scholarly journals Analysis of Monolithic and Sandwich Panels Subjected To Non-Uniform Thickness-Wise Boundary Conditions

2016 ◽  
Vol 5 (1) ◽  
pp. 232-249
Author(s):  
Riccardo Vescovini ◽  
Lorenzo Dozio
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Sandwich Plate ◽  
Sandwich Plates ◽  
Vibration Frequencies ◽  
Thickness Direction ◽  
Finite Element Analyses ◽  
Uniform Thickness ◽  
Bending Problems ◽  
High Degree

Abstract The analysis of monolithic and sandwich plates is illustrated for those cases where the boundary conditions are not uniform along the thickness direction, and run at a given position along the thickness direction. For instance, a sandwich plate constrained at the bottom or top face can be considered. The approach relies upon a sublaminate formulation,which is applied here in the context of a Ritz-based approach. Due to the possibility of dividing the structure into smaller portions, viz. the sublaminates, the constraints can be applied at any given location, providing a high degree of flexibility in modeling the boundary conditions. Penalty functions and Lagrange multipliers are introduced for this scope. Results are presented for free-vibration and bending problems. The close matching with highly refined finite element analyses reveals the accuracy of the proposed formulation in determining the vibration frequencies, as well as the internal stress distribution. Reference results are provided for future benchmarking purposes.

Dynamic Analysis of Sandwich Plates with Isotropic Skins and Viscoelastic Core

2019 ◽  
Vol 19 (03) ◽  
pp. 1950033 ◽  
Author(s):  
R. K. Ojha ◽  
S. K. Dwivedy
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Forced Vibration ◽  
Sandwich Plate ◽  
Vibration Suppression ◽  
Loss Modulus ◽  
Harmonic Excitation ◽  
Sandwich Plates ◽  
Isotropic Layer ◽  
Lagrange Principle

The free and forced vibration characteristics of three-layered sandwich plates with thin isotropic faces and Leptadenia pyrotechnica rheological elastomer (LPRE) core are studied in this investigation. The LPRE core is fabricated and experimented to determine its shear storage modulus and loss modulus. It is observed that the stiffness and damping characteristics of the LPRE core is significantly higher than those of the room-temperature vulcanized silicone rubber elastomer (RTVE) core. The governing equation of motion for the sandwich plate is derived by the Lagrange principle and given in finite element form. The natural frequencies and loss factors of the three-layered sandwich plate are studied by varying the thicknesses of the core and the constraining isotropic layer, and material of the constraining layer with different boundary conditions. The results are compared with those of similar structures with different core materials and boundary conditions. In addition, a LPRE-based sandwich plate is fabricated and its fundamental frequency is determined experimentally and compared with the finite element result. The forced vibration response of the three-layered sandwich plate is also explored under a harmonic excitation force. This study provides supports for the application of the LPRE-based sandwich plates potentially to the passive vibration suppression of structures.

A four-node quadrilateral element for vibration and damping analysis of sandwich plates with viscoelastic core

2017 ◽  
Vol 21 (3) ◽  
pp. 1072-1118 ◽  
Author(s):  
Shanhong Ren ◽  
Guozhong Zhao
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Element Formulation ◽  
Sandwich Plates ◽  
Complex Eigenvalue ◽  
Constrained Layer Damping ◽  
Quadrilateral Element ◽  
Frequency Dependent ◽  
Viscoelastic Core ◽  
Rectangular Element

Constrained layer damping treatments have been widely used as an effective way for vibration control and noise reduction of thin-walled plates and shells. Despite extensive application in vibration and damping analysis of sandwich plates with viscoelastic core, the rectangular element is challenged by irregular structural forms in practical engineering. In this paper, a three-layer four-node quadrilateral element with seven degrees of freedom at each node is presented. Compared with classical rectangular element, the four-node quadrilateral element has stronger adaptability in complex structural forms and boundary conditions. Based on the layer-wise theory where the constrained layer and the base layer meet Kirchhoff theory and the viscoelastic layer satisfies first-order shear deformation theory, the finite element formulation of the sandwich plate with viscoelastic core is derived by the Hamilton principle in variational form and based on the generalization of the discrete Kirchhoff Quadrilateral plate element. The complex modulus model is employed to describe the viscoelastic core of sandwich plates, allowing for the material’s frequency dependent characteristics. The natural frequencies and associated modal loss factors are computed based on the complex eigenvalue problems. The frequency dependent characteristic of the viscoelastic core is considered and an iterative procedure is introduced to solve the nonlinear eigenvalue problem. At last, six verification numerical examples that include three sandwich beam-plates and three sandwich plates are provided to compare present method with experiment, analytical method, Galerkin method, finite element methods and commercial software (NASTRAN). The results show that the proposed finite element can accurately and efficiently simulate the sandwich plates treated with constrained layer damping with a variety of structural forms and boundary conditions.

scholarly journals Three-Dimensional Vibration Analysis of a Functionally Graded Sandwich Rectangular Plate Resting on an Elastic Foundation Using a Semi-Analytical Method

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3401 ◽  
Author(s):  
Cui ◽  
Zhou ◽  
Ye ◽  
Gaidai ◽  
Li ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Rectangular Plate ◽  
Elastic Foundation ◽  
Power Law ◽  
Analytical Method ◽  
Sandwich Plate ◽  
Natural Frequencies ◽  
Three Dimensional ◽  
Functionally Graded ◽  
Sandwich Plates

The three-dimensional vibration of a functionally graded sandwich rectangular plate on an elastic foundation with normal boundary conditions was analyzed using a semi-analytical method based on three-dimensional elasticity theory. The material properties of the sandwich plate varied with thickness according to the power law distribution. Two types of functionally graded material (FGM) sandwich plates were investigated in this paper: one with a homogeneous core and FGM facesheets, and another with homogeneous panels and an FGM core. Various displacements of the plates were created using an improved Fourier series consisting of a standard Fourier cosine series along with a certain number of closed-form auxiliary functions satisfying the essential boundary conditions. The vibration behavior of the FGM sandwich plate, including the natural frequencies and mode shapes, was obtained using the Ritz method. The effectiveness and accuracy of the suggested technique were fully verified by comparing the natural frequencies of sandwich plates with results from investigations of other functionally graded sandwich rectangular plates in the literature. A parametric study, including elastic parameters, foundation parameters, power law exponents, and layer thickness ratios, was performed, and some new results are presented.

Thermo-mechanical induced vibration characteristics of shear deformable functionally graded ceramic—metal plates using finite element method

2010 ◽  
Vol 225 (1) ◽  
pp. 50-65 ◽  
Author(s):  
M Talha ◽  
B N Singh
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Temperature Field ◽  
Boundary Conditions ◽  
Vibration Characteristics ◽  
Functionally Graded ◽  
Thickness Direction ◽  
Aspect Ratios ◽  
Shear Deformable ◽  
Element Method

This paper deals with the thermomechanical-induced vibration characteristics of shear deformable functionally graded material (FGM) plates. Theoretical formulations are based on higher-order shear deformation theory with a significant improvement in the transverse displacement using finite-element method. The mechanical properties of the plate are assumed to be temperature-dependent and graded in the thickness direction according to a power-law distribution in terms of the volume fractions of the constituents. The temperature field is ascertained to be a uniform distribution over the plate surface and varied in the thickness direction only. The fundamental equations for FGM plates are derived using variational approach by considering traction-free boundary conditions on the top and bottom faces of the plate. A C0 continuous isoparametric Lagrangian finite-element with 13 degrees of freedom (DOF) per node have been used to accomplish the results. Convergence and comparison studies have been performed for square plates to demonstrate the efficiency of the present model. The numerical results are obtained for different thickness ratios, aspect ratios, volume fraction index, and temperature rise with different boundary conditions. The results reveal that the temperature field and the gradient in the material properties have significant effect on the vibration characteristics of the FGM plates.

Buckling Analysis of Soft-Core Composite Sandwich Plates Using 3D Finite Element Method

2011 ◽  
Vol 105-107 ◽  
pp. 1768-1772 ◽  
Author(s):  
Mohammad Mahdi Kheirikhah ◽  
Seyyed Mohammad Reza Khalili ◽  
Keramat Malekzadeh Fard
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Sandwich Plate ◽  
Core Layer ◽  
Element Model ◽  
Soft Core ◽  
Geometrical Parameters ◽  
Sandwich Plates ◽  
Fe Model ◽  
3D Finite Element

In the present paper, an accurate 3D finite element model is presented for bucking analysis of soft-core rectangular sandwich plates. The sandwich plate is composed of three layers: top and bottom skins and core layer. Finite element model of the problem has been constructed in the ANSYS 11.0 standard code area. The effect of geometrical parameters of the sandwich plate is studied. Comparison of the present results with those of plate theories confirms the accuracy of the proposed model. The overall buckling loads calculated by FE model are higher than that of the accurate results and the maximum discrepancy is less than 10 percent.

scholarly journals Structural Analysis of Rear Pressure Bulkhead of Typical Transport Aircraft

2020 ◽  
Vol 8 (4S) ◽  
pp. 14-16
Keyword(s):  
Finite Element ◽  
Structural Analysis ◽  
Boundary Conditions ◽  
Normal Stress ◽  
Honeycomb Structure ◽  
Finite Element Analyses ◽  
Maximum Displacement ◽  
Transport Aircraft ◽  
Maximum Normal Stress ◽  
Modeling Software

In this study, many researchers studied flat bulkhead, but Dome-shaped bulkhead is more preferable as it withstands pressure loads. We modeled a rear pressure bulkhead of a typical transport aircraft using CATIA V5 modeling software. Finite element analyses were carried out by the rear pressure bulkhead subjected to the boundary conditions (Fuselage is fixed and attached to the aircraft honeycomb structure and 0.1Mpa pressure is applied to the bulkhead). From the FEA of the rear pressure bulkhead, we obtained Von-Misses stresses and the deformations were obtained. The maximum displacement of 5.46mm was observed on the dome. The maximum normal stress at the circumferential direction was about 306Mpa.

Effect of Boundary Conditions on Transient Response of Sandwich Plates with Electrorheological Fluid Core

2011 ◽  
Vol 462-463 ◽  
pp. 372-377
Author(s):  
Jafar Rahiminasab ◽  
Jalil Rezaeepazhand
Keyword(s):  
Finite Element ◽  
Electric Field ◽  
Boundary Conditions ◽  
Transient Response ◽  
Sandwich Plate ◽  
Natural Frequencies ◽  
Plate Theory ◽  
Equations Of Motion ◽  
Electrorheological Fluid ◽  
Fluid Core

Electrorheological (ER) fluids are a kind of smart material whose rheological properties can be controlled by an external electric field. In the present paper, the transient vibration of a rectangular three layer sandwich plate with electrorheological fluid core is analyzed based on the classical plate theory. The Bingham plastic model is used to consider the post-yield behavior of ER fluid. The structure is modeled using a finite element method. Hamilton’s principle is employed to derive the finite element equations of motion. The constant average acceleration scheme is used to integrate the equations of motion. The effects of change in electric field and core thickness on the structure settling time and its natural frequencies are studied for various boundary conditions. The results show that the thickness of the core layer and the electric field strength has significant effects on damping behavior of the sandwich plate. When the applied electric field increases a linear decay in transient response of the structure is observed. It is also found that the electric field changes have no influence on the system natural frequencies.

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.

Residual Stresses Due to Rigid Cylinder Indentation and Rolling at a Very High Rolling Load

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
M. Y. Ali ◽  
J. Pan
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Boundary Conditions ◽  
Pressure Distribution ◽  
Plane Strain ◽  
Peak Pressure ◽  
Computational Results ◽  
Finite Element Analyses ◽  
Finite Plate ◽  
Rolling Load

In this paper, residual stresses due to indentation and rolling of a rigid cylinder on a finite plate at a very high rolling load with a relative peak pressure of 22 are examined by two-dimensional plane strain finite element analyses using abaqus for the first time. In the finite element analyses, the roller is modeled as rigid and has frictionless contact with the finite plate. The geometry of the finite plate and its boundary conditions are assigned to correspond to those of fillet rolling of crankshafts with the constraint in the rolling direction. Finite element analyses with different meshes for single indentation on an elastic flat plate under plane strain conditions are first carried out, and the results are benchmarked with those of the elastic Hertzian solutions to establish the requirement of the finite element meshes for acceptable numerical results. The results show that the accuracy of computational results is limited by the discretization of the finite element analysis by a plot of the contact width as a function of the load. For accurate peak pressure, a total of at least eight linear elements are needed. Finite element analyses with different meshes for single indentation on an elastic–plastic flat plate under plane strain conditions are then carried out. The plate material is modeled as an elastic–plastic power-law strain hardening material with a nonlinear kinematic hardening rule for loading and unloading. The computational results are compared to establish the requirement of the finite element meshes for acceptable numerical results within 4 mm distance to the rolling surface for the crankshaft fatigue analyses. The computational results for rolling at the relative peak pressure of 22 show that the symmetric Hertzian or modified Hertzian pressure distribution should not be used to represent the contact pressure distribution for rolling simulation, while the computational results for rolling at the relative peak pressure of 5 show that the symmetric Hertzian or modified Hertzian pressure distribution may be used to represent the contact pressure distribution for rolling simulation. The computational results for the rolling case also show a significantly higher longitudinal compressive residual stress and a lower out-of-plane compressive residual stress along the contact surface when compared to those for the single indentation case. The results suggest that the effects of rolling must be accounted for when two-dimensional finite element analyses of crankshaft sections are used to investigate the residual stresses due to fillet rolling of the crankshafts under the prescribed roller loads. Due to the boundary conditions of the finite plate, the compressive residual stresses are larger when compared to those when the boundary conditions of the finite plate are fully relaxed.

scholarly journals Vibration-based damage identification for ship sandwich plate using finite element method

2020 ◽  
Vol 10 (1) ◽  
pp. 744-752
Author(s):  
Abdi Ismail ◽  
Achmad Zubaydi ◽  
Bambang Piscesa ◽  
Rizky Chandra Ariesta ◽  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Boundary Conditions ◽  
Sandwich Plate ◽  
Natural Frequencies ◽  
Damage Identification ◽  
Identification System ◽  
Structural Failure ◽  
Hull Structure ◽  
Element Method

AbstractThe sandwich plate can be used to replace the conventional steel stiffened plates on the ship’s hull structure. By using the sandwich plate, not only the stiffness of the plate can be increased but also the overall ship weight can be reduced, as well as the ship payload can be increased. The sandwich plate should be accompanied by the damage identification system to prevent ship structural failure. In this paper, the global damage identification method, which is based on the vibration analysis, is investigated. For that purpose, the vibration-based damage identification using the Finite Element Method (FEM) is explored. The variables being investigated are the damage sizes, damage locations, and the boundary conditions which affect the natural frequencies of the structures. The sandwich plate considered in this study consisted of steel faceplates with the polyurethane elastomer core, which has been checked to meet Lloyd’s register, an international maritime standard. From the analysis, it is found that the fully clamped boundary conditions accompanied by high vibration modes are more sensitive to the presence of artificial damage. The changes in the natural frequencies can be used as a reference to identify the size and location of damage in the sandwich plate.

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