Rotordynamic Analysis

Industry-Leading Knowledge and Tools

Along with the rotor, the bearings and seals are the most influential components in rotating equipment vibrations. With our deep understanding of bearings and seals, Bearings Plus can develop rotor models, characterize unbalance and destabilizing forces, and recommend solutions to address high vibration and stability issues. The end result: improved overall performance and service life for the equipment.

Our industry-leading analytical tools include transfer matrix, polynomial transfer matrix and finite element–based rotordynamic analysis tools. The accuracy of our analyses and predictions allows us to optimize the dynamic characteristics of bearings and seals for your individual operating system to ensure optimal performance, whether it is for a new bearing design or repair on an existing design.

Example of rotor model for rotordynamic analysis

Torsional, Axial and Lateral Analysis

Torsional, axial and lateral vibrations can each affect the efficiency and reliability of rotating equipment. Torsional vibration is an angular vibration, or twisting, of the shaft. Axial vibration occurs along the axis of rotation. Lateral vibration occurs perpendicular to the axis – side to side or up and down or both.

Upon receipt of the relevant information, our engineers build a rotor model and analyze the bearings and seals using proprietary codes. The customer receives a comprehensive report of the findings, based on the type and scope of analysis performed.

Lateral Rotordynamic Analysis

  • Undamped critical speed (UCS) analysis
  • Damped critical speed analysis
  • Eigenvalue analysis (critical speeds, mode shapes)
  • Unbalance response analysis
  • API stability analysis (level I and II)
  • Bearing and seal optimization
  • ISFD optimization, if needed
  • Brush seal contact-induced stability and unbalance analysis, if needed
Example of lateral rotordynamic analysis plot

Torsional Rotordynamic Analysis

  • Torsional natural frequencies
  • Eigenvalue analysis (critical speeds, mode shapes)
  • Damped torque or stress response analysis, if needed
  • Transient analysis for start-up or short circuit analysis for motor or generator trains
  • Transient torsional stress analysis on critical points (e.g., coupling, rotor)
Example of torsional rotordynamic analysis plot
Steam turbine

Typical Applications

  • Compressors
  • Steam and gas turbines
  • Expanders (radial turbines)
  • Turbochargers
  • Microturbines
  • Motors
  • Generators
  • Pumps
  • Gearboxes
  • Propulsion shafts
  • Blowers
  • Fans


Vibration Solutions

Flexure Pivot tilt pad journal bearing

Flexure Pivot® Journal Bearings

Flexure Pivot tilt pad journal bearings achieve high stability while eliminating pivot wear, high contact stresses and pad flutter that can affect conventional tilt pad designs.

Integral Squeeze Film Damper

Our ISFD technology provides precise stiffness and damping to meet rotordynamic requirements, and is suitable for both new and retrofit installations.

Damper Seals

Bearings Plus damper seal technologies combine leakage control and system damping for reliable rotordynamic operation in high-performance applications.

Related Case Studies

Steam turbine for power generation

Achieving Full Power Output

For a power generation customer in Scandinavia, Doosan Škoda Power engineered a 46 MW steam turbine as part of a combined cycle system. When high subsynchronous vibrations forced a trip in turbine operation at just 27 MW versus the rated 46 MW, Bearings Plus stepped in with a damper solution.
Overhung blower bearing design - Flexure Pivot tilt pad journal bearing with ISFD technology

Increased Production

At the Dow Chemical Company operation in Deer Park, Texas, product buildup on an overhung blower was leading to mass imbalance and high synchronous vibrations that could cause catastrophic failure. The company brought in Bearings Plus to provide a greater stability margin and reduce the sensitivity to imbalance.