Effects of spatially uncertain structural properties on helicopter aeroelastic response predictions using high dimensional model representation

Murugan, S., Chowdhury, R., Adhikari, S. and Friswell, M.I. (2011) Effects of spatially uncertain structural properties on helicopter aeroelastic response predictions using high dimensional model representation. In: 52nd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference, Denver, CO, USA, 4-7 Apr 2011, (doi: 10.2514/6.2011-2048)

Abstract

This paper studies the effects of spatially uncertain material properties of composite helicopter rotors on vibratory hub load predictions. The flap, lag and torsional stiffnesses of the rotor blades are considered to vary spatially along the axis of the rotor blades. The spatial uncertainty analysis is performed with rotors modeled as both isotropic rotors and dissimilar rotor systems. In isotropic rotor systems, the uncertainty is considered to be similar for all of the four blades and the uncertainty effects on the 4/rev vibratory hub loads are studied. To reduce the computational expense of uncertainty analysis, a high dimensional model representation (HDMR) method is developed to approximate the vibratory loads as functions of blade stiffness properties modeled as random fields. In the HDMR formulation, a Karhunen-Lo'eve expansion and a low order expansion are used to represent the input and outputs, respectively. Monte Carlo simulations are then performed with the developed HDMR models. The proposed approach decouples the computationally expensive aeroelastic simulations of uncertainty analysis. MCS, performed with computationally less expensive HDMR models, shows that spatial uncertainty has considerable influence on the 4/rev vibratory hub loads. In the uncertainty analysis of dissimilar rotor systems, the spatial uncertainty of each blade of the rotor is assumed to be independent of the other blades. Spatial uncertainties of the rotor with dissimilar blades have considerable influence on the 1/rev and 2/rev vibratory hub loads in addition to the 4/rev vibratory hub loads. The 1/rev and 2/rev harmonics of longitudinal and lateral vibratory hub forces, and 1/rev of vertical vibratory hub force and all three vibratory hub moments are highly sensitive to spatially uncertain material properties.

• Item Type: Conference Proceedings
• Additional Information: Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference, article number AIAA 2011-2048.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Adhikari, Professor Sondipon
• Authors: Murugan, S., Chowdhury, R., Adhikari, S., and Friswell, M.I.
• College/School: College of Science and Engineering > School of Engineering > Infrastructure and Environment
• Journal Name: Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference

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