25.01.2011_07 - Effect of Uncertainty on Hub Vibration...

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Unformatted text preview: Effect of Uncertainty on Hub Vibration Response of Composite Helicopter Rotor Blades Young Hyun You ∗ and Sung Nam Jung † Konkuk University, Seoul 143-701, Republic of Korea Prashant M. Pawar ‡ Shri Vithal Education and Research Institute, Tal-Pandharpur 413 304, India and Eui Sup Shin § Chonbuk National University, Jeonju 561-756, Republic of Korea DOI: 10.2514/1.44477 In this study, an assessment is made to quantify the in fl uence of random material properties and fabrication/ manufacturing uncertainties on the aeroelastic response and hub vibratory loads of composite rotor blades. The random variables include lamina stiffness properties, ply thicknesses and fi ber orientation angles of the laminate structures, and the elastic-axis offset from the aerodynamic center in the section of the blade. The stochastic behavior of the random variables obtained from previous experimental or analytical studies are used to evaluate the stochastic behavior of the cross-sectional stiffnesses of the blades. The uncertainties in the stiffness properties result in the dissimilarity of the rotor system, which brings extra non- N b = rev vibrations. It is observed that the probability histograms of N b = rev hub vibratory loads exhibit a normal distribution, whereas those of non- N b = rev hub loads shownon-Gaussian-type distributions. Numerical resultsshowing theeffects of material andgeometricuncertaintiesshownon-Gaussian-type distributions....
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