Buckling Of Composite Plates Research Articles

Buckling analysis of CNTRC plates in the thermal environment based on combination of the incremental load technique and dynamic relaxation method

In this article, the buckling of composite plates reinforced with functionally graded distributions of single-walled carbon nanotubes along the thickness direction are studied in the thermal surroundings. The properties of carbon-nanotubes reinforced composite (CNTRC) plate were determined through the modified rule of mixture. All governing equations are obtained incrementally based on first-order shear deformation theory and von Karman nonlinear strain. The nonlinear equilibrium equations are solved through a combination of dynamic relaxation and incremental load methods. A detailed parametric study is carried out to investigate the buckling load of nanocomposite plates with different boundary conditions.

Mechanical Stability Investigation of Advanced Composite Plates Resting on Elastic Foundations Using a New Four-Unknown Refined Theory

A refined and simple shear deformation theory for mechanical buckling of composite plate resting on two-parameter Pasternak’s foundations is developed. The displacement field is chosen based on assumptions that the in-plane and transverse displacements consist of bending and shear components, and the shear components of in-plane displacements give rise to the parabolic variation of shear strain through the thickness in such a way that shear stresses vanish on the plate surfaces.Therefore, there is no need to use shear correction factor. The number of independent unknowns of present theory is four, as against five in other shear deformation theories.It is assumed that the warping of the cross sections generated by transverse shear is presented by a hyperbolic function. The stability equations are determined using the present theory and based on the existence of material symmetry with respect to the median plane.The nonlinear strain-displacement of Von Karman relations are also taken into consideration. .The boundary conditions for the plate are assumed to be simply supported in all edges. Closed-form solutions are presented to calculate the critical load of mecanical buckling, which are useful for engineers in design. The effects of the foundation parameters,side-to-thickness ratio and modulus ratio, the isotropic and orthotropic square plates are considered in this analysis.are presented comprehensively for the mechanical buckling of rectangular composite plates.

Thermal buckling of temperature-dependent composite super elliptical plates reinforced with carbon nanotubes

ABSTRACTIn this work, the problem of thermal buckling of composite plates reinforced with carbon nanotubes (CNTs) is investigated. Distribution of CNTs as reinforcements through the thickness direction of the plate is assumed to be either uniform or functionally graded (FG). Properties of the reinforcement and matrix are both temperature dependent. Properties of the composite media are obtained according to a refined rule of mixture approach where the efficiency parameters are introduced. The plate is in a super elliptical shape where the simple elliptical shape and rectangular shapes are obtained as especial cases. In these types of plates due to the round corners, stress concentration phenomenon is eliminated. Based on the Ritz method where the shape functions are of the polynomial type, the governing equations are obtained. These equations are solved using an iterative eigenvalue problem since the properties are temperature dependent. Numerical results are validated for the simple case of an isotropic plate. Novel numerical results are provided for plates reinforced with CNTs in different shapes, various volume fractions and different patterns of CNT distribution. It is shown that FG-X pattern of CNTs in matrix results in the maximum critical buckling temperature.

Buckling of cross-ply composite plates with linearly varying In-plane loads

Buckling of composite plates with linearly varying in-plane loads has been studied. Loaded edges are assumed as simply supported and the remaining ones are arbitrary. First order and third order shear deformation plate theories are used in the formulation of the problem. Ritz method has been utilized with simple polynomials in displacement field. By modifying displacement field components, the continuity of transverse stresses is satisfied among the layers of cross-ply symmetric lay-up composite plates. Results are obtained for different material, geometrical properties and loading conditions.

Buckling analysis of circular and annular composite plates reinforced with carbon nanotubes using FEM

The critical compressive load in the buckling of circular and annular composite plates reinforced with carbon nanotubes (CNTs) is calculated using finite element method. The developed model is based on the third-order shear deformation theory for moderately thick laminated plates. Effects of CNTs orientation angles and thickness-to-inner radius ratio on the buckling of composite plates are discussed. The results are compared with those obtained by analytical method based on classical plate theory. The finite element method shows lower values for critical buckling load because of the elimination of shear strain in the classical plate theory.

Studies of the buckling of composite plates in compression

As part of the Network of Excellence on Marine Structures (MARSTRUCT), a series of studies has been carried out into the buckling of glass-fibre-reinforced polymer plates with in-plane compression loading. The studies have included fabrication and testing of square, laminated panels with various thicknesses and initial geometrical imperfections, material testing, advanced finite element modelling studies and finally parametric studies covering a range of slendernesses and imperfection amplitudes. The paper provides an overview of the studies, which involved several participants in the Network.

Compressive Buckling of Composite Plates with a Delamination

Compressive buckling of laminate plates with a delamination are simulated using ABAQUS 6.8 software. Effects of sizes, positions, asymmetric and shapes of delamination on the compressive buckling are investigated without the consideration of delamination growth and contact. The results indicate the sizes, positions, asymmetric and shapes of delamination have an important influence on compressive buckling.

Buckling of Laminated Composite Plates by a New Element Based on Higher Order Shear Deformation Theory

The simple higher-order shear deformation theory proposed by Reddy has been successfully implemented in a triangular element recently developed by the authors. In this paper the element is applied to buckling of composite plates to study its performance. In this plate theory the transverse shear stress has parabolic through thickness variation and it is zero at top and bottom surfaces of the plate. Moreover, it does not introduce any additional unknown in the formulation. Thus, the plate theory is quite simple and elegant but it cannot be implemented in most of the elements, as the plate theory demands C 1 continuity of transverse displacement along the element edges. This has inspired the authors to develop this new element, which has shown an excellent performance in static analysis of composite plates. To demonstrate the performance of the element in the problem of buckling, examples of isotropic and composite plates under different situations are solved. The results are compared with the analytical solutions and other published results, which show the precision and range of applicability of the proposed element in the present problem.

Nonlinear coupled mechanics and initial buckling ofcomposite plates with piezoelectric actuators and sensors

The nonlinear mechanics for piezoelectric laminates andplates is presented, including nonlinear effects due tolarge displacements and rotations. The mechanics isincorporated into the piezoelectric mixed-field laminate theory.Using this mechanics, a nonlinear finite-element method and anincremental solution are formulated for the nonlinear analysisof adaptive plate structures. An eight-node-plate finiteelement is developed. The mechanics is applied to predict thebuckling of piezoelectric plates induced by combinedelectromechanical loading. Application cases quantify the mechanical buckling of composite beams and plates withpiezoelectric sensors, the piezoelectric buckling of activebeams and plates, and the feasibility of active bucklingcompensation.

Effects of Random Material Properties on Buckling of Composite Plates

Composites exhibit a considerable amount of variation in their material properties because their fabrication/manufacturing process involves a large number of parameters that cannot be controlled effectively. In the present study, the material properties have been modeled as random variables for better prediction of the system behavior. The classical laminate theory and first-order and higher-order shear deformation theories have been employed in deriving the governing equations for buckling of laminated rectangular plates. A mean-centered first-order perturbation technique has been used to find the second-order statistics of the buckling load. The approach has been validated by comparison with results of Monte Carlo simulation. Typical results have been presented for a plate with all edges simply supported. The effectiveness of the theories in predicting the buckling load dispersions has been examined. The sensitivity of buckling loads to change in the standard deviation of random material properties and ...

Effect of aspect ratio on buckling of composite plates

In this paper, buckling loads have been determined for different aspect ratios. It is observed that the effect of boundary conditions on the buckling load increases with increasing aspect ratio.

Comment on "Buckling of Composite Plates with a Free Edge in Edgewise Bending and Compression"

T ABLE 2 of Ref. 1 presented buckling loads for a laminated rectangular plate with two loaded edges simply supported, one side free and the opposite side either simply supported or clamped, for linearly varying edge loads. Since the analysis of Ref. 1 is based on classical plate theory, it is of interest to compare those results with buckling loads that include the effect of transverse shear deformations. Such buckling loads have been presented for plates with uniformly loaded edges. These were calculated using the shell-of-revolution program FASOR by considering the plate as part of a cylinder of very large radius. The circumferential direction of the cylindrical model corresponds to the longitudinal (loaded) direction of the plate, and the axial length of the cylinder equals the plate width b. The plate buckling load is obtained by minimizing the model buckling load with respect to the circumferential wave number N subject to the condition N=nirR/a, where n is the number of longitudinal half-waves of the plate buckle, R is the radius of the cylindrical model, and a is the length of the plate. This procedure is also applicable to plates with linearly varying edge loading. The dimensions of the laminated plate analyzed in Ref. 1 are 0 = 254 mm (10 in.) and 6 = 50.8 mm (2 in.). It is made of 0.127-mm (0.005-in.)-thick tape with the following insurface elastic properties: EX/E2 = 10.05, G12/E2 = Q.349, Hi =0.34, and E2 = 13.03 GPa (1.89x 10 psi), where 1 and 2 signify directions parallel and transverse, respectively, to the fibers and /*, is the major Poisson's ratio. The laminate definition is [±453/03]5 (erroneously reported as [±453 / 03/903]5in Ref. 1), thus giving a laminate thickness /z = 2.286 mm (0.090 in.) Neglecting the small anisotropic effect, this laminate has the bending stiffness matrix given by Eq. (25) of Ref. 1. Since the values of the transverse shear moduli G13 and G23 are unavailable, it is assumed that G13 = G23 = G12. (For typical unidirectional laminae, G23<G12 .) Again neglecting the small anisotropic effect, FASOR gives the transverse shear stiffness matrix [K] =8.951 x 10 N/m (5.112xl0 Ib/in.) [/], where [/] is the 2 x 2 unit matrix. Table 1 compares the classical plate theory results of Ref. 1 with the transverse shear deformation theory results Simply supported

Buckling of composite plates

The buckling of composite plates is a very complicated subject about which at least 200 references are already available. The present paper examines the characteristics and parameters which may need to be considered, both from mathematical and physical points of view, and provides perspective and organization to the subject. The first part deals with classical bifurcation buckling analysis, discusses the relevant plate equations and their solutions, and considers shapes, edge conditions and loadings which may arise. The second part treats classical complicating effects (those still yielding linear eigenvalue problems with bifurcation) including: elastic foundation, variable thickness, shear deformation, hygrothermal effects and inplane heterogeneity. The third part takes up non-classical considerations—postbuckling, geometric imperfections, parametric excitation, follower forces and inelastic material.