scholarly journals Broadband Asymmetric Propagation in Pillared Meta-Plates

Crystals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 702
Author(s):  
Lin Chen ◽  
Wei Wang ◽  
Guohua Nie ◽  
Yabin Jin ◽  
Daniel Torrent ◽  
...  
Keyword(s):  
Elastic Waves ◽  
Mechanical Energy ◽  
Thin Plates ◽  
Challenging Problem ◽  
Novel Structure ◽  
Wide Range ◽  
Propagation Of Elastic Waves ◽  
Asymmetrically Distributed

The asymmetric propagation of mechanical energy across interfaces is a challenging problem with a wide range of applications. In this work, we present a novel structure presenting the asymmetric propagation of elastic waves in thin plates in a broadband range. The structure consists of a combination of symmetrically and asymmetrically distributed pillars, so that the former decouple the different Lamb modes and the latter mix all of them. We show that a combination in tandem with these two structures can realize an efficient broadband asymmetric propagation at the subwavelength range and achieve a transmission difference larger than 200 dB between forward and backward directions. The proposed pillared meta-plate brings a new way for subwavelength and broadband wave manipulation in the fields of wave isolation, sensing and communication, among others.

A Dispersive Homogenization Model Based on Lattice Approximation for the Prediction of Wave Motion in Laminates

2012 ◽  
Vol 79 (2) ◽  
Author(s):  
G. Carta ◽  
M. Brun
Keyword(s):  
Elastic Waves ◽  
Wave Motion ◽  
Impact Excitation ◽  
Stratified Medium ◽  
Model Approximation ◽  
Wide Range ◽  
Lattice Approximation ◽  
Homogenization Model ◽  
Elastic Impedance ◽  
Propagation Of Elastic Waves

The propagation of elastic waves in a periodic laminate is considered. The stratified medium is modeled as a homogenized material where the stress depends on the strain and additional higher order strain gradient terms. The homogenization scheme is based on a lattice model approximation tuned on the dispersive properties of the real laminate. The long-wave asymptotic approximation of the model shows that, despite the simplicity of the parameters identification, the proposed approach agrees well with the exact solution in a wide range of elastic impedance contrasts, also in comparison with different approximations. The effect of increasing order of approximation is also investigated. A final example of a finite structure under an impact excitation proves that the model behaves well when applied in the transient regime and that it can be considered a simple but consistent approach to build efficient algorithms for the numerical analysis of elastodynamics problems.

scholarly journals Carbon Nanotube Films for Energy Applications

Energies ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1890
Author(s):  
Monika Rdest ◽  
Dawid Janas
Keyword(s):  
Carbon Nanotube ◽  
Mechanical Energy ◽  
Research Community ◽  
Thermal Interface Materials ◽  
Thermal Interface ◽  
Conductive Coatings ◽  
Storage Devices ◽  
Energy Applications ◽  
Wide Range ◽  
Interface Materials

This perspective article describes the application opportunities of carbon nanotube (CNT) films for the energy sector. Up to date progress in this regard is illustrated with representative examples of a wide range of energy management and transformation studies employing CNT ensembles. Firstly, this paper features an overview of how such macroscopic networks from nanocarbon can be produced. Then, the capabilities for their application in specific energy-related scenarios are described. Among the highlighted cases are conductive coatings, charge storage devices, thermal interface materials, and actuators. The selected examples demonstrate how electrical, thermal, radiant, and mechanical energy can be converted from one form to another using such formulations based on CNTs. The article is concluded with a future outlook, which anticipates the next steps which the research community will take to bring these concepts closer to implementation.

scholarly journals Propagation of Elastic Waves in Prestressed Media

2010 ◽  
Vol 2010 ◽  
pp. 1-11 ◽  
Author(s):  
Inder Singh ◽  
Dinesh Kumar Madan ◽  
Manish Gupta
Keyword(s):  
Elastic Waves ◽  
Plane Waves ◽  
Dynamical Equations ◽  
P Waves ◽  
General Solutions ◽  
External Forces ◽  
Propagation Of Elastic Waves

3D solutions of the dynamical equations in the presence of external forces are derived for a homogeneous, prestressed medium. 2D plane waves solutions are obtained from general solutions and show that there exist two types of plane waves, namely, quasi-P waves and quasi-SV waves. Expressions for slowness surfaces and apparent velocities for these waves are derived analytically as well as numerically and represented graphically.

Parametrization of the Propagation of Elastic Waves in a Medium with Ensembles of Disc-Shaped Inclusions

2018 ◽  
Vol 54 (1) ◽  
pp. 130-137 ◽  
Author(s):  
V. V. Mykhas’kiv ◽  
Ya. І. Kunets’ ◽  
V. V. Маtus ◽  
О. V. Burchak ◽  
О. К. Balalaev
Keyword(s):  
Elastic Waves ◽  
Propagation Of Elastic Waves

Crack Growth Prediction and Leakage Potential of Steam Generator Tubes Subjected to Flow Induced Vibrations

2014 ◽  
Author(s):  
Salim El Bouzidi ◽  
Marwan Hassan ◽  
Jovica Riznic
Keyword(s):  
Crack Growth ◽  
Steam Generator ◽  
Power Plants ◽  
Mechanical Energy ◽  
Steam Generators ◽  
Two Phase ◽  
Element Analysis ◽  
Wide Range ◽  
Flow Induced Vibrations ◽  
Crack Growth Model

Nuclear steam generators are critical components of nuclear power plants. Flow-Induced Vibrations (FIV) are a major threat to the operation of nuclear steam generators. The two main manifestations of FIV in heat exchangers are turbulence and fluidelastic instability, which would add mechanical energy to the system resulting in great levels of vibrations. The consequences on the operation of steam generators are premature wear of the tubes, as well as development of cracks that may leak radioactive heavy water. This paper investigates the effect of tube support clearance on crack propagation. A crack growth model is used to simulate the growth of Surface Flaws and Through-Wall Cracks of various initial sizes due to a wide range of support clearances. Leakage rates are predicted using a two-phase flow leakage model. Non-linear finite element analysis is used to simulate a full U-bend subjected to fluidelastic and turbulence forces. Monte Carlo Simulations are then used to conduct a probabilistic assessment of steam generator life due to crack development.

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