Modal FEA-EMA CrossMAC analysis of a Bell UH-1H helicopter tail rotor blade using FEA software and open source algorithms

Daniel J.  Winarski; Marc D.  Lamparelli; Tyson Y.  Winarski

doi:10.59400/sv3923

Modal FEA-EMA CrossMAC analysis of a Bell UH-1H helicopter tail rotor blade using FEA software and open source algorithms

Daniel J. Winarski
Independent Researcher, Tucson, AZ 85710, USA
Marc D. Lamparelli
Spectral Dynamics, Technical Support Contractor, Troy, MI 48098, USA
Tyson Y. Winarski
Sandra Day O’Conner College of Law, Phoenix Campus, Arizona State University, Phoenix, AZ 85004, USA

Article ID: 3923

Keywords: helicopter; tail rotor blade; STAR7; modal analysis; Mecway; finite element analysis; GNU Octave; modal assurance criterion

Abstract

Our challenge was the data integration between the output of two disparate commercial software packages, one for analytical finite element analysis and the other for experimental modal analysis. Our primary objective was the augmentation of two existing free open source subroutines with our own programming to create a versatile analysis tool capable of calculating the Cross-Application Modal Assurance Criterion (CrossMAC) comparison of mode shapes between experimental modal analysis and analytical finite element analysis of a stationary tail rotor blade of a Bell UH-1H helicopter. The key contribution of our work was the creation of an original GNU Octave main program with four original subroutines, along with the two existing open source subroutines and one modification to one of these existing subroutines, to integrate the experimental modal analysis done using Spectral Dynamics STAR7 software and the analytical finite element analysis using Mecway. Both the STAR7 and Mecway commercial software packages were chosen because each permitted access by our GNU Octave program to critical node locations and mode shape data for three out-of-plane flapping modes as well as a torsional mode of vibration. By changing from a fixed to an elastic support, and enabling grid refinement, our analytical modal frequencies agreed well with our experimental ones, giving a Pearson correlation of 99.1% between our experimental and analytical data. Our open source software framework and methodology offers an extensible and robust approach for validating experimental modal data against analytical finite element modeling, with direct applicability to a broad diversity of vibration applications.

Published

2026-04-08

How to Cite

Winarski, D. J., Lamparelli, M. D., & Winarski, T. Y. (2026). Modal FEA-EMA CrossMAC analysis of a Bell UH-1H helicopter tail rotor blade using FEA software and open source algorithms . Sound & Vibration, 60(2). https://doi.org/10.59400/sv3923

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Vol. 60 No. 2 (2026): in progress

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

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