Letteratura scientifica selezionata sul tema "High-shearing force"

Abrasion resistant (AR) steels offer excellent hardness and strength properties in applications as mining and earth moving machines. As an outcome of high hardness AR steels can be used to produce durable, light-weight and energy saving products. However, their mechanical processing can be challenging as the hardness of the material approaches the hardness of the tooling used. This places high forces on cutting tools and machines, which, in turn, increases wear and causes early breakdown. This research examines whether the laser treatment of AR steels can be used to aid guillotine shearing. The tested material was abrasion resistant steel with hardness of 400 HBW. Two different laser treatments were examined: local laser heat treatment and laser milling. The aim of laser heat treatment was to change the original martensitic microstructure locally into weaker structure, beneficially for shearing. Narrow grooves were made along the cut line by laser milling, and then the plate cut along them. The effect of local laser heat treatment and the fracture initiating effect of the groove was evaluated from the cutting force. Microhardness tests and micro photos were taken after laser heat treatments. The results indicated that the shearing force of AR steels can be reduced up to 25% with the aid of laser heat treatments. Laser milling had only a slight effect to the shearing force of up to about 8%. In addition, the relative depth of the laser milled groove is estimated at the same range, thus force reduction is mainly due to reduction of material thickness.

This article researches the effect of Sn-based solder alloys on flip-chip light-emitting diode LED (FC-LED) filament properties. SEM images, shearing force, steady-state voltage, blue light luminous flux, and junction temperature were examined to demonstrate the difference between two types of FC-LED filaments welded with two solders. The microstructure surface of Sn90Sb10 filament solder joints was smoother and had fewer voids and cracks compared with that of SAC0307 filament solder joints, which indicates that the Sn90Sb10 filaments had a higher shearing force than the SAC0307 filaments; moreover, the average shearing force was beyond 200 gf (standard shearing force). The steady-state voltage and junction temperature of the Sn90Sb10 solder-welded FC-LED filament were lower, and the Sn90Sb10 filament had a relatively higher blue light luminous flux. If high reliability of the solder joints and better photoelectric properties of the filaments are required, this Sn90Sb10 solder is the best bonding material for FC-LED filament welding.

Lightweight structural components made of carbon fibre reinforced plastics are manufactured near-net-shape. However, in order to fulfil geometrical or functional requirements, carbon fibre reinforced plastic components have to be trimmed and pierced in a finish processing step. Shearing is a highly productive technology that is potentially suitable for cost-effective finishing of carbon fibre reinforced plastic components in high-volume series production. Shearing of carbon fibre reinforced plastic has not yet been sufficiently researched. Cutting force is an important characteristic of the shearing process. Up to now, there exists limited knowledge on numerical modelling of the cutting forces in carbon fibre reinforced plastic shearing. In order to address this, a finite element process model of carbon fibre reinforced plastic trimming was developed in this work. The process modelling included a formulation of continuum mechanical material model for a unidirectional ply as well as a development of a kinematic model of the trimming process. The developed finite element process model was validated by means of experimental data. The simulated and experimentally determined maximum specific cutting forces demonstrated a very good qualitative and quantitative agreement.

AbstractTo meet the modern demands for lightweight construction and energy efficiency, hard-to-machine materials such as ceramics, superalloys, and fiber-reinforced plastics are being used progressively. These materials can only be machined with great effort using conventional machining processes due to the high cutting forces, poor surface qualities, and the associated tool wear. Vibration-assisted machining has already proven to be an adequate solution in order to achieve extended tool lives, better surface qualities, and reduced cutting forces. This paper presents an analytical force model for longitudinal-torsional vibration-assisted milling (LT-VAM), which can predict cutting forces under intermittent and non-intermittent cutting conditions. Under intermittent cutting conditions, the relative contact ratio between the rake face and the sliding chip is utilized for modelling the shearing forces. Ploughing forces and shearing forces under non-intermittent cutting conditions are calculated by using an extended macroscopic friction reduction model, which can predict the reduced frictional forces under parallel and perpendicular vibration superimposition. The force model was implemented in MATLAB and can predict cutting forces without using any experimental vibration-assisted milling (VAM) data input.

To characterize the effect of shearing on function of fibrillar adhesive microstructure, friction and shear-related changes in pull-off force of a biomimetic polyvinylsiloxane mushroom-shaped fibrillar adhesive microstructure were studied. In contrast to a control flat surface, which exhibited pronounced stick–slip motion accompanied with high friction, the fibrillar microstructure demonstrated a stable and smooth sliding with a friction coefficient approximately four times lower. The structured contact also manifested zero pull-off force in a sheared state, while the flat surface exhibited highly scattered and unreliable pull-off force when affected by contact shearing. It appears that the fibrillar microstructure can be used in applications where a total attachment force should be generated in a binary on/off state and, most surprisingly, is suitable to stabilize and minimize elastomer friction.

Objective: This study evaluated the effect of pressure injury (PI) prophylactic dressings used for patients at high risk of PI development to reduce friction, shear force and pressure, and their combined force, in an original polymer-based skin model. Method: A low-friction outer-layer hydrocolloid (LFH) dressing and a multilayered silicone foam (MSF) dressing were used. Before application, compression and friction properties were measured. Our original experimental model—the ‘simulated skin-shearing test’—consisted of: a weight; a polyurethane-based skin model containing a three-axis tactile sensor; dressings; a table covered with bedsheets; and a mechanical tester, by which the interface friction force, internal shear force and pressure were measured continuously during skin model movements. An estimated combined force generated by internal shear and pressure was represented as a vector. A model with no dressing was used as a control. Results: The LFH dressing had significantly higher compression strength versus the MSF dressing. In contrast, the dynamic coefficient of friction was lower for the LFH dressing versus the MSF dressing (p<0.05). In simulated skin-shearing test results, shear forces were 0.45N and 0.42N for LFH and MSF dressings, respectively, with no significant difference. The estimated combined force was lower for the MSF dressing compared with that of the LFH dressing and control. Conclusion: The shear force-reducing effect in the skin model was equivalent between the LFH and MSF dressings. However, the MSF dressing significantly reduced the force generated by a combination of internal shear force and pressure compared with the LFH dressing.

This paper mainly researches on the effect from high-speed shearing tool to the quality of stainless steel tube cutting. At first, the relationship between contour line of vertical blade and the direction of shear force and chip flow are studied, and the influence on the quality of shearing caused by the size of blanking clearance is analyzed. Then a new blade contour line that made most of the iron chippings is located outside of the tube and reasonable blanking clearance is obtained. Further, based on the tearing caused by single-blade shear on the top of steel tube, the shape and angle of the vertical blade are studied, and the structure of the vertical blade nose is optimized, which improves the shearing quality of the blade. Finally, the numerical simulation of the process of shearing is done to verify the feasibility of the designed structure by the finite element software DEFORM.

Current models of dispersion in marine sediments include losses due to fluid viscosity and shearing at grain-grain contacts. An additional loss mechanism, which is well established in granular physics but is not included in existing models, is the inelasticity of normal compression at grain-grain contacts. Additionally, force-bearing contact networks, often called “force chains,” involve primarily normal compressive forces. These “force chains” are known to play a dominant role in force transmission in granular materials, including wave propagation. Using theoretical analysis of a 1D model “force chain” as well as DEM simulations in higher spatial dimension, we show that this granular mechanics perspective, where forces are transmitted along lossy force chains, may be able to explain salient features of the acoustic properties of marine sediments. In particular, the low and high-frequency behavior of the attenuation coefficient match a large collection of experimental data. [This was supported by the Office of Naval Research.]

The knowledge of the physical characteristics of fertiliser particles is essential for the constructors and operators of fertiliser distributors. Among physical characteristics, the most important are the frictional and aerodynamic properties for the description of particle movement. Adjustable angled slopes, shearing boxes and various rotating disks are used to identify frictional properties. We have developed a high precision shearing box with digital force measuring cells and a distance signaller (incremental transducer) that we use for slide tests efficiently. We measured the frictional characteristics of 6 different fertilisers: the inner coefficient of friction and the coefficient of friction on ten test surfaces most commonly used in machinery, and we specified the relationship between displacement, loading and the coefficient of friction. We can conclude that the material of the frictional surface significantly influences the force of friction.However, our experience tells us that the shearing box is not suitable for the measurement of the inner friction, since the examined particles slide on the metal surface of the shearing box in a growing extent in the course of displacement, so it does not measure the real inner friction. Therefore, in our experiment we have developed rotating shearing equipment with a constant shearing surface to identify the inner friction. We tested the equipment with fertilisers and we identified the inner frictional characteristics of 6 different fertilisers. With the developed rotating shearing apparatus we could measure the real inner friction of the particles.To identify the aerodynamic characteristics of granules, wind tunnels and free-fall tests are used. An elutriator have been developed for our investigation. We have used fertilisers for testing the measuring equipment and we have identified the aerodynamic characteristics of 6 different fertilisers.

L'objectif de ce travail de thèse est de proposer une nouvelle méthodologie pour préparer des supports de catalyseurs pour la réaction de méthanation. En particulier,l’application d’une technique d’enrobage de particules en voie sèche. L'enrobage à sec des particules est considéré comme une technique respectueuse de l'environnement et peu coûteuse. Cependant, il est crucial de comprendre le mécanisme du processus d'enrobage à sec, les facteurs qui affectent la performance de l'enrobage, l'évaluation de la qualité de l'enrobage, la production à grande échelle ainsi que l'exploration de nouveaux champs d'application.Dans ce travail, la méthode de préparation de nouveaux supports de catalyseurs consiste à enrober des particules de γ-Al2O3 et d’acier 316L avec des nanoparticulesde TiO2, SiO2, et Zeolite. Cependant, ces poudres (TiO2, SiO2, et Zeolite) sont très cohésives et forment des agglomérats de tailles incontrôlables, l'échelle nanométrique des poudres pose un problème majeur dans la précision des mesures de la taille. Le processus de revêtement nécessite une analyse des nanoparticules. Cinq techniques d’analyses ont été appliquées et comparées. Le principe de base du processus d'enrobage des particules en voie sèche consiste à mélanger des particules hôtes et invitées sous l'effet des forces mécaniques (impact/compression/force de cisaillement). Particules hôtes : γ-Al2O3 et l’acier 316L ont un diamètre moyen d'environ 67μm et 98.3 μm seront utilisées comme particules hôtes pour préparer de nouveaux supports. Les particules invitées : TiO2, SiO2 et Zeolite de taille nanométrique seront utilisées pour revêtir la surface de γ-Al2O3 et d’acier 316L pour préparer les nouveaux supports (tels que TiO2/γ-Al2O3, SiO2/γ-Al2O3, zéolite/γ-Al2O3, TiO2/S316L,SiO2/S.S316L, zéolite/S316L). L'enrobage des particules en voie sèche est dû aux forces mécaniques/cisaillements et il dépend des paramètres comme les mouvements des particules forces de collisions, interactions entre les particules et l'impact des conditions opératoires (la vitesse de rotation et le temps d'enrobage) dans le mélangeur.Ainsi, on a mis en place un programme de modélisation numérique par DEM (Discrete Element Method) qui semble indispensable pour permettre de répondre et d'expliquer les phénomènes et le mode d'enrobage.Les résultats de l'analyse des nanoparticules ont montré que la technique de diffraction/diffusion laser (LD) met en évidence une plus grande taille de particules de nanopoudres (surestimation) par contre la diffusion dynamique de la lumière (DLS) montre une taille plus petite. La microscopie électronique à transmission (TEM)indique le plus petit diamètre des nanopoudres. Les résultats de l'enrobage met en évidence un bon enrobage par nanoparticules SiO2, TiO2, et Zeolite sur la surface des solides γ-Al2O3 et acier 316L sous 3500 rpm et 5 min. Cependant, pour les mêmes particules invitées avec différentes particules hôtes, le revêtement de l’acier316L montre un enrobage excellent. La modélisation numérique révèle que les principaux facteurs affectant la simulation sont : la vitesse de rotation et la taille des particules. La simulation de l’enrobage, indique que l'énergie interfaciale entre l'hôte et l'invité s'est avérée être le principal paramètre affectant le revêtement
The objective of this thesis is to propose a new methodology – dry particle coating technique to prepare catalyst supports for the methanation reaction. Dry particlecoating is considered as an environmentally friendly and low-cost technique. However, it is crucial to understand the mechanism of the dry coating process, the factorsaffect the coating performance, the evaluation of the coating quality, the large-scale production as well as the exploration of new application fields.In this work, the method of preparing new catalyst supports is to coat γ-Al2O3 and 316L steel (S.S316L) particles with TiO2, SiO2, and Zeolite nanoparticles. However,these powders (TiO2, SiO2, and Zeolite) are highly cohesive and form agglomerates of uncontrollable sizes, the nanoscale of the powders poses a major problem inthe accuracy of size measurements. The coating process requires analysis of the nanoparticles. Four analytical techniques were applied and compared. The basicprinciple of the dry particle coating process is the mixing of particles under mechanical force (impact/compression/shear force). Host particle: γ-Al2O3 and S.S316Lhave an average diameter of about 67 μm and 98.3 μm will be used as host particles to prepare new carriers. The guest particles: TiO2, SiO2 and Zeolite with nanosizewill be used to coat the surface of γ-Al2O3 and S.S316L to prepare the new substrates (such as TiO2/S.S316L, SiO2/S.S316L, Zeolite/S.S316L and TiO2/γ-Al2O3,SiO2/γ-Al2O3, Zeolite/γ-Al2O3,). The coating of particles in dry process is due to mechanical/shear forces and it depends on collisions, particle movements, interactionsbetween particles and the impact of operating conditions (the rotation speed and coating time) in the mixer. A numerical modeling DEM (Discrete Element Method)has been implemented to answer and explain the phenomena and the coating process.The results of the analysis of the nanoparticles showed that the technique of diffraction/laser scattering (LD) highlights a larger size of particle of the nanopowder(overestimation) on the other hand the dynamic diffusion of the light (DLS) shows a smaller size. Transmission electron microscopy (TEM) indicates the smallerdiameter of the nanopowder. The coating results highlight a good coating by SiO2, TiO2, and Zeolite nanoparticles on the surface of γ-Al2O3 and S.S316L under 3500rpm and 5 min. However, for the same guest particles with different host particles, the S.S316L coating shows excellent coating. Numerical modeling reveals that themain factors affecting the simulation are: rotational speed and particle size. Simulation of the coating indicates that the interfacial energy between the host and theguest is the main parameter affecting the coating

Abstract In dynamic hardness tests, the test force is applied to the defined indenter in an accelerated way (with a high application rate). Dynamic test methods relate hardness to the elastic response of a material, whereas the classical static indentation tests determine hardness in terms of plastic behavior. This chapter describes the most important and widespread dynamic hardness testing methods. These tests fall into two categories: methods in which the deformation is measured and methods in which the energy is measured. Methods that measure deformation include the Poldi hammer method, the shearing force method, the Baumann hammer method, and the Dynatest method. Methods that measure energy include the Shore method, the Leeb method, and the Nitronic method. The chapter concludes with a discussion of applications of dynamic hardness testing.

Blowout Preventers (BOP) are safety devices used to prevent uncontrolled flow of liquids and gases during a blowout. Blind Shear Rams (BSR) is one of the critical components of a BOP responsible for shearing the drill pipe and sealing the wellbore during a blowout scenario. Tests were conducted by shearing a drill pipe under non-flowing conditions to obtain the maximum shearing force, shape of sheared drill pipes, shearing time. A FE methodology has been developed to model the shearing process using Abaqus Explicit finite element solver. Simulations were performed to replicate the shop test and the results are compared with the shop test and found to be in good agreement. The current study uses a validated model for evaluating some of the challenges being faced by the BOP shear ram technology. These include drill pipe centralization in the well bore, shearing of a drill pipe subjected to axial tension, compression and buckling, and shearing in flowing well conditions. All these studies are performed and their effect on shearing process is discussed. The effect of high velocity formation fluid through the drill pipe and annulus in the localized shearing region is also assessed separately by performing Computational Fluid Dynamics (CFD) simulations and it is found that the resistance offered by flowing fluid is not significant compared to the high pressure from accumulators required to shear the pipe. A shear ram design accommodating the results of the study is verified for increased efficiency of the shearing process. The study is conducted as part of a Technology Assessment Programs (TAP) for the Bureau of Safety and Environmental Enforcement (BSEE) in the areas of BOP stack sequencing, monitoring and kick detection.

Abstract Combined effects of natural convection and radiation on a laminar boundary-layer flow over a semi-infinite horizontal flat plate are studied. Increasing the natural convection-radiation interaction in the boundary layer increases the shearing stress on the wall, the boundary-layer thickness, the maximum velocity attainable by fluid, and the buoyancy force in the boundary layer. However, the temperature gradient at the plate decreases with increasing interaction. They generally increase with increasing temperature ratio. Automated computations of the dimensionless velocity, temperature, and buoyancy force in the boundary layer yield convergent solutions which are substantially different from those available in the literature for high natural convection-radiation interactions.

This paper proposes three methods to fabricate synthetic gecko foot-hair high aspect ratio polymer micro/nanostructures. In the first method, nano-robotically indented templates are molded with liquid polymers, and the cured polymer is peeled off or etched away. Atomic force microscope and scanning tunneling microscope probe tips are used to emboss/indent flat wax surfaces, and silicone rubber micro/nano-bump structures are demonstrated. The second one uses a self-organized polycarbonate nano-pore membrane as the molding template. PDMS is molded into these micro/nano-pores under vacuum, and 1:2 and 1:9 aspect ratio pillar structures with 5 micron and 0.6 micron diameters are manufactured successfully. Finally, a directed self-assembly technique is proposed to grow regularly spaced and oriented micro/nano-pillars. Here, instability of a liquid polymer thinfilm under a DC electric field is used to grow nano-pillars, and stretching and shearing of the grown hairs enable high aspect ratio and oriented hair structures. These hair structures will be utilized as novel biomimetic dry adhesives in future miniature space and surgical robot feet.

Abstract Oil-based mud (OBM) is the first choice for complex deep wells due to its advantages of high-temperature resistance, good lubrication and borehole stability. But barite sagging under ultra-high temperature during the long-time stationary completion operation may lead to serious problems in ultra-deep wells, for instance, pipe sticking, density variation and well control problems. In this paper, the influence of high-temperature and high-pressure (HTHP) on the performance of oil-based completion fluid was studied, and a model of rheological parameters was established with HTHP static sag law. The barite sagging stability was evaluated by a high temperature (220°C) and high pressure (100MPa) sag instrument. The results indicated that RM6 value and static shearing force were the main factors of affecting the settlement stability. The viscosity of the completion fluid significantly decreased with the increase of temperature, but increased with the increase of pressure. In addition, the relationship was also studied between HTHP rheology and atmospheric pressure rheology at 50°C. The results showed that when RM6 value was kept above 10, the sag stability factor (SF) of oil-based completion fluid was less than 0.52 at 190°C for 10 days, which proved a good high-temperature sag stability. Furthermore, the anti-high temperature property of oil-based completion fluid was improved through enhancing the temperature-resistance of the additives. And the high-temperature-resistant organic soil was introduced to raise the RM6 value and the static shearing force. Based on these solutions, the barite sag under high temperature of the oil-based completion fluid was prevented during drilling and completion operation in ultra-high temperature wells. The oil-based completion fluid was successfully used in Well Keshen 17 (175°C,7475 m) in Kuche piedmont structure and TT 1 well (210°C,6500 m) in Sichuan basin. The casing run smoothly, the oil-test operation was completed smoothly for 15 days, and no barite sag happened. It testified that the oil-based completion fluid had excellent of high-temperature sag stability. Therefore, this oil-based completion fluid is expected to be used widely in ultra-deep wells.

Abstract. Endless fiber-reinforced plastics are being used to an increasing extent as alternative materials for highly stressed or lightweight components instead of metallic materials. In order to achieve the geometric requirements, peripheral machining of the raw parts is necessary. Instead of the currently mainly used cutting processes, which are not suitable for clocked production, high-speed impact cutting (HSIC) was examined in the presented experiments. This technology is known as adiabatic cutting from the processing of metallic materials. Due to the high process energy which is released in a very short time resulting in high punch speed, the prevailing separation mechanism changes. Instead of bending the fibers due to the shear force the high-speed cutting experiments with a punch speed of 10 m/s lead to a brittle shearing of the glass fibers and a locally very limited heating and hence softening of the matrix material resulting in a clean surface of the cut specimen. The inter fiber breakage, meaning the separation between fibers and matrix called delamination, can be avoided or at least be sealed at the surface due to heat induced smearing of the matrix material. The resulting surface quality of the cutting edge is exceptionally good. However, the technically necessary cutting clearance leads to a jump in diameter within the cut surface.

In this work, we detail the design, fabrication, and initial modeling of a compact, high-strength series elastic element designed for use in snake robots. The spring achieves its elasticity by torsionally shearing a rubber elastomer that is bonded to two rigid plates, and it is able to achieve mechanical compliance and energy storage that is an order of magnitude greater than traditional springs. Its novel design features a tapered conical cross-section that creates uniform shear stress in the rubber, improving the ultimate strength. Tests show that the torque-displacement profile of these springs is approximately linear, and initial results are reported on creating more accurate models that account for the element’s hysteresis and viscoelastic properties. Low-bandwidth force control is demonstrated by measuring the element’s torsional deflection to estimate the torque output of one of our snake robot modules.

A new global spatial discretization method is developed to accurately calculate natural frequencies and dynamic responses of two-dimensional continuous systems such as membranes and Kirchhoff plates. The transverse displacement of a two-dimensional continuous system is separated into a two-dimensional internal term and a two-dimensional boundary-induced term; the latter is interpolated from one-dimensional boundary functions that are further divided into one-dimensional internal terms and one-dimensional boundary-induced terms. The two- and one-dimensional internal terms are chosen to satisfy predetermined boundary conditions, and the two- and one-dimensional boundary-induced terms use additional degrees of freedom at boundaries to ensure satisfaction of all boundary conditions. A general formulation of the method that can achieve uniform convergence is established for a two-dimensional continuous system with an arbitrary domain shape and arbitrary boundary conditions, and it is elaborated in detail for a general rectangular Kirchhoff plate. An example of a rectangular Kirchhoff plate that has three simply-supported boundaries and one free boundary with an attached Euler-Bernoulli beam is investigated using the developed method and results are compared with those from other global and local spatial discretization methods. Natural frequencies and dynamic responses that include the displacement, the velocity, rotational angles, a bending moment, and a transverse shearing force are calculated using both the developed method and the assumed modes method, and compared with results from the finite element method and the finite difference method, respectively. Advantages of the new method over local spatial discretization methods are much fewer degrees of freedom and much less computational effort, and those over the assumed modes method are better numerical property, a faster calculation speed, and much higher accuracy in calculation of the bending moment and the transverse shearing force that are related to high-order spatial derivatives of the displacement of the plate with an edge beam.

Solid particles ingestion can deteriorate performance and stability of gas turbines through the build-up of deposits on the aerofoils. In some cases, the effect is sufficient to require an engine shut-down or to cause a failure. The fouling phenomenon can be characterized by two different phases: particle sticking and deposit evolution. The sticking process of an impinging particle has been deeply studied with several models available in the literature, both deterministic and stochastic. A less investigated phase is the the evolution of the deposit over time. A deposit is subjected to several forces that either tend to make it sticking to the surface or to detach from it. In the hot section of the gas turbine, the forces that act on the build-up tending to make it to adhere to the surface can be traced back to the van der Waals forces and, possibly capillary force if a certain amount of liquid phase is present. On the other hand, the detaching mechanism is related to the component investigated: if the particle is deposited on a vane, the drag and the shearing force are the only forces that tend to detach the particle, if a rotor blade is investigated, the centrifugal forces must be considered as well. On top of that, the deposit evolves over time in what is called sintering. During this process, the single particles deposited can melt together forming necks. If the temperature is sufficiently high, these necks increase in size until the former pores among particles are completely filled. This process is of paramount importance if the effect of the applied forces on the deposit needs to be investigated. The amount of material detached is indeed strongly dependent on the tension exchanged within various layers that constitute the build-up. This article focuses on the prediction of the build-up evolution on an HPT nozzle. The sintering process is modeled and related to the resisting strength of the deposit: an increasing sintering time reduces the deposit porosity and thus increase its strength. In order to monitor the stability of the deposit, the balance among detaching and attaching forces is carried out. The evolution of the vane shape is taken into account by using a moving mesh technique.

Abstract A microstructural constitutive theory of ER suspensions was formulated in this investigation. The framework was based on the internal variable theory and the mechanism analysis. The ER suspension consists of fine particles with high dielectric constant and the supporting fluid. Under the action of the electric field, the polarized particles will aggregate together to form the chain-like structures along the direction of the electric field. As the size and orientation of the particle aggregates are volatile, and they adjust according to the applied electric field and strain rate, the energy conservation equation and the force equilibrium equation were thus established to determine the orientation and size of the aggregates. Following that, a three-dimensional, explicit form of the constitutive equation was derived based on the interaction energy and the dissipation function of the system. The response of the system under the action of a simple shearing load was considered and discussed in detail. It is found that the shear-thinning viscosity of an ER suspension is well approximated by the power-law ∝ (Mn)−0.82.

The purpose of the present study is to improve the current prediction capabilities of the entrainment fraction in horizontal gas-liquid flow. Since it is recognized that waves at the gas-liquid interface are the main source of entrainment, an experimental and theoretical work has been carried out to characterize the waves at the gas-liquid interface and to develop a model for entrainment calculations based on such characteristics. The model consists of three sub-models, namely, onset of entrainment, maximum entrainment and entrainment values in between. The onset of entrainment model determines the conditions at which the gas starts shearing the wave crests through a force balance between drag and surface tension forces. The maximum entrainment model provides the maximum fraction of liquid that can be entrained at high gas velocities by integration of the turbulent velocity profile to a determined dimensionless film thickness within the buffer sub layer. The entrainment fraction in between onset and maximum boundaries is calculated from an equilibrium between atomization and deposition rates. The atomization rate is calculated by first determining the wave mass flux in the liquid film and second by calculating the fraction of a single wave that is sheared by the gas through a force balance. The deposition rate is calculated as a linear function of the droplet concentration in the gas. Closure relationships have been developed from data for wave celerity, frequency, amplitude and width which are used in the entrainment model. A review of the most used correlations for calculating the entrainment fraction is presented and their performance evaluated. The present model shows better prediction than available models when compared to the acquired experimental data and the available experimental data in the literature.