scholarly journals Stress-driven two-phase integral elasticity for Timoshenko curved beams

2021 ◽  
pp. 239779142199051
Author(s):  
Marzia S Vaccaro ◽  
Francesco P Pinnola ◽  
Francesco Marotti de Sciarra ◽  
Marko Canadija ◽  
Raffaele Barretta
Keyword(s):  
Solution Procedure ◽  
Small Scale ◽  
Curved Beams ◽  
Sensors And Actuators ◽  
Two Phase ◽  
Design And Optimization ◽  
Local Responses ◽  
Size Dependent ◽  
Classical Boundary ◽  
Phase Integral

In this research, the size-dependent static behaviour of elastic curved stubby beams is investigated by Timoshenko kinematics. Stress-driven two-phase integral elasticity is adopted to model size effects which soften or stiffen classical local responses. The corresponding governing equations of nonlocal elasticity are established and discussed, non-classical boundary conditions are detected and an effective coordinate-free solution procedure is proposed. The presented mixture approach is elucidated by solving simple curved small-scale beams of current interest in Nanotechnology. The contributed results could be useful for design and optimization of modern sensors and actuators.

Design and optimization of small-scale methanol production from sour natural gas by integrating reforming with hydrogenation

2020 ◽  
Vol 45 (59) ◽  
pp. 34483-34493
Author(s):  
Hua Liu ◽  
Jinghui Qu ◽  
Ming Pan ◽  
Bingjian Zhang ◽  
Qinglin Chen ◽  
...  
Keyword(s):  
Natural Gas ◽  
Small Scale ◽  
Methanol Production ◽  
Design And Optimization

Generative Textiles for Non-Rotary Power Production From Wind

2012 ◽  
Author(s):  
Scott Lux ◽  
Christopher Foster ◽  
Meredith Sellers ◽  
Andrew Friedl ◽  
Carl Feickert ◽  
...  
Keyword(s):  
Probability Distributions ◽  
Human Locomotion ◽  
Small Scale ◽  
Engineering Research ◽  
Design And Optimization ◽  
Wind Energy Generation ◽  
Harvesting Systems ◽  
Practical Engineering ◽  
Wind Simulation ◽  
Operational Envelope

The U.S. Army Engineer Research and Development Center, Construction Engineering Research Laboratory (ERDC-CERL) is developing a new class of flexible, generative textile as a novel means of sustainable wind energy generation. Flexible, generative carbon nanotube (CNT)-based textiles may have excellent potential for electrical capacitive storage and reuse in conjunction with small-scale energy-harvesting systems, both from wind for fixed applications and from human locomotion. This paper describes the design and optimization of a three-layer generative textile composed of discrete layers for generation, distribution, and storage. Initial results suggest that improvement in the generation layer will provide the highest increase in overall performance. The output of the electromagnetic tests shows a power density of 0.17 mW/cm3. However, the efficiency can be significantly improved through increasing the voltage output of the generation layer from 20 mV to around 1V. In an analysis of the operational envelope, wind data collected locally at ERDC-CERL and at other sites around the world reveal close similarity in the probability distributions, which could allow for a practical engineering approach capable of harvesting the steady “ram” component in addition to a variable energy component of the wind. To further study the textile-wind interactions, a wind simulation environment is being developed and has been able to obtain reproducible wind speed data thus far.

Effective rheology of a two-phase subduction shear zone: insights from numerical simple shear experiments and implications for subduction zone interfaces

2021 ◽  
Author(s):  
Paraskevi Io Ioannidi ◽  
Laetitia Le Pourhiet ◽  
Philippe Agard ◽  
Samuel Angiboust ◽  
Onno Oncken
Keyword(s):  
Simple Shear ◽  
Large Scale ◽  
Confining Pressure ◽  
Shear Zones ◽  
Dislocation Creep ◽  
Small Scale ◽  
Two Phase ◽  
Weak Phase ◽  
Pure Phases ◽  
Geodynamic Models

<p>Exhumed subduction shear zones often exhibit block-in-matrix structures comprising strong clasts within a weak matrix (mélanges). Inspired by such observations, we create synthetic models with different proportions of strong clasts and compare them to natural mélange outcrops. We use 2D Finite Element visco-plastic numerical simulations in simple shear kinematic conditions and we determine the effective rheology of a mélange with basaltic blocks embedded within a wet quartzitic matrix. Our models and their structures are scale-independent; this allows for upscaling published field geometries to km-scale models, compatible with large-scale far-field observations. By varying confining pressure, temperature and strain rate we evaluate effective rheological estimates for a natural subduction interface. Deformation and strain localization are affected by the block-in-matrix ratio. In models where both materials deform viscously, the effective dislocation creep parameters (A, n, and Q) vary between the values of the strong and the weak phase. Approaching the frictional-viscous transition, the mélange bulk rheology is effectively viscous creep but in the small scale parts of the blocks are frictional, leading to higher stresses. This results in an effective value of the stress exponent, n, greater than that of both pure phases, as well as an effective viscosity lower than the weak phase. Our effective rheology parameters may be used in large scale geodynamic models, as a proxy for a heterogeneous subduction interface, if an appropriate evolution law for the block concentration of a mélange is given.</p>

Design and optimization of acoustic liners with a shear grazing flow: OPAL software platform applications

2021 ◽  
Vol 263 (6) ◽  
pp. 152-163
Author(s):  
Remi Roncen ◽  
Pierre Vuillemin ◽  
Patricia Klotz ◽  
Frank Simon ◽  
Fabien Méry ◽  
...  
Keyword(s):  
Noise Reduction ◽  
Low Frequency ◽  
Small Scale ◽  
Software Platform ◽  
Total Size ◽  
Linearized Euler Equations ◽  
Design And Optimization ◽  
Acoustic Liners ◽  
Frequency Regime ◽  
Grazing Flow

In the context of noise reduction in diverse applications where a shear grazing flow is present (i.e., engine nacelle, jet pump, landing gear), improved acoustic liner solutions are being sought. This is particularly true in the low-frequency regime, where space constraints currently limit the efficiency of classic liner technology. To perform the required multi-objective optimization of complex meta-surface liner candidates, a software platform called OPAL was developed. Its first goal is to allow the user to assemble a large panel of parallel/serial assembly of unit acoustic elements, including the recent concept of LEONAR materials. Then, the physical properties of this liner can be optimized, relatively to given weighted objectives (noise reduction, total size of the sample, weight), for a given configuration. Alternatively, properties such as the different impedances of liner unit surfaces can be optimized. To accelerate the process, different nested levels of optimization are considered, from 0D analytical coarse designs in order to reduce the parameter space, up to 2D plan or axisymmetric high-order Discontinuous Galerkin resolution of the Linearized Euler Equations. The presentation will focus on the different aspects of liner design considered in OPAL, and present an application on different samples made for a small scale aeroacoustic bench.

scholarly journals Flow topologies in bubble-induced turbulence: a direct numerical simulation analysis

2018 ◽  
Vol 857 ◽  
pp. 270-290 ◽  
Author(s):  
Josef Hasslberger ◽  
Markus Klein ◽  
Nilanjan Chakraborty
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Turbulent Flows ◽  
Volume Fraction ◽  
Fluid Velocity ◽  
Small Scale ◽  
Flow Topology ◽  
Two Phase ◽  
Local Flow ◽  
Interface Curvature

This paper presents a detailed investigation of flow topologies in bubble-induced two-phase turbulence. Two freely moving and deforming air bubbles that have been suspended in liquid water under counterflow conditions have been considered for this analysis. The direct numerical simulation data considered here are based on the one-fluid formulation of the two-phase flow governing equations. To study the development of coherent structures, a local flow topology analysis is performed. Using the invariants of the velocity gradient tensor, all possible small-scale flow structures can be categorized into two nodal and two focal topologies for incompressible turbulent flows. The volume fraction of focal topologies in the gaseous phase is consistently higher than in the surrounding liquid phase. This observation has been argued to be linked to a strong vorticity production at the regions of simultaneous high fluid velocity and high interface curvature. Depending on the regime (steady/laminar or unsteady/turbulent), additional effects related to the density and viscosity jump at the interface influence the behaviour. The analysis also points to a specific term of the vorticity transport equation as being responsible for the induction of vortical motion at the interface. Besides the known mechanisms, this term, related to surface tension and gradients of interface curvature, represents another potential source of turbulence production that lends itself to further investigation.

scholarly journals Combined piezoelectric and flexoelectric effects in resonant dynamics of nanocantilevers

2018 ◽  
Vol 29 (20) ◽  
pp. 3949-3959 ◽  
Author(s):  
Adriane G Moura ◽  
Alper Erturk
Keyword(s):  
Barium Titanate ◽  
Frequency Response ◽  
Coupling Coefficient ◽  
Electromechanical Coupling ◽  
Analytical Framework ◽  
Electromechanical Coupling Coefficient ◽  
Sensors And Actuators ◽  
Energy Harvesters ◽  
Size Dependent ◽  
Resonant Dynamics

We establish and analyze an analytical framework by accounting for both the piezoelectric and flexoelectric effects in bimorph cantilevers. The focus is placed on the development of governing electroelastodynamic piezoelectric–flexoelectric equations for the problems of resonant energy harvesting, sensing, and actuation. The coupled governing equations are analyzed to obtain closed-form frequency response expressions via modal analysis. The combined piezoelectric–flexoelectric coupling coefficient expression is identified and its size dependence is explored. Specifically, a typical atomistic value of the flexoelectric constant for barium titanate is employed in the model simulations along with its piezoelectric constant from the existing literature. It is shown that the effective electromechanical coupling of a piezoelectric material, such as barium titanate, is significantly enhanced for thickness levels below 100 nm. The electromechanical coupling coefficient of a barium titanate bimorph cantilever increases from the bulk piezoelectric value of 0.065 to the combined piezoelectric–flexoelectric value exceeding 0.3 toward nanometer thickness level. Electromechanical frequency response functions for resonant power generation and dynamic actuation also capture the size-dependent enhancement of the electromechanical coupling. The analytical framework given here can be used for parameter identification and design of nanoscale cantilevers that can be used as energy harvesters, sensors, and actuators.

Size-dependent bending behavior of three-layered doubly curved shells: Modified couple stress formulation

2018 ◽  
Vol 22 (7) ◽  
pp. 2210-2249 ◽  
Author(s):  
Mohammad Arefi
Keyword(s):  
Applied Voltage ◽  
Couple Stress ◽  
Virtual Work ◽  
Couple Stress Theory ◽  
Shear Deformation Theory ◽  
Small Scale ◽  
Size Dependent ◽  
Modified Couple Stress ◽  
Doubly Curved ◽  
Piezoelectric Shell

In this paper, modified couple stress formulation of a small scale doubly curved piezoelectric shell resting on Pasternak's foundation is presented based on first-order shear deformation theory. Size-dependent electro-elastic results of doubly curved shell are presented based on an analytical approach. The doubly curved piezoelectric shell is subjected to uniform transverse loads and applied voltage. To account the size dependency, modified couple stress theory is employed in conjunction with principle of virtual work. The numerical results are presented in both tabular and graphical forms to show the influence of small scale parameter, applied voltage, geometries and two parameters of Pasternak's foundation on the electro-elastic results of size-dependent doubly curved piezoelectric shell.

scholarly journals Software In-The-Loop Simulation of an Advanced SVM Technique for 2ϕ-Inverter Control Fed a TPIM as Wind Turbine Emulator

Electronics ◽  
2022 ◽  
Vol 11 (2) ◽  
pp. 187
Author(s):  
Intissar Moussa ◽  
Adel Khedher
Keyword(s):  
Wind Turbine ◽  
Pulse Width ◽  
Pulse Width Modulation ◽  
Small Scale ◽  
Modulation Scheme ◽  
Space Vector ◽  
Two Phase ◽  
Phase Inverter ◽  
Vector Modulation ◽  
Scheme Selection

An appropriate modulation scheme selection ensures inverter performance. Thus, space vector modulation (SVM) is more efficient and has its own distinct advantages compared to other pulse width modulation (PWM) techniques. This work deals with the development of an advanced space vector pulse width modulation (SVM) technique for two-phase inverter control using an XSG library to ensure rapid prototyping of the controller FPGA implementation. The proposed architecture is applied digitally and in real time to drive a two-phase induction motor (TPIM) for small-scale wind turbine emulation (WTE) profiles in laboratories with minimum current ripple and torque oscillation. Four space voltage vectors generated for the used SVM technique do not contain a zero vector. Hence, for an adequate adjustment of these four vectors, a reference voltage vector located in the square locus is determined. Considering the asymmetry between the main and auxiliary windings, the TPIM behavior, which is fed through the advanced SVM controlled-two-phase inverter (2ϕ-inverter), is studied, allowing us to control the speed and the torque under different conditions for wind turbine emulation. Several quantities, such as electromagnetic torque, rotor fluxes, stator currents and speed, are analyzed. To validate the obtained results using both Simulink and XSG interfaces, the static and dynamic characteristics of the WTE are satisfactorily reproduced. The collected speed and torque errors between the reference and actual waveforms show low rates, proving emulator controller effectiveness.

scholarly journals A two-phase solution approach for a manufacturing-distribution problem with rework, outsourcing, and multi-shipment policy

2020 ◽  
Vol 18 (4) ◽  
pp. 505-509
Author(s):  
Chiu Peter ◽  
Peng-Cheng Sung ◽  
Victoria Chiu
Keyword(s):  
Cost Minimization ◽  
Algebraic Approach ◽  
Solution Procedure ◽  
Batch Size ◽  
Real Problem ◽  
Two Phase ◽  
Solution Approach ◽  
Straightforward Solution ◽  
The Cost ◽  
Phase Solution

In a recent study, a manufacturing batch-size and end-product shipment problem with outsourcing, multi-shipment, and rework was investigated using mathematical modeling and derivatives in its solution procedure. This study demonstrates that a simplified two-phase algebraic approach can also solve the problem and decide the cost-minimization policies for batch-size and end-product shipments. Our proposed straightforward solution approach enables the practitioners in the production planning and controlling filed to comprehend and efficiently solve the best replenishing batch-size and shipment policies of this real problem.

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