Free Vibration Analysis of Rotating Laminated Composite Panels Using Finite Strip Method with Modified Shape Functions (original) (raw)
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Free vibration analysis of rotating laminated composite plate type blades with variable thickness
Materials Today: Proceedings, 2021
The dynamic behaviour of rotating flexible bodies, such as turbine blades/exhaust fan blades are significantly different from those of stationary bodies as centrifugal force come into effect in addition to gravity. Such rotating blades may be modelled as cantilever beam / plate / panel. A finite element formulation for vibration analysis of rotating laminated composite panels is employed in this article; based on the first order shear deformation theory, an accurate relationship between strains and displacements of pre-twisted panels are derived. The governing equations of motion are derived considering centrifugal force. Here studied the effect of rotation speed (x), setting angle (u), twist angle (w), fibre orientation angle (h) and variable thickness of panels on the vibration behaviour of cantilever composite panels. Also noticed the loci veering and loci crossing phenomena occurs between symmetric and skewsymmetric modes, respectively at different rotation speeds.
Finite Element Studies on Free Vibration of Laminated Composite Cylindrical Skew Panels
This paper presents the finite element studiesmade on free vibration of isotropic and laminated composite cylindrical skew panels. A finite element analysis is performed using CQUAD4 and CQUAD8 elements of MSC/NASTRAN software. The effects of the panel angle, skew angle, aspect ratio, and length-to-thickness-ratio on fundamental natural frequency of vibration of isotropic cylindrical skew panels are studied. The effects of additional parameters such as fiber orientation angle, numbers of layers (keeping total thickness constant), and laminate stacking sequence on the fundamental frequency of vibration of antisymmetric composite laminates have also been studied. During validation and convergence study, it is found that the CQUAD8 element yields more accurate results than the CQUAD4 element. Hence the CQUAD8 element has been employed for the remaining part of the investigation.Thefundamental frequency is found to increasewith the panel angle and skewangle.The variation of the fundamental frequency with the number of layers is not appreciable when the number of layers is greater than about 6. It is also seen that the boundary conditions have significant influence on the fundamental frequency.
2014-Finite Element Studies on Free Vibration of Laminated Composite Cylindrical Skew Panels.pdf
This paper presents the finite element studies made on free vibration of isotropic and laminated composite cylindrical skew panels. A finite element analysis is performed using CQUAD4 and CQUAD8 elements of MSC/NASTRAN software. The effects of the panel angle, skew angle, aspect ratio, and length-to-thickness-ratio on fundamental natural frequency of vibration of isotropic cylindrical skew panels are studied. The effects of additional parameters such as fiber orientation angle, numbers of layers (keeping total thickness constant), and laminate stacking sequence on the fundamental frequency of vibration of antisymmetric composite laminates have also been studied. During validation and convergence study, it is found that the CQUAD8 element yields more accurate results than the CQUAD4 element. Hence the CQUAD8 element has been employed for the remaining part of the investigation. The fundamental frequency is found to increase with the panel angle and skew angle. The variation of the fundamental frequency with the number of layers is not appreciable when the number of layers is greater than about 6. It is also seen that the boundary conditions have significant influence on the fundamental frequency.
Computers & Structures, 2016
A method is presented to study the free vibrations of rectangular laminated composite plates with general layups and arbitrary boundary conditions. Based on the first-order shear deformation theory, the governing differential equations and boundary conditions are deduced via Hamilton's principle. Generalised displacements are expanded as series with Legendre polynomials as a base functions. A generalised eigenvalue problem is obtained by following a variational approach, where energy functional is extremised and boundary conditions are introduced by means of Lagrange multipliers. In order to overcome some difficulties in obtaining the natural frequencies and corresponding mode shapes, a new numerical strategy is proposed.
Free Vibration Analysis Of Composite Laminate For Different Simply Supported Boundary Condition
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Study of Free Vibration Analysis of Rectangular Laminated Plate without Cut-Out
IJSTE - International Journal of Science Technology & Engineering, 2018
Composite materials are made from the combination of two or more materials with different chemical and physical properties, which when combined give a new material with enhanced material properties. Our study is concerned with the analysis of free vibration of rectangular plate without cut-out. We study the effects of aspect/size ratio, thickness ratio, and angle of the laminate, number of laminates, material properties and different boundary conditions.
FREE VIBRATION ANALYSIS OF LAMINATED COMPOSITES BY A NINE NODE ISO- PARAMETRIC PLATE BENDING ELEMENT
Composite laminates are being widely used in engineering industry primarily due to their high strength-to-weight ratio. Considerable research has been carried out to understand the static and dynamic behaviour of laminated composite plates. There is much demand for developing efficient finite element codes which can predict the dynamic responses of laminated structures at affordable computational cost. In this paper a nine node isoparametric plate bending element has been used for free vibration analysis of laminated composite plate. The first-order shear deformation theory (FSDT) has been incorporated in the element formulation. Composite plates with different side-to-thickness ratio (a/h), ply orientations and number of layers have been analysed. Based on comparison with literature data, we propose that the present formulation is capable of yielding highly accurate results. Laminated composites with central cutouts are also studied. Novel data is reported for skew laminated composites. It is found that the natural frequency increases with the increase in skew angle (α) and decreases with increase in aspect ratio (b/a) and thickness (h).
Some studies on free vibration of composite laminates
Composite Structures, 1986
Free vibration analysis is carried out to study the vibration characteristics of composite laminates using the modified shear deformation, layered, composite plate theory and employing the Rayleigh-Ritz energy approach. The analysis is presented in a unified form so as to incorporate all different combinations of laminate boundary conditions and with full coverage with regard to the various design parameters of a laminated plate. A parametric study is made using a beam characteristic function as the admissible function for the numerical calculations. The numerical results presented here are for an example case of fully clamped boundary conditions and are compared with previously published results. The effect of parameters, such as the aspect ratio of plates, ply-angle, number of layers and also the thickness ratios of plies in laminates on the frequencies of the laminate, is systematically studied. It is found that for anti-symmetric angle-ply or cross-ply laminates unique numerical values of the thickness ratios exist which improve the vibration characteristics of such laminates. Numerical values of the nondimensional frequencies and nodal patterns, using the thickness ratio distribution of the plies, are then obtained for clamped laminates, fabricated out of various commonly used composite materials, and are presented in the form of the design curves. NOTATION a, b Sides of plates. Aij In-plane stiffness coefficients.
An efficient meshfree method for vibration analysis of laminated composite plates
Computational Mechanics, 2011
A detailed analysis of natural frequencies of laminated composite plates using the meshfree moving Kriging interpolation method is presented. The present formulation is based on the classical plate theory while the moving Kriging interpolation satisfying the delta property is employed to construct the shape functions. Since the advantage of the interpolation functions, the method is more convenient and no special techniques are needed in enforcing the essential boundary conditions. Numerical examples with different shapes of plates are presented and the achieved results are compared with reference solutions available in the literature. Several aspects of the model involving relevant parameters, fiber orientations, lay-up number, length-to-length, stiffness ratios, etc. affected on frequency are analyzed numerically in details. The convergence of the method on the natural frequency is also given. As a consequence, the applicability and the effectiveness of the present method for accurately computing natural frequencies of generally shaped laminates are demonstrated.
The application of FEM is shown for free vibration analysis of moderately thick laminated composite plates with edges elastically restrained against translation and rotation. The governing equations employed are based on the first order shear deformation theory including the effects of rotary inertia. Several combinations of translational and rotational elastic edge constraints are considered. Convergence study with respect to the number of nodes has been carried out and the results are compared with those from past investigations available only for simpler problems. Angle-ply and cross-ply laminates with different thickness-to-length ratios are examined. Comparisons are made with results for thin as well as moderately thick laminated plates.