Direct writing of three-dimensional woodpile BaTiO3 structures

2014 ◽  
Vol 28 (14) ◽  
pp. 1450108
Author(s):  
Jijiao Li ◽  
Bo Li ◽  
Hongya Wu ◽  
Ji Zhou
Keyword(s):  
Barium Titanate ◽  
Rheological Properties ◽  
Yield Stress ◽  
Storage Modulus ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Lattice Structures ◽  
Direct Writing ◽  
3D Geometry ◽  
High Storage

Barium titanate ( BaTiO 3) woodpile structures with designed, three-dimensional (3D) geometry have been fabricated by direct-writing assembly techniques. Concentrated BaTiO 3 inks with suitable rheological properties were prepared to enable the fabrication of the complex 3D structures. It was demonstrated that BaTiO 3 inks with a total solids volume fraction of 0.41 are shear thinning and have a high storage modulus 1 × 105 Pa with a yield stress of 300 Pa. Additionally, the woodpile lattice structures exhibited an excellent self-supporting feature.

Dispersion of solids in fracturing flows of yield stress fluids

2017 ◽  
Vol 830 ◽  
pp. 93-137 ◽  
Author(s):  
S. Hormozi ◽  
I. A. Frigaard
Keyword(s):  
Yield Stress ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Three Dimensional ◽  
Process Variations ◽  
Model Framework ◽  
Shear Rates ◽  
Low Viscosity ◽  
High Shear Rates ◽  
Solids Concentration

Solids dispersion is an important part of hydraulic fracturing, both in helping to understand phenomena such as tip screen-out and spreading of the pad, and in new process variations such as cyclic pumping of proppant. Whereas many frac fluids have low viscosity, e.g. slickwater, others transport proppant through increased viscosity. In this context, one method for influencing both dispersion and solids-carrying capacity is to use a yield stress fluid as the frac fluid. We propose a model framework for this scenario and analyse one of the simplifications. A key effect of including a yield stress is to focus high shear rates near the fracture walls. In typical fracturing flows this results in a large variation in shear rates across the fracture. In using shear-thinning viscous frac fluids, flows may vary significantly on the particle scale, from Stokesian behaviour to inertial behaviour across the width of the fracture. Equally, according to the flow rates, Hele-Shaw style models give way at higher Reynolds number to those in which inertia must be considered. We develop a model framework able to include this range of flows, while still representing a significant simplification over fully three-dimensional computations. In relatively straight fractures and for fluids of moderate rheology, this simplifies into a one-dimensional model that predicts the solids concentration along a streamline within the fracture. We use this model to make estimates of the streamwise dispersion in various relevant scenarios. This model framework also predicts the transverse distributions of the solid volume fraction and velocity profiles as well as their evolutions along the flow part.

scholarly journals Relating foam and interfacial rheological properties of β-lactoglobulin solutions

Soft Matter ◽  
2014 ◽  
Vol 10 (48) ◽  
pp. 9626-9636 ◽  
Author(s):  
M. Lexis ◽  
N. Willenbacher
Keyword(s):  
Rheological Properties ◽  
Yield Stress ◽  
Volume Fraction ◽  
Laplace Pressure ◽  
Model Predictions ◽  
Order Of Magnitude ◽  
Gas Volume Fraction ◽  
Gas Volume ◽  
Β Lactoglobulin

Interfacial elasticity can strongly increase the modulus and yield stress of protein foams by more than an order of magnitude compared to widely accepted model predictions only including contributions from Laplace pressure and gas volume fraction.

scholarly journals Effects of Volume Fraction and Surface Area of Aggregates on the Static Yield Stress and Structural Build-Up of Fresh Concrete

2020 ◽  
Author(s):  
Irina Ivanova ◽  
Viktor Mechtcherine
Keyword(s):  
Rheological Properties ◽  
Yield Stress ◽  
Surface Area ◽  
Cement Paste ◽  
Volume Fraction ◽  
Fresh Concrete ◽  
Total Surface Area ◽  
Rheological Parameters ◽  
Static Yield ◽  
Static Yield Stress

With increasing interest in the use of additive manufacturing techniques in the construction industry, static rheological properties of fresh concrete have necessarily come into focus. In particular, the knowledge and control of static yield stress (SYS) and its development over time are crucial for mastering formwork-free construction, e.g. by means of layered extrusion. Furthermore, solid understanding of the influences of various concrete constituents on the initial SYS of the mixture and the structural build-up rate is required for purposeful material design. This contribution is concentrated on the effect of aggregates on these rheological parameters. The volume fraction of aggregates was varied in the range of 35 to 55 % by volume under condition of constant total surface area of the particles. The total surface area per unit volume of cement paste was equal to 5.00, 7.25 and 10.00 m²/l, conditioned on the constant volume fraction of aggregates. Both variations were enabled by changing the particle size distributions of the aggregates while holding the cement paste composition constant for all concrete mixtures. To characterise the SYS and the structural build-up, constant shear rate tests with a vane-geometry rotational rheometer were performed. It was found that in the ranges under investigation the variation in volume fraction had a more pronounced effect on the static rheological properties of concrete than did the variation in surface area. An accurate mathematical description of the relationship between the initial SYS of concrete and the relative volume fraction of aggregate based on the Chateau-Ovarlez-Trung model was proposed. Challenges in deriving a similar relationship for the structural build-up rate of concrete were highlighted.

scholarly journals Effects of Volume Fraction and Surface Area of Aggregates on the Static Yield Stress and Structural Build-Up of Fresh Concrete

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1551 ◽  
Author(s):  
Irina Ivanova ◽  
Viktor Mechtcherine
Keyword(s):  
Rheological Properties ◽  
Yield Stress ◽  
Surface Area ◽  
Cement Paste ◽  
Volume Fraction ◽  
Fresh Concrete ◽  
Total Surface Area ◽  
Rheological Parameters ◽  
Static Yield ◽  
Static Yield Stress

With increasing interest in the use of additive manufacturing techniques in the construction industry, static rheological properties of fresh concrete have necessarily come into focus. In particular, the knowledge and control of static yield stress (SYS) and its development over time are crucial for mastering formwork-free construction, e.g., by means of layered extrusion. Furthermore, solid understanding of the influences of various concrete constituents on the initial SYS of the mixture and the structural build-up rate is required for purposeful material design. This contribution is concentrated on the effect of aggregates on these rheological parameters. The volume fraction of aggregates was varied in the range of 35% to 55% by volume under condition of constant total surface area of the particles. The total surface area per unit volume of cement paste was equal to 5.00, 7.25 and 10.00 m²/L, conditioned on the constant volume fraction of aggregates. Both variations were enabled by changing the particle size distributions of the aggregates while holding the cement paste composition constant for all concrete mixtures. To characterise the SYS and the structural build-up, constant shear rate tests with a vane-geometry rotational rheometer were performed. It was found that in the ranges under investigation the variation in volume fraction had a more pronounced effect on the static rheological properties of concrete than did the variation in surface area. An accurate mathematical description of the relationship between the initial SYS of concrete and the relative volume fraction of aggregate based on the Chateau–Ovarlez–Trung model was proposed. Challenges in deriving a similar relationship for the structural build-up rate of concrete were highlighted.

scholarly journals Multidimensional Phononic Bandgaps in Three-Dimensional Lattices for Additive Manufacturing

Materials ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 1878 ◽  
Author(s):  
Waiel Elmadih ◽  
Wahyudin P. Syam ◽  
Ian Maskery ◽  
Dimitrios Chronopoulos ◽  
Richard Leach
Keyword(s):  
Additive Manufacturing ◽  
Elastic Waves ◽  
Internal Resonance ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Destructive Interference ◽  
Lattice Structures ◽  
Wave Modelling ◽  
Material Choice ◽  
High Computational Efficiency

We report on numerical modelling of three-dimensional lattice structures designed to provide phononic bandgaps. The examined lattice structures rely on two distinct mechanisms for bandgap formation: the destructive interference of elastic waves and internal resonance. Further to the effect of lattice type on the development of phononic bandgaps, we also present the effect of volume fraction, which enables the designer to control the frequency range over which the bandgaps exist. The bandgaps were identified from dispersion curves obtained using a finite element wave propagation modelling technique that provides high computational efficiency and high wave modelling accuracy. We show that lattice structures employing internal resonance can provide transmissibility reduction of longitudinal waves of up to −103 dB. Paired with the manufacturing freedom and material choice of additive manufacturing, the examined lattice structures can be tailored for use in wide-ranging applications including machine design, isolation and support platforms, metrology frames, aerospace and automobile applications, and biomedical devices.

Effect of high-pressure homogenisation on rheological properties of rennet-induced skim milk and standardised milk gels

2009 ◽  
Vol 76 (3) ◽  
pp. 294-300 ◽  
Author(s):  
Kristina Lodaite ◽  
François Chevalier ◽  
Emanuele Armaforte ◽  
Alan L. Kelly
Keyword(s):  
High Pressure ◽  
Rheological Properties ◽  
Storage Modulus ◽  
Volume Fraction ◽  
Skim Milk ◽  
Small Deformation ◽  
Formation Time ◽  
Casein Micelle ◽  
Gel Formation ◽  
Deformation Properties

The effects of high-pressure homogenisation (HPH) in the pressure range 100–300 MPa on the gel formation and rheological properties of rennet-induced skim milk (0·08%, fat, w/w) and standardised milk (3·60% fat, w/w) gels at pH 6·60 were studied. The average casein micelle size in skim milk was significantly reduced and the gel formation time decreased when skim milk was subjected to the pressures of 200 and 300 MPa. The storage modulus of rennet-induced skim milk gels at 2700 s after rennet addition was higher for samples homogenised at higher pressures, which contained smaller casein particles. HPH had little effect on the large deformation properties of rennet-induced skim milk gels. The gel formation time of renneted standardised milk was significantly reduced as a result of HPH, while the storage modulus of rennet-induced milk gels 2700 s after rennet addition increased with increasing homogenising pressure. The apparent fracture stress was slightly higher for standardised milk gels formed from HPH-treated milk, whereas the apparent strain at fracture was lower, than that of unhomogenised milk. In conclusion, HPH treatment influenced gel formation processes of skim milk and its small-deformation rheological properties, mainly through modification of casein micelles. HPH also significantly affected the gel formation process of standardised milk gels and its rheological properties as a result of an increase in volume fraction of aggregating particles, while the particle size was of lesser importance.

RHEOLOGICAL PROPERTIES OF ER-FLUIDS IN TERM OF MULTIPARTICLE PHYSICAL MODEL AND MONTE-CARLO COMPUTER SIMULATION

2005 ◽  
Vol 19 (07n09) ◽  
pp. 1184-1190
Author(s):  
Yu. G. Yanovsky ◽  
V. E. Zgaevskii ◽  
A. V. Teplukhin ◽  
Yu. N. Karnet
Keyword(s):  
Monte Carlo ◽  
Electric Field ◽  
Rheological Properties ◽  
Volume Fraction ◽  
Structural Characteristics ◽  
Three Dimensional ◽  
Viscoelastic Body ◽  
Fluid Phase ◽  
Particle Model ◽  
Dynamic Shear Modulus

An electrorheological fluids (ERF) are the suspensions consisting of dielectric rigid particles in the viscous (or viscoelastic) media. Based on the three-dimensional well-ordered multi-particle model (the crystal model) we describe rheological properties of ERF. We use the model of cubic body-centered lattice. We also assume that the electric field is orthogonal to the velocity of shear of fluid's layers. The displacement gradients are assumed to be different (from small to finite values). For small deformations in the framework of the approach proposed and under assumptions made it was stated that the ERF can be treated as a viscoelastic body and it is consequently described on the basis of the linear theory of viscoelasticity. We obtain a complex dynamic shear modulus as a function of the electric field strength, volume fraction of filler, electric properties of components of ERF and viscosity of the fluid phase. For finite deformation the relation between stresses and shear rate gradients has also been made. The relation does not keeps whatever phenomenological or arbitrary parameters and takes into account contribution an electrostatic interaction painted by external field dipoles. From other side a bunch of computational experiments by Monte-Carlo approximation to model both the structure and the peculiarities of ERF were made. We use a procedure by Metropolis for canonic NVT ensemble and parallel computational technologies. The structural characteristics, density, energetic parameter and others for system under consideration have been estimated. In order to verify a theoretical predictions we compare both approaches and some experimental data.

Instrumentation For Quantitative Microscopy

1977 ◽  
Vol 35 ◽  
pp. 206-209
Author(s):  
B. Ralph ◽  
A.R. Jones
Keyword(s):  
Volume Fraction ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Automatic Data ◽  
Phase Volume Fraction ◽  
Statistical Confidence ◽  
Resultant Data ◽  
Automatic Data Collection ◽  
Third Dimension ◽  
Evolution Of Microstructure

In all fields of microscopy there is an increasing interest in the quantification of microstructure. This interest may stem from a desire to establish quality control parameters or may have a more fundamental requirement involving the derivation of parameters which partially or completely define the three dimensional nature of the microstructure. This latter categorey of study may arise from an interest in the evolution of microstructure or from a desire to generate detailed property/microstructure relationships. In the more fundamental studies some convolution of two-dimensional data into the third dimension (stereological analysis) will be necessary.In some cases the two-dimensional data may be acquired relatively easily without recourse to automatic data collection and further, it may prove possible to perform the data reduction and analysis relatively easily. In such cases the only recourse to machines may well be in establishing the statistical confidence of the resultant data. Such relatively straightforward studies tend to result from acquiring data on the whole assemblage of features making up the microstructure. In this field data mode, when parameters such as phase volume fraction, mean size etc. are sought, the main case for resorting to automation is in order to perform repetitive analyses since each analysis is relatively easily performed.

A Study on Utilization of Three-Dimensional Sensor Lip Image for Developing a Pronunciation Recognition System

2019 ◽  
Vol 63 (5) ◽  
pp. 50402-1-50402-9 ◽  
Author(s):  
Ing-Jr Ding ◽  
Chong-Min Ruan
Keyword(s):  
Principal Component Analysis ◽  
Automatic Speech Recognition ◽  
Feature Fusion ◽  
Three Dimensional ◽  
Principal Component ◽  
Recognition System ◽  
Geometrical Characteristics ◽  
3D Geometry ◽  
Different Types ◽  
The Disabled

Abstract The acoustic-based automatic speech recognition (ASR) technique has been a matured technique and widely seen to be used in numerous applications. However, acoustic-based ASR will not maintain a standard performance for the disabled group with an abnormal face, that is atypical eye or mouth geometrical characteristics. For governing this problem, this article develops a three-dimensional (3D) sensor lip image based pronunciation recognition system where the 3D sensor is efficiently used to acquire the action variations of the lip shapes of the pronunciation action from a speaker. In this work, two different types of 3D lip features for pronunciation recognition are presented, 3D-(x, y, z) coordinate lip feature and 3D geometry lip feature parameters. For the 3D-(x, y, z) coordinate lip feature design, 18 location points, each of which has 3D-sized coordinates, around the outer and inner lips are properly defined. In the design of 3D geometry lip features, eight types of features considering the geometrical space characteristics of the inner lip are developed. In addition, feature fusion to combine both 3D-(x, y, z) coordinate and 3D geometry lip features is further considered. The presented 3D sensor lip image based feature evaluated the performance and effectiveness using the principal component analysis based classification calculation approach. Experimental results on pronunciation recognition of two different datasets, Mandarin syllables and Mandarin phrases, demonstrate the competitive performance of the presented 3D sensor lip image based pronunciation recognition system.

scholarly journals Experimental demonstration of negative refraction with 3D locally resonant acoustic metafluids

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Benoit Tallon ◽  
Artem Kovalenko ◽  
Olivier Poncelet ◽  
Christophe Aristégui ◽  
Olivier Mondain-Monval ◽  
...  
Keyword(s):  
Experimental Data ◽  
Yield Stress ◽  
Multiple Scattering ◽  
Silicone Rubber ◽  
Acoustic Waves ◽  
Scattering Theory ◽  
Negative Refraction ◽  
Volume Fraction ◽  
Experimental Demonstration ◽  
Acoustic Beam

AbstractNegative refraction of acoustic waves is demonstrated through underwater experiments conducted at ultrasonic frequencies on a 3D locally resonant acoustic metafluid made of soft porous silicone-rubber micro-beads suspended in a yield-stress fluid. By measuring the refracted angle of the acoustic beam transmitted through this metafluid shaped as a prism, we determine the acoustic index to water according to Snell’s law. These experimental data are then compared with an excellent agreement to calculations performed in the framework of Multiple Scattering Theory showing that the emergence of negative refraction depends on the volume fraction $$\Phi$$ Φ of the resonant micro-beads. For diluted metafluid ($$\Phi =3\%$$ Φ = 3 % ), only positive refraction occurs whereas negative refraction is demonstrated over a broad frequency band with concentrated metafluid ($$\Phi =17\%$$ Φ = 17 % ).

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