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

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.

Author(s):  
Sushila Chowdhary ◽  
Mesfin Kebede Kassa ◽  
Yitbarek Gashaw Tadesse ◽  
Ananda Babu Arumugam ◽  
Rajeshkumar Selvaraj

In this study, the instability regions of a honeycomb sandwich plate are investigated for different end conditions under periodic in-plane loading. The core layer of the sandwich plate is made of carbon nanotube (CNT)/glass fiber-reinforced honeycomb and the face layers of CNT/glass fiber- reinforced laminated composite. The governing equations are derived using classical laminated plate theory (CLPT) and solved numerically by using finite element formulation. The effectiveness of the developed finite element formulation is demonstrated by comparing the results in terms of natural frequencies with those available in the literature. The effects of CNT wt.% on the core material, CNT wt.% on the skin material, ply orientation and various end conditions on the variation of natural frequencies, loss factors and instability regions are studied. Finally, some inferences for the effects of CNT reinforcement on the honeycomb sandwich plate subjected to the periodic in-plane loads are discussed.


2014 ◽  
Vol 936 ◽  
pp. 1451-1455 ◽  
Author(s):  
Xiao Xia Jiang ◽  
Liang Zhu ◽  
Ji Sen Qiao ◽  
Yi Xiong Wu ◽  
Zhu Guo Li ◽  
...  

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.


2013 ◽  
Vol 135 (1) ◽  
Author(s):  
H. D. Chalak ◽  
Anupam Chakrabarti ◽  
Mohd. Ashraf Iqbal ◽  
Abdul Hamid Sheikh

Free vibration behavior of laminated soft core sandwich plates with stiff laminated face sheets is investigated using a new C0 finite element (FE) model based on higher order zigzag theory (HOZT) in this paper. The in-plane displacement variations are considered to be cubic for both the face sheets and the core, while the transverse displacement is assumed to vary quadratically within the core and remains constant in the faces beyond the core. The plate theory ensures a shear stress-free condition at the top and bottom surfaces of the plate. Thus, the plate theory has all of the features required for an accurate modeling of laminated sandwich plates. As very few elements based on this plate theory (HOZT) exist and they possess certain disadvantages, an attempt has been made to develop this new element. The nodal field variables are chosen in such a manner to overcome the problem of continuity requirement of the derivatives of transverse displacements, i.e., no need to impose any penalty stiffness in the formulation. A nine node C0 quadratic plate finite element is implemented to model the HOZT for the present analysis. A new C0 element has been utilized to study some interesting problems on free vibration analysis of laminated sandwich plates. Many new results are also presented which should be useful for future research.


2018 ◽  
Vol 4 (1) ◽  
pp. 18 ◽  
Author(s):  
Yaprak Itır Özdemir

The purpose of this paper is to study shear locking-free parametric earthquake analysis of thick and thin plates resting on Winkler foundation using Mindlin’s theory, to determine the effects of the thickness/span ratio, the aspect ratio and the boundary conditions on the linear responses of thick and thin plates subjected to earthquake excitations. In the analysis, finite element method is used for spatial integration and the Newmark-β method is used for the time integration. Finite element formulation of the equations of the thick plate theory is derived by using higher order displacement shape functions. A computer program using finite element method is coded in C++ to analyze the plates clamped or simply supported along all four edges. In the analysis, 8-noded finite element is used. Graphs are presented that should help engineers in the design of thick plates subjected to earthquake excitations. It is concluded that 8-noded finite element can be effectively used in the earthquake analysis of thick plates. It is also concluded that, in general, the changes in the thickness/span ratio are more effective on the maximum responses considered in this study than the changes in the aspect ratio.


AIAA Journal ◽  
2000 ◽  
Vol 38 ◽  
pp. 525-533
Author(s):  
S. Oskooei ◽  
J. S. Hansen

2012 ◽  
Vol 28 (3) ◽  
pp. 439-452 ◽  
Author(s):  
A. M. Zenkour ◽  
M. Sobhy

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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