ARMD Software: ROTLAT V6.2

Package for Rotor Dynamic Analysis


Model dedicated to a rotordynamic analysis


The rotor dynamics package “ROTLAT V6.2” uses a finite-element based formu­lation for per­forming damped and un­damped lateral natural fre­quen­cies, mode shapes, stability, un­balance response, and time-transient response of rotating systems. ROTLAT has its own user inter­face and integrates four modules: ROSTAB, ROTORMAP, ROSYNC, and RORESP. The user inter­face controls the modules to provide a complete lateral vibration analysis environ­ment.

ROTLAT permits user selectable output units between CPM or Hz, in accordance with the user’s preference, or the industry stan­dard format, which can be set simply by checking a box in the options form. Also damping para­meter (ratio or log. dec.) can be selected. Full user control for generating critical speed maps with or without speed or gyroscopic effects are provided. Additionally, forces (excitations) such as unbalance considered in synchronous response analysis can be combined with gravita­tional body forces and any externally applied forces and moments in the time transient response simu­la­tions.

Typical ROTLAT application


ROTLAT results include:


(Modules “ROSTAB”+ “ROTORMAP”)

  • Natural frequencies and mode shapes
  • Damped and undamped simulation
  • Stability parameters (damping ratio, logarithmic decrement)
  • Rotor orbit direction (forward/reverse precession)
  • Critical speed map
  • Stability map / Campbell diagrams
  • Bearing reaction forces
  • Shaft weight, deflection, centerline slope, shaft moment, shear, and fiber stress diagrams

ROTLAT analysis and animation of mode shapes


(Module “ROSYNC”)

  • Multiple unbalance planes/forces
  • Magnitude and phase (Bode plot)
  • Dynamic forces and moments
  • Vibratory amplitudes and orbits
  • Forces and moments transmitted to bearing and foundation
  • Foundation vibratory amplitudes
  • API amplification factors

Max. vibratory torques vs. speed


(Module “RORESP”)

  • Gravitational and external forces: multiple sinusoidal, step, ramp, pulse and unbalance
  • Vibratory amplitudes time history
  • Rotor orbits
  • Dynamic forces and moments
  • Dynamic stresses
  • Transmitted forces and moments
  • Pedestal vibratory amplitudes

Time-transient response analysis


Figures and screenshots provided with kind permission of RBTS.