Rotordynamic Tool Suite

The Xdot "Rotordynamics Tool Suite" has been under continuous development since Xdot was founded. This unique suite of Matlab based tools has been developed with two main goals:

  1. Analysis and post-processing automation
  2. Meeting unique client analysis requirements

The analysis and post-processing automation tools are primarily a set of functions to provide an analysis executive which wraps around Dyrobes. This analysis executive allows us to quickly, accurately and efficiently generate a set of results for a particular machine. This is especially valuable in the case of an API analysis, where a large number of plots need to be generated. Likewise, for a steady-state torsional fatigue life analysis, there are a large number of fairly repetitive calculations to be made. In each case, the analysis executive not only makes it more efficient, but drastically reduces the opportunities for error. We believe this set of tools is one of the most sophisticated suites in use by a rotordynamics consultant, and probably is more powerful than most of the heavily automated analysis capabilities in use at large original equipment manufacturers.

Since each machine and application is slightly different, the toolset is readily reconfigurable, and includes enhanced capabilities for nearly all of analyses normally done on a machine. It also has the capability of saving all of the plots that are generated into a Word document for easy inclusion in a report.

One example of the enhanced capabilities is being able to quickly perform a parametric study for nearly any result, changing nearly any model parameter. Some examples include:

  • Torsional natural frequencies versus coupling stiffness (used for coupling tuning)
  • Undamped or damped natural frequencies versus shaft dimensions (used for system design tradeoff studies)
  • Amplification factors and critical speeds versus bearing parameters (used for tuning a squeeze film damper design)
  • Stability versus bearing parameters (used for sensitivity studies)
Lateral Unbalance Response
Lateral Whirlspeed Map

The analysis executive is augmented by a set of Matlab based analyses modules that provide that ability to solve the standard rotordynamic problems (undamped, damped eigenvalues, unbalance response, etc), but with greater control over the mathematical model and solution. These tools are designed to be near-seamless alternatives to analysis using Dyrobes to perform the calculations. These tools allow us to build a model in Dyrobes, export the system matrices to Matlab, then add other model elements to give a combined system model. The approach also allows many of the same set of post-processing routines developed for the analysis executive to be used.

These tools can be used to quickly generate an analysis package for unusual machine configurations, and almost any analysis requirement.

Some examples of ways this capability have been used include:

  • Coupled torsional-lateral analysis (including damped critical speeds, unbalance response, torsional steady-state response)
  • Active magnetic bearing analysis (more...)
  • Zero coupling moment machine train alignment
  • Train torsional analysis with a Voith Vorecon variable speed coupling (undamped natural frequencies, steady-state response and fatigue life, start-up transient)


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