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Piezoelectric materials have been widely used in modern science and technology due to their electro-mechanical coupling response. Sometimes, because of the stiff and brittle nature of some piezoelectric materials, the piezoelectric devices with defects may face fracture or failure during their service procedures. Therefore, it has become important to investigate the failure behaviors caused by defects, such as cracks and holes. Based on the study of the dynamic anti-plane characteristics for radial crack emanating from a circular cavity in piezoelectric bi-materials, this paper aims to analyzes the dynamic incident anti-plane shearing (SH-wave) in piezoelectric bi-materials, which contains two interfacial cracks, near an eccentric elliptical hole. Green’s function method, the conformal mapping method, the interface conjunction techniques and the crack-deviation techniques are utilized to obtain a series of first kind Fredholm’s equations, based on which the dynamic stress intensity factor (DSIF) at the outer and the inner cracks’ tips are theoretically expressed. Numerical examples were graphically presented to illustrate the effects of the piezoelectric parameter, the effective piezoelectric elastic modulus, the dimensionless incident wave number and geometric parameters on the DSIF at both of the tips. Previous studies are not comprehensive, especially when the center of the hole deviates from the interface. Therefore, the impact of eccentric distance on DSIF is considered in this paper. The solution of this problem provides a more accurate and efficient method for the investigation of dynamic fracture properties of piezoelectric materials and has an important theoretical significance in engineering design.

Corrugated plate dryer is a extremely vital equipment for steam-water separation in the fields of heat transfer and nuclear engineering. The corrugated plate is also a commonly used steam-water separator in steam generators in nuclear power plants. It is meaningful to study the breakdown characteristics and mechanism of the water film on corrugated plate wall. Water film thickness of steady flow is measured based on plane laser induced fluorescence (PLIF) technique and time series and its fitted equation of water film thickness are obtained, respectively. Besides, fluctuation characteristics of water film are analyzed by probability density function (PDF). Based on the dimensionless approach, the water film breakdown model at the corner of the corrugated plate is established. And the calculation equation of the relative position of the water film breakdown at the corner is deprived. The specific conclusions are as follows. The theoretical equation agrees well with the relative position of the water film breakdown at the corrugated plate corner. The evolution of the surface wave of water film is carried out in time and space. The PDF curve have no significant peak characteristics. Therefore, the spectrum has no characteristic frequency, that is, the water film has multi-frequency characteristics. Gravity of water film can be ignored in the water film model. The thickness sequences for falling film is measured and fitted. The two-dimensional model of water film breakdown at the corner is set up. The equation for the film thickness when the water film is just ruptured is obtained. Relative position of the water film rupture at the corner of the corrugated plate is theoretically related only to the structural parameters of the corrugated plate, the parameters of the gas phase and the liquid phase, and the Reynolds number of the liquid film. However, in the low Reynolds number region, the airflow velocity is extremely large, which causes certain fluctuations and nonlinear characteristics of the water film boundary position. Therefore, the theoretical formula is not particularly good at predicting the relative position of the breakdown in this region. I think that this nonlinear feature has obvious chaotic characteristics. The study of the chaotic characteristics generated by shearing the liquid film by high velocity flow airflow at the corner of the corrugated plate may become a prospect for future research.

The aerospace propulsion industry has seen strides in the use of the additive manufacturing (AM) technology in the rapid prototyping and geometric design flexibility of aerospace parts, with concurrent efforts on 3D printing turbine engine blades of Inconel 718 material [1] for use in aircraft engines. The tensile, compressive and axial fatigue response of AM Inconel 718, along with associated constitutive modeling of the material response exhibited under these mechanical test conditions have been reported. However, in addition to understanding the axial behavioral response exhibited by this material, assessing the role of cyclic shear stresses, through experimental testing and constitutive modeling can provide preliminary insight into the mechanical behavior of AM Inconel 718 under multiaxial loading conditions. This study has presented a novel approach to constitutively model the experimental cyclic shearing deformation of as-built direct metal laser sintered (DMLS) Inconel 718, manufactured along varying build orientations in the xy, yz and xz planes, compared with wrought annealed Inconel 718. Specimens were subjected to completely reversible torsional fatigue tests at room temperature, under angle of twist control. The experimental cyclic shearing response was modeled through the use of the Chaboche model, from which optimized constants are reported with build orientation; and the specimen deformation, under angle of twist control, was captured through a finite-element simulation model of the cylindrical gauge section of the specimens. Overall this study yields a comprehensive understanding of the experimental and modeled cyclic shearing response of an additively manufactured metal, which is vital to develop these components to be conducive for the multiaxial fatigue conditions to which they are subjected to in the gas turbine industry.

The treatment of early age cyclic loading (EAC) on pile-sleeve grouted connections is one of the challenging problems encountered in the design of offshore jacket structures. ISO 19902 appears to be the only offshore structural design code that quantifies the strength de-rating due to EAC. However, the mechanism of EAC considered in the ISO standard is little understood. Main provision is that the strength reduction due to EAC is considered to be linearly proportional to the compressive strength of the grout. This provision is conservatively applicable for medium strength grouts. However, it is over-conservative when modern high-performance grouts are used, and it can be further argued that it actually loses its physical meaning. Thus, a further investigation into the mechanics of the problem is deemed beneficial in order to understand better its underlying mechanism. Using existing experimental evidence and a simple mechanical model, it is shown that the EAC mechanism considered in ISO 19902 triggers the grout matrix failure mechanism of the grouted connections. This behavior is characteristic of segregating grout materials. The benefit of the approach followed is that it links the interpretation of EAC to the grout material properties. The phenomenon is then understood using methods and experimental results that are well established in concrete mechanics. After a comparison with existing experimental evidence on grouted connections and concrete members, it is suggested that the strength drop for the specific shearing mechanism is independent of the uniaxial compressive strength of the grout material.

This paper deals with the detailed analysis of the lateral process forces in rolling-cut shearing of heavy steel plates and their impact on edge defects. Rolling-cut shearing is still the most common method of heavy-plate side trimming. However, this method can entail edge defects like uneven longitudinal shape as well as burr and fractures in the area of the cut-changeover (beginning and end of the periodical cuts). In the existing literature, neither the root cause of these edge defects nor their nexus with the upper blade trajectory (blade drive-kinematics) has been analyzed in detail. In this work, these issues will be explored based on the finite element method (FEM) simulations and measurements from an industrial plant. The complex interrelation between drive-kinematics, varying lateral force, unintended lateral motion of the upper blade, unintended variation of the blade clearance, and quality defects is analyzed. The variation of the lateral force is identified as the root cause of such quality defects and a physical explanation for variations of the lateral force is given. The detailed understanding of the shearing process serves as a solid basis for an optimization and re-design of the drive-kinematics in a future work. Measurements from an industrial plant and simulation results show good agreement and thus confirm the theory. The results are transferable to other rolling-cut trimming shears.

The effect of the nozzle top lip thickness on a two-dimensional wall jet was examined experimentally in a wind tunnel using hot-wire anemometry. Lip thicknesses of 0.125b, 0.5b, 1b, and 2b, where b is the jet nozzle height, were considered at a Reynolds number of 30,700 based on the jet nozzle height and jet velocity. Noticeable differences in the flow profiles were observed at the jet outlet, but by 10b downstream these differences became insignificant. Different lip thicknesses resulted in different maximum velocity decay rates. The spread of the wall jet was found to be insensitive to the lip thickness.

Charged particles are emitted when materials undergo tribological interactions, plastic deformation, and failure. In machining, plastic deformation and shearing of work piece material takes place continuously along with intense tool-chip rubbing contact interactions; hence, the emission of charged particles can be expected. In this work, an in-situ sensor has been developed to capture the emitted positive (positive ion) and negative (electron and negative ion) charged particles in real-time in an orthogonal machining process at atmospheric conditions without the use of coolant. The sensor consists of a Faraday plate, mounted on the flank face of the cutting tool, to collect the emitted ions and the intensity of emissions is measured with an electrometer. Positively and negatively charged particles are measured separately by providing suitable bias voltage supply to the Faraday plate. Ion emissions are measured during machining of three different work piece materials (mild steel, copper, and stainless steel) using a carbide cutting tool. The experimental results show a strong correlation between the emission intensity and the variation in machining parameters and material properties. Increasing material removal rate increases the intensity of charged particle emissions because of the increase in volume of material undergoing shear, fracture, and deformation. It is found that emission intensity is directly proportional to the resistivity and strength of workpiece material. Charged particles emission intensity is found to be sensitive to the machining conditions which enables the use of this sensor as an alternate method of condition monitoring.

With over 30 million people worldwide in need of assistive devices, there is a great need for low-cost, high performance prosthetic technologies in the developing world. A majority of the hydraulic dampers used in prosthetic knee designs are highly specialized, expensive, require regular maintenance, and are incompatible for use with low-cost, single-axis prosthetic knees popular in developing countries. In this study, optimal damping coefficients were computed based on a theoretical analysis of gait, specifically during the transition from the stance to swing phase of human walking when a large damping torque is needed at the knee. A novel rotary hydraulic damper prototype was designed using high-viscosity silicone oil and a concentric meshing of fins for shearing the oil. The prototype was validated experimentally to provide the desired damping torque profile. For preliminary, user-centric validation of the prototype, a gait study on one above-knee amputee in India was conducted with four different damping magnitudes. Feedback from the subject validated the optimal damping torque magnitude predicted for minimizing gait deviations and for enabling able-bodied knee kinematics. The new rotary hydraulic damper design is novel, passive, and compatible with low-cost, single-axis knee prostheses.

A Marcellus shale rock fracture was subjected to four shearing steps and at the end of each shearing step CT (computed tomography) scans with resolution of 26.8 μm were obtained. The CT images were used to generate full aperture maps of the fracture configuration at the end of each shearing phase. The pressure drops along the fracture were also measured for different water flow rates through the fracture. The aperture map of the fracture was used to generate the geometry of the fracture for use in numerical simulations. The water flows and pressure drops in the fracture were simulated with different computational methods that included the full Navier-Stokes simulation, Modified Local Cubic Law (MLCL), and Improved Cubic Law (ICL) methods. Full 3-D Navier-Stokes simulation is the most accurate computational approach which was done with use of the ANSYS-Fluent software for each shear step and different flow rates. The MLCL is a 2-D relatively fast method which is commonly used for prediction of transmissivity of fractures. ICL is a 1-D method proposed in this study in which the effects of surface roughness and tortuosity were included in calculation of the effective aperture height of fractures. To provide an understanding of the accuracy of each of these models their predictions were compared with each other and with the experimental data. Also, to examine the effects of resolution of CT scans and the surface roughness on prediction of fractures transmissivity, similar simulations were performed on average aperture maps. Here the fracture of the full resolution data was averaged over 10 × 10 pixels. Comparing the results of the average aperture maps with those of the full maps showed that the lower resolution of CT scans led to underestimation of the fracture pressure drop due to missing the small features of the fracture surfaces and smoothing out their roughness.

A state-of-the-art, portable dispersion characterization rig (P-DCR) is used to investigate the effect of nanoparticles (NP) on oil-water emulsion formation and stabilization. Spherical silica NP of different wettabilities were used to investigate their effect on separation kinetics of solid stabilized emulsions in terms of solid particle concentration, wettability, initial dispersion phase, water-cut, and shearing time. The main findings of the study include the following: NP, even at concentrations as low as 0.005% or 0.01% (by weight), can significantly increase separation time of oil/water emulsions from a few minutes to several hours or even days. The P-DCR is recommended as an effective inline tool to measure emulsion stability in the field.

A subsea Blowout Preventer system plays an extremely important role in providing safe working conditions for drilling activities in deepwater oil exploration. However, estimating the performance of Shear Ram Blowout Preventeris still a challenge for the industry. This paper considers different scenarios that may influence the shear capability of a typical subsea Blind Shearing Ram: the pipe size, ram shape, preload of pipe, off-center distance and tool joint of pipe. Element method analysis is conduct on the Abaqus software to calculate the maximum required shearing force for each scenario. Results of those simulations are collected and analyzed according to mechanic theories and oil field experience. Furthermore, some recommendations are offered both in theoretical and practical aspects to build the criterion for the shear ability of a specific type of Blind Shearing Ram. Factors influencing shearing capabilities have been listed according to the result of the numerical simulation.

Drilling fluids are visco-elastic materials, i.e. they behave as a viscous fluid when subject to a sufficient shear stress and like an elastic solid otherwise. Both their elastic and viscous properties are time-dependent, i.e. drilling fluids are thixotropic. Because of thixotropy, it takes a finite time before the effective viscosity of a drilling fluid attains an equilibrium when the fluid is subject to a change of shear rate. This effect is visible when one changes the applied shear rate in a rheometer, as the fluid will gradually adapt to the new shearing conditions. When the velocity of a drilling fluid changes, for instance due to a change in pump flow rate, movement of the drill string, or change of flow geometry, the fluid will exhibit a time-dependent response to the new shearing conditions, requiring a certain time to reach the new equilibrium condition. Unfortunately, the time-dependence of the rheological properties of drilling fluids are usually not measured during drilling operations and therefore it is difficult to estimate how thixotropy impacts pressure losses in drilling operations. For that reason, we have systematically measured the time-dependence of the rheological properties of several samples of water-based, oil-based and micronized drilling fluids with a scientific rheometer in order to capture how drilling fluids systems respond to variations of shear rates. Based on these measurements, we propose to investigate how one existing thixotropic model manages to predict the shear stress as a function of the shear rate while accounting for the shear history and gelling conditions. Then we propose a modified model that fits better, overall, with the measurements even though there are still noticeable discrepancies, especially when switching back to low shear rates.

The Morton Effect refers to a phenomenon of special instability for rotors supported by fluid-film-bearings and present with asymmetric heating for the journal part. This problem tends to occur when rotors exhibit synchronous vibrations. Originating from the temperature gradients during the eccentric orbiting of rotor journals, the Morton Effect has been a latent threaten to rotor stability since the fluid-bearing-supported rotating machinery was first in service. This paper extends the modeling scope to a general scenario when the heating source is not limited only to the viscous shearing effect. Such an extension could apply to the Newkirk effect, a problem induced by light rubbing but exhibiting similar phenomenon as the Morton Effect. The simplified coupled model enables the coupling between the thermal field and structural vibrations directly. To better understand the roles played by the thermal factors in the Morton Effect, this paper extracts the influence of temperature increase in the bearing fluid film on bearing dynamic coefficients. The investigation results show that the temperature rise, an accompany of increased speeds, has a significant influence on the cross-coupled stiffness coefficients but a negligible impact on other components of dynamic coefficients. In general, the speed plays a dominant role in the change of dynamic coefficients. In the end, the coupled dynamic model is validated by a case study of a mid-span rotor model investigated in the literature. Good agreements with the reference imply that the model assembled here is effective and reliable for the analysis of the Morton Effect.

A state-of-the-art, Portable Dispersion Characterization Rig (P-DCR) is used to investigate the effect of nanoparticles on oil-water emulsion formation and stabilization. Mineral oil and distilled water are used as the test fluids and separation profiles are obtained from the experiments using a sophisticated software. Spherical silica nanoparticles of average primary particle size of 20 nm were selected as the emulsifying agent, since silica is commonly found in the produced fluids. Nanoparticles of different wettabilities were used to investigate their effect on separation kinetics of solid stabilized emulsions in terms of solid particle concentration, wettability, initial dispersion phase, water-cut, and shearing time. In one series of experiments the emulsions were prepared with intermediate-wet nanoparticles. Both simple water-in-oil (W/O), as well as multiple oil-in-water-in-oil (O/W/O) emulsions were observed. Faster separation occurred when the particles were initially dispersed in oil. Increased nanoparticle concentration, as well as shearing time typically resulted in slower emulsion separation rates. Another series of experiments was performed with hydrophobic and hydrophilic nanoparticles. Very fast separation rates were observed when using hydrophilic silica nanoparticles and 25% water-cut regardless of solid concentration. However, when the water-cut was increased to 50% and 75% very stable emulsions were produced. Emulsions prepared using hydrophobic particles were the most stable across all water-cuts. For the case of 25% water-cut, no water coalescence was observed for a wide range of oil-wet nanoparticle concentrations. Oil creaming was promoted as the concentration of solids decreased, and the emulsions remained oil continuous and highly resistant to water coalescence even for very low solid concentration (100 ppm), resulting in a dispersed phase volume fraction as high as 93%. The effect of nanoparticles on the properties of pure fluids, namely, density, viscosity and surface/interfacial tension is also reported. The main findings of the study include the following: Nanoparticles, even at low concentrations, can significantly decrease separation rates of oil and water emulsions. The Portable Dispersion Characterization Rig (P-DCR) is recommended as an effective way to measure emulsion stability in the field.

The Kelvin–Helmholtz instability of viscoelastic flows was examined through a linear instability analysis. Due of the position change of viscoelastic effects, different unstable responses of liquid elastic effects and medium viscous effects were fully investigated. Finally, a comparison of gas/liquid shearing and inviscid aerodynamic effects on sheet instability is conducted.

A procedure for Electron Beam Welding (EBW) was developed for the manufacturing of a follower fuel assembly made of an AA 6061-T6 aluminum straps for a U-Mo plate-type fuel proposed to be used in the future in Korea’s Kijang Research Reactor (KJRR) project. The initial welding trials of the weld samples were carried out with a high vacuum chamber using the EBW process. After investigating the welds, EB welding parameters for the full-sized samples were optimized for the required depth of penetration and weld quality. Subsequently, the weld samples made by the filler specimens showed higher shearing strengths than those of the non-filler specimens. This procedure made by EBW process was also confirmed based on the results of the shearing strength test, an examination of the macro-cross sections, and the fracture surfaces of the welded specimens.

In order to evaluate the shearing quality, the material inhomogeneity through thickness after shearing is introduced by the authors. This study investigates the shearing and local formability of hot-rolled high-strength steel (HSS) plate, which is generally exploited for the manufacturing of the beam of heavy trucks. Various kinds of plates with different thicknesses and strengths are used to figure out the effect of material properties on the shearing quality. Both the shear surface morphology and microhardness distribution of the sheared edge are considered for evaluating the influence of the sheared-edge quality on local formability during the following forming process. Vickers hardness tests are conducted to analyze the microhardness distribution on the shear surface, which is proved to have significant effect on the local formability of the sheared edge. Furthermore, two kinds of bending tests and simulation are employed to study the edge cracking phenomenon, and the results indicate that the junctional zone of burnished zone and fracture zone, which is defined as peak hardness zone (PHZ), has a significant impact on major strain distribution on shear surface in the side bending test and this region is the main cause of edge cracking in normal bending test.

Particle image velocimetry and particle scattering measurements are taken over a flat multi-row film cooled surface. The effect of coolant mass flow (characterized by blowing ratio, momentum flux ratio or velocity ratio) is investigated. The array investigated has 8 rows containing 52 holes of 3.8 mm diameter with inclination angles of 20° and hole length-to-diameter ratios of 11.2. The lateral and streamwise pitches are 7.5 times the diameter. The holes are in a staggered arrangement. PIV measurements are taken with CO2 as coolant injecting into an air primary stream. Two streamwise aligned planes are measured; a centerline plane and a plane spaced laterally half a diameter from centerline. The PIV results provide a quantitative view of the flow over eight rows of injection as well as the recovery region. Images are acquired at 8 Hz and have a spatial resolution of 10.3 interrogation windows per hole diameter. The tunnel has low freestream turbulence (1%) and is low speed, so the primary turbulence production mechanism is shearing. As a result, the M = 0.45 blowing ratio case shows higher levels of turbulent kinetic energy compared with the M = 1.05 blowing ratio case. Uncertainty in the PIV measurements is estimated via the correlation statistics method.

There is an increasing demand for product miniaturization and parts with features as low as few microns. Micromilling is one of the promising methods to fabricate miniature parts in a wide range of sectors including biomedical, electronic, and aerospace. Due to the large edge radius relative to uncut chip thickness, plowing is a dominant cutting mechanism in micromilling for low feed rates and has adverse effects on the surface quality, and thus, for a given tool path, it is important to be able to predict the amount of plowing. This paper presents a new method to calculate plowing volume for a given tool path in micromilling. For an incremental feed rate movement of a micro end mill along a given tool path, the uncut chip thickness at a given feed rate is determined, and based on the minimum chip thickness value compared to the uncut chip thickness, the areas of plowing and shearing are calculated. The workpiece is represented by a dual-Dexel model, and the simulation properties are initialized with real cutting parameters. During real-time simulation, the plowed volume is calculated using the algorithm developed. The simulated chip area results are qualitatively compared with measured resultant forces for verification of the model and using the model, effects of cutting conditions such as feed rate, edge radius, and radial depth of cut on the amount of shearing and plowing are investigated.

Jazdzewska, Agata/0000-0003-4351-8101 WOS: 000354033800022 Recently, deep cryogenic treatment is performed to improve the mechanical responses (wear, hardness, fatigue, and thermal conductivity) of various steel components. Researchers have tried to evaluate the eco-friendly and nontoxic process to optimize the parameters. Cold-shearing punches used to manufacture various holes that undergo severe impact loading and wear in the metal forming process. This study concerns the effect of soaking time (24 hr, 36 hr) at liquid nitrogen temperature (-145 degrees C) during the deep cryogenic treatment on the microstructural changes which are carbide distribution and retained austenite percentage of AISI D3 tool steel punches. It was shown that the deep cryogenic treatment reduces retained austenite and enhanced uniform distribution of carbide particles. It is concluded that for significantly improved punch life and performance, it is an advisable application of 36 hr deep cryogenic treatment.

For solder joint reliability reasons, direct chip attach technology uses an underfill material to restrict the movement of the silicon die relative to the substrate due to differences in their coefficients of thermal expansion. Modeling the fatigue life of a solder joint assembled with this technology requires a shear strain versus applied shear stress relationship. The direct chip attach configuration can be modeled as a tri-layer lamination that bends and shears with temperature excursions from the stress-free temperature. The present analysis formulates an axisymmetric, tri-layer, elastic material stress model with finite radii for the silicon die and underfill layer and an infinite sized substrate layer. A closed form solution to the shear distributions at the interfaces and the bending of the lamination is presented. This solution is a function of the reactant forces exerted by solder joints and forms the basis of a fatigue life model.

In the present investigation the cutting edge of a slender punch was bevelled in an attempt to prevent bending or breakage in use. Tests with Kovar sheet showed that use of a bevelled punch significantly reduces the risk of bending or breakage, a particular problem when clearance on both sides of the punch is unbalanced. This is because the punch guides itself in the later stage of the stroke. Tool life tests shearing Kovar sheet with the bevelled punch produced a smaller burr on the product than with the conventional punch. The application of such punches is found to be most suitable for thin materials such as are used in the manufacture of IC and LSI parts.

This work deals with the effect of surface roughness parameters on the frictional properties of nanowire-based lubrication systems (NBLS) across Cu surfaces with various topographies. The friction coefficient was discussed in the context of surface roughness parameters including the rms height, inter-island separation and a combined roughness parameter related to the pressure experienced by each nanowire. It was concluded that the rms height of asperity should not be lower than the radius of nanoparticles for effective lubrication. In addition, when the inter-island separation is an integer multiple of the nanowire length, nanowires perform as effective lubricants. Furthermore, the friction coefficient increased when the mean pressure experienced by the nanowires increased. The results obtained in this original study offer some interesting insights into the frictional properties of NBLS as a function of surface roughness parameters. This could lead to a great impact on the selection of nanoparticle-based lubricant aimed at reducing wear and energy losses for various applications.

In order to investigate the size effect on elastohydrodynamic lubrication (EHL) of roller pairs, complete numerical solutions for both the Newtonian fluid and the Eyring fluid thermal EHL problems of roller pairs under steady state conditions have been achieved. It can be seen that there is no size effect on the isothermal EHL performance; however, there is a very strong size effect on the thermal EHL performance. Results show that the term of shearing heat is the most important factor for the film temperature when the size of a contact changes. Comparison between the Newtonian solution and the Eyring solution has been made under some operating conditions. It is interesting to see that the effective viscosity of the Eyring fluid is nearly the same as that of the Newtonian fluid when the size of a contact is large enough. The non-Newtonian effect, therefore, can be ignored when the size of a contact is very large. It is equally interesting to see that the thermal effect can be ignored when the size of a contact is very small. In addition, the influence of the velocity parameter, the load parameter, and the slide-roll ratio on the lubricating performance for various sizes of contacts has been investigated.

The analytical prediction of forces in a tapered mill is of vital interest to the accurate machining of complex blade shapes for the aerospace industry. Failure of these cutters is more often by chipping and fracture as opposed to gradual wear. Geometry of the cutters along with duration and length during cutting is analyzed using known parameters. The influence of the geometrical parameters on the spatial distribution of cutting forces is derived from kinematics and the basic shearing processes. Shear strain is approximately obtained with the use of Stabler’s rule. Stress on the shear plane is found from appropriate shear stress-strain curves. A coefficient of friction on the cutting edge is used to evaluate the shear as well as normal forces. As a consequences, torque experienced by the cutter is evaluated. Finally, verification of the analysis is presented through sample calculations and correlations with experimental data measured with a dynamometer.

Efficient and accurate solutions of the interlaminar stresses in a layered beam under a temperature loading are obtained by a variational method using stress functions and the principle of complementary virtual work. Polynomial expansions of the fifth or lower degrees are used to approximate the variation of the stress functions in the thickness direction of each layer. Comparison of the solutions of the various orders with the existing numerical and analytical solutions indicates that the variational solutions converge rapidly as the degree of the polynomial expansion increases and that even the lowest-order variational solutions yield satisfactory results for the interlaminar stresses. Over short segments of the interface adjacent to the free edge, the resultant forces of the interlaminar normal and shearing stresses are given by the first-order derivatives of the stress functions. These global measures of the severity of interlaminar peeling and shearing action are predicted accurately by the lowest-order variational solution.

The short stroke shearing tests with simulated fuel pin bundle were carried out in engineering scale. The shearing device was designed to handle the simulated Monju (FBR prototype reactor) type fuel pin bundle. Monju type and Commercial reactor type simulated fuel pins were used for the test. The length of sheared pin and the opening ratio of sheared section were measured under several shearing settings such as the pressure to hold pin bundle, the shearing speed and the filling-ratio of pins in the pin magazine. Both types of fuel pin were able to be sheared accurately at the length of about 10mm, and the opening ratio of sheared section was not significantly reduced. As the results, fundamental data of the short stroke shearing characteristics were obtained and that shearing method was confirmed to be promising with the reliable shearing device.Copyright © 2009 by ASME

Droplet formation in a co-flowing microfluidic device is investigated with the lattice Boltzmann method (LBM). This LBM code was validated with two benchmarks such as Poiseuille flow through a straight duct and Taylor deformation on droplets between two shearing plates. A comparison of experimental droplet formation in a microchannel (Cramer et al, 2004) showed good quantitative agreement with our modeling results. With this code, a large number of simulations were carried out with various inlet flow rate ratios at various Re and various interfacial tensions in the co-flowing microfluidic system. All resulting droplet sizes are discussed quantitatively with the nondimensional parameters, which is helpful for droplet control in different co-flowing devices.Copyright © 2007 by ASME

The interaction and load transfer between multiple shells of a multi-walled carbon nanotube (MWNT) is the subject of intense research by both analysts and experimentalists. Observations of both lubricated sliding and adhesion between the shells of the MWNT have been observed. While the atomic interactions due to simple separation have been successfully modeled by the Lennard-Jones interaction potential for graphene structures, modeling of the shearing deformation mode has been problematic. In the present work, the authors utilize two approaches in continuum mechanics to examine the shearing transfer between shells in a MWNT subjected to extensional and torsional loading wherein the load is transferred through the outer most shell to interior shells. The first approach follows the earlier developments of the authors wherein imperfect bonding between the shells is governed by a shearing transfer efficiency that varies between perfect bonding and frictionless sliding. The second approach utilizes a classical shear lag model to study the shearing transfer between the shells. A comparison between the shear lag and shear transfer models shows the equivalence of the two approaches for two-shell MWNT and numerical solutions are presented for the shear lag model for multiple layers beyond two. Agreement between the two models for multi-shells is demonstrated by varying an adjustable parameter that depends solely on the MWNT geometry. The simplicity of the shear transfer model as compared to the shear lag model constitutes an important advantage. The fundamental discrepancy between the two models lies in the fact that length dependence is inherent to the shear lag analysis, while according to the shear transfer model, stress transfer does not depend explicitly on length.Copyright © 2006 by ASME

The production of nanocrystalline wear debris containing components from the worn specimen, from the counterface and from the environment does not support any of the better known wear models or wear equations based on adhesion, delamination, fatigue or oxidation. In this presentation, plastic deformation, mechanical mixing and patterns of flow determined from experiments will be compared with molecular dynamics (MD) simulations and a continuum analysis of two ‘fluids’ shearing in opposite directions. Together, these suggest generic behavior that needs to be included in any realistic sliding wear model.Copyright © 2005 by ASME

We develop a finite-element method for the simulation of dynamic fracture and fragmentation of thin-shells. The shell is spatially discretized with subdivision shell elements and the fracture along the element edges is modeled with a cohesive law. In order to follow the propagation and branching of cracks, subdivision shell elements are pre-fractured ab initio and the crack opening is constrained prior to crack nucleation. This approach allows for shell fracture in an in-plane tearing mode, a shearing mode, or a bending of hinge mode. The good performance of the method is demonstrated through the simulation of petalling failure experiments in aluminum plates.

Flow of granular materials has been a subject of numerous investigations in the past few decades. A number of experimental techniques have been used in these studies. Examples include PEPT (Positron Emission Particle Tracking), NMR (Nuclear Magnetic Resonance), HSP (High-Speed Photography), and various tomographic methods. These techniques have been used to study a number of model systems such as rotating drums, chute flows, vibro-beds, hopper flows, fluidised beds, and shear cells, in order to gain an insight into the behaviour of granular flows. In this paper, a brief review of these experimental techniques and model systems will be made first. Attention will then be paid to the work on rotating drums and fluidised beds using the non-invasive PEPT technique. Finally, future directions of the experimental aspects of shearing granular materials will be discussed.Copyright © 2002 by ASME

The paper shows that detailed viscoelastic properties of helical flow can be exactly determined from those known for simple shearing as soon as a constitutive equation is specified. This paper also demonstrates the calculated characteristics of helical flow compared with experimental data.

Since the apparent stiffness due to contact of one surface on another relates directly to the localized resonant frequencies, it is believed that accurate account of this property will lead to the fundamental understanding of causes of friction-induced vibration and noise. The mathematical model of contact is utilized to develop formulae for normal and tangential contact stiffness. The inclusion of a study in which the various modes of elastic deflections of an asperity are also considered, as well as their effects. The bending, shear and Hertz contact modes of elastic deflection are assumed to simultaneously occur for an asperity. Investigation of the combined effect of bending, shear and Hertzian contributions to the contact stiffness is indicating that the equivalent contact stiffness is best represented, among the three types of stiffness, by that due to Hertzian contact.

A survey of secondary flows of viscoelastic liquids in straight tubes is given including recent work pointing at striking analogies with transversal deformations associated with the simple shearing of solid materials. The importance and implications of secondary flows of viscoelastic fluids in heat transfer enhancement are explored together with the difficulties in detecting weak secondary flows (dilute, weakly viscoelastic solutions) in a laboratory setting. Recent new work by the author and colleagues which explores for the first time the structure of the secondary flow field in the pulsating flow of a constitutively nonlinear simple fluid, whose structure is defined by a series of nested integrals over semi-infinite time domains, in straight tubes of arbitrary cross-sections is summarized. The transversal field arises at the second order of the perturbation of the nonlinear constitutive structure, and is driven by first order terms which define the linearly viscoelastic longitudinal flow in the hierarchy of superposed linear flows stemming from the perturbation of the constitutive structure. Arbitrary conduit contours are obtained through a novel approach to the concept of domain perturbation. Time averaged, mean secondary flow streamline contours are presented for the first time for triangular, square and hexagonal pipes.

The central theme of this paper is the representation of tolerances in engineering design and manufacturing. A sub-problem of this central theme is the structure of form and size errors created by typical machining processes. This subproblem is addressed using a fractal-based procedure. In particular, workpiece profiles are generated for the shaping manufacturing process, using a simulation model and incorporating the basic shearing mechanism of machining with typical error sources. The resultant profiles are analyzed using a fractal-based, box counting algorithm. The results, which reveal the presence of variational structure, are discussed, emphasizing the relationship between total variability and function. Finally, modifications and future directions to the research are presented.

In this paper, the framework for a sheet metal part design and manufacturing assessment environment is presented. Based on an investigation of the characteristics of sheet metal part design, form feature methodology is employed to facilitate design and provide information for assessment. The tasks, rules, and the significant items for manufacturing assessment are identified and formalized into a knowledge base with object-oriented techniques. The knowledge base is used for design assessment including evaluation for compatibility with press-working processes, modification of preliminary designs into better ones given cost considerations, and evaluation to avoid defects and failures. To support on-line design evaluations, a part model is constructed by extracting the required feature and connectivity data from a CAD database. The research is concentrated on box-type sheet metal parts primarily made by cutting (e.g., shearing, blanking, punching, etc.), bending, flanging, and local stretching. These parts are produced by both stampers and fabricators.

This article highlights warning signs that a composite panel may be delaminating or thinning, but engineers have a powerful nondestructive testing tool in shearography. This is a laser interferometric method developed originally for full-field observation of surface strains of components. Flaws usually induce strain concentrations around them, and shearography can be employed to detect those flaws. A relatively new variation, digital speckle-shearing interferometry (DSSI), uses a charged-coupled device (CCD) camera and computer image processing to capture and process the interferometric fringe patterns. The digital version is faster than conventional shearography, and does not require any film or Fourier filtering. The main advantages of digital speckle shearing interferometer are the ease and speed with which fringe patterns can be obtained.

Twist-off testing of solder joint interconnections is regarded by many reliability engineers in the microelectronic industry as an attractive alternative to shear-off testing. In this paper we briefly discuss the merits and shortcomings of both techniques and determine the relationship between the ultimate torque and the ultimate shearing force. We also suggest a simple experimental method for the evaluation of the shearing strength of solder joints on the basis of twist-off testing. It should be emphasized that such testing can be used not only for a tentative comparative evaluation of different interconnections but as a quality control vehicle as well.

Metal machining is one of the fundamental manufacturing processes. The principal cost of shaping metal parts is generated both in the work involved in shearing metal from the original stock, at the area where the chips are formed, and also in the work required to overcome the high frictional forces that exist between the chip and rake face. Current techniques for the lubrication and cooling of this area are not very effective, resulting in a machining cost which is much higher than need be. A more efficient lubricooling effect can be achieved by the use of a high-pressure water jet directed into the tool/chip interface. The study of this idea was prompted by results achieved in the 1950’s, but now extended to much higher jet injection pressures (up to 280 MPa). The emphasis of this article is on the comparison of the coefficient of friction at the tool/rake interface for conventional and high-pressure jet cooling and also on reporting some practical results. Evaluation of these results indicates both a significant gain in the material removal rate as well as an improvement in the chip shape. The results are for a UNS 1020 steel—a representative of the poorly machinable materials.

The paper investigates possible interface waves between two solids in presence of separation and frictional slip and examines the effect of the waves on the sliding motion of the bodies. It is shown that interface waves are mathematically feasible between solids with identical mechanical properties, and that they can propagate with any phase velocity that falls between the Rayleigh and shear wave speeds. In the presence of such interface waves, global sliding may take place at much lower applied shearing tractions than would be required to slide the solids as rigid bodies. The waves also involve singular interface tractions that lead to energy emission and absorption at the singular points, and some aspects of them appear controversial.

A new method of design, using the concept of equivalent solid thick plate on elastic foundation is described. Component theory that takes into account the influence of transverse shearing strain and uses more exact expressions for normal stresses, is employed. Use of more accurate values of effective elastic constants for thick plates and generalized plane strain case and the local stress multipliers due to Slot and O’Donnell [14] and Porowski and O’Donnell [15], respectively, is suggested. Effects of solid annular rim, differential expansions between tubes and shell, and interaction between tubesheet and shell/channel are also taken into account.

Experimental results obtained by in situ machining within a Scanning Electron Microscope of a resulphurized steel containing Type I manganese sulphide inclusions are presented. The data obtained from slow speed machining tests show that chip formation in these steels involves decohesion and cavitation at the sulphide-matrix interface as well as fracture of sulphide inclusions. While these processes promote fracture in the shearing region during chip formation (confirming an earlier hypothesis due to Tipnis and Cook), it is argued that these phenomena cannot be responsible for better tool life, surface finish, and lowered power requirements usually encountered with free machining alloys under typical industrial cutting conditions. The role of thermal dissipation during machining and its effect in altering the chip formation through thermally induced changes in plastic flow behavior of Type I sulphide inclusions are discussed.

The hydroelastic stability of short, simply supported, thin-walled tubes conveying fluid is examined with an emphasis on the effects of shearing loads and in-plane boundary conditions. The Donnell shell equation is used in conjunction with linearized, potential flow theory. The solution is obtained by using Fourier integral theory and Galerkin’s method. It is found that an increase of the shearing load reduces the critical divergence velocity and raises the corresponding number of circumferential waves. A change in the in-plane boundary conditions exerts the significant effect on the critical divergence velocity of short tubes.

The magnitude and the distribution of stresses in bi-metal thermostats subjected to uniform heating or cooling are determined. The suggested approach enables one to evaluate the normal stresses in the thermostat plates, as well as the shearing and normal (“peeling”) stresses in the interface. The developed approach is applicable, generally speaking, to any elongated lap shear assembly.

Asymmetries like welds or shoulders, may eliminate one of the two shear zones of symmetrically fully plastic cracked parts and thus give crack propagation along the remaining active slip band through pre-strained material instead of through the relatively unstrained region between two shear bands of the symmetric case. One thus expects a reduced ductility in the single shear band asymmetric case. A macro-mechanical analysis provides a physical basis for explaining the development of deformation in both geometries, as observed from tests on several alloys. The asymmetric case is approximated as Mode II shearing, with the crack extension occurring by sliding off along a single slip plane and fracture. In the symmetric Mode I case, the crack is assumed to extend by alternating shear on two symmetric slip planes and fracture.

The equations describing the stress and strain fields in an elastically isotropic shallow shell containing a crack are reduced, via Fourier transforms, to four coupled singular integral equations plus side conditions. A perturbation solution, useful for relatively short cracks, is constructed for a pressurized shell of revolution containing a stress-free crack that makes an arbitrary angle with a line of curvature of the midsurface. First-order corrections due to curvature and crack orientation of the mode I (opening) and mode II (shearing) stress-intensity factors for a plate are computed analytically.

Heat effects in lubricating films are analyzed on the basis of simple shear of the lubricant, Reynolds logarithmic formula relating lubricant viscosity and temperature, and an equation relating the heat generation and heat flow in the film. The film-temperature dependence on velocity is determined, and the result is used to obtain the shearing stress and shearing rates. The formulas thus derived are useful in analyzing the performance of oil-film bearings. Experiments have been carried out with measurement of shaft- and bearing-surface temperatures, as well as friction; the tests support the analytical results. An approximate means for judging the importance of film heating in a given case in terms of velocity and lubricant viscosity is suggested.

A concentrated force applied to an infinite matrix near a smooth circular inclusion is discussed. The smooth interface is defined as one that allows slip, but does not transmit shearing tractions. The solution is partially in terms of series, but for certain combinations of materials the series sum to elementary functions. The solution which is of significance for applications in micromechanics exhibits interesting behavior also from the point of view of classical elastostatics. When the force is allowed to approach the interface, the singularity for the force shows dependence on the curvature of the interface. In this respect the smooth interface between two materials in two dimensions resembles a curved boundary in three dimensions.