Helicopter Blade Stability Analysis Using Aeroelastic Frequency Response Functions

Document Type : Research Paper

Authors
Mostafa Mohagheghi 1
Ali Salehzadeh Nobari 2
Alireza Seyed Roknizadeh 3
1 Faculty of New Sciences and Technologies, Aerospace group, University of Tehran, Iran
2 Department of Aerospace Engineering, Amirkabir University of Technology, Tehran, Iran
3 Engineering Faculty, Department of Mechanical Engineering, Shahid Chamran University of Ahwaz, Iran
10.22055/jacm.2015.11076
Abstract
In the present paper, the aeroelastic stability of helicopter rotor blade is determined using Aeroelastic Frequency Response Function. The conventional methods of aeroelastic stability usually use an iterative procedure while the present method does not require such approach. Aeroelastic Frequency Response Functions are obtained by inverting dynamic stiffness matrix of the aeroelastic system. System response could be obtained through exciting each degree of freedom. The resulting response was then plotted and the behavior of this function was investigated to find out the stability criteria and system natural frequencies. The results of this method are compared with stability boundaries obtained from the conventional p-k method and it can be inferred that, compared to other methods, the present algorithm is of less numerical cost.
Keywords
aeroelastic frequency response function
rotor blade
aeroelastic stability
critical pitch angle
Subjects
[1]. Hassig H. J., “An Approximate True Damping Solution of the Flutter Equation by Determinant Iteration”, Journal of Aircraft, 8(11), pp. 885-890, 1971.
[2]. Imregun M., “Prediction of Flutter Stability Using Aeroelastic Frequency Response Functions”, Journal of Fluids and Structures, 9 (4), pp. 419-434, 1995.
[3]. Roknizadeh, S. A. S., “Stability Analysis of Aeroelastic Systems Based on Aeroelastic FRF and Condistion Number”, Aircraft Engineering and Aerospace Technology, Vol. 84, No. 5, pp. 299-310, 2012.
[4]. Ewins D. J., Modal Testing: Theory, Practice and Application. 2Ed., Research Studies Press, Hertfordshire, England, 2000.
[5]. Hodges D. H. and Dowell E. H., “Nonlinear Equations of Motion for the Elastic Bending and Torsion of Twisted Nonuniform Rotor Blades”, NASA TN D-7818, 1974.
[6]. Hodges D. H. and Ormiston R. A., “Stability of Elastic Bending and Torsion of Uniform Cantilever Rotor Blades in Hover with Variable Structural Coupling”, NASA TN D-8192, 1976.
[7]. Shahverdi H., “Aeroelastic Analysis of Helicopter Rotor Blades Using Reduced Order Aerodynamic Model”, Ph. D. Dissertation, Amirkabir University of Technology, 2006.
[8]. Afagh F. F. and Nitzsche F. and Morozova N., “Dynamic Modeling and Stability of Hingeless Helicopter Blades with a Smart Spring”, The Aeronautical Journal, 108 (1085), pp. 369-377, 2004.
[9]. Nariman M., “Vibration Computation of Helicopter Rotor Blades Using Unsteady Aerodynamic Theory”, M.Sc. Thesis, Amirkabir University of Technology, 2007.
[10]. Gennaretti M. and Molica Colella M. and Bernardini G., “Analysis of Helicopter Vibratory Hub Loads Allevation by Cyclic Trailing-edge Blade Flap Actuation”, The Aeronautical Journal, 113 (1146), pp. 549-556, 2009.
[11]. Johnson W., Helicopter Theory, Princeton University Press, New Jersey, 1980.
[12]. Bielawa R. L., Rotary Wing Structural Dynamics and Aeroelasticity, AIAA Inc., Washington, 1992.
[13]. Sotoodeh Z., “Aeroelastic Analysis of Helicopter Cantilever Rotor Blade with Piters-Hey Induced Flow Model in Hover”, M.Sc. Thesis, Sharif University of Technology, 2007.
[14]. Haddadpour H. and Firouz-Abadi R. D., “True Damping and Frequency Prediction for Aeroelastic Systems: The PP Method”, Journal of Fluids and Structures, 25(7), pp. 1177-1188, 2009.
Journal of Applied and Computational Mechanics
Volume 1, Issue 3 - Serial Number 3
Summer 2015
Pages 152-160