Effect of Uncertainty on Hub Vibration Response of Composite Helicopter Rotor Blades

DOI: 10.2514/1.44477 In this study, an assessment is made to quantify the influence 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 fiber orientation angles of the laminate structures,andtheelastic-axisoffsetfromtheaerodynamiccenterinthesectionoftheblade.Thestochasticbehavior oftherandomvariablesobtainedfrompreviousexperimentaloranalyticalstudiesareusedtoevaluatethestochastic 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-Nb=rev vibrations. It is observed that the probability histograms of Nb=rev hub vibratory loads exhibit a normal distribution, whereas those of non-Nb=rev hub loads shownon-Gaussian-typedistributions.Numericalresultsshowingtheeffectsofmaterialandgeometricuncertainties on the aeroelastic response and hub vibration behavior of composite rotor blades are illustrated and important conclusions are drawn based on the observations.

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