Volume Fraction Of Component Research Articles

Reduction of Dimensionality in Monte Carlo Simulation of Diffusion in Extracellular Space Surrounding Cubic Cells.

The real-time iontophoretic method has measured volume fraction and tortuosity of the interstitial component of extracellular space in many regions and under different conditions. To interpret these data computer models of the interstitial space (ISS) of the brain are constructed by representing cells as Basic Cellular Structures (BCS) surrounded by a layer of ISS and replicating this combination to make a 3D ensemble that approximates brain tissue with a specified volume fraction. Tortuosity in such models is measured by releasing molecules of zero size into the ISS and allowing them to execute random walks in the ISS of the ensemble using a Monte Carlo algorithm. The required computational resources for such simulations may be high and here we show that in many situations the 3D problem may be reduced to a quasi-1D problem with consequent reduction in resources. We take the simplest BCS in the form of cubes and use MCell software to perform the Monte Carlo simulations but the analysis described here may be extended in principle to more complex BCS and an ISS that has a defined viscosity and an extracellular matrix that interacts with diffusing molecules. In the course of this study we found that the original analytical description of the relation between volume fraction and tortuosity for an ensemble of cubes may require a small correction.

Coupled nonlinear elasticity, plastic slip, twinning, and phase transformation in single crystal titanium for plate impact loading

High purity single crystal titanium (Ti) under shockwave loading in plate impact experiment is modeled and simulated, with help of the finite element. A thermodynamically consistent system of equations is formulated in the frame of large deformation to consider material anisotropy, rate dependence, and multi-physics including nonlinear elasticity, dislocation based plastic slip, deformation twinning, and phase transformation. A novel kinematics is proposed to consider phase transformation in the α twin variants and also to consider the dislocation based slip in all of components of parent material, primary twins and the ω phase. The thermodynamically consistent driving forces for plastic slip, twinning, and phase transformation are developed based upon the second law of thermodynamics. For nonlinear elasticity, the stiffness matrix is dependent on the volume fractions of all components, and the volumetric part of Cauchy stress is obtained from the nonlinear equation of state. Dislocation based plastic slip in multi-variant and multiphase heterogeneous materials is developed and interactions of dislocations among all slip modes are taken into account. A mechanism for dislocation density evolution during twinning and phase transformation is proposed. The shock loading along the [0001] and [101¯1] directions of single crystal high purity Ti is investigated computationally. Very good correspondence between simulation and experiment is obtained, which includes pole figures, volume fractions of components, free surface velocity, peak pressure, and phase transformation pressure. Multiple experimental phenomena are interpreted based upon the progression of dislocation slip, deformation twinning, and phase transformation. In compression with the [101¯1] crystal, a higher volume fraction in the primary twins but a lower secondary twin volume fraction in the [0001] crystal in experiment was observed. The higher propensity for phase transformation occurs in the [0001] crystal is reproduced. In addition to material texture, distributions of temperature, stresses, and plastic strains dependent on the impact loading directions are revealed.

Catalyst: Size Distribution in Self-Assembly Matters

Dafni Moatsou completed her PhD in chemistry at the University of Warwick in 2015, was a Marie Sklodowska-Curie fellow at the Adolphe Merkle Institute until 2017, and is a junior research group leader at the Karlsruhe Institute of Technology, where she focuses on sequence control and self-assembly of polymers. Rachel O’Reilly completed her PhD in 2003 at Imperial College London. She currently holds a chair in chemistry within the College of Engineering and Physical Sciences at the University of Birmingham. In August 2018 she became the head of the School of Chemistry. Her research targets the design, synthesis, and application of polymeric materials, where control over architecture, functionality, and reactivity are central to their application.

Improved exchange bias and blocking temperature of PtCr/PtMn bilayer antiferromagnets

Herein, we investigated exchange coupling in PtCr/CoFe, PtCr/PtMn/CoFe, and PtMn/CoFe film structures, demonstrating that Pt51Cr49(30 nm)/Co90Fe10(10 nm), Pt51Cr49(27.2 nm)/Pt50Mn50/(2.8 nm)/Co90Fe10(10 nm), and Pt50Mn50(30 nm)/Co90Fe10(10 nm) structures annealed at 350 °C for 20 h in a 10-kOe field featured unidirectional anisotropy constants (Jk) of 0.09, 0.56, and 0.32 erg/cm2, respectively. In the case of the Ni50Fe12Cr38(4 nm)/Pt51Cr49(30 − X nm)/Pt50Mn50(X nm)/Co90Fe10(10 nm)/Ta(10 nm) [X = 0–30 nm] film system, Jk linearly and steeply increased with increasing X to reach a maximum of 0.56 erg/cm2 at X = 2.8 nm and then decreased in a complicated nonlinear fashion as X further increased to 30 nm. On the other hand, the blocking temperature of Pt51Cr49(28 nm)/Pt50Mn50/(2 nm)/Co90Fe10(10 nm) was determined as 500 °C and nearly equaled that of Pt51Cr49(30 nm)/Co90Fe10(10 nm), significantly exceeding the value of 400 °C determined for Pt50Mn50(30 nm)/Co90Fe10(10 nm). These results imply that the exchange bias field of the Ni50Fe12Cr38(4 nm)/Pt51Cr49(30 − X nm)/Pt50Mn50/(X nm)/Co90Fe10(10 nm)/Ta(10 nm) system is ultimately determined by the chemical composition and the modification of the antiferromagnetic spin structure at the ferromagnet–antiferromagnet interface, while the blocking temperature is almost entirely determined by the volume fraction of the PtCr component.

Calculation of Filament Volume Fraction in Dry Roving and Constants of Parameters of Composites Made of Unidirectional Fibers

The paper presents a method making it possible to reveal the minimum cross-sectional area, maximum volume fraction of filaments (fibers) of a roving, and minimum volume fraction of the interfilament gaps of a dry roving, which are independent parameters (constants) of roving. Each kind of roving taken separately has parameters relevant only to it (technical data). Practical application of the method is demonstrated by examples of determination of these data for rovings of carbon (CF) and ultrahigh-molecular-weight polyethylene (UHMWPE). The ratio of the cross-sectional areas of the resin-impregnated and dry roving depends on the amount of matrix within the interfilament gaps and is a constant, which is assigned by the impregnation technology. The constants of rovings are a base for calculation of the reinforcement factors for components of composite. The constants make it possible to simplify the calculation of the number of rovings at prespecified concentration of reinforcement components in hybrid composites made of unidirectional fibers. Examples of utilization of the constants for the calculation of volume, required quantity, density, and volume fractions of reinforcement components in composites made of unidirectional fibers are presented. The difference of degree between actual volume fractions of fibers in the rovings and ideal values calculated for hexagonal and tetragonal spacing of fibers is revealed too.

Microimaging-informed continuum micromechanics accurately predicts macroscopic stiffness and strength properties of hierarchical plant culm materials

Plant materials exhibit a wide range of highly anisotropic mechanical behavior due to a hierarchy of microheterogeneous structures at different length scales. In this article, we present a micromechanics approach that derives a hierarchical microstructure driven model of macroscopic stiffness and strength properties of anisotropic culm materials. As model input, it requires mechanical properties of the base constituents such as cellulose and lignin as well as morphology and volume fractions of all heterogeneous components at each hierarchical level. The latter can be retrieved from imaging data at different length scales, obtained from scanning electron and transmission electron microscopy. We illustrate our modeling approach for the example of bamboo that has gained increasing attention in the last decade due to its role as a sustainable building material. Validating its predictions of macroscopic stiffness moduli and ultimate strength with corresponding experimental measurements, we demonstrate that the micromechanics model provides excellent accuracy without any further phenomenological calibration. We also show that the multiscale modeling approach enables a better physics-based understanding of the origins of bamboo stiffness and strength across different scales.

The histological microstructure and in vitro mechanical properties of the human female postmenopausal perineal body

The perineal body connects muscles from the pelvic floor and is critical for support of the lower part of the vagina and proper function of the anal canal. We determined mechanical parameters and volume fractions of main components of the human female postmenopausal perineal body. The specimens were taken from 15 fresh female cadavers (age 74 ± 10, mean ± standard deviation). Seventy-five specimens from five regions of the perineal body were processed histologically to assess volume fractions of tissue components using stereological point testing grid. Fifteen specimens taken from the midline region were loaded uniaxially with 6 mm/min velocity until tissue rupture to determine Young's modulus of elasticity, ultimate stresses, and strains. The perineal body was composed of collagen (29%), adipose cells (27%), elastin (7%), smooth muscle (11%), and skeletal muscle (3%). The residual tissue (19%) constituted mostly peripheral nerves, lumina of blood vessels, fibroblasts, and fibrocytes. Young's modulus of elasticity at midline region was 18 kPa (median) at small and 232 kPa at large deformations, respectively. The ultimate stress was 172 kPa and the ultimate strain was 1.4. We determined the structural and mechanical parameters of the perineal body. The resultant data could be used as input for models simulating pelvic floor prolapse or dysfunction.

Phase behavior and morphology of multicomponent liquid mixtures.

Multicomponent systems are ubiquitous in nature and industry. While the physics of few-component liquid mixtures (i.e., binary and ternary ones) is well-understood and routinely taught in undergraduate courses, the thermodynamic and kinetic properties of N-component mixtures with N > 3 have remained relatively unexplored. An example of such a mixture is provided by the intracellular fluid, in which protein-rich droplets phase separate into distinct membraneless organelles. In this work, we investigate equilibrium phase behavior and morphology of N-component liquid mixtures within the Flory-Huggins theory of regular solutions. In order to determine the number of coexisting phases and their compositions, we developed a new algorithm for constructing complete phase diagrams, based on numerical convexification of the discretized free energy landscape. Together with a Cahn-Hilliard approach for kinetics, we employ this method to study mixtures with N = 4 and 5 components. We report on both the coarsening behavior of such systems, as well as the resulting morphologies in three spatial dimensions. We discuss how the number of coexisting phases and their compositions can be extracted with Principal Component Analysis (PCA) and K-means clustering algorithms. Finally, we discuss how one can reverse engineer the interaction parameters and volume fractions of components in order to achieve a range of desired packing structures, such as nested "Russian dolls" and encapsulated Janus droplets.

Modeling of Austenitization Kinetics under Continuous Heating of Steels with Complex Microstructure

A quantitative mathematical model describing the austenitization kinetics of steels with complex microstructure and predicting austenite grain size in dependence on the heating rate, chemical composition, volume fractions of structural components (ferrite, pearlite, bainite, martensite) and ferrite grain size was developed. The set of empirical parameters of the model was obtained basing on the experimental data on kinetics of austenitization under continuous heating of various microstructures of 8 industrial steel grades with wide range of chemical compositions (С(0.08÷0.66), Mn(0.37÷1.55), Si(0.20÷0.56), Cr(0.10÷1.08), Ni(0.06÷1.94), Mo(0.01÷0.52), Nb(0.003÷0.041), V(0.002÷0.15), Ti(0.002÷0.063) (mass.%)), as well as on the final austenite grain size. In the initial state steels had pearlitic, ferritic-pearlitic, ferritic-bainitic, bainitic-martensitic and other more complex microstructures. Before studying austenitization under continuous heating from room temperature at rates of 0.5, 1, 3, 10, 50 °C/s, steels samples were thermally pretreated to obtain the desired spectrum of microstructures. All experiments were performed using the Pocket Jaw unit of Gleeble 3800 complex. The kinetics of steels austenitization and austenite grain size predicted by the developed model are in good agreement with experimental data.

Nonlinear mixing law for magnetic resonance transverse-relaxation measurements of dispersed mixtures

Nuclear magnetic resonance (NMR) has been used to estimate the permeability of water-saturated rocks with uniform grain-surface composition. Geologic formations, however, usually consist of layers of rocks with different grain-surface compositions. In the absence of water diffusional coupling between adjacent layers, the NMR [Formula: see text] distribution measured by a borehole logging tool is a weighted average (i.e., it obeys a linear mixing law) of the [Formula: see text] distributions of each layer. However, when the layers are very thin (compared with the self-diffusion length of water) or the different grain types form a dispersed mixture (i.e., they are finely mixed), the resultant [Formula: see text] distribution does not obey a linear mixing law anymore. The question arises as to whether it is possible to differentiate between dispersed and layered formations using mixing laws. We have developed a nonlinear mixing law to calculate the NMR [Formula: see text] distribution of a water-saturated sample composed of a fine mixture of two different grain types from the [Formula: see text] distributions of the water-saturated samples for each grain type. Water-saturated mixtures of crushed Texas Cream limestone and white silica sand were prepared in different volume ratios; we used the new nonlinear mixing law to compute the [Formula: see text] distribution of the mixtures using the [Formula: see text] distributions of the pure water-saturated samples and their volume fractions. Conversely, we also applied the nonlinear mixing law to the mixture to calculate the volume fractions of pure components using the [Formula: see text] distributions of the pure components and the mixtures. Our results indicate that enough differences exist between the nonlinear and linear NMR mixing laws predictions that they can be used to establish whether in a given rock formation with two different grain types the pure components form layers or they are present in dispersed form.

Microstructure and Texture of Cold Rolled and Recrystallized CrNoNi Medium-Entropy Alloy

An equiatomic CrCoNi medium-entropy alloy plate was heavily deformed by conventional cold rolling and subsequently annealed at different temperatures. Microstructure and texture evolution of the deformed and annealed sheets were investigated by electron backscatter diffraction and X-ray diffraction. Heavy cold rolling induces an alloy type α-fibre texture with major brass component. This type of texture is indicative of low stacking fault energy of the CrCoNi alloy. Annealing at 700 °C leads to a homogeneously recrystallized microstructure with ultrafine grains of about 800 nm average size. The volume fraction of different texture components is almost similar after annealing at different temperatures. However, the overall texture intensity after annealing is very weak. Finally, in order to understand the microstructure and texture evolution of the CrCoNi alloy, it is critically compared with other low stacking fault energy FCC materials.

Effects of the Mg/Si Ratio on Microstructure, Mechanical Properties, and Precipitation Behavior of Al⁻Mg⁻Si⁻1.0 wt %-Zn Alloys.

Aluminum alloys are widely used as first-choice materials for lightweight automotive applications. It is important that an alloy have a balance between strength and formability. In this study, the alloys were melted, cast, hot rolled, and cold rolled into 1 mm-thick sheets. The microstructure, mechanical properties, and precipitation behavior of Al–Mg–Si–1.0 wt %-Zn alloys with Mg/Si ratios of 0.5, 1, and 2 after solution treatment were studied using optical and electron microscopy, a tensile test, the Vickers hardness test, and differential scanning calorimetry. The results showed that a high density and number of Al–Fe–Si particles were observed in the matrix, thus causing the formation of more homogeneous and smaller recrystallized grains after treatment with the solution. In addition, a higher volume fraction of cubeND and P-types texture components formed during solution treatment. Also, a high r value and excellent deep drawability were achieved in the medium-Mg/Si-ratio alloy. The formation of denser strengthening precipitates led to a better paint-bake hardening effect in comparison with the other two alloys. Furthermore, the precipitation kinetics were enhanced by the addition of Si, and the addition of Zn did not alter the precipitation sequence of the Al–Mg–Si alloy. The dual-phase strengthening effect was not achieved in the studied alloys during paint-bake treatment at 175 °C.

Multi-field mechanical behavior of a rotating porous FGMEE circular disk with variable thickness under hygrothermal environment

A rotating porous functionally graded magneto-electro-elastic (FGMEE) annular plate with variable thickness under hygrothermal environment is studied in this paper. The FG index is expressed by the volume fraction of piezoelectric component, and the porosity which depends on the volume fraction of each solid component takes various pores (inherent pores in components and structural pores at the interfaces) into account. Considering the effect of pores on both mass density and moisture of the structure, steady-state heat conduction and nonlinear moisture diffusion equations are built and solved by the differential quadrature method (DQM). Applying a linear hygrothermal electro-magneto-elastic constitutive relation, and combining the stress equilibrium equation with static electric and magnetic equations, governing equations expressed by displacement, electric and magnetic potentials are derived and also solved by DQM. In the numerical examples, influences of material property (FG index and porosity parameters), geometric structure (inner-outer thickness ratio and its change index) as well as external conditions (temperature and moisture boundary conditions) to the multi-field responses of the porous FGMEE annular plate are studied in detail. The theoretical process and conclusions will be helpful to the design and manufacture of novel porous FG structures applying in complex multi-field environment and conditions.

Effects of nanosized particles on microstructure and mechanical properties of an aged in-situ TiB2/Al-Cu-Li composite

The effects of nanosized TiB2 particles on microstructural and mechanical properties of the hot extruded in-situ TiB2/Al-Cu-Li composite after T6 heat treatment are quantitatively evaluated by using scanning electron microscopy, transmission electron microscopy, electron backscatter diffraction technique and X-ray diffraction. Most TiB2 particles are aggregated together to form the particle bands. The composite develops the typical fiber textures, <111> and <l00> paralleling to extruded direction, while the matrix alloy only develops weak <111> and <113> textures. The intensity and volume fraction of major texture components can increase significantly with the addition of TiB2 particles. Due to the introduction of TiB2 particles, T1 and S phases not only have higher number density, but also are smaller. In addition, the T1 phases can connect with each other to form a continuous network in the composite. The θ’ phase, identified in matrix alloy, is rarely observed in the composite. The yield strength and ultimate tensile strength of composite have increased by 248 MPa and 152 MPa compared with matrix alloy, respectively.

Stiffness to Weight Ratio of Various Mechanical and Thermal Loaded Hyper Composite Plate Structures

In this study, several models of the rocket fins were made of hyper composite materials (with two or more reinforced materials) with different volume fractions of components used to produce isotropic composite plate structures. The reinforcement of polyester resin material was done in two ways, with fibre reinforcement and powder reinforcement. The types of fibresthat used were chopped glass fibre and chopped carbon fibre, and the type of powder used was carbon powder. A concentrated load was applied to the models in the form of a cantilever plate. The effect of adding carbon powder on the stiffness to weight ratio and the effect of temperature on this stiffness to weight ratio were studied and discussed. It was observed that hybridization improves the properties of composite materials at certainspecific volume fractions of carbon powder. The best percentage of improvement of the value of stiffness was69.87% in a specimenmade of 50% polyester, 30% glass fibres, and 20% carbon powderin terms of models reinforced with glass fibres, while for models reinforced with carbon fibres, it was 79.94% in the model made of 60% polyester, 30% carbon fibre, and 10% carbon powder. In addition, the results showed that an increase in temperature leads to a decrease in the stiffness to weight ratio for all models. The smallest effect of temperature on the stiffness to weight ratio was shown in the sample composed of 50% polyester, 30% glass fibres, and 20% carbon powder, at 45.83% for the models reinforced with chopped glass fibres, and in the model made of 60% polyester, 20% carbon fibres, and 20% carbon powder at 57.54% for models reinforced with carbon fibres.

The Investigation of Microhardness of Grey Cast Iron Dendritic Structure

The dependence of the dendritic crystals of primary austenite microhardness on indentation load within the range from 0,01 to 2 N is investigated. Tests are carried out on specimens with a volume fraction of a dendritic component of 15%, 30% and 60%. It is found that at any volume of dendritic fraction microhardness increases with an increase in load from 0,01 to 0,1 N and then, in the process of a further indentation load growth, decreases a little. Decrease in microhardness in the range of loadings from 0,1 N to 2 N can be accounted for by growth of an impression size and a spread of plastically deformed volume to a dendritic crystal surface.

The effect of Mn content on the texture of aluminium alloys in cold rolled and annealed state

The crystallographic texture greatly influences the properties of the cold rolled and hot rolled semi-products. As semi-products undergo further shaping (and heat treatment) before reaching their final condition, it is important to know their crystallographic texture. During our research, three different alloy aluminium alloys were tested (3003, 3103, unalloyed Al sheet) with different Mn content. In the first step the initial hot-rolled sheets were cold rolled to ∼1 mm thickness without intermediate annealing. In the second step the sheets were cold rolled to 3 mm and annealed. In parallel, an intermediate annealing was applied at ∼3 mm thickness for the 3103 alloy and subsequently cold rolled to 1 mm and annealed. The annealings were performed at 300°C for 3 hours in an air furnace. The resulting textures are characterized by the volume fractions of the main texture components, which were calculated from the orientation distribution function (ODF). The dominant texture components were determined for the different alloys in different states.

The aging mode for reducing the thermal expansion of the piston from alloy AK21

The effect of temperature and aging time (1÷10 h) at 100-300 °C on the microstructure and thermal expansion of the engine piston YaMZ 5363 from the hypereutectic silumin of AK21 type was studied. It is established that low-temperature aging at 100 °C for 1 hour, allows the temperature coefficient of linear expansion (TCLE) to be reduced in the operating temperature range of heavy-loaded engines (250-350 °C) by 3-6%. The increase in the aging time of pistons up to 3, 5 and 10 h does not lead to the further decrease in TCLE, as well as the increase in the aging temperature to 150, 200, 250 and 300 °C. Moreover, low-temperature aging does not lead to significant changes in the structure of the pistons of the engines in the delivery state, with the exception of coagulation of some of the volume fraction of the eutectic component of Al-Si or Al-Si-Cu.

Effects of porosity and composition on seismic wave velocities and elastic moduli of lower cretaceous rocks, central Lebanon

We collected 40 rock samples from the Cretaceous strata exposed at central Lebanon in order to study the effects of porosity and rock composition on their seismic wave velocities and elastic moduli. Several sedimentological and mineralogical studies were conducted to evaluate the rock composition, provenance, depositional conditions, and the diagenetic history of the studied rocks. Porosity, bulk and grain densities and seismic wave velocities were measured for 35 drilled core samples at ambient conditions in the laboratory. Velocity measurements were conducted on the dry core samples utilizing the pulse transmission technique. Petrographically, four lithofacies have been identified under the polarizing microscope. From oldest to youngest, these comprise arenitic sandstone, lithic limestone, oolitic limestone, and micritic limestone. Investigations of representative rock samples under the SEM revealed that a number of diagenetic processes have impacted the studied rocks, and thereby affected their petrophysical properties. The XRD analysis, on the other hand, revealed that quartz and calcite are the dominant minerals in the sandstones of the Chouf Formation and the limestones of the Abeih and Mdairej Formations, respectively. The measured porosity, bulk density, and compressional and shear wave velocities of the investigated rocks vary, respectively, between 2.14–10.05%, 2.41–2.67 g/cm3, 3885–6385 m/s and 2246–3607 m/s. The grain density was calculated from the measured porosity and bulk density data and varies narrowly between 2.64 and 2.78 g/cm3. We further calculated the Poisson’s ratio and the moduli of shear, bulk, and Young from the measured bulk density and seismic wave velocities. Calculated values of these parameters vary between 0.18–0.28, 1.23–3.43 × 1010 Pa, 2.03–6.18 × 1010 Pa and 3.06–8.69 × 1010 Pa, respectively. The generalized mixture rule is used to provide a unified description of the physical properties of the studied rocks regarding their component properties, volume fractions, and microstructures. We constructed a number of relationships between the measured petrophysical and elastic properties to evaluate the mutual interdependence of these parameters and assess the effects of porosity and rock type on these important rock characteristics.

Characterization of crystallographic texture of Zirconium alloy components by neutron diffraction

The reproducibility of the determination of crystallographic texture of Zr-based components by neutron diffraction has been studied through a small round-robin exercise, with the participation of texture and residual stress diffractometers from five international laboratories. Both constant-wavelength and polychromatic neutron beams have been used to define the texture of specimens from a warm-rolled and annealed Zircaloy-4 plate, and from a Zr-2.5%Nb pressure tube. Measurements were also compared to synchrotron high energy X-ray diffraction experiments, as a complementary volumetric technique with much shorter data collection times compared to neutrons. Results are qualitatively consistent and reproducible in terms of pole figures and orientation distribution function, underlining the suitability of neutrons for bulk texture measurements. Expected uncertainty of measurements has been quantified by global parameters such as texture indexes and Kearns factors, and local parameters associated to the main texture components (volume fraction, centroids, and widths of fiber components). The typical uncertainties found for these parameters are compared to spatial differences found in a small batch of cold-rolled Zr-2.5%Nb pressure tubes.