Dynamic Stability of Laminated Composite Twisted Curved Panels (original) (raw)

Parametric Resonance Characteristics of Laminated Composite Twisted Cantilever Panels

2008

The present study deals with the parametric resonance behaviour of laminated composite curved shell panels in a hygrothermal environment using Bolotin's approach. A simple laminated model is developed using first order shear deformation theory (FSDT) for the vibration and dynamic stability analysis of laminated composite shells subjected to hygrothermal conditions. A computer program based on the finite element method (FEM) in a MATLAB environment is developed to perform all necessary computations. Quantitative results are presented to show the effects of curvature, ply-orientations, degree of orthotropy and geometry of laminates on the parametric instability of composite curved shell panels for different temperature and moisture concentrations. The excitation frequencies of laminated composite panels decrease with the increase of temperature and moisture due to reduction of stiffness for all laminates.

Parametric Resonance Characteristics of Angle-Ply Twisted Curved Panels

International Journal of Structural Stability and Dynamics, 2008

The present study deals with the dynamic stability of laminated composite pre-twisted cantilever panels. The effects of various parameters on the principal instability regions are studied using Bolotin's approach and finite element method. The first-order shear deformation theory is used to model the twisted curved panels, considering the effects of transverse shear deformation and rotary inertia. The results on the dynamic stability studies of the laminated composite pre-twisted panels suggest that the onset of instability occurs earlier and the width of dynamic instability regions increase with introduction of twist in the panel. The instability occurs later for square than rectangular twisted panels. The onset of instability occurs later for pre-twisted cylindrical panels than the flat panels due to addition of curvature. However, the spherical pre-twisted panels show small increase of nondimensional excitation frequency.

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.

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.

Vibrations of twisted cantilever plates—a comparison of theoretical results

International Journal for Numerical Methods in Engineering, 1985

Previously published literature shows widely different results for the free vibration frequencies of twisted cantilever plates. Inasmuch as it is important to know the vibration characteristics of turbomachinery blades, which may have considerable twist, it would be desirable to have a comprehensive, definitive set of results, and to establish which of the numerous theoretical methods available can adequately analyse such problems. For this purpose, a joint government/industry/university research study was organized. Numerical results were obtained for a set of 20 different twisted plates having various aspect ratios, thickness ratios and pretwist angles. Nineteen distinct theoretical methods were employed, 15 using finite elements, two using shell theory, and two using beam theory. Although some of the best-known computational procedures (especially finite element codes) were used by analysts with great experience, the numerical results obtained showed considerable disagreement. The present paper describes the analytical methods used and exhibits samples of the type of results obtained.

Comparison of Beam and Plate Theories for Free Vibrations of Metal Matrix Composite Pre-Twisted Blades

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.

Parametric Resonance Characteristics of Laminated Composite Doubly Curved Shells Subjected to Non-Uniform Loading

Journal of Reinforced Plastics and Composites, 2001

The parametric resonance characteristics of laminated composite doubly curved panels subjected to various in-plane static and periodic compressive edge loadings, including partial and concentrated edge loading are studied using finite element analysis. The first order shear deformation theory is used to model the doubly curved panels, considering the effects of transverse shear deformation and rotary inertia. The theory used is the extension of dynamic, shear deformable theory according to the Sander's first approximation for doubly curved laminated shells, which can be reduced to Love's and Donnell's theories by means of tracers. The effects of number of layers, static load factor, side to thickness ratio, shallowness ratio, boundary conditions, degree of orthotropy, ply orientations and various load parameters on the principal instability regions of doubly curved panels are studied in detail using Bolotin's method. Quantitative results are presented to show the effects of shell geometry, lamination details and load parameters on the stability boundaries. Results of plates and cylindrical shells are also presented as special cases and are compared with those available in the literature.

Parametric Resonance Characteristics of Laminated Composite Curved Shell Panels in a Hygrothermal Environment

International Journal of Aeronautical and Space Sciences, 2012

The parametric resonance characteristics of laminated composite doubly curved panels subjected to various in-plane static and periodic compressive edge loadings, including partial and concentrated edge loading are studied using finite element analysis. The first order shear deformation theory is used to model the doubly curved panels, considering the effects of transverse shear deformation and rotary inertia. The theory used is the extension of dynamic, shear deformable theory according to the Sander's first approximation for doubly curved laminated shells, which can be reduced to Love's and Donnell's theories by means of tracers. The effects of number of layers, static load factor, side to thickness ratio, shallowness ratio, boundary conditions, degree of orthotropy, ply orientations and various load parameters on the principal instability regions of doubly curved panels are studied in detail using Bolotin's method. Quantitative results are presented to show the effects of shell geometry, lamination details and load parameters on the stability boundaries. Results of plates and cylindrical shells are also presented as special cases and are compared with those available in the literature.

Analysis of Twisted Composite Plates Using Finite Element Method

2018

Abstract: A numerical study is carries out using finite element method to examine the twisted composite plate by varying the angle of twisting and number of layers in the composite laminate. A cross ply laminate subjected to cantilever boundary conditions with axial load analyzed by varying the twisting angle of the plate from 5 to 45. The variation of axial, normal and shear stresses are evaluated. Further the natural frequency, buckling load factor of the twisted composite plate is estimated with finite element based software ANSYS. It is observed that the varying the twisting angle, number of layers have a substantial influence on structural, natural frequency and buckling load factor of the composite materials.

Theoretical study to calculate the vibration modes of a wind turbine blade with a new composite material

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.