Free vibration analysis of rotating laminated composite plate type blades with variable thickness (original) (raw)
Related papers
Proceedings of the ASME …, 2011
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.
Vibration characteristics of initially twisted rotating shell type composite blades
Composite Structures, 2004
Vibration analysis of a rotating composite blade is the main purpose of this study. A general formulation is derived for an initially twisted rotating shell structures including the effect of centrifugal force and Coriolis acceleration. In this work, the blade is assumed to be a moderately thick open cylindrical shell that includes the transverse shear deformation and rotary inertia, and is oriented arbitrarily with respect to the axis of rotation to consider the effects of disc radius and setting angle. For a thick shell, we must consider the transverse shear deformation as well as rotary inertia. Thus, based on the concept of the degenerated shell element with the Reissner-Mindlin's assumptions, the finite element method is used for solving the governing equations. In the numerical study, effects of various parameters are investigated: initial twisting angles, thickness to radius ratios, layer lamination and fiber orientation of composite blades. Also, they are compared with the previous works and experimental data.
Dynamic Analysis of Rotating Composite Cantilever Blades with Piezoelectric Layers
2015
Rotating plates in form of turbine blades or machinery parts are often encountered in industrial engineering. The dynamic characteristics of these plates are useful information from design point of view. This paper deals with vibrational analysis of the skew composite plates with piezoelectric layers. In this paper an attempt has been made to study the influence of skew angle and rotational velocity on the free vibration frequencies of a cantilever composite plate with piezoelectric layers. A commercial finite element package ANSYS is used as solver for the problem. The obtained results are compared with existing literature and good convergence in results is seen.
Vibration Analysis of Rotating Composite Beam with Dynamic Stiffness Matrix Method
The turbine, propeller, helicopter blades are idealized as rotating cantilever beams in the analysis of its different characteristics. The motive of this paper is to find the natural frequency of rotating composite beams. In the present work a rotating composite beam is considered and the natural frequencies of the beam are determined using dynamic stiffness matrix method. The Dynamic Stiffness matrix method developed for the homogeneous cantilever beams is implemented to composite cantilever beams. First the effective young's modulus is determined for the composite material. The effective young's modulus is used to predict the frequency of rotating composite beam for various parameters. The results obtained, indicates how the natural frequency is influenced by various parameters such as speed, hub radius and number of layers in composite.
Journal of Sound and Vibration, 1996
Vibration characteristics of pre-twisted metal matrix composite blades are analyzed by using beam and plate theories. A beam element with eight degrees of freedom per node has been developed with torsion-flexure, flexure-flexure and shear-flexure couplings which are encountered in twisted composite beams. In the bean analysis, reduced three-dimensional constitutive relations are used. A triangular plate element presented in the literature is used for the composite material to model the beam as a plate structure. Both the theories have been validated for the isotropic case. This paper summarizes the quantitative comparison of natural frequencies of composite blade obtained by these theories. A parametric study is carried out for both the beam and plate elements results, the parameters being twist angle, fiber orientation, taper ratio and lamination scheme.
Refined Structural Dynamics Model for Composite Rotor Blades
Aiaa Journal, 2001
A re ned one-dimensional beam formulation based on a mixed approach has been developed for structural dynamics analyses of rotating and nonrotating composite beams and blades of general section shape with openor closed-section contours. The theory uses a mixed variational approach and accounts for the effects of elastic coupling, shell-wall thickness, warping, warping restraint, and transverse shear deformations. The analysis is validated against experimental data and other analytical results for composite cantilevered beams of various cross sections. Good correlation is achieved for all of the cases considered. The in uence of wall thickness and transverse shear on the free vibration characteristics of composite beams with either bending-torsion or extension-torsion coupling is investigated. For a bending-torsion coupled beam, the in uence of wall thickness becomes important when the thickness-to-depth ratio of the beam reaches about 30%. The frequency error in neglecting transverse shear exibility is about 50% for a bending-torsion coupled composite box beam with a slenderness ratio of 5.
Dynamic Stability of Laminated Composite Twisted Curved Panels
2006
The twisted cantilever panels have significant applications in wide chord turbine blades, compressor blades, fan blades, particularly in gas turbines. This range of practical applications demands a proper understanding of their vibration, static and dynamic stability characteristics. Due to its significance, a large number of references deal with the free vibration of twisted plates. Structural elements subjected to in-plane periodic forces may lead to parametric resonance, due to certain combinations of the values of load parameters. The instability may occur below the critical load of the structure under compressive loads over wide ranges of excitation frequencies. Composite materials are being increasingly used in turbo-machinery blades because of their specific strength, stiffness and these can be tailored through the variation of fiber orientation and stacking sequence to obtain an efficient design. Thus the parametric resonance characteristics of laminated composite twisted ca...
World Journal of Environmental Research, 2018
A precise understanding of the dynamics of a blade is essential for its design, especially in the development of new structures and the resolution of noise and vibration problems. This understanding involves the study of experimental and/or theoretical modal analysis. These latter present effective tools for describing, understanding and modelling the dynamic aspect of each structure, in the present work, we are going to establish the Eigen-mode of a wind turbine blade made by a new composite material ‘hemp fibre’ using theoretical calculation for flap-wise, edge-wise and torsional mode using the finite element method applied to a structure consisting of a beam embedded at one end, based on the Euler-Bernoulli hypothesis and the equation of beam’s motion. Furthermore; we compare the obtained results with those of composite material made by fibreglass. Keywords: Blade, Eigen-mode, hemp fibre, flap-wise, edge-wise, torsional, fibreglass.
Coupled Vibration Analysis of Composite Wind Turbine Blades
An analytical model for the free vibration of non-uniform, anisotropic, thin-walled wind turbine blade is presented. The blade is constructed from laminated fibrous composite materials with variable thickness and stiffness. The study focuses on the blade spar that represents the main supporting structure within a wind turbine blade. Two specific lay-up configurations; namely, Circumferentially Asymmetric Stiffness (CAS) and Circumferentially Uniform Stiffness (CUS) are analyzed. The transfer matrix method is used to study the vibration behavior of a tapered spar by dividing it into multiple uniform segments, each of which has different length, cross sectional dimensions and material properties. The influence of coupling on the vibration modes is identified and the functional behavior of the frequencies with the lamination parameters is thoroughly investigated and discussed.