scholarly journals Boundary and interface conditions in the relaxed micromorphic model: Exploring finite-size metastructures for elastic wave control

2021 ◽  
pp. 108128652110489
Author(s):  
Gianluca Rizzi ◽  
Marco Valerio d’Agostino ◽  
Patrizio Neff ◽  
Angela Madeo
Keyword(s):  
Finite Element ◽  
Finite Size ◽  
Interface Conditions ◽  
Short Term ◽  
Element Simulation ◽  
Wide Range ◽  
Unit Cells ◽  
Energy Focusing ◽  
Scattering Response ◽  
Well Posed

In this paper, we establish well-posed boundary and interface conditions for the relaxed micromorphic model that are able to unveil the scattering response of fully finite-size metamaterial samples. The resulting relaxed micromorphic boundary value problem is implemented in finite-element simulations describing the scattering of a square metamaterial sample whose side counts nine unit cells. The results are validated against a direct finite-element simulation encoding all the details of the underlying metamaterial’s microstructure. The relaxed micromorphic model can recover the scattering metamaterial’s behavior for a wide range of frequencies and for all possible angles of incidence, thus showing that it is suitable to describe dynamic anisotropy. Finally, thanks to the model’s computational performances, we can design a metastructure combining metamaterials and classical materials in such a way that it acts as a protection device while providing energy focusing in specific collection points. These results open important perspectives for the short-term design of sustainable structures that can control elastic waves and recover energy.

A NEW INTERFACE CEMENT EQUILIBRATED MORTAR (NICEM) METHOD WITH ROBIN INTERFACE CONDITIONS: THE P1 FINITE ELEMENT CASE

2013 ◽  
Vol 23 (12) ◽  
pp. 2253-2292 ◽  
Author(s):  
CAROLINE JAPHET ◽  
YVON MADAY ◽  
FREDERIC NATAF
Keyword(s):  
Finite Element ◽  
Error Analysis ◽  
Domain Decomposition ◽  
Decomposition Method ◽  
Domain Decomposition Method ◽  
Numerical Results ◽  
New Method ◽  
Interface Conditions ◽  
Well Posed

We design and analyze a new non-conforming domain decomposition method, named the NICEM method, based on Schwarz-type approaches that allows for the use of Robin interface conditions on non-conforming grids. The method is proven to be well posed. The error analysis is performed in 2D and in 3D for P1 elements. Numerical results in 2D illustrate the new method.

Enhanced Performance of Fabry–Perot Tunable Filter by Groove Geometry Design of Double Folded Cantilever

2020 ◽  
Vol 15 (6) ◽  
pp. 687-692
Author(s):  
Yifan Ding ◽  
Haigang Hou ◽  
Qingwei Huang ◽  
Junlin Liu ◽  
Shahid Hussain ◽  
...  
Keyword(s):  
Finite Element ◽  
Tunable Filter ◽  
Driving Voltage ◽  
Geometry Design ◽  
Element Simulation ◽  
Wide Range ◽  
Fabry Perot ◽  
Maximal Stress ◽  
Maximal Displacement ◽  
Rectangular Groove

Different grooves (v-shaped groove, trapezoidal groove and rectangular groove) are introduced into the traditional double-folded cantilever of Fabry–Perot Tunable Filter (FPTF) for the optical sensor. Using finite element simulation, the influence of groove geometry on the voltage–displacement relationship, stress distribution and reflector flatness of the FPTF are studied. The results show that the reflector supported by double folded cantilever with rectangular groove has a maximal displacement of 0.88 μm under 8 V driving voltage, which is 95% higher than double folded cantilever without groove. At 0.5 μm, the best flatness (warping angle of reflector) is only 0.0032° for reflector supported by double folded cantilever with rectangular groove, where the generated maximal stress in the double folded cantilever is 8.49 MPa. Compared with other double folded cantilevers with v-shaped groove, trapezoidal groove and without groove, the unique properties of double folded cantilever with rectangular groove are attributed to lower elastic modulus. The double folded cantilever with rectangular groove enlarges displacement results in wide range of bandpass wavelength of FPTF, and a best flatness to enhance the monochrome of bandpass wavelength.

Finite Element Simulation of Magnetohydrodynamic Mixed Convection in a Double-Lid Driven Enclosure With a Square Heat-Generating Block

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
M. M. Rahman ◽  
M. M. Billah ◽  
N. A. Rahim ◽  
R. Saidur ◽  
M. Hasanuzzaman
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Mixed Convection ◽  
Convection Flow ◽  
Weighted Residuals ◽  
Thermal Fields ◽  
Flow And Heat Transfer ◽  
Element Simulation ◽  
Wide Range ◽  
Element Technique

Magnetohydrodynamic (MHD) mixed-convection flow and heat transfer characteristics inside a square double-lid driven enclosure have been investigated in this study. A heat-generating solid square block is positioned at the centre of the enclosure. Both of its vertical walls are lid-driven and have temperature Tc and uniform velocity V0. In addition, the top and bottom surfaces are kept adiabatic. Discretization of governing equations is achieved using finite element technique based on Galerkin weighted residuals. The computation is carried out for a wide range of pertinent parameters such as Hartmann number, heat-generating parameter, and Richardson number. Numerical results are reported for the effects of aforesaid parameters on the streamline and isotherm contours. In addition, the heat transfer rate in terms of the average Nusselt number and temperature of the fluid as well as block center are presented for the mentioned parametric values. The obtained results show that the flow and thermal fields are influenced by the above-mentioned parameters.

Finite element simulation of complex dense granular flows using a well-posed regularization of the μ(I)-rheology

2019 ◽  
Vol 188 ◽  
pp. 102-113 ◽  
Author(s):  
Linda Gesenhues ◽  
José J. Camata ◽  
Adriano M.A. Côrtes ◽  
Fernando A. Rochinha ◽  
Alvaro L.G.A. Coutinho
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Granular Flows ◽  
Element Simulation ◽  
Well Posed ◽  
Dense Granular Flows

Modelling and Measuring Residual Stresses in Pipe Girth Welds: Lessons From the Style Framework 7 Project

2014 ◽  
Author(s):  
Mike C. Smith ◽  
Ondrej Muransky ◽  
David Smith ◽  
Son Cao Do ◽  
P. John Bouchard ◽  
...  
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Measurement Techniques ◽  
Simulation Techniques ◽  
Element Simulation ◽  
Weld Residual Stress ◽  
Wide Range ◽  
Girth Welds ◽  
Welded Pipe ◽  
Stress Simulation

A number of girth-welded pipe mock-ups have been manufactured and investigated during the STYLE project, using a wide range of measurement techniques accompanied by extensive finite element simulation campaigns. This paper gives an overview of the work carried out and presents preliminary conclusions on the performance of finite element weld residual stress simulation techniques in the different mock-up designs.

scholarly journals Finite-Element Simulation of the Thermal Regime of the Erebus Glacier Tongue, Antarctica

1986 ◽  
Vol 32 (112) ◽  
pp. 530-534
Author(s):  
D.F.E. Stolle ◽  
F.A. Mirza
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Temperature Field ◽  
Steady State ◽  
Temperature Distribution ◽  
Velocity Field ◽  
Thermal Regime ◽  
Short Term ◽  
Glacier Tongue ◽  
Element Simulation

AbstractFinite-element method is used to determine the temperature distribution within the Erebus Glacier tongue based on information from short-term observations (Holdsworth, 1982). It is shown that, provided the up-stream temperature profile along the depth is known, steady-state assumptions are reliable for computing the temperature field within most of the ice mass at any given time for a glacier tongue. Numerical results from analyses of the Erebus Glacier tongue also indicate that the main transport of heat is through advection as expected and, hence, a realistic estimate of the velocity field becomes important.

A Micromechanics-Based Finite Element Model for Compressive Failure of Notched Uniply Composite Laminates Under Remote Biaxial Loads

1999 ◽  
Vol 121 (3) ◽  
pp. 360-366 ◽  
Author(s):  
Jung H. Ahn ◽  
Anthony M. Waas
Keyword(s):  
Finite Element ◽  
Composite Laminates ◽  
Finite Size ◽  
Kink Band ◽  
Dominant Mode ◽  
Form Analysis ◽  
Failure Initiation ◽  
Multiaxial Compression ◽  
Wide Range ◽  
Rectangular Area

A micromechanics based failure initiation predictive capability for analyzing notched composite laminates loaded remotely in multiaxial compression is reported. The model relies on the results from a previous experimental study that investigated compression failure mechanisms in special “uniply” composite laminates. The finite element method (FEM) was used in the solution process. The experimental results showed that the dominant mode of failure initiation was kink banding near the hole edge. The kink band was confined in extent to a distance within one half of the hole radius. The fibers within the kink band were rotated both in plane and out of the plane of the laminate. The position of the kink band with respect to the center of the notch depended on the remote biaxial load ration. In the FEM, the region in which kink banding takes place is contained within a finite size rectangular area, and is meshed as an alternatingly stacked region of fiber and matrix layers. The values of boundary loads on this rectangular area which correspond to kink banding is related to the remotely applied loads via an available closed form analysis for orthotropic laminates. Good agreement is found between experiment and analysis for a wide range of notch sizes.

scholarly journals Finite-Element Simulation of the Thermal Regime of the Erebus Glacier Tongue, Antarctica

1986 ◽  
Vol 32 (112) ◽  
pp. 530-534
Author(s):  
D.F.E. Stolle ◽  
F.A. Mirza
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Temperature Field ◽  
Steady State ◽  
Temperature Distribution ◽  
Velocity Field ◽  
Thermal Regime ◽  
Short Term ◽  
Glacier Tongue ◽  
Element Simulation

AbstractFinite-element method is used to determine the temperature distribution within the Erebus Glacier tongue based on information from short-term observations (Holdsworth, 1982). It is shown that, provided the up-stream temperature profile along the depth is known, steady-state assumptions are reliable for computing the temperature field within most of the ice mass at any given time for a glacier tongue. Numerical results from analyses of the Erebus Glacier tongue also indicate that the main transport of heat is through advection as expected and, hence, a realistic estimate of the velocity field becomes important.

scholarly journals Welding Simulation Used in the Design of Metallic Armor Systems

2014 ◽  
Vol 996 ◽  
pp. 518-524
Author(s):  
Lee Fredette ◽  
Elvin Beach
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Finite Element Simulation ◽  
Heat Affected Zone ◽  
Heat Input ◽  
Welding Process ◽  
Welding Simulation ◽  
Finite Element Software ◽  
Element Simulation ◽  
Wide Range

Welding steel armor reduces the armor materials protection capability. Several industrial and military welding standards exist for welding armor materials with the primary focus on joint strength rather than ballistic integrity.The Heat Affected Zone (HAZ) created by the welding process introduces vulnerabilities in the protection system. The process and designs that we have demonstrated include mitigation features that eliminate the ballistic degradation and provide uniform protection across all armor materials.In this study we used finite element simulation of the welding process to perform trade studies evaluating welded joint designs, and to show how the designs could be altered to both optimize armor performance and reduce welding heat input. A beneficial effect of reduced heat input was the corresponding reduction in welding-induced residual stresses, an overall reduction in assembly distortion in the assembly, and improvement of the armor performance.The simulated welding process included the creation of the heat affected zone and the development of residual stresses in the structure. ABAQUS finite element software was used for the simulation with the aid of an extensive material property database created over the wide range of welding temperatures.The finite element simulation predictions were validated and verified with excellent results by metallography and micro-hardness measurements. Live-fire ballistic tests were used as the final proof of measurable design improvements. Finite element welding simulation was shown to be an effective tool for improving upon standard welded armor designs, and above all in improving human safety.

Short-Term Creep Behavior in P91 Heat-Resistant Steel at Low Stress

2016 ◽  
Vol 850 ◽  
pp. 922-926 ◽  
Author(s):  
Peng Shuo Zhao ◽  
Jun Jie Shen ◽  
Hui Zhang
Keyword(s):  
Finite Element ◽  
Creep Behavior ◽  
Power Plants ◽  
Resistant Steel ◽  
Pure Torsion ◽  
Short Term ◽  
Heat Resistant Steel ◽  
Element Simulation ◽  
Term Creep ◽  
Short Term Creep

P91 heat-resistant steel is widely used in the high temperature of piping components of thermal power plants and nuclear power plants. In these conditions, the typical failure of P91 is mainly caused by creep at low stress. In this investigation the short-term creep behavior in P91 at low stress was investigated by helicoid spring creep test due to its high strain-sensitivity. The helicoid spring creep was based on the assumption of pure torsion. The mechanics field was firstly studied by ANSYS finite-element simulation to find the establishing conditions of pure torsion. Secondly, the creep properties of P91 were studied under the conditions of the temperatures of 0.38Tm<T<0.46Tm and the stresses of 14.6 MPa, 25 MPa, 34 MPa, respectively. The ANSYS finite-element simulation shows that the creep deformation is considered to be pure torsion when the pitch spacing of coil is between 2mm to 4mm. The creep curves show "Normal type ", and “the stress exponent” is n=0.9.

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