Torsional vibration

The rotational or torsional vibration is a form of mechanical vibrations. In contrast to the translational vibration in the rotational vibration occurs, vibration at the rotational degree of freedom of a system.

General

In the single-mass oscillator, the resulting oscillation period (period ) depends on the stiffness of the torsion spring and the rotational moment of inertia of the coupled rotational mass (see vibration ). In multi- mass oscillator are the torsion springs usually torque transmitting components such as shafts and couplings, between which the rotational inertia ( as gears or flywheels ) are located. In the art rotational oscillations have an important meaning.

Desirable torsional vibrations

Are desirable torsional vibrations in areas where they are needed as a time standard, such as swinging balance in mechanical watches.

Unwanted torsional vibrations

In vehicles or marine propulsion systems with internal combustion engine torsional vibrations are often excited by the torsional vibrations of the crankshaft and must therefore be attenuated accordingly. These torsional vibrations are undesirable (eg in mechanical drive systems ) where they are the cause of component failure, disturbing sound or vibration. The calculation of the torsional vibration characteristics ( natural frequencies, mode shapes ) is therefore a fundamental task in the design of a drive system.

In rail vehicles, the term is used burnishing. Burnishing called torsional vibrations of the two wheels of a wheelset against each other, resulting in a torsional vibration in the axle result. By the torsional vibrations produced wear can be prevented by a protective roller burnishing.

Damping of torsional vibrations

To damper elements such as special elastic couplings (for example, dual-mass flywheel ) or additional flywheel masses ( mass dampers ) are often integrated in the drive train. Torsional vibrations in fact uniformly running systems can be stabilized by means of solenoids which apply oscillations in push-pull.

Simulation of torsional vibrations

In order to develop powertrains better torsional vibrations of an internal combustion engine can be simulated with a rotational vibration generator.