scholarly journals Anhysteretic Magneto-Elastic Behaviour of Terfenol-D: Experiments, Multiscale Modelling and Analytical Formulas

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5165
Author(s):  
Laurent Daniel ◽  
Mathieu Domenjoud
Keyword(s):  
Mechanical Behaviour ◽  
Mechanical Response ◽  
Operating Conditions ◽  
Elastic Behaviour ◽  
Multiscale Approach ◽  
Magnetic Signal ◽  
Strain Behaviour ◽  
Giant Magnetostrictive Materials ◽  
Standard Operating ◽  
Analytical Formulas

Giant magnetostrictive materials such as Terfenol-D and Galfenol are used to design actuators and sensors, converting magnetic input into a mechanical response, or conversely, mechanical input into a magnetic signal. Under standard operating conditions, these materials are subjected to stress. It is therefore important to be able to measure, understand and describe their magneto-mechanical behaviour under stress. In this paper, a comprehensive characterisation of the anhysteretic magneto-mechanical behaviour of Terfenol-D was performed. An energy-based multiscale approach was applied to model this behaviour. Finally, it was shown that the strain behaviour of Terfenol-D can be satisfactorily described using an analytical model derived from the full multiscale approach.

Virtual trabecular bone models and their mechanical response

2008 ◽  
Vol 222 (8) ◽  
pp. 1185-1195 ◽  
Author(s):  
F E Donaldson ◽  
P Pankaj ◽  
A H Law ◽  
A H Simpson
Keyword(s):  
Finite Element ◽  
Trabecular Bone ◽  
Mechanical Behaviour ◽  
Mechanical Response ◽  
Elastic Response ◽  
Anatomical Site ◽  
Virtual Samples ◽  
Micro Level ◽  
Architectural Characteristics

The study of the mechanical behaviour of trabecular bone has extensively employed micro-level finite element (μFE) models generated from images of real bone samples. It is now recognized that the key determinants of the mechanical behaviour of bone are related to its micro-architecture. The key indices of micro-architecture, in turn, depend on factors such as age, anatomical site, sex, and degree of osteoporosis. In practice, it is difficult to acquire sufficient samples that encompass these variations. In this preliminary study, a method of generating virtual finite element (FE) samples of trabecular bone is considered. Virtual samples, calibrated to satisfy some of the key micro-architectural characteristics, are generated computationally. The apparent level elastic and post-elastic mechanical behaviour of the generated samples is examined: the elastic mechanical response of these samples is found to compare well with natural trabecular bone studies conducted by previous investigators; the post-elastic response of virtual samples shows that material non-linearities have a much greater effect in comparison with geometrical non-linearity for the bone densities considered. Similar behaviour has been reported by previous studies conducted on real trabecular bone. It is concluded that virtual modelling presents a potentially valuable tool in the study of the mechanical behaviour of trabecular bone and the role of its micro-architecture.

scholarly journals Analysis of Capacitance to Ground Formulas for Different High-Voltage Electrodes

Energies ◽  
2018 ◽  
Vol 11 (5) ◽  
pp. 1090 ◽  
Author(s):  
Jordi-Roger Riba ◽  
Francesca Capelli
Keyword(s):  
High Voltage ◽  
Fem Simulation ◽  
Operating Conditions ◽  
Power Supplies ◽  
Measuring Instruments ◽  
Stray Capacitance ◽  
Analytical Formulas ◽  
Circular Rings ◽  
Available Information ◽  
Limited Scope

Stray capacitance can seriously affect the behavior of high-voltage devices, including voltage dividers, insulator strings, modular power supplies, or measuring instruments, among others. Therefore its effects must be considered when designing high-voltage projects and tests. Due to the difficulty in measuring the effects of stray capacitance, there is a lack of available experimental data. Therefore, for engineers and researchers there is a need to revise and update the available information, as well as to have useful and reliable data to estimate the stray capacitance in the initial designs. Although there are some analytical formulas to calculate the capacitance of some simple geometries, they have a limited scope. However, since such formulas can deal with different geometries and operating conditions, it is necessary to assess their consistency and applicability. This work calculates the stray capacitance to ground for geometries commonly found in high-voltage laboratories and facilities, including wires or rods of different lengths, spheres and circular rings, the latter ones being commonly applied as corona protections. This is carried out by comparing the results provided by the available analytical formulas with those obtained from finite element method (FEM) simulation, since field simulation methods allow solving such problem. The results of this work prove the suitability and flexibility of the FEM approach, because FEM models can deal with wider range of electrodes, configurations and operating conditions.

scholarly journals Mechanotransmission of haemodynamic forces by the endothelial glycocalyx in a full-scale arterial model

2019 ◽  
Vol 6 (6) ◽  
pp. 190607 ◽  
Author(s):  
P. Sáez ◽  
D. Gallo ◽  
U. Morbiducci
Keyword(s):  
In Silico ◽  
Mechanical Response ◽  
Carotid Bifurcation ◽  
Endothelial Glycocalyx ◽  
Multiscale Approach ◽  
Vascular Endothelial ◽  
Shear Forces ◽  
Endothelial Lining ◽  
Time Histories ◽  
Order Of Magnitude

The glycocalyx has been identified as a key mechano-sensor of the shear forces exerted by streaming blood onto the vascular endothelial lining. Although the biochemical reaction to the blood flow has been extensively studied, the mechanism of transmission of the haemodynamic shear forces to the endothelial transmembrane anchoring structures and, consequently, to the subcellular elements in the cytoskeleton, is still not fully understood. Here we apply a multiscale approach to elucidate how haemodynamic shear forces are transmitted to the transmembrane anchors of endothelial cells. Wall shear stress time histories, as obtained from image-based computational haemodynamics models of a carotid bifurcation, are used as a load and a continuum model is applied to obtain the mechanical response of the glycocalyx all along the cardiac cycle. The main findings of this in silico study are that: (1) the forces transmitted to the transmembrane anchors are in the range of 1–10 pN, which is in the order of magnitude reported for the different conformational states of transmembrane mechanotranductors; (2) locally, the forces transmitted to the anchors of the glycocalyx structure can be markedly different from the near-wall haemodynamic shear forces both in amplitude and frequency content. The findings of this in silico approach warrant future studies focusing on the actual forces transmitted to the transmembrane mechanotransductors, which might outperform haemodynamic descriptors of disturbed shear as localizing factors of vascular disease.

scholarly journals Mechanical Properties of SLM-Printed Aluminium Alloys: A Review

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4301 ◽  
Author(s):  
Panneer Ponnusamy ◽  
Rizwan Abdul Rahman Rashid ◽  
Syed Hasan Masood ◽  
Dong Ruan ◽  
Suresh Palanisamy
Keyword(s):  
Mechanical Properties ◽  
Aluminium Alloys ◽  
Mechanical Response ◽  
Value Added ◽  
High Strength ◽  
Operating Conditions ◽  
Future Research ◽  
Powder Bed ◽  
Treatment Conditions ◽  
Future Research Directions

Selective laser melting (SLM) is a powder bed fusion type metal additive manufacturing process which is being applied to manufacture highly customised and value-added parts in biomedical, defence, aerospace, and automotive industries. Aluminium alloy is one of the widely used metals in manufacturing parts in SLM in these sectors due to its light weight, high strength, and corrosion resistance properties. Parts used in such applications can be subjected to severe dynamic loadings and high temperature conditions in service. It is important to understand the mechanical response of such products produced by SLM under different loading and operating conditions. This paper presents a comprehensive review of the latest research carried out in understanding the mechanical properties of aluminium alloys processed by SLM under static, dynamic, different build orientations, and heat treatment conditions with the aim of identifying research gaps and future research directions.

scholarly journals Effects of cement and foam addition on chemo-mechanical behaviour of lightweight cemented soil (LWCS)

2019 ◽  
Vol 92 ◽  
pp. 11006 ◽  
Author(s):  
Domenico De Sarno ◽  
Enza Vitale ◽  
Dimitri Deneele ◽  
Marco Valerio Nicotera ◽  
Raffaele Papa ◽  
...  
Keyword(s):  
Mechanical Response ◽  
Construction Material ◽  
Thermo Gravimetric Analysis ◽  
Water System ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
Thermo Gravimetric ◽  
Soil Cement ◽  
Strain Behaviour ◽  
Insight Into

One of the main problems encountered in civil engineering is the management of large amounts of excavated soil, especially when the mechanical properties of this soil are not suitable for its reuse as a construction material. However, the excavated soil could represent a resource if appropriately improved. A suitable solution is the addition of cement and foam to produce lightweight cemented soils (LWCS). In this paper, an insight into the influence of foam on chemo-mineralogical and microstructural features of soil-cement-water system is presented. Time dependent mineralogical and microstructural changes have been monitored by means of X-Ray Diffraction, Thermo-gravimetric analysis and Mercury Intrusion Porosimetry. The present study shows that addition of foam does not alter the chemo-physical evolution of the soil-cement-water system. Large voids are present in the samples as footprint of air bubbles upon mixing, thus increasing porosity. Macroscopic behaviour of treated samples has been investigated by direct shear and oedometric tests. Chemo-physical evolution induced by cement addition is the major responsible for mechanical improvement showed by treated samples. Porosity of samples induced by foam addition plays a key role in the mechanical response of LWCS, inducing a transition of stress-strain behaviour from brittle and dilative to ductile and contractive as a function of increasing foam content.

scholarly journals Anisotropic mechanical behaviour of calendered nonwoven fabrics: Strain-rate dependency

2020 ◽  
pp. 002199832097679
Author(s):  
V Cucumazzo ◽  
E Demirci ◽  
B Pourdeyhimi ◽  
VV Silberschmidt
Keyword(s):  
Strain Rate ◽  
Mechanical Behaviour ◽  
Mechanical Response ◽  
Tensile Tests ◽  
Elastic Response ◽  
Uniaxial Tensile ◽  
Rate Dependency ◽  
Fibrous Matrix ◽  
Nonwoven Fabrics ◽  
Linear Elastic

Calendered nonwovens, formed by polymeric fibres, are three-phase heterogeneous materials, comprising a fibrous matrix, bond-areas and interface regions. As a result, two main factors of anisotropy can be identified. The first one is ascribable to a random fibrous microstructure, with the second one related to orientation of a bond pattern. This paper focuses on the first type of anisotropy in thin and thick nonwovens under uniaxial tensile loading. Individual and combined effects of anisotropy and strain rate were studied by conducting uniaxial tensile tests in various loading directions (0°, 30°, 45°, 60° and 90° with regard to the main fabric’s direction) and strain rate (0.01, 0.1 and 0.5 s−1). Fabrics exhibited an initial linear elastic response, followed by nonlinear strain hardening up to necking and final softening. The studied allowed assessment of the extent the effects of loading direction (anisotropy), planar density and strain rate on the mechanical response of the calendered fabrics. The evidence supported the conclusion that anisotropy is the most crucial factor, also delineating the balance between the fabric’s load-bearing capacity and extension level along various directions. The strain rate produced a marked effect on the fibre’s response, with increased stress at higher strain rate while this effect in the fabric was small. The results demonstrated the differences of the mechanical behaviour of fabrics from that of their constituent fibres.

Simulation Research of a Type of Pressure Vessel under Complex Loading Part 2 Complex Load of the Numerical Analysis

2013 ◽  
Vol 756-759 ◽  
pp. 4662-4667
Author(s):  
Jun Chen Li ◽  
Jie Sheng ◽  
Zhang Yu Fu
Keyword(s):  
Pressure Vessel ◽  
Large Scale ◽  
Mechanical Response ◽  
Simulation Analysis ◽  
Complex Loading ◽  
Operating Conditions ◽  
Small Scale ◽  
Simulation Research ◽  
Complex Load ◽  
Calculation Results

Loading of pressure vessel was usually complicated in practical service operating conditions. Simulation model of pressure vessel was built by method of finite element simulation analysis, and structured mesh generation was realized. Numerical calculation was come true, stress/strain distribution of pressure vessel was obtained in applying of the multi-load. On this basis, this condition compared with alone applied many loadings. The calculation results indicate the validity of this model, and results are evaluated according to relevant standards, which provide a way to study mechanical response in the actual working conditions. In addition, sub-model is analyzed for key part of pressure vessel, and transition is come true from large scale simulation to small scale simulation.

Microstructural Properties of Common Yew and Norway Spruce Determined with Silviscan

IAWA Journal ◽  
2009 ◽  
Vol 30 (2) ◽  
pp. 165-178 ◽  
Author(s):  
Daniel Keunecke ◽  
Robert Evans ◽  
Peter Niemz
Keyword(s):  
Mechanical Behaviour ◽  
Mechanical Response ◽  
Elastic Anisotropy ◽  
Longitudinal Direction ◽  
Structural Features ◽  
Structure Property ◽  
Tangential Plane ◽  
Cross Sectional ◽  
X Ray ◽  
The Difference

Yew wood holds a special position within the softwoods with regard to its exceptional elasto-mechanical behaviour. Despite a relatively high density, it is highly elastic in the longitudinal direction (the modulus of elasticity is low and the stretch to break high). In the radial-tangential plane, its elastic anisotropy is clearly less pronounced compared to other softwoods such as spruce. Knowledge of the anatomical organisation of yew wood is an indispensable precondition for the correct interpretation of this conspicuous mechanical behaviour. The aim of this study, therefore, was to interpret the difference in elasto-mechanical behaviour of yew and spruce (as a reference) through their relative microstructures as measured by SilviScan, a technology based on X-ray densitometry, X-ray diffractometry and optical microscopy. This system is able to measure a variety of structural features in a wood sample. The results reveal that the elasto-mechanical response of yew is primarily due to large microfibril angles and a more homogeneous cross-sectional tissue composition (regarding tracheid dimensions and density distribution) compared to spruce. With respect to structure-property relationships, it was concluded that yew wood combines properties of normal and compression wood and therefore takes an intermediate position between them.

A Multiscale Model of the Si LPCVD Process

2004 ◽  
Vol 859 ◽  
Author(s):  
Maurizio Rondanini ◽  
Maurizio Masi ◽  
Sergio Carrà ◽  
Carlo Cavallotti ◽  
Politecnico di Milano
Keyword(s):  
Kinetic Monte Carlo ◽  
Morphological Evolution ◽  
Industrial Process ◽  
Chemical Vapor ◽  
Multiscale Model ◽  
Operating Conditions ◽  
Multiscale Approach ◽  
3 Dimensional ◽  
Growth Regime ◽  
Pressure Chemical

ABSTRACTThe Low Pressure Chemical Vapor Deposition of Si from SiH4 is an industrial process that can be used to deposit epitaxial Si at relatively low surface temperatures. Multiscale models are necessary in order to tune the operating conditions to optimize the quality of the deposited materials. In this work we present a multiscale approach meant to describe the film morphological evolution at different time and length scales. The reactor fluid dynamics and overall mass and temperature balances are solved with the finite element method. The morphological evolution of the film is investigated with 3D kinetic Monte Carlo. We have systematically investigated the dependence of the growth morphology from temperature, pressure and gas phase composition (SiH4/H2 ratio) with the aim of determining the operating parameters window that can lead to the best film morphology. We found that the presence of a significant amount of hydrogen on the surface can significantly influence the surface morphology. In particular hydrogen can be considered as the principal responsible of the transition from an order terrace step flow growth regime, which prevails at high temperatures, to a disordered 3 dimensional growth regime. It is also worth noting that our KMC simulations show that the hydrogen surface chemistry active at low temperatures is probably richer than expected, since the formation of a significant number of island on the surface dramatically increases the concentration of steps, and thus the variety of configurations by which two adsorbed H atoms can interact.

Strain Rate Effect on Microstructure of Dynamically Compressed Magnesium Alloy AZ31B

2013 ◽  
Vol 535-536 ◽  
pp. 137-140 ◽  
Author(s):  
Iram Raza Ahmad ◽  
Muhammad Syfiqu ◽  
Xiao Jing ◽  
Dong W. Shu
Keyword(s):  
Magnesium Alloy ◽  
Strain Rate ◽  
Fuel Consumption ◽  
Mechanical Behaviour ◽  
Mechanical Response ◽  
Microstructural Analysis ◽  
Strain Rate Effect ◽  
Strain Rates ◽  
Magnesium Alloy Az31b ◽  
Protective Structures

Lightweight materials have been in focus in recent times for their use in automobiles, planes and protective structures for numerous benefits ranging from reduction in fuel consumption and increased payload in vehicles to lighter and stronger protective structures. For efficient use of materials in applications where they are subjected to unusual higher sudden loads, it is necessary to understand their mechanical behaviour under such conditions.In present study, the effect of strain rate on deformation of magnesium alloy AZ31Bunder compression has been investigated. The alloy is subjected to various strain rates as 10-4s-1, 500s-1 and 2500s-1 and the microstructural analysis was performed to see the changes in the microstructure of the alloy and their effect on the mechanical response of the alloy is portrayed.

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