Cylindrical Buckling of Sandwich Plates

1946 ◽  
Vol 13 (4) ◽  
pp. A253-A260
Author(s):  
J. N. Goodier
Keyword(s):  
Plane Strain ◽  
Sandwich Plate ◽  
Core Material ◽  
Sandwich Plates ◽  
The Core

Abstract In the buckling of “sandwich plates” with a relatively easily deformed interior, or core, material, the core is not stiff enough to keep plane sections plane when the bending occurs. The core must then be analyzed according to the equations of plane strain, but the fact that the bending takes place in the presence of thrust means that terms representing the destabilizing tendency of the thrust must be included. The resulting problem is solved in the present paper for a sandwich plate in “cylindrical buckling”—that is in a mode analogous to that of the hinged column.

Vibration analysis of a multifunctional hybrid composite honeycomb sandwich plate

2018 ◽  
Vol 22 (8) ◽  
pp. 2818-2860 ◽  
Author(s):  
Paul Praveen A ◽  
Vasudevan Rajamohan ◽  
Ananda Babu Arumugam ◽  
Arun Tom Mathew
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Hybrid Composite ◽  
Sandwich Plate ◽  
Core Material ◽  
Sandwich Plates ◽  
Composite Sandwich ◽  
Honeycomb Sandwich ◽  
Vibration Responses ◽  
Stiffness And Damping

In the present study, the free and forced vibration responses of the composite sandwich plate with carbon nanotube reinforced honeycomb as the core material and laminated composite plates as the top and bottom face sheets are investigated. The governing equations of motion of hybrid composite honeycomb sandwich plates are derived using higher order shear deformation theory and solved numerically using a four-noded rectangular finite element with nine degrees of freedom at each node. Further, various elastic properties of honeycomb core materials with and without reinforcement of carbon nanotube and face materials are evaluated experimentally using the alternative dynamic approach. The effectiveness of the finite element formulation is demonstrated by performing the results evaluated experimentally on a prototype composite sandwich plate with and without carbon nanotube reinforcement in core material. Various parametric studies are performed numerically to study the effects of carbon nanotube wt% in core material, core thickness, ply orientations, and various boundary conditions on the dynamic properties of composite honeycomb sandwich plate. Further, the transverse vibration responses of hybrid composite sandwich plates under harmonic force excitation are analyzed at various wt% of carbon nanotubes and the results are compared with those obtained without addition of carbon nanotubes to demonstrate the effectiveness of carbon nanotube reinforcement in enhancing the stiffness and damping characteristics of the structures. The study provides the guidelines for the designer on enhancing both the stiffness and damping properties of sandwich structures through carbon nanotube reinforcement in core materials.

Consideration of Both Extensional and Shear Strain of Core Material in Modal Property Estimation of Sandwich Plates

1995 ◽  
Author(s):  
Byung-Chan Lee ◽  
Kwang-Joon Kim
Keyword(s):  
Shear Strain ◽  
Layer Thickness ◽  
Sandwich Beam ◽  
Base Layer ◽  
Core Material ◽  
Viscoelastic Layer ◽  
Sandwich Plates ◽  
Modal Parameter ◽  
The Core ◽  
Plate Length

Abstract In vibration analysis of sandwich beam/plates, it is often assumed that there occurs shear deformation only, i.e. no extension or compression, in the core viscoelastic layer. Certainly, this assumption may have limitations, for example, with increase of the core thickness or frequency range of vibration. The purpose of this paper is to consider the extentional as well as shear strain of the core for modal parameter estimation of the sandwich plates and to investigate how much error will be caused by neglecting the extension or compression in the core material. Natural frequencies and modal loss factors are estimated for a simply supported square plates under each of the above two assumptions. Nondimensional characteristic equations are formulated and solved for various ratios of the base layer thickness to plate length, core to base layer thickness, and constraining layer to base layer thickness.

Forced Flexural Vibrations of Sandwich Plates in Plane Strain

1960 ◽  
Vol 27 (3) ◽  
pp. 535-540 ◽  
Author(s):  
Yi-Yuan Yu
Keyword(s):  
Plane Strain ◽  
Sandwich Plate ◽  
Classical Method ◽  
Separation Of Variables ◽  
Flexural Vibration ◽  
Time Dependent ◽  
Sandwich Plates ◽  
Simply Supported ◽  
Transverse Deflection ◽  
Plane Strain Case

On the basis of the new flexural theory of elastic sandwich plates recently developed [1–3], the problem of general forced flexural vibration of sandwich plates in the plane-strain case is solved. The classical method of separation of variables combined with the Mindlin-Goodman procedure [4] for treating time-dependent boundary conditions is used. As an example, the results are made use of in solving the problem of a simply supported sandwich plate in plane strain with one of the two end sections prescribed a transverse deflection varying with time.

Nonlinear, Damped Vibrations of Sandwich Plates With Time-Dependent Temperature

1993 ◽  
Author(s):  
S. Lukasiewicz ◽  
Z. Q. Xia
Keyword(s):  
Sandwich Plate ◽  
Rapid Change ◽  
Time Dependent ◽  
Viscoelastic Damping ◽  
Sandwich Plates ◽  
Simply Supported ◽  
Geometrical Nonlinearities ◽  
The Core

Abstract The paper studies the effect of the rapid change of temperature on the vibrations of simply supported sandwich plates. It has been taken into consideration that the properties of the facings and of the core of the sandwich plate materials change with the change of the temperature. The effects of the viscoelastic damping and geometrical nonlinearities on the behaviour of the plate have also been included. It was found that the rapid change of temperature affects the amplitude and frequency of the vibrations.

Bending Properties of Laser Welded Web-Core Steel Sandwich Plates

2014 ◽  
Vol 936 ◽  
pp. 1451-1455 ◽  
Author(s):  
Xiao Xia Jiang ◽  
Liang Zhu ◽  
Ji Sen Qiao ◽  
Yi Xiong Wu ◽  
Zhu Guo Li ◽  
...  
Keyword(s):  
Finite Element ◽  
Sandwich Plate ◽  
Finite Element Simulations ◽  
Bending Test ◽  
Sandwich Plates ◽  
Bending Properties ◽  
Three Point Bending ◽  
Weld Width ◽  
The Core ◽  
Good Agreement

This paper presents a detailed discussion of the bending properties of laser welded web-core steel sandwich plates and the influence of weld width on stiffness and strength. The over-hanging three point bending test was conducted on the laser welded web-core steel sandwich plates with various welds width by self-designed device, together with the finite element simulations. A good agreement is obtained between the 2D FE analyses and experiment results. The stiffness and strength of the sandwich plates increased with the increasing of weld width, especially for the weld width lower than 60% thickness of the core plate. It is necessary to consider the weld width in the design and evaluation of the stiffness and strength of the laser welded web-core sandwich plate. Base on the results, the FEM is the priority to analysis bending properties of laser welded web-core steel sandwich plates.

Study on Bending, Buckling and Free Vibration of Hard-Core Sandwich Plate Based on Revising the Soft-Core Reissner Theory

2014 ◽  
Vol 945-949 ◽  
pp. 790-794 ◽  
Author(s):  
Hai Yan Zeng ◽  
Ren Jun Yan ◽  
Yao Yu Hu
Keyword(s):  
Free Vibration ◽  
Sandwich Plate ◽  
Hard Core ◽  
High Strength ◽  
Soft Core ◽  
Sandwich Plates ◽  
The Core ◽  
Reissner Theory ◽  
Core Theory ◽  
Low Weight

The use of sandwich structures in various engineering fields is growing rapidly because of advantageous features such as low weight and high strength-to-weight ratio.The existing theories are all based on soft core assumption. In this case, the in-plane stress and the stiffness of the core are not included. It has been shown that Ressiner theory is inadequate for the analysis of hard-core sandwich plates. Different revision factors were put forward in this paper to revise the bending, buckling and free vibration results of soft-core Reissner theory for hard-core sandwich plates. The results show that the revised results go well with the hard core theory, so that its validity is confirmed.

A novel finite element formulation based on extended higher-order theory for sandwich plates of arbitrary aspect ratio

2020 ◽  
pp. 109963622097529
Author(s):  
Shehzaib Irfan ◽  
Faisal Siddiqui
Keyword(s):  
Finite Element ◽  
Aspect Ratio ◽  
Sandwich Plate ◽  
Plate Theory ◽  
Higher Order ◽  
Element Formulation ◽  
Sandwich Plates ◽  
Two Dimensional ◽  
Elasticity Solution ◽  
The Core

The extended higher-order sandwich plate theory for plates with arbitrary aspect ratio was formulated for two-dimensional orthotropic sandwich plates. The novelty of the theory is that it considers five generalized co-ordinates in the core (two axial and one transverse displacements at centroid of the core, one rotation at the centroid of the core about x-axis and one rotation at the centroid of the core about y-axis). Theory is very accurate when compared with the exact elasticity solution in terms of stresses and displacement both. In the current paper, a novel two dimensional rectangular element is developed based on the extended higher-order sandwich plate theory. Elemental equations along with the procedure to derive these is given in the paper. Developed finite element model is validated by comparing the results with elasticity solution and the theory itself for two sandwich plate configurations. The comparison shows that results obtained from the proposed finite element are in very good agreement with elasticity in terms of displacements and stresses both. Thus the proposed element is a powerful analysis tool which can be used for accurately analyzing the real world structures involving sandwich plates at a low computational cost.

Effects of Normal Strain in Core Material on Modal Property of Sandwich Plates

1997 ◽  
Vol 119 (4) ◽  
pp. 493-503 ◽  
Author(s):  
Byung-Chan Lee ◽  
Kwang-Joon Kim
Keyword(s):  
Elastic Modulus ◽  
Shear Modulus ◽  
Layer Thickness ◽  
Dynamic Modeling ◽  
Core Layer ◽  
Base Layer ◽  
Core Material ◽  
Sandwich Plates ◽  
The Core ◽  
Plate Length

In vibration analysis of sandwich beam/plates, it is often assumed that there is shear deformation only, without extension or compression in the viscoelastic layer. Certainly, this assumption may have limitations, for example, with increase of the core thickness or frequency range of vibration. The purpose of this paper is to consider the normal, as well as shear strain of the core material for modal parameter estimation of the sandwich plates and to investigate how much error will be caused by neglecting the extension or compression in the core material. Natural frequencies and modal loss factors are estimated for a simply supported square plate by taking the normal as well as shear deformation into account for dynamic modeling. Nondimensional characteristic equations are formulated and solved numerically for various ratios of the base layer thickness to plate length, core layer thickness to base layer, constraining layer thickness to base layer, and shear modulus of core material to elastic modulus of base layer. The effects of the various parameters on the modal properties are shown to be intercorrelated to each other and hence difficult to summarize in one phrase. Normal deformation of the core material plays an important role when the thickness ratio of constraining layer to base layer is 0.5 and its Poisson’s ratio is smaller than 0.49, and hence need to be included in the dynamic modeling especially for estimation of modal damping when one of the following conditions are met; 1) the ratio of base layer thickness to plate length is greater than 0.02, 2) the thickness ratio of core layer to base layer is greater than 0.01, 3) the wavelength of a mode is less than one third of the plate length, 4) the ratio of shear modulus of core material to elastic modulus of base material is less than 10−5.

Numerical Analysis on Failure Behavior of Composite Sandwich Plate

2013 ◽  
Vol 284-287 ◽  
pp. 178-182
Author(s):  
Yao Hsu
Keyword(s):  
Finite Element ◽  
Failure Mechanism ◽  
Sandwich Plate ◽  
Core Material ◽  
Structural Safety ◽  
Failure Behavior ◽  
Sandwich Plates ◽  
Composite Sandwich ◽  
Finite Element Software ◽  
The Impact

The Composite sandwich plate is made of two laminated face-sheets and one core material. Since such a kind of structure has many advantages, they have been widely used in structural manufacturing industry. However, when sandwich plates are impacted by transverse loadings, damages that are usually invisible would occur inside the sandwich plate and those damages would potentially reduce the structural safety. Therefore, it is necessary to elucidate the failure mechanism and how they affect the failure behaviors of sandwich structures for safety purpose. To this end, the present study is to investigate the impact failure behaviors of sandwich plates subjected to a rigid spherical impactor. Numerical simulation approach is carried out by finite element method. To predict the initial failure, several failure criteria to face-sheets and core material are proposed. In addition, to further simulate the progressive failure behaviors, a stiffness modification method is proposed and incorporated into the finite element software. The analytical results show that the local failure including fiber breakages, delamination, core cracking and plasticity is the main failure mechanism of cases studied. Furthermore, parametric study is also conducted and discussed in the paper.

Elastic Foundation Analysis of Uniformly Loaded Functionally Graded Viscoelastic Sandwich Plates

2012 ◽  
Vol 28 (3) ◽  
pp. 439-452 ◽  
Author(s):  
A. M. Zenkour ◽  
M. Sobhy
Keyword(s):  
Power Law ◽  
Sandwich Plate ◽  
Plate Theory ◽  
Functionally Graded ◽  
Sandwich Plates ◽  
Equilibrium Equations ◽  
Graded Material ◽  
Plate Aspect Ratio ◽  
Type V ◽  
Power Law Index

AbstractThis paper deals with the static response of simply supported functionally graded material (FGM) viscoelastic sandwich plates subjected to transverse uniform loads. The FG sandwich plates are considered to be resting on Pasternak's elastic foundations. The sandwich plate is assumed to consist of a fully elastic core sandwiched by elastic-viscoelastic FGM layers. Material properties are graded according to a power-law variation from the interfaces to the faces of the plate. The equilibrium equations of the FG sandwich plate are given based on a trigonometric shear deformation plate theory. Using Illyushin's method, the governing equations of the viscoelastic sandwich plate can be solved. Parametric study on the bending analysis of FG sandwich plates is being investigated. These parameters include (i) power-law index, (ii) plate aspect ratio, (iii) side-to-thickness ratio, (iv) loading type, (v) foundation stiffnesses, and (vi) time parameter.

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