Numerical Assessment of the Performance of Elastic Cloaks for Transient Flexural Waves

A relevant application of transformation elastodynamics has shown that flexural waves in a Kirchhoff-Love plate can be diverted and channeled to cloak a region of the ambient space. To achieve the goal, an orthotropic meta-structural plate should be employed. However, the corresponding mathematical transformation leads to the presence of an unwanted strong compressive prestress, likely beyond the buckling threshold of the structure, with a set of in-plane body forces to warrant equilibrium. In addition, the plate must possess, at the same time, high bending stiffnesses, but a null twisting rigidity. With the aim of estimating the performance of cloaks modelled with approximate parameters, an in-house finite element code, based on a subparametric technique, is implemented to deal with the cloaking of transient waves in orthotropic thin plates. The tool allows us to explore the sensitivity of specific stiffness parameters that may be difficult to match in a real cloak design. In addition, the finite element code is extended to investigate a meta-plate interacting with a Winkler foundation, to confirm how the subgrade modulus should transform in the cloak region.

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Forced vibration analysis of Mindlin plates resting on Winkler foundation

Challenge Journal of Structural Mechanics ◽

10.20528/cjsmec.2018.01.004 ◽

2018 ◽

Vol 4 (1) ◽

pp. 18 ◽

Cited By ~ 1

Author(s):

Yaprak Itır Özdemir

Keyword(s):

Finite Element Method ◽

Finite Element ◽

Aspect Ratio ◽

Plate Theory ◽

Thin Plates ◽

Winkler Foundation ◽

Element Formulation ◽

Spatial Integration ◽

Thick Plates ◽

Element Method

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.

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Joints representation strategy: performance evaluation by a Finite Element code. A feasibility analysis of a tunnel infrastructure in the Carnian Alps

Rendiconti online della Società Geologica Italiana ◽

10.3301/rol.2016.161 ◽

2016 ◽

Vol 41 ◽

pp. 333-336 ◽

Cited By ~ 1

Author(s):

Giacomo Tedesco ◽

Lisa Borgatti ◽

Stefano Bonduà ◽

Gianluca Marcato

Keyword(s):

Finite Element ◽

Performance Evaluation ◽

Feasibility Analysis ◽

Finite Element Code ◽

Strategy Performance

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THE USE OF AN OPEN SOURCE FINITE ELEMENT CODE FOR AEROELASTIC ANALYSES

10.26678/abcm.encit2016.cit2016-0182 ◽

2016 ◽

Author(s):

Adolfo Gomes Marto ◽

João Luiz F. Azevedo

Keyword(s):

Finite Element ◽

Open Source ◽

Finite Element Code

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Development of Simulation Based p-Multipliers for Laterally Loaded Pile Groups in Granular Soil Using 3D Nonlinear Finite Element Model

Applied Sciences ◽

10.3390/app11010026 ◽

2020 ◽

Vol 11 (1) ◽

pp. 26

Author(s):

Muhammad Bilal Adeel ◽

Muhammad Asad Jan ◽

Muhammad Aaqib ◽

Duhee Park

Keyword(s):

Finite Element ◽

Element Model ◽

Design Guidelines ◽

American Petroleum Institute ◽

Winkler Foundation ◽

Group Effect ◽

Pile Groups ◽

Element Analysis ◽

Laterally Loaded Pile ◽

Laterally Loaded

The behavior of laterally loaded pile groups is usually accessed by beam-on-nonlinear-Winkler-foundation (BNWF) approach employing various forms of empirically derived p-y curves and p-multipliers. Averaged p-multiplier for a particular pile group is termed as the group effect parameter. In practice, the p-y curve presented by the American Petroleum Institute (API) is most often utilized for piles in granular soils, although its shortcomings are recognized. In this study, we performed 3D finite element analysis to develop p-multipliers and group effect parameters for 3 × 3 to 5 × 5 vertically squared pile groups. The effect of the ratio of spacing to pile diameter (S/D), number of group piles, varying friction angle (φ), and pile fixity conditions on p-multipliers and group effect parameters are evaluated and quantified. Based on the simulation outcomes, a new functional form to calculate p-multipliers is proposed for pile groups. Extensive comparisons with the experimental measurements reveal that the calculated p-multipliers and group effect parameters are within the recorded range. Comparisons with two design guidelines which do not account for the pile fixity condition demonstrate that they overestimate the p-multipliers for fixed-head condition.

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