An Energy-Based Analysis for Machining Novel AZ91 Magnesium Composite Foam Dispersed With Ceramic Microspheres

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
S. Kannan ◽  
S. Pervaiz ◽  
R. J. Klassen ◽  
D. Huo ◽  
M. Haghshenas
Keyword(s):  
Load Transfer ◽  
Volume Fraction ◽  
Mechanistic Model ◽  
Interfacial Strength ◽  
Industrial Applications ◽  
Force Model ◽  
Electron Microscopic ◽  
Matrix Cracks ◽  
Modes Of Failure ◽  
Az91 Magnesium

Abstract Metal syntactic foams are a novel grade of materials that find potential applications in the manufacture of lightweight structural components and biomedical applications. For these materials to be inducted into industrial applications, it becomes imperative to study their machining behavior. In this article, for the first time in the literature, machining characteristics of AZ91 magnesium foam reinforced with thin-walled hollow alumina ceramic microspheres being studied. Through cutting experiments, it is found that finer the size of hollow microspheres and higher their volume fraction, higher was the magnitude of cutting forces recorded. The failure mechanisms that constituted chip formation during cutting AZ91 foam has been explicated through a mechanistic cutting force model. The proposed force model takes into account key hollow alumina microsphere properties such as wall thickness-to-diameter ratio, average microsphere size, and volume fraction. The scanning electron microscopic (SEM) analysis showed two key modes of failure during cutting metallic foams. Microsphere bursts and fractures control matrix plastic deformation through an effective load transfer mechanism. The transverse matrix cracks, which are initiated as a result of induced shear stress, promote the propagation of longitudinal adhesive cracks. This rapid crack growth takes place along the direction of maximum energy release rate, thus weakening the interfacial strength and reducing effective load transfer. This leads to microsphere separation, and further matrix densification due to the collapse of microsphere cavities leads to chip separation. The developed mechanistic model was in better agreement with experimental results.

scholarly journals On the Role of Hollow Aluminium Oxide Microballoons during Machining of AZ31 Magnesium Syntactic Foam

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3534 ◽  
Author(s):  
Sathish Kannan ◽  
Salman Pervaiz ◽  
Abdulla Alhourani ◽  
Robert J. Klassen ◽  
Rajiv Selvam ◽  
...  
Keyword(s):  
Chip Formation ◽  
High Speed ◽  
Load Transfer ◽  
Volume Fraction ◽  
Syntactic Foam ◽  
Aluminium Oxide ◽  
Surface Friction ◽  
Force Model ◽  
Thin Wall ◽  
Machining Forces

The role played by hollow ceramic thin-walled aluminium oxide microballoons on the shear deformation characteristics of AZ31 Magnesium syntactic foam is studied through high-speed machining. The ceramic microballoons embedded in the AZ31 matrix provides the necessary stiffness for these novel foams. The effect of hollow ceramic microballoon properties, such as the volume fraction, thin wall thickness to diameter ratio, and microballoon diameter, profoundly affects the chip formation. A novel force model has been proposed to explain the causes of variation in cutting forces during chip formation. The results showed an increase in machining forces during cutting AZ31 foams dispersed with higher volume fraction and finer microballoons. At a lower (Davg/h) ratio, the mode of microballoon deformation was a combination of bubble burst and fracture through an effective load transfer mechanism with the plastic AZ31 Mg matrix. The developed force model explained the key role played by AZ31 matrix/alumina microballoon on tool surface friction and showed a better agreement with measured machining forces.

Preparation of Electron Transparent Metal-Matrix Composites

1968 ◽  
Vol 26 ◽  
pp. 334-335 ◽  
Author(s):  
M. R. Pinnel ◽  
A. Lawley
Keyword(s):  
Stainless Steel ◽  
Load Transfer ◽  
Volume Fraction ◽  
Steel Wire ◽  
Initial Step ◽  
Interfacial Region ◽  
Matrix Composites ◽  
Specific Test ◽  
The Matrix ◽  
The One

Numerous phenomenological descriptions of the mechanical behavior of composite materials have been developed. There is now an urgent need to study and interpret deformation behavior, load transfer, and strain distribution, in terms of micromechanisms at the atomic level. One approach is to characterize dislocation substructure resulting from specific test conditions by the various techniques of transmission electron microscopy. The present paper describes a technique for the preparation of electron transparent composites of aluminum-stainless steel, such that examination of the matrix-fiber (wire), or interfacial region is possible. Dislocation substructures are currently under examination following tensile, compressive, and creep loading. The technique complements and extends the one other study in this area by Hancock.The composite examined was hot-pressed (argon atmosphere) 99.99% aluminum reinforced with 15% volume fraction stainless steel wire (0.006″ dia.).Foils were prepared so that the stainless steel wires run longitudinally in the plane of the specimen i.e. the electron beam is perpendicular to the axes of the wires. The initial step involves cutting slices ∼0.040″ in thickness on a diamond slitting wheel.

“Cavity” formation in superplastically deformed aluminium alloys

1990 ◽  
Vol 48 (4) ◽  
pp. 958-959
Author(s):  
A. Cziráki ◽  
E. Ková-csetényi ◽  
T. Torma ◽  
T. Turmezey
Keyword(s):  
Grain Boundaries ◽  
Aluminium Alloys ◽  
Superplastic Deformation ◽  
Volume Fraction ◽  
Superplastic Forming ◽  
Polished Surface ◽  
Cavity Formation ◽  
Stress Concentrations ◽  
Electron Microscopic ◽  
Commercial Aluminium

It is known that the formation of cavities during superplastic deformation can be correlated with the development of stress concentrations at irregularities along grain boundaries such as particles, ledges and triple points. In commercial aluminium alloys Al-Fe-Si particles or other coarse constituents may play an important role in cavity formation.Cavity formation during superplastic deformation was studied by optical metallography and transmission scanning electron microscopic investigations on Al-Mg-Si and Al-Mg-Mn alloys. The structure of particles was characterized by selected area diffraction and X-ray micro analysis. The volume fraction of “voids” was determined on mechanically polished surface.It was found by electron microscopy that strongly deformed regions are formed during superplastic forming at grain boundaries and around coarse particles.According to electron diffraction measurements these areas consist of small micro crystallized regions. See Fig.l.Comparing the volume fraction and morphology of cavities found by optical microscopy a good correlation was established between that of micro crystalline regions.

Study of pumping effect in flow-through electrolysers

1983 ◽  
Vol 48 (8) ◽  
pp. 2232-2248 ◽  
Author(s):  
Ivo Roušar ◽  
Michal Provazník ◽  
Pavel Stuhl
Keyword(s):  
Natural Convection ◽  
Balance Equation ◽  
Volume Fraction ◽  
Industrial Applications ◽  
Pumping Effect ◽  
Flow Through ◽  
The Mean ◽  
The Difference

In electrolysers with recirculation, where a gas is evolved, the pumping of electrolyte from a lower to a higher level can be effected by natural convection due to the difference between the densities of the inlet electrolyte and the gaseous emulsion at the outlet. An accurate balance equation for calculation of the rate of flow of the pumped liquid is derived. An equation for the calculation of the mean volume fraction of bubbles in the space between the electrodes is proposed and verified experimentally on a pilot electrolyser. Two examples of industrial applications are presented.

Uncertainty Reduction for Model Error Detection in Multiphase Shock Tube Simulation

2021 ◽  
Author(s):  
Chanyoung Park ◽  
Samaun Nili ◽  
Justin Mathew ◽  
Frederick Ouellet ◽  
Rahul Koneru ◽  
...  
Keyword(s):  
Shock Tube ◽  
Error Detection ◽  
Parametric Design ◽  
Volume Fraction ◽  
Model Error ◽  
Uncertainty Reduction ◽  
Lessons Learned ◽  
Force Model ◽  
Numerical Flux ◽  
Compressible Multiphase Flow

Abstract Uncertainty quantification (UQ) is an important step in the verification and validation of scientific computing. Validation is often inconclusive when uncertainty is larger than an acceptable range for both simulation and experiment. Therefore, uncertainty reduction (UR) is important to achieve meaningful validation. A unique approach in this paper is to separate model error from uncertainty such that UR can reveal the model error. This paper aims to share lessons learned from UQ and UR of a horizontal shock tube simulation, whose goal is to validate the particle drag force model for the compressible multiphase flow. Firstly, simulation UQ revealed the inconsistency in simulation predictions due to the numerical flux scheme, which was clearly shown using the parametric design of experiments. By improving the numerical flux scheme, the uncertainty due to inconsistency was removed, while increasing the overall prediction error. Secondly, the mismatch between the geometry of the experiments and the simplified 1D simulation model was identified as a lack of knowledge. After modifying simulation conditions and experiments, it turned out that the error due to the mismatch was small, which was unexpected based on expert opinions. Lastly, the uncertainty in the initial volume fraction of particles was reduced based on rigorous UQ. All these UR measures worked together to reveal the hidden modeling error in the simulation predictions, which can lead to a model improvement in the future. We summarized the lessons learned from this exercise in terms of empty success, useful failure, and deceptive success.

A Mechanistic Force Model of the 5-Axis Milling Process

2000 ◽  
Author(s):  
Paul A. Clayton ◽  
Mohamed A. Elbestawi ◽  
Tahany El-Wardany ◽  
Dan Viens
Keyword(s):  
High Speed ◽  
Mechanistic Model ◽  
Back Propagation ◽  
High Speed Steel ◽  
Cutting Edge ◽  
Analytic Description ◽  
Force Model ◽  
Force Output ◽  
Five Axis ◽  
Milling Force Model

Abstract This paper presents a five-axis milling force model that can incorporate a variety of cutters and workpiece materials. The mechanistic model uses a discretized cutting edge to calculate an area of intersection which is multiplied by the specific cutting pressure to produce a force output along the primary cartesian coordinate system. By using an analytic description of the cutting edge with a non-specific cutter and workpiece intersection routine, a model was created that can describe a variety of cutting situations. Furthermore, a back propagation neural network is used to calibrate the model, providing robustness and scalability to the calibration process. Testing was performed on 1020 steel using various cutting parameters with a high speed steel two flute cutter and a tungsten carbide insert cutter. Furthermore, both linear cuts and a test die surface yielded good agreement between predicted and measured results.

Experimental Study of Grinding Characteristics on SiCp/Al Composites

2011 ◽  
Vol 487 ◽  
pp. 135-139 ◽  
Author(s):  
Li Zhou ◽  
Shu Tao Huang ◽  
Xiao Lin Yu
Keyword(s):  
Volume Fraction ◽  
Ground Surface ◽  
Diamond Wheel ◽  
Feed Speed ◽  
Grinding Forces ◽  
Electron Microscopic ◽  
Sic Particles ◽  
Scanning Electron Microscopic ◽  
Grinding Machine ◽  
Sic Particle

This paper deals with the grinding performances of SiCp/Al composites with higher volume fraction and larger SiC particle. The effects of the grinding parameters on the grinding force, removal mechanisms of SiC particles have been investigated. The grinding tests were carried out by using diamond wheel on surface grinding machine. The results indicate that the feed speed of worktable has more significant effect on the grinding forces than that of grinding depth. The scanning electron microscopic images of the machined surfaces indicate that the material removal of SiC particles was primarily due to the failure of the interface between the reinforcement and matrix, and resulting from microcracks along the interface and many fracture or crushed SiC particles on the ground surface.

scholarly journals Collisions of Two-Phase Liquid Droplets in a Heated Gas Medium

Entropy ◽  
2021 ◽  
Vol 23 (11) ◽  
pp. 1476
Author(s):  
Pavel Tkachenko ◽  
Nikita Shlegel ◽  
Pavel Strizhak
Keyword(s):  
Volume Fraction ◽  
Industrial Applications ◽  
Droplet Breakup ◽  
Liquid Volume ◽  
Liquid Droplets ◽  
Vapor Bubbles ◽  
Two Phase ◽  
Relative Volume Fraction ◽  
Phase Liquid ◽  
Gas Medium

The paper presents the experimental research findings for the integral characteristics of processes developing when two-phase liquid droplets collide in a heated gas medium. The experiments were conducted in a closed heat exchange chamber space filled with air. The gas medium was heated to 400–500 °C by an induction system. In the experiments, the size of initial droplets, their velocities and impact angles were varied in the ranges typical of industrial applications. The main varied parameter was the percentage of vapor (volume of bubbles) in the droplet (up to 90% of the liquid volume). The droplet collision regimes (coalescence, bounce, breakup, disruption), size and number of secondary fragments, as well as the relative volume fraction of vapor bubbles in them were recorded. Differences in the collision regimes and in the distribution of secondary fragments by size were identified. The areas of liquid surface before and after the initial droplet breakup were determined. Conditions were outlined in which vapor bubbles had a significant and, on the contrary, fairly weak effect on the interaction regimes of two-phase droplets.

Thermal effects on the physical properties of limestone from the Yucatan Peninsula

2014 ◽  
Vol 1611 ◽  
pp. 171-176
Author(s):  
W.S. Gónzalez-Gómez ◽  
J. May-Crespo ◽  
P. Quintana ◽  
A. May-Pat ◽  
F. Avilés ◽  
...  
Keyword(s):  
Physical Properties ◽  
Thermal Effects ◽  
Yucatan Peninsula ◽  
Industrial Applications ◽  
Thermal Treatments ◽  
Matrix Cracks ◽  
Compression Strain ◽  
Yucatán Peninsula ◽  
Limestone Rock ◽  
Loss Of Mass

ABSTRACTRocks are composed of minerals, bounding matrix, cracks and pores. The study of changes in the physical properties of rocks as a function of heat treatment is relevant to various engineering and industrial applications. The effect of thermal damage on the compression, strength, ultimate compression strain, color and loss of mass of two different limestones extracted from the Yucatan Peninsula is studied. Different thermal treatments are applied by heating the sample from room temperature up to 600°C, with steps of 100°C. The results show a high correlation between the heat transport characteristics, mechanical properties, content of organic matter and the presence of carbonates and iron oxides in each type of limestone rock.

scholarly journals The making of natural iron sulfide nanoparticles in a hot vent snail

2019 ◽  
Vol 116 (41) ◽  
pp. 20376-20381 ◽  
Author(s):  
Satoshi Okada ◽  
Chong Chen ◽  
Tomo-o Watsuji ◽  
Manabu Nishizawa ◽  
Yohey Suzuki ◽  
...  
Keyword(s):  
Deep Sea ◽  
Iron Sulfide ◽  
Natural Habitat ◽  
Industrial Applications ◽  
White Population ◽  
Iron Sulfides ◽  
Electron Microscopic ◽  
Metal Chalcogenide ◽  
Natural Iron ◽  
Single Exception

Biomineralization in animals exclusively features oxygen-based minerals with a single exception of the scaly-foot gastropod Chrysomallon squamiferum, the only metazoan with an iron sulfide skeleton. This unique snail inhabits deep-sea hot vents and possesses scales infused with iron sulfide nanoparticles, including pyrite, giving it a characteristic metallic black sheen. Since the scaly-foot is capable of making iron sulfide nanoparticles in its natural habitat at a relatively low temperature (∼15 °C) and in a chemically dynamic vent environment, elucidating its biomineralization pathways is expected to have significant industrial applications for the production of metal chalcogenide nanoparticles. Nevertheless, this biomineralization has remained a mystery for decades since the snail’s discovery, except that it requires the environment to be rich in iron, with a white population lacking in iron sulfide known from a naturally iron-poor locality. Here, we reveal a biologically controlled mineralization mechanism employed by the scaly-foot snail to achieve this nanoparticle biomineralization, through δ34 S measurements and detailed electron-microscopic investigations of both natural scales and scales from the white population artificially incubated in an iron-rich environment. We show that the scaly-foot snail mediates biomineralization in its scales by supplying sulfur through channel-like columns in which reaction with iron ions diffusing inward from the surrounding vent fluid mineralizes iron sulfides.

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