rotational Inerter

Inertia in mechanical rotational systems.

rotational inerter

Description

The Rotational Inerter unit is a device that imparts torque proportional to the rate of change in relative angular velocity (angular acceleration) between ports. It is essentially an inertia unit that operates on the velocity difference between ports, rather than the absolute velocity.

This block can be used in models of high performance suspension systems or in modelling a passively tuned response of the mass-spring-shock absorber type.

The block is described by the following equations:

ω

ωωω

where

Torque transmitted through the block

Rotational moment of inertia

ω

Relative angular velocity

ωω

Absolute angular velocities at ports R and C respectively

Positive block direction from port R to port C. This means that the torque is positive if it acts in the direction from R to C.

Ports

R - rod
`rotational mechanics

A mechanical port of rotation associated with a shaft, that is, with a moving body.

C is the body
`rotational mechanics

A mechanical port of rotation associated with a body, that is, a fixed body.

Parameters

Rotational inertance, kg*m^2 - moment of inertia
`1.0 kg*m² (by default)

Coefficient of proportionality between torque and rate of change of relative angular velocity.

Initial value of rotational velocity, rad/s - initial value of angular velocity, rad/s
0.0 (by default)

Initial value of rotational velocity.

Initial value of torque, N*m - initial value of torque
0.0 (By default)

Initial value of torque.