Multi-state lead-lag damper development and validation

Conor Marr, Zach Fuhrer, George A. Lesieutre, Edward Smith

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


A multi-state lead-lag damper was designed and developed to reduce damper forces when damping is not required. This was achieved via a set of bypass channels that can be opened or closed in order to vary the damper forces. A first generation prototype was built and bench tested to validate the multi-state behavior of the design. Additionally, to predict the damper behavior, an analytical model and a computational fluid dynamics (CFD) model using the commercial program FLUENT® were developed and compared to the experimental data. The prototype damper was bench tested over a range of frequencies and dynamic displacements in both the open and closed configurations. Comparison between the open and closed configurations demonstrated the ability of the bypass channels to reduce damper force by more than 70%, with the capability to widely tune this value by varying the bypass channel diameter. The CFD model allows detailed investigation into the internal flow dynamics of the damper device and is able to capture the shape of the experimental force vs. displacement hysteresis loops. It over predicts damper forces in the closed configuration with an average error in peak force prediction of approximately 30% and slightly under predicts damper forces in the open configuration, though the error in peak force approximation is only around 1%. Prediction errors of the loss stiffness are close to 30%. The analytical model greatly under predicts both the open and closed configurations of the experimental damper. The initial bench testing and CFD study verify the validity of the bypass damper concept, and prove the device ready for the next stage of development and testing.

Original languageEnglish (US)
Title of host publication67th American Helicopter Society International Annual Forum 2011
Number of pages15
StatePublished - Jul 28 2011
Event67th American Helicopter Society International Annual Forum 2011 - Virginia Beach, VA, United States
Duration: May 3 2011May 5 2011

Publication series

NameAnnual Forum Proceedings - AHS International
ISSN (Print)1552-2938


Other67th American Helicopter Society International Annual Forum 2011
Country/TerritoryUnited States
CityVirginia Beach, VA

All Science Journal Classification (ASJC) codes

  • Engineering(all)


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