Modeling and experiments of Force-Frequency Shifting with stationary active components

Scott W. Murdoch, Martin W. Trethewey, Leonard L. Koss

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Force Frequency Shifting (FFS) has been developed for low frequency (less that 1 Hz) vibration excitation of large structures (i.e., buildings, bridges, stadiums, ballroom floors, etc.). Initial implementation of the method applied a time variant force to the test structure in a spatially varying fashion. More recent work has demonstrated that low frequency excitation performance gains may be realized through the use of carefully placed stationary components with controllable time variant damping and/or stiffness. This work will present the modeling and experimental results from a subscale laboratory test bed for one such implementation configuration. The FFS design uses a hinged beam supported by an active magneto-rheological damper. A system model is developed and numerically solved in Matlab-Simulink. A subscale hardware prototype of the configuration was designed and constructed. The prototype was instrumented to capture the important component forces, motions and operational parameters. A comprehensive set of experiments was performed and the results compared to the model. The comparison demonstrated that the model was capable of accurately capturing the Force Frequency Shifting phenomena. Further evaluation of the correlated model provides insight into the hardware requirements for a FFS shaker design with active elements that would be suitable for the target structures.

Original languageEnglish (US)
Title of host publicationIMAC-XXIII
Subtitle of host publicationConference and Exposition on Structural Dynamics - Structural Health Monitoring
StatePublished - 2005
Event23rd Conference and Exposition on Structural Dynamics 2005, IMAC-XXIII - Orlando, FL, United States
Duration: Jan 31 2005Feb 3 2005

Publication series

NameConference Proceedings of the Society for Experimental Mechanics Series
ISSN (Print)2191-5644
ISSN (Electronic)2191-5652


Other23rd Conference and Exposition on Structural Dynamics 2005, IMAC-XXIII
Country/TerritoryUnited States
CityOrlando, FL

All Science Journal Classification (ASJC) codes

  • General Engineering
  • Computational Mechanics
  • Mechanical Engineering


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