Creating a vibrational digital-twin of a Bell UH-1H helicopter tail-rotor blade for use in simulating centrifugal stiffening

Daniel Winarski; Marc Lamparelli; Keith Landry; Tyson Winarski

doi:10.59400/sv3662

Creating a vibrational digital-twin of a Bell UH-1H helicopter tail-rotor blade for use in simulating centrifugal stiffening

Daniel Winarski Independent Researcher, Tucson, AZ 85710, USA
Marc Lamparelli
Spectral Dynamics, Inc., Troy, MI 48098, USA
Keith Landry Independent Researcher, Savannah, GA 31405, USA
Tyson Winarski Sandra Day O’Connor College of Law, Phoenix Campus, Arizona State University, Phoenix, AZ 85004, USA

Article ID: 3662

Keywords: helicopter; tail-rotor blade; modal analysis; structural dynamics modification; centrifugal-stiffening; mode indicator function; modal assurance criterion; artificial intelligence

Abstract

Our objective was to study the centrifugal stiffening in the tail-rotor of a Bell UH-1H helicopter under operational rotation. Our method involved creating a digital-twin of the vibrations of a stationary model of this tail-rotor blade using empirical modal analysis, and STAR7 software from Spectral Dynamics to process 45 empirical frequency response functions.The results from the STAR7 modal analysis identified three out-of-plane flapping modes as well as a torsional mode of vibration. We assessed our digital-twin via the use of the Modal Assurance Criterion (MAC) as well as comparisons to analytical Euler-Bernoulli beam theory and ANSYS finite element analysis simulations. Then we augmented this stationary model to an operational rotating velocity of 173.2 rad/sec via use of the Structural Dynamics Modification (SDM) feature of STAR7 to enable quantification of the centrifugal stiffening of the tail-rotor across the blade’s primary flapping and torsional modes. We concluded that the first flapping mode of vibration had the most centrifugal stiffening, and the succeeding modes experienced less stiffening as the modal frequency increased, which was consistent with modal energy being relatively constant across these modes. The digital twin approach demonstrated excellent agreement with analytical and numerical models, indicating its effectiveness for evaluating rotational stiffening in helicopter rotor components. Overall, the methodology demonstrated that empirical digital twin construction, combined with SDM techniques, provided a means of predicting the dynamic behavior of helicopter rotor components under rotation. This approach may serve as a foundation for applying artificial intelligence to rotorcraft diagnostics, structural health monitoring, and predictive maintenance.

Published

2025-09-12

How to Cite

Winarski, D., Lamparelli, M., Landry, K., & Winarski, T. (2025). Creating a vibrational digital-twin of a Bell UH-1H helicopter tail-rotor blade for use in simulating centrifugal stiffening. Sound & Vibration, 59(5). https://doi.org/10.59400/sv3662

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Vol. 59 No. 5 (2025)

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Article

This work is licensed under a Creative Commons Attribution 4.0 International License.

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