Skip Navigation LinksPendant-Vibration-Analysis




Thomas Instrument is an award winning provider of engineering, manufacturing and repair/overhaul services to major aerospace OEMs (click here to visit Thomas Instrument's website). Thomas Instrument received an order to design and manufacture a replacement winch, and the associated control pendant, for use in the cargo area of a large transport aircraft.

As part of the order, Thomas Instrument was required to demonstrate that the winch and control pendant could meet certain design life requirements when subjected to in-service conditions. One of these requirements stated that they must be able to withstand the vibrations experienced while in-flight. In order to satisfy this requirement, Thomas Instrument was given the option of performing a vibration test using a shaker table or performing a finite element vibration analysis. Thomas Instrument chose the latter and turned to Endesin to perform the analysis. This synopsis details the control pendant analysis. The synopsis for the winch analysis will be posted soon.



The steps used to perform the analysis were as follows

  • CAD models were received from Thomas Instrument in the form of Solid Edge files.
  • The CAD models were simplified to remove any features that did not contribute to the structural integrity of the control pendant or were too small to be meshed reliably.
  • The control pendant components relevant to the dynamic response of the control pendant were meshed using 10-node parabolic tetrahedral elements. These elements were chosen because they have the greatest ability to conform to the curved surfaces prevalent throughout the control pendant components.
  • All other components were treated as beam elements (screws and bolts) or concentrated mass elements (switches and miscellaneous hardware). These elements were connected to the tetrahedral mesh using rigid elements.
  • An area was chosen on the finite element model where the excitation would be applied. The area corresponded to two spring clamps the held the control pendant in place during flight.
  • The first analysis was a resonant frequency analysis to ensure that the resonant frequencies of the control pendant did not lie within the spectrum against which the control pendant was going to be analyzed.
  • Following the resonant frequency analysis, a series of direct frequency response analyses were run to determine the response of the control pendant to the spectrum associated with in-flight conditions.
  • The final analysis was a fatigue analysis whereby the maximum stress experienced by the control pendant for any of the direct frequency response analyses was used to determine the minimum fatigue life of the control pendant for the given spectrum.



The analysis was completed using NX Advanced Simulation for pre and post processing and the solver was NX Nastran.



Given the option of performing a Finite Element Analysis in place of physical testing, Thomas Instrument turned to Endesin and was able to verify the vibrational properties of their design and ensure its integrity in-flight. The winch and control pendant will be in service soon.