ARMD Software: TORSION V6.2

Package for Torsional Vibration Analysis

The torsional vibration package “TORSION V6.2” uses a finite-element based formulation for per­forming damped and undamped torsional natural frequencies, mode shapes, stability, steady-state response, and time-transient response of complete mechanical drive trains. TORSION consists of three modules: TORNAT, TORHRM, and TORRSP integrated by TORSION’s module messenger. The messenger controls the modules to provide a complete torsional vibration analysis environ­ment.

One of TORSION’s important advantages is that the package accepts/imports models generated with the rotor dynamics package ROTLAT. Thus, TORSION can use the ROTLAT models (without bearing influence).

Furthermore TORSION has advanced modeling features and capabilities including the mo­del­ing of multi-shaft and multi-branch systems, coupling stiff­ness and damping, gear tooth flexi­bi­li­ty, stiff­ness / mass / inertia diameter, torsional springs to ground, various types of external excitations containing harmonic parts, syn­chronous motor start-up torque (in­cluding com­plete run-up), dynamic load torques (e.g. by a recip com­pressor), user specified time varying torques, electrical faults and start-up scenarios for motor and generator, and many others.

Among the features incorporated in TORSION package are electrically-induced, time-varying exciting torques associated with genera­tor and induction motor operation that include:

Generator

• 3-phase short circuit
• Line-to-line short circuit
• False coupling short circuit

Induction Motor

• Start from standstill
• 3-phase short circuit at terminals
• 2-phase short circuit at terminals
• High-speed automatic reclosing

TORSION results include:

NATURAL FREQUENCY, MODE SHAPES
(Module “TORNAT”)

• Damped and undamped
• Growth factors and damping ratios
• Vibration mode shapes
• Critical speed map (Campbell diagrams)

STEADY-STATE RESPONSE
(Module “TORHRM”)

• Vibratory amplitudes (displacement, velocity and acceleration)
• Dynamic torques
• Dynamic stresses
• Dynamic heat dissipation

TIME-TRANSIENT RESPONSE
(Module “TORRSP”)

• Dynamic shaft-torque time-history
• Dynamic stresses
• Fatigue life

Detailed information on TORSIONAL VIBRATIONS including advanced engineering service are presented on a special site.

Figures and screenshots provided with kind permission of RBTS / Concepts NREC.