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Some commercial nuclear power plants have been permanently shut down to date and decommissioned using dismantling methods. Other operating plants have decided to undergo an upgrade process that includes replacement of reactor internals. In both cases, there is a need to perform a segmentation of the reactor vessel internals with proven methods for long term waste disposal. Westinghouse has developed several concepts to dismantle reactor internals based on safe and reliable techniques, including plasma arc cutting (PAC), abrasive waterjet cutting (AWJC), metal disintegration machining (MDM), or mechanical cutting. Mechanical cutting has been used by Westinghouse since 1999 for both Pressurized Water Reactors (PWR’s) and Boiling Water Reactors (BWR’s) and its process has been continuously improved over the years. The complexity of the work requires well designed and reliable tools. Different band saws, disc saws, tube cutters and shearing tools have been developed to cut the reactor internals. All of those equipments are hydraulically driven which is very suitable for submerged applications. Westinghouse experience in mechanical cutting has demonstrated that it is an excellent technique for segmentation of internals. In summary, the purpose of this paper will be to provide an overview of the Westinghouse mechanical segmentation process, based on actual experience from the work that has been completed to date.Copyright © 2010 by ASME

Experiments were conducted to examine the effects of friction coefficient on sliding velocity at a slider pad/disk interface lubricated by MoS2 powder film. The powder film was obtained by shearing compacted pellets of MoS2 against a tungsten carbide (WC) disk and was responsible for supporting the slider pad load. The results from the experiments showed that an adverse interfacial friction coefficient leads to a decrement in the sliding velocity. Contrarily, an increased sliding velocity accompanies a favorable (i.e., smaller) friction coefficient at the WC slider pad/disk interface lubricated by the MoS2 powder lubricant film.Copyright © 2010 by ASME

The formation of micro droplets involved a complex mechanism deriving from the competition between the interfacial tension, viscous shearing and other counterparts. In the present study, a volume-of-fluid (VOF) method within FLUENT software was used to study the droplet formation in a T-junction microchannel. By varying the velocity of continuous phase, we got droplet formation in “squeezing” process, and the shifting to “dripping” regime at a critical Capillary number. The pressure and velocity changing in both regimes were investigated in detail, supporting the result that the squeezing was dominated by the upstream pressure rising and the dripping was driven by shearing force. The numerical results hold a good agreement with the previously experimental measurements using confocal micro-PIV system. Furthermore, the motion inside an emerging droplet was also studied, showing intricate circulation flow.Copyright © 2010 by ASME

This paper compares results from the the rod-chain model with those from results based on Jeffery’s equation. A concept of critical buckle aspect ratio is employed to define the rigidity or flexibility of a fiber, above which point a fiber is flexible enough to be bent and twisted. When a fiber has an aspect ratio less than the critical buckle aspect ratio, fiber motion predicted by the rod-chain model corresponds perfectly with that of Jeffery’s equation. The trajectories of a single rigid fiber with different initial orientations are shown by the rod-chain model, which are in line with what Jeffery’s equation predicts. Results are also shown for the configuration of a single flexible fiber at various times under a pure shearing flow. The “blind area” of the rod-chain model is discussed.

This paper describes a new structural type of end closure with use of the metallic self-energized n-ring as its sealing gasket and the D-section shearing bolts as its load-carrying connection between the head and the top flange. The connection installs easily and quickly for pressure vessels. The strength analyses of connection component are presented.Copyright © 2010 by ASME

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

The process of stamping stainless steel bipolar plates is developed from initial plate design through manufacturing and use in a fuel cell stack. A stamped design incorporating a serpentine flow field for the cathode and an interdigitated flow field for the anode is designed. This bipolar plate consists of only one piece of thin stainless steel sheet. The process of rubber-pad stamping was chosen to reduce shearing of the thin sheet. Dies were designed and made. Stainless steel plates were stamped, but stress were higher than anticipated and die failure was observed. The plates were tested both in-situ and by doing simulated fuel cell testing. Although sealing was an issue due to lack of proper gaskets and endplates, tests determined that the stamped bipolar plates will work in a PEM fuel cell stack. Dies were redesigned to improve durability. Gaskets and endplates were designed to complete the stack construction.Copyright © 2008 by ASME and U.S. Government

The authors have studied for the effect of supplying oxygen into water with micro bubbles produced by the shearing method, and found that the micro bubbles are very effective for the oxygen supplying compared with general size bubbles. We also generate micro bubbles which make water cloudy through the pressurizing dissolution method. The average diameter of micro bubbles generated with this method is about 40 micro meters in our laboratory. They are much smaller than those produced by the shearing method, and are the similar size to the tracer or the reflector used to measure the flow field by the PIV or the UVP (Ultrasonic Velocity Profile monitor). Moreover, they are very economical and ecological compared with solid tracer particles. Therefore, we examine to apply micro bubbles generated with the pressurizing dissolution method to the measurement of liquid flow field using the PIV or the UVP. A flow in a square cavity at Re = 1000 was measured using the PIV and the UVP. We could recognize a clear vortex. A flow around a circular cylinder was also measured using the PIV. We can recognize the possibility of micro bubbles for these applications.Copyright © 2007 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 fatigue failure mechanism was investigated for the rubber CVT (continuously variable transmission) belts. There are three major crack initiation modes in the rubber CVT belts, namely the adhesive rubber crack, the backing rubber crack and the bottomland crack. Especially, the mode of the adhesive rubber crack is important to strengthen the rubber CVT belts, because the crack is the most difficult to find out during the driving. In this study, the failure morphology of the damaged belts was observed using an optical microscope and a X-ray CT scan after some fatigue tests. Moreover, the failure mechanism of the adhesive rubber crack was discussed basing on the FEM and simplified mechanical analyses. The fatigue damage was accumulated along the interface between the cog rubber and the adhesive rubber. The interface was de-bonded by the shearing strain, which was induced by the dishing deformation of the belt within the pulley groove.Copyright © 2007 by ASME

Stress intensity factors are found for a crack emanating from a circular hole in an elastic solid which is in a state of plane deformation resulting from loads applied at infinity or pressure applied internally at the faces of the crack and the hole. The results, including Mode-I (opening) and Mode-II (shearing) stress intensity factors, are obtained numerically by means of a dislocation model which conveniently allows for general loading and, consequently, can easily handle the case where a crack emanates non-radially from a hole. Good agreement is found with published values for the special case when the crack is radial and the loading consists of remote tension and uniform pressure at the surface of the hole. Also included in the present paper are results for the case when both the hole and the crack are pressurized. Although the subject elastic solid is an infinite medium, the results of this paper serve as good estimates when the hole is relatively small in a finite component and is distant from the component edge. Since in most circumstances a real crack does not orient itself radially from a hole, this paper provides analysts information to decide whether Mode-II fracture needs to be considered in assessing the structural integrity of a component with a hole. Similarly, when the problem is 3-dimensional, the results of this paper imply that Mode-III (tearing) fracture may also need to be considered.Copyright © 2006 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 fundamental principle of MR fluid fan clutch in transmitting torque is analyzed, in the meantime, a shear model of MR clutch is proposed; MR fluid fan clutch having simple, novel structure is designed and made; At the same time, on the basis of experiments, the characteristic of velocity regulating of the clutch is studied in detail. The experimental results indicate that, compared with the shearing rate, the change of magnetic fields has a tremendous influence on the speed regulating characteristic of a fan clutch, and output torque of fan clutch can satisfy demand of engine cooling fan.

Attempts have been made to correlate the scratch behaviour and basic material properties of polymers and a correlation has been established between the scratch damage and friction coefficient. However, no clear relationship has yet been established between the bulk response and scratch damage. The scratch behaviour of three solid polymers (PMMA, PC and CR39) was investigated to determine how the behaviour of the bulk material affects the scratch resistance. The bulk damage responses of these materials are well known: crazing, shearing and cracking, respectively. The surfaces were scratched under progressive scratch loading and an imaging system was used to record real time photographs of the in-situ contact area and scratch damage. PMMA exhibited crazing under the apex of the scratching tip while the shearing of PC started under the front part of the contact area and cracking appeared in CR39 at the rear edge of the contact. Numerical simulations confirmed these damage mechanisms.Copyright © 2005 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

In this paper, predictive modeling of cutting and ploughing forces, stress distributions on tool faces and temperature distributions in the presence of tool flank wear are presented. The analytical and thermal modeling of orthogonal cutting that is introduced in Karpat, Zeren and Ozel [3] extended for worn tool case in order to study the effect of flank wear on the predictions. Work material constitutive model based formulations of tool forces and stress distributions at tool rake and worn flank faces are utilized in calculating non-uniform heat intensities and heat partition ratios induced by shearing, tool-chip interface friction and tool flank face-workpiece interface contacts. In order to model forces and stress distributions under the flank wear zone, a force model from Waldorf [4] is adapted. Model is tested and validated for temperature and force predictions in machining of AISI 1045 steel and AL 6061-T6 aluminum.Copyright © 2005 by ASME

Modern product design and manufacturing often utilizes a wide variety of materials. Where once low carbon steel predominated, a variety of different materials such as aluminum alloys and advanced high-strength steels (AHSS) are now being utilized. Although such alternative materials may provide a variety of benefits in manufacturing and design, these same materials may present difficulties when subjected to manufacturing processes originally designed for low carbon steel. One such manufacturing area where difficulties may arise is in trimming operations. A defect that may arise directly in the trimming operation are burrs. Burrs decrease the quality and accuracy of stamped parts and cause splits in stretch flanging and hemming. Current standards limit the production of burrs through accurate alignment of the upper and lower edges of the trim knives. The clearance between the shearing edges should be less than 10% of the material thickness. For automotive exterior sheet, this requires a gap less than 0.06mm. Unfortunately, tolerances often exceed the capabilities of many trim dies resulting in the production of burrs. To satisfy the current standards of quality and to meet customer satisfaction, stamped parts frequently need an additional deburring operation, which is often accomplished as a metal-finish operation and conducted manually. The objective of the research described in this paper was to study the mechanisms of burr generation and the impact on AHSS formability in stretch flanging. Results on both the conventional trimming process and a recently developed robust trimming process, which has the potential to expand tolerances of trim die alignment, will be discussed.Copyright © 2005 by ASME

It was reported that CNx coating showed low friction coefficient less than 0.01 when it slid against Si3 N4 ball in dry N2 . It is suggested that the super-low friction was caused by the structural change of CNx surface to graphite-like structure during sliding in N2 . In this study, to investigate the effect of N2 gas on shearing and adhesive strength of CNx, micro scratching tests were examined in N2 and air with a diamond tip (radius = 2.0 μm). Main results are the followings: (1) CNx surface after sliding in N2 against Si3 N4 ball showed lower scratching friction coefficient in N2 than that in air. (2) Adhesive strength Si was estimated as 1/10 times lower than that in air.Copyright © 2005 by ASME

For the purpose of more safety boats, the large thickness of outer plates is required to increase flexural stiffness, strength and impact properties. Some problems in mechanical properties are generated by increasing in thickness because the effect of interlaminar shearing of Thick-composites on whole mechanical properties is greater than that of thin-composites. We have investigated the matrix hybrid composite with two kinds of unsaturated polyester, one was hard type resin with low toughness and the other was flexible type resin with low modulus and high toughness. In this study, matrix hybrid composite was focused and applied to Thick-composites. First, the flexural properties were investigated and the micro fracture progress was precisely observed with in-situ observation using replica method. Then, impact properties of the Thick-composites were examined and the availability of matrix hybrid composite was investigated. It was concluded that the matrix hybrid composite achieved high performance in both static and impact load.Copyright © 2004 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.

In this paper, the influence of large particles on the contact force net-work (structure) and their impact on the macroscopic shear resistance of a slowly sheared dense granular medium three dimensional) having a binary size distribution is presented. The evolution of deviator fabric tensor of the ‘strong’ and ‘weak’ contacts in the granular assembly is presented here. The ability of the granular material to establish a strongly anisotropic force net-work of strong contacts is ‘diluted’ by the presence of large particles during shearing. Previous studies [for example, Antony, S. J., 2001, Physical Review E, 63, 011302 and references there in] have shown that the shear strength of granular materials subjected to slow shearing depends on the ability of the material to built up a strongly anisotropic net work of contacts carrying strong (greater than average) contact normal force.

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

For a generalized helical end mill, this paper presents a frequency domain force model considering the ploughing as well as the shearing mechanisms. The differential chip load and the corresponding cutting forces are first formulated through differential geometry for a general helical cutting edge. The differential cutting force is assumed to be a linear function of the chip load with a proportional shearing force and a constant ploughing force. The total milling force in the angle domain is subsequently composed through convolution integration and analyzed by Fourier analysis. The frequency domain model has the parameters of a general milling process all integrated in a single framework with their roles clearly defined so that Fourier coefficients of the milling force can be obtained for any analytically definable helical cutter. Applications are illustrated for three common helical cutters: the cylindrical, taper, and ball end mills. Furthermore, as an inverse application, a linear algebraic equation is formulated for the identification of six cutting constants from the average forces of two slot milling tests. Demonstration and verification of the milling force model as well as the identification of cutting constants are carried out through experiments with three types of milling cutters.Copyright © 2002 by ASME