1 Copyright c 2011 by ASME Proceedings of the ASME 2011 International Mechanical Engineering Congress & Exposition IMECE2011 November 11-17, 2011, Denver, Colorado, USA IMECE2011-62269 FREE VIBRATION ANALYSIS OF ROTATING LAMINATED COMPOSITE PANELS USING FINITE STRIP METHOD WITH MODIFIED SHAPE FUNCTIONS Mohammad Homayoun Sadr Aerospace Engineering Department Amirkabir University of Technology Tehran, Tehran, Iran Sadr@aut.ac.ir Hadi Ghashochi Bargh Aerospace Engineering Department Amirkabir University of Technology Tehran, Tehran, Iran Ghashochi.b@aut.ac.ir Mostafa Khorram Nejadi Aerospace Engineering Department Amirkabir University of Technology Tehran, Tehran, Iran m.khorram5@gmail.com Hoofar Pourzand Aerospace Engineering Department Pennsylvania State University University Park, PA, USA hpourzand@gmail.com ABSTRACT In this paper, free vibration analysis of rotating laminated composite panels is investigated. The formulation is based on the classical laminated plate theory (CLPT), and the method of analysis is the semi-analytical finite strip approach which has been developed on the basis of full energy method with modified shape functions. In the longitudinal direction, the combinations of trigonometric and polynomial functions are used for the out-of-plane displacements, and the trigonometric functions are utilized to estimate the in-plane displacements, to satisfy the kinematic conditions prescribed at the two ends of the strip. Also in the transverse direction, the Hermite cubic shape functions are used for the out-of-plane displacements and the first-order Lagrange shape functions are applied for the in-plane displacements. The panel is considered to be clamped at the rim of a central hub and is free along the other three edges. The effects of different parameters including length/width ratio, number of layers, fiber orientation angles, rotation speed on dimensionless natural frequencies are investigated and discussed in the paper. To check the validity, the results generated by the finite strip procedure are compared with the results of previous studies and finite element code, wherever possible. INTRODUCTION Rotating panels are regularly used as structural components to model blades of wind turbines, steam and gas turbines, satellite panels, helicopter rotors and aircraft propellers. The knowledge of natural frequencies and mode shapes of these structures is essential in the design stages for studying their dynamical behavior on resonance and for flutter analysis. Several researchers have reported different studies on vibration of Rotating panels. An excellent survey of the existing literature in the field of vibration of rotating blades has been done by Leissa et al. [1-4]. Zienkiewicz investigated the effect of shape functions on the natural frequencies of both stationary as well as rotating plate [5]. Rawtani and Dokainish also investigated that with different shape functions [6]. In the recent years, powerful computational methods available by modern computers make possible for researchers to employ more accurate hence complicated methods for vibration analysis of rotating beams and plates, in order to obtain more precise values of natural frequencies and mode shapes [7-14]. In the current paper, free vibration analysis of rotating laminated composite panels is studied. Numerical results are obtained with a finite strip method (FSM) with modified shape functions. In the longitudinal direction, the combinations of trigonometric and polynomial functions are used for the out-of- plane displacements, and the trigonometric functions are utilized to estimate the in-plane displacements, to satisfy the kinematic conditions prescribed at the two ends of the strip. Using this type of shape functions has allowed the energy integrations to be performed analytically in the longitudinal direction. Also in the transverse direction, the Hermite cubic shape functions are used for the out-of-plane displacements and the first-order Lagrange shape functions are applied for the in- plane displacements. The panel is considered to be clamped at