Multi-Frequency Cloaking with Metamaterial Layered Shells

2007 ◽  
Author(s):  
Andrea Alù ◽  
Nader Engheta
Keyword(s):  
Layered Shells

scholarly journals An Effective Method of Modeling the Deformation Behavior of Polymer Sandwich Structures with Adhesive Joints

2021 ◽  
Author(s):  
László Takács ◽  
Ferenc Szabó
Keyword(s):  
Deformation Behavior ◽  
Sandwich Structures ◽  
Experimental Tests ◽  
Mechanical Tests ◽  
Adhesive Joints ◽  
Core Material ◽  
Full Vehicle ◽  
Novel Approach ◽  
Stiffness Matrices ◽  
Layered Shells

AbstractPolymer sandwich structures have high bending stiffness and strength and also low weight. Therefore, they are widely used in the transportation industry. In the conceptual design phase, it is essential to have a method to model the mechanical behavior of the sandwich and its adhesive joints accurately in full-vehicle scale to investigate different structure partitioning strategies. In this paper, a novel approach using finite element modeling is introduced. The sandwich panels are modeled with layered shells and the joint lines with general stiffness matrices. Stiffness parameters of the face-sheets and the core material are obtained via mechanical tests. Stiffness parameters of the joints are determined by using the method of Design of Experiments, where detailed sub-models of the joints serve as a reference. These models are validated with experimental tests of glass-fiber reinforced vinyl ester matrix composite sandwich structure with a foam core. By using two joint designs and three reference geometries, it is shown that the method is suitable to describe the deformation behavior in a full-vehicle scale with sufficient accuracy.

Design of anisotropic layered shells by the finite-elements method

1985 ◽  
Vol 17 (7) ◽  
pp. 1003-1010
Author(s):  
T. A. Balan ◽  
O. V. Razdorozhnaya
Keyword(s):  
Finite Elements ◽  
Finite Elements Method ◽  
Layered Shells

scholarly journals An advanced shell model for the analysis of geometrical and material nonlinear shells

2020 ◽  
Vol 66 (6) ◽  
pp. 1353-1376
Author(s):  
F. Gruttmann ◽  
W. Wagner
Keyword(s):  
Shell Model ◽  
Geometrical Nonlinearity ◽  
Local Equilibrium ◽  
Deformation Gradient ◽  
Computing Time ◽  
Strain Tensor ◽  
Shell Element ◽  
Field Equations ◽  
Residual Vector ◽  
Layered Shells

AbstractIn this paper layered shells subjected to static loading are considered. The displacements of the Reissner–Mindlin theory are enriched by a an additional part. These so-called fluctuation displacements include warping displacements and thickness changes. They lead to additional terms for the material deformation gradient and the Green–Lagrangian strain tensor. Within a nonlinear multi-field variational formulation the weak form of the boundary value problem accounts for the equilibrium of stress resultants and couple resultants, the local equilibrium of stresses, the geometrical field equations and the constitutive equations. For the independent shell strains an ansatz with quadratic shape functions is chosen. This leads to a significant improved convergence behaviour especially for distorted meshes. Elimination of a set of parameters on element level by static condensation yields an element stiffness matrix and residual vector of a quadrilateral shell element with the usual 5 or 6 nodal degrees of freedom. The developed model yields the complicated three-dimensional stress state in layered shells for elasticity and elasto-plasticity considering geometrical nonlinearity. In comparison with fully 3D solutions present 2D shell model requires only a fractional amount of computing time.

Vibration Control of Conical Shells Using Viscoelastic Materials

1992 ◽  
Vol 206 (3) ◽  
pp. 167-178 ◽  
Author(s):  
K N Khatri
Keyword(s):  
Equations Of Motion ◽  
Geometrical Parameters ◽  
Viscoelastic Materials ◽  
Complex Moduli ◽  
Conical Shells ◽  
Harmonic Vibrations ◽  
End Conditions ◽  
Layered Shells ◽  
The Subject ◽  
Viscoelastic Layers

The vibration and damping analysis of multi-layered conical shells incorporating layers of viscoelastic materials in addition to elastic ones, the former causing dissipation of vibratory energy, is the subject matter of this paper. The analysis given herein uses Hamilton's variational principle for deriving equations of motion of a general multi-layered conical shell. In view of the correspondence principle of linear viscoelasticity which is valid for harmonic vibrations, the solution is obtained by replacing the moduli of viscoelastic layers by complex moduli. An approximate solution for axisymmetric vibrations of multi-layered conical shells with two end conditions—simply supported edges and clamped edges—is obtained by utilizing the Galerkin procedure. The damping effectiveness in terms of the system loss factor for all families of modes of vibrations for three-, five- and seven-layered shells is evaluated and its variation with geometrical parameters is investigated.

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