Publication:
Estimation of rotor blade torsional deformations from measured blade torsion moments

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Authors
Volkin, Ronald S.
Subjects
Rotor Wing Structural Dynamics
Torsional Deflection
Rotor Blade Aeroelasticity
Holzer’s Method
Strain Pattern Analysis
Helicopter Dynamics
Advisors
Wood, E. Roberts
Bousman, William
Date of Issue
2002-03
Date
Publisher
Monterey, California. Naval Postgraduate School
Language
Abstract
The strain pattern analysis (SPA) method is applied to estimate rotor blade torsional deflections. The SPA technique requires calculated mode shapes for the tested rotor blade and strain measurements from the rotor's wind tunnel or flight test. The Holzer method is developed to calculate the required mode shapes from rotor blade stiffness and mass properties and the torsional equation of motion. The Holzer method is tested with numerous theoretical and experimental cases and is proven accurate. The strain measurements are from wind tunnel tests conducted by the Army, NASA, United Technologies Research Center (UTRC) and Sikorsky at DNW with a (1:5.73) model-scale UH-60A rotor blade with an advance ratio of 0.301, an advancing tip Mach number of 0.8224 and an average Reynolds number of 1,278,729. The SPA method predicts slightly larger torsional deflections that compare well with the overall trend and range of UTRC static method integrated deflections. The SPA method was evaluated to determine the tolerance to change in the number of measurements and the modes applied, errors in the measurements, and errors in rotor blade stiffness and mass properties. The method is tolerant to all effects except a decrease in the number of measurements and modes.
Type
Thesis
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Format
xix, 136 p. : ill. ;
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Distribution Statement
Approved for public release; distribution is unlimited.
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This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.
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