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Gas foil thrust bearings have been utilized in high speed lightweight machines for many decades. These bearings are environment-friendly and capable of withstanding extreme conditions. However, there are also some challenges for foil thrust bearings at high speed conditions, such as insufficient heat dissipation and thermal management. The heat generated by viscous shearing continues to raise the temperature inside the gas film and may cause failures. Among all the methods to enhance heat dissipation, a promising passive thermal management method is modifying the top foil’s trailing edge shape. This modification will enhance the air mixing in between the bearing pads. The aim of this study is to identify the optimal design of the top foil trailing edge shape and provide a guideline for future bearing design. A 3-D computational fluid dynamics (CFD) model for a thrust foil bearing was created using ANSYS-CFX software. The trailing edge of the top foil was modified to a chevron shape. A sensitivity study was conducted to investigate the connection between the top foil trailing edge shape and the thermal conditions in the gas film. The maximum temperature inside the air gas film is selected as the output. The design of experiments (DOE) technique was used to generate the sampling points. A surrogate model was generated based on the output data by using the neural network method. The surrogate model was used together with a genetic multi-objective algorithm to minimize the maximal temperature inside the gas film and maximize the load carrying capacity. The optimal design was then compared with the baseline model. Results suggest the optimized trailing edge shape is capable of reducing the temperature inside the gas film. This optimal design approach can be used for improvements of chevron foil thrust bearing design.

Currently, the shaped parts combined with straight, concave, and convex portions are increasingly fabricated. To produce the straight portion, the shearing theory is usually applied. As well as, to produce the concave and convex portions, the punching and blanking theories are usually applied. However, with the same die-cutting process parameters, the comparison of cut surface features of straight, concave, and convex portions has not been investigated yet. Therefore, in the present research, the comparison of the cut surface features in various die-cutting processes, including shearing, blanking, and punching processes are investigated. The finite element method (FEM) was used as a tool to investigate these cut surface features. The cut surface features were investigated and clearly identified via the changes of the stress distribution analyses. The results elucidated that with the same die-cutting process parameters, the different cut surface features were obtained. Specifically, the crack formations were easily generated in the case of blanking process, following by the shearing and punching processes, respectively. Therefore, the smooth cut surface was smallest in the case of blanking process, following by the shearing and punching processes, respectively. The laboratory experiments were carried out to verify the accuracy of the FEM simulation results. Based on the cut surface features, the FEM simulation results showed good agreement with the experimental results in terms of the cut surface features. Therefore, to design the die-cutting process parameters to meet the product requirements of complicated shapes, the understanding on these working process parameters being upon the shaped parts is necessarily.

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.

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 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.

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.

The press forming process of paperboard trays is challenging. The production of trays that fulfill all functional and visual property requirements is demanding. Blank preparation is an essential part of paperboard tray press forming. The aim of this work was to study how a creasing pattern can be utilized in the compaction and folding of the substrate in tray corners. The investigation of creasing pattern designs focused on the positioning of creases, the optimization of the amount of creases, and the width of the creases. The results of the study show that the amount of creases in the tray corner is the most important variable in the pattern design. The substrate folds more evenly and the wall of the tray is smoother when the material has the optimum amount of folds for it to compact during the press forming process. Changes in the creasing pattern primarily affect the amount of unclosed creases in the flange of the tray, which can make tight lidding of the tray impossible. The outcome of the study is a morphological analysis of the introduced creasing pattern alternatives and a selection of formulas that can be utilized in the creasing pattern design process.

This paper proposes a novel approach to fine blanking. The V-ring indenter used in conventional fine blanking is no longer required; a trough on the die is used instead. In this approach, the cutting process combined with high hydrostatic stresses produced from the trough on the die cutting edge can substantially decrease the fracture in the shear zone. A series of experimental tests with experimental specimens of various thicknesses was conducted. The burnished surface obtained from this approach can nearly achieve the complete thickness of the blank in one operation, suggesting that the fracture zone can be nearly eliminated. In addition, the surface roughness of the burnished surface range was measured between 0.03 and 0.08 μm, and the tolerance band for the diameter was between IT2 and IT4. These results indicate an improvement in the values obtained using conventional fine blanking.

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.

Article history: Received 10 January 2012 Accepted May 24 2012 Available online 25 May 2012 Wire electrical discharge machining (WEDM) is well known process for generating intricate and complex profiles in hard metal matrix composites. But damaged surface layer with poor surface integrity is a major disadvantage of WEDM. Beside poor damaged surface layer, after rough/first cut in WEDM, some surface area remains unmachined on work surface during intricate machining such as in die cutting. This paper presents a study on unmachined surface area named as surface projection, in die cutting after rough cut in WEDM. Using scanning electron microscope images, length of unmachined surface projections have been determined. In order to minimize these surface projections from small cavities having complex geometries, trim cutting operation is the best alternative. Results show that using more than one trim cut with appropriate wire offset value, surface projections can be minimized, successfully. © 2012 Growing Science Ltd. All rights reserved

Position stability analysis of gripper bars on die-cutting machine is one of the important factor which affects machining quality and production capacity. By introducing comprehensive influence parameter period ratio such as machine speed and mechanism natural frequency,mathematical model of gripper bars in stopping period has been established. The results indicate that dynamic motion error of gripper bars in stopping period show an increasing tendency so as to affect stable position with the increasing of period ratio. To ensure a stable position state in stopping period, finally two solutions are given out to satisfy high accuracy.

NextGen’s work on the DARPA sponsored Next Generation Morphing Aircraft Structures (N-MAS) program [1]–[6] designed and successfully tested novel morphing wing designs that were enabled by “shear-morphing” skins capable of withstanding up to 400 psf air-loads while simultaneously undergoing shear strains in excess of 100%. These ad-hoc skin designs consisted of high-strain silicone facesheets supported by an intricate aluminum under-structure made of thin, closely-spaced aluminum ribbons glued to the facesheets and bounded by pin-jointed frames. While these performed well in wind tunnel and flight tests, two areas for improvement were identified: (1) reduction in manufacturing complexity, and (2) reduction in actuation force requirements. In this research program, through use of high-fidelity modeling (ANSYS) and in-house testing, a new design was obtained that met both of the desired objectives using novel materials and single-piece support structure fabrication. The optimization modeling code was designed to be adaptable to a range of design inputs, and as such can be used on future programs as well, at various scales from UAV to MAV. The thorough understanding of the design space gained from non-linear FEM modeling guided design, manufacturing and testing in the later portion of the research. Using the optimized design from analysis, as well as variations in facesheet prestrain, the ANSYS code was validated through manufacture and testing of panels. This report details the results of testing and compares them to both predictions of the ANSYS code and N-MAS baseline designs values through various test setups. Results presented include shear morphing forces/energy, out-of-plane displacement under air loading, and 3D photometric analysis of shearing panels for identification of stresses/strains and wrinkling initialization in the skin. Testing provided substantiation of the ANSYS code, matching the general predicted trends despite wide variability in material properties.

Asymmetric plunge cutting by using a grooved knife edge plate was proposed for advanced die cutting of a polycarbonate (PC) sheet. By varying the tip angle αU and the tip thickness w U of knife edge in the counter plate, and combining a standard steel cutting rule of 42° center bevel blade, a cutting load response of PC sheet was experimentally investigated, and the deformation was also observed by a CCD camera. Furthermore, an FEM simulation was carried out by varying the lower tip thickness for revealing the effect of interference of lower grooved counter plate. Through this work, the following were found: 1) there were two deformation modes of sheared profile; 2) the lower tip thickness w U was a primary factor, compared to the lower tip angle of αU; 3) the equivalent wedge angle effect was revealed with respect to the upper/lower angles α and αU, while the PC sheet was bent up by the lower knife indentation.

To prove the indentation quality of packaging products, the indentation depth and the bottom die width were changed to study the effect of the indentation on the indentation quality and make sure the best indentation depth with HANATEK indentation tester for 20kinds of paper. The relationship between the performance of paper and the best indentation depth is analyzed by the method of linear regression. The result shows that the deeper the indentation depth is, the bigger the folding angle is. The folding angle of steel wire and paper fibers in parallel rows is bigger than that in vertical rows. The deflection and longitudinal tensile strength of paper have notable effect on the indentation depth, transverse tensile strength and tightness are poor and the folding endurance has no remarkable influence.Printing packing profession in our country has made significant progress with the rapid growth of economy and the rapid expansion of international trade. The postpress technology plays a key role to the quality of printing packing and the die cutting indentation is the important technique of production. The die cutting indentation makes the print artistic and suitable , it suits all kinds of print surface finishing process and is widely applied in book cover, trademark, label, as well as carton. So how the quality of the die cutting indentation has directly effect on the market image. However, the indentation processing basically depends on the experience of technical staff in the factory at present. To study the relationship between the performance of paper and the indentation condition can provide certain scientific basis for the choice of indentation process.

The important component--- pressure device in die-cutting is analyzed by Solidworks and ANSYS Workbench. With analyzing the structure of the pressure device, some simplification is made, and the tool of draft mirror and feature mirror is often used in building the model in the Solidworks. Loads of the pressure device in different load conditions are analyzed and calculated. Stress and displacement of the pressure device are plotted after static finite element analysis. Its stress is analyzed by ANSYS. Stress and strain distribution is found. Which can provides mechanical simulation for the design of the pressure device, and provides scientific basis for selecting structure type, deciding structural parameters, increasing static and dynamic properties, reducing manufacture cost of the integral body of the pressure device.

In the car body stamping process, trim/blank die cutting edges are subjected to very high tribological loads that result in loss of tool material from both the punch and die cutting edges. According to Archard’s wear model, normal contact force and sliding distance directly affects the wear. Therefore, knowledge of the acting forces on local contact areas has a pivotal role towards the prediction of tool wear. This paper presents a finite element modelling approach to determining the contact pressure distribution on the tool cutting edges during a trimming/blanking process. Characteristic areas on sheared edge profile, variation of punch force and high contact pressures affected areas have also been analysed.

In shearing, the crack occurrence may be controlled by elevating a hydrostatic pressure of a material near tool cutting edges. Since hydrostatic pressure is affected by constraint of material, the influence of constraint on shearing characteristics was investigated by the experiments and FEM analysis. The results of this study clarified the followings. The smooth sheared surface of blanked product is increased by constraint of material. When the material is tightly constrained, crack earlier occurs at the material near punch cutting edge than that of die cutting edge. This tendency agrees with the magnitude of hydrostatic pressure at punch and die cutting edges. It is confirmed that the constraint of material prevents cracks by adequate controlling of material flow aiming the hydrostatic pressure rise. It is also confirmed that the dishing of product is affected by the condition of the constraint.

In industry a die cutting system is one of the important technologies for manufacturing paper packages. The cutting productivity or quality is maintained by operators’ experience. Various kinds of automatic techniques for the cutting condition have been evaluated. It was been confirmed that the acoustic estimation methods are useful for detecting the variation of the blade tip shape. From before reports, the relation of the variation of blade tip shape and applied load on the cutting edge has been clarified experimentally. The generation of acoustical signals also changes with the blade tip thickness. To investigate the origin of acoustic phenomena during the cutting process, some trials are carried out with the private designed machine. The acoustic phenomena are due to the collision behavior between the blade tip and counter plate. The cutting behavior of paperboard can be related to the acoustical differential of the displacement and vibration energy.

Because of large scale and heavy weight, end closures of high pressure vessels are usually hard to assemble and disassemble. In this paper, a new quick-opening seal device connected by D-shaped shearing bolts is introduced. This device is compact in structure, reliable in sealing, easy in assembly and disassembly, and very appropriate for end closures of pressure vessels or for pipe joints. Strength calculation formulas for the major parts are proposed analytically, and stress analysis using the finite element method for a C-ring seal has been performed. An application of this device shows that its sealing and strength is reliable.

In Part II of this paper, experimental and analytical methods have been developed to estimate the values of the process faults defined in Part I of this paper. The additional faults introduced by the microend mill design are shown to have a significant influence on the total net runout of the microend mill. The dynamic model has been validated through microend milling experiments. Using the dynamic model, the effects of minimum chip thickness and elastic recovery on microend milling stability have been studied over a range of feed rates for which the cutting mechanisms vary from ploughing-dominated to shearing-dominated. The minimum chip thickness effect is found to cause feed rate dependent instability at low feed rates, and the range of unstable feed rates depends on the axial depth of cut. The effects of process faults on microend mill vibrations have also been studied and the influence of the unbalance from the faults is found to be significant as spindle speed is increased. The stability characteristics due to the regenerative effect have been studied. The results show that the stability lobes from the second mode of the microend mill, which are generally neglected in macroscale end milling, affect the microend mill stability significantly.

This paper extends analytical modeling of the milling process to include process damping effects. Two cutting mechanisms (shearing and plowing mechanisms) and two process damping effects (directional and magnitude effects) are included. The directional effect is related to vibration energy dissipation due to directional variation of cutter/workpiece relative motion. The magnitude effect is associated with change in force magnitude due to variation of rake angle and clearance angle. Process damping is summarized as containing these separate components; direction-shearing, direction-plowing, magnitude-shearing and magnitude-plowing. The total force model including the process damping effect is obtained through convolution integration of the local forces. The analytical nature of this model makes it possible to determine unknown process damping coefficients from measured vibration signal during milling. The effects of cutting conditions (cutting speed, feed, axial and radial depths of cut) on process damping are systematically examined. It is shown that total process damping increases with increasing feed, axial and radial depths of cut, but decreases with increasing cutting velocity. Predictions based on the analytical model are verified by experiment. Results show that plowing mechanism contributes more to the total damping effect than the shearing mechanism, and magnitude-plowing effect has by far the greatest influence on total damping.Copyright © 2005 by ASME

Paperboard die cutting, which includes creasing, is a production technique widely spread in many fields such as foods, stationery packaging. For the improvement of productivity or the improvement of quality on die cutting, the estimation of endurance on die tools and the estimation of material properties on paperboard are required. Creasing is one of most important mechanical behavior for paperboard die cutting. This paper reports on a fundamental deformation behavior and fracture modes as delamination patterns of coated paperboard creased. The creasing characteristics were investigated by varying the crease depth and the lateral deviation of rule clearance. By reviewing the bending moment resistance and by observing the delamination process of creased part under a folding test, the variance of bending moment characteristics of creased part was discussed. Furthermore, by adding the lateral deviation of rule clearance, the correlation between the moving direction of the folding point and the non-symmetrically delaminated zones was also investigated.

This paper describes the possibility of sensing for machining, using the sound that occurs under paperboard die cutting, which is commonly used for making various paper packages. Among the actual production lines, it is important to estimate the wear of die tools. And any kind of automatic technique for detecting cutting condition is required for increasing productivity and reducing operator's task. In this study, the sound radiated in the cutting process was measured by varying several machining conditions on the test machine, and analyzed. The following results were obtained: The sound seems to be caused by impulsive strike between a blade tip and a counter plate; The repeatability of sound waveform is very good in the same machining condition; Obvious feature is not revealed in the sound spectrum for distinguishing each condition; On the other hand, a sound pressure level (SPL) denotes obvious difference among each condition; The radiated sound energy is almost in proportion to the elastic energy stored in the machine just before completion of cutting. Hence, the SPL would become a good index to denote the wear of blade tip, the occurrence of harmful thread dross, etc.

Progressive microforming is an attractive option for manufacturing high aspect-ratio micro-parts out of sheet metal. It is a highly economical alternative to both MEMS processing and micro-machining due to the ability to produce near-net shape parts through parallel forming processes. Current limitations in the field include precise alignment of microforming tools and an understanding of forces encountered when scaling down traditional forming processes. A five stage micro-progressive aluminum die set consisting of four shearing stages and one bending stage was fabricated by micro-machining. The die set was designed to produce right angle micro-brackets from 25 um thick annealed copper foil, with a measured average grain size of 47 um. Die clearances were set at 3 um along shearing edges and 38 um along the bending edge, corresponding to 12% and 152% material thickness, respectively. The produced micro-brackets are intended to be used as electrical connectors and consist of a nominally 280 um by 260 um tab extending vertically from a 780 um by 260 um base. In order to implement and investigate the progressive microforming process, a novel micro-press system was constructed which allows for precision alignment of the die set and workpiece. Using a prepared workpiece, forces at the first stage of the die set were measured and compared to analytical predictions based on models from the literature.

Offshore monopiles are usually designed using the p-y method for cyclic loading. While the method works for static loading, it was not developed for high numbers of cycles. Since the turbines are highly sensitive towards tilting, cyclic loading must be considered. The static results should therefore be combined with results from cyclic model tests with a high number of cycles to account for the accumulation of displacement or rotation during the lifetime of these structures. These model tests can underestimate the accumulation, however, as it has recently been shown that a change of loading direction can increase the accumulation considerably. These results have been verified using small scale modeling and centrifuge testing. The results from modeling the full problem of a laterally loaded pile are compared here with results from cyclic simple shear tests with a change of shearing direction during the cyclic loading. For these tests, a newly developed apparatus is used. This allows further insight into the question how a soil can “retain a memory” of its loading history.Copyright © 2014 by ASME

The cold-forging process analysed in this paper deals with the production of a hexagonal shape on the head of a bolt. The process utilises a die known as a “Standard Trim Die” which is forced at velocity onto the workpiece to form the bolt head. This process is a combination of cutting and forging. By definition, a cold-forging operation occurs at a temperature below the recrystallisation range of the metal being forged. Due to this fact very high forging loads are required, which in turn cause very high stresses within the die material. These high stresses can cause die failure due to overloading or fatigue. The main focus of this analysis was to predict the level of these stresses during the forging operation, and if possible to find the optimum operating conditions which would increase tool life. The analysis consisted of creating a range of different trim die geometry’s using AutoCAD/mechanical desktop and importing them into the finite-element analysis (FEA) package DEFORM. Due to geometrical considerations and computational limitations the initial tests consisted of two-dimensional (2D) models. Extensive analysis of these results enabled a more accurate simulation of the forging operation using three-dimensional (3D) models. Full elasto-plastic FEA, including contact and friction, was performed in order to produce the most realistic results possible for the stress distribution within both the tooling and workpiece. The FEA analysis indicated that the highest stress concentration occurred within the body of the tool and not along the contact surfaces as might first be expected. Results showing the variation in tool stress as a function of changes to the trim die cutting edge corner geometry are also presented. From these results it was possible to predict the corner fillet radii required to give the optimum geometry and hence produce the lowest stress concentration within the trim die.

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.

This work examines the traditional and advanced trimming of AA6111-T4 aluminum sheets with finite element simulations. The Rice-Tracy damage model is used for the simulation with damage parameters estimated from experimental observation of grain aspect ratio near the fracture surface of trimmed parts. Fine meshes at the shearing zone, adaptive meshing, and adaptive contact techniques are used to accurately capture the contact interactions between the sharp corner of the trimming tools and the blank to be trimmed. To the knowledge of the authors, these are the first trimming simulations that can predict the effects of shearing clearance on burr heights with quantitative accuracy for AA6111-T4 aluminum sheets. In addition, the models have also accurately reproduced the crack initiation site as well as burr and sliver formation mechanisms observed experimentally.

An analytical expression is derived for determining the maximum solder joint shearing displacement occurring in an a real-array interconnect under global CTE mismatch loading. The result may be viewed as a “load correction factor” to be applied to the commonly used estimate which is based on the free thermal expansion of component and substrate. The new expression for the correction factor includes the following parameters: (a) dimensions and material properties of component and substrate; (b) array size and population; (c) material properties of solder; and (d) geometric parameters of the individual joints. The theoretical result is based on modeling the assembly as two circular elastic disks connected by a shear-type “elastic foundation” whose distributed shear stiffness is related to the joint/array characteristics. The analytical expression and the graphical aids presented herein may provide convenient alternatives to performing time-consuming and expensive finite element “macro-analyses” on the assembly for the purpose of specifying boundary conditions for a subsequent “micro-analysis” on a single joint.

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.Copyright © 2013 by ASME

The Omni-Max anchor is a new type of dynamically installed anchor featuring a mooring arm located close to the anchor tip that is free to rotate about the anchor length. An experimental programme has been undertaken on a geotechnical centrifuge to assess the anchor performance in calcareous silt. The testing programme includes (i) anchor drops and measurement of the penetration depth, and (ii) anchor pull and assessment of the anchor trajectory. An anchor embedment model based on strain rate enhanced shearing resistance is capable of satisfactorily predicting anchor embedment using model parameters that are similar to those used for clay. The diving behaviour of the anchor, post keying, is demonstrated, provided that the initial embedment after impact is deep enough to prevent a shallow mechanism to develop during anchor keying.

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.

A beveled shear hole piercing process has recently been developed for advanced high strength steel (AHSS). The preliminary results have shown the new process is able to improve the quality of the sheared edge and the edge stretchability of AHSS. The goal of the current study is to optimize the beveled shearing process and identify the optimal shearing conditions for AHSS. Four different advanced high strength steels, including DP600, DP780, TRIP780, and DP980 with various thicknesses together with a conventional high strength steel, HSLA50, are selected in this study. The hole expansion test is used to evaluate the effect of shear edge conditions on the edge stretchability. The results show that an optimal selection of the die clearance and the shearing angle results in a less damaged edge, which significantly delays edge fracture in the forming process and increases the edge stretchability for AHSS. To further validate the advantages of the beveled shearing process in improving the shear edge quality of AHSS, a straight edge shearing device with the capability of adjusting the shearing variables (rake angles and die clearance) with respect to different sheet thicknesses was also developed and built. The edge stretchability of the straight edge sheared specimen was then evaluated using the sheared edge tension test. A similar trend to the beveled shear hole piercing process of AHSS is observed, and a significant improvement in the edge stretchability is also obtained with optimal shearing conditions.

When two thin plates or layers are bonded together, an extremely thin bond layer of third material exists between the two layers. This research work examines the effect of bond layer on the interfacial shearing and peeling stresses in a bimaterial model. Earlier papers on this topic are based on several mutually contradictory expressions for the shear compliance of the bond layer. This paper is aimed at resolving this ambiguity and presents derivation of shear compliance on a rational basis. A numerical example is carried out for a silicon-copper system with a gold-tin solder bond layer. The results obtained are likely to be useful in interfacial stress evaluation and physical design of bimaterial assemblies used in microelectronics and photonics applications.

A method for the determination of load sharing among the instantaneously engaged worm threads and gear teeth of double enveloping worm gears and for the calculation of load distribution along their instantaneous contact lines is presented. The bending and shearing deflection of worm thread and gear tooth, the contact deformation, the axial deformation of worm body, and the manufacturing and alignment errors of worm and gear are included. The obtained system of integral equations is solved by using approximations and an iterative technique. The corresponding computer program is developed. By using this program, the load distribution in the classical and in a new type of double enveloping worm gear drives is calculated. The influence of design parameters on load distribution factor and on maximum tooth pressure is investigated and 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

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

Modules attached to circuit cards by peripheral J- and gullwing leads were studied for their behavior under flexure. Three aspects of mechanical behavior were focused upon: the stiffness of the system, the forces arising in the leads, and the fatigue strength of the latter. The effective stiffness of a module-reinforced circuit card was measured experimentally in several configurations (load on card and load-on-module, double-sided and stacked). The leaded attachments were in two parallel rows. Analytical modeling of these tests were performed considering the leads as a continuous elastic foundation connecting the module and the card; test results were corroborated. Experiments were also conducted to establish the elastic and elastoplastic range of lead stiffness in three perpendicular directions: in two shearing planes and axially. The latter was the stiffest and most significant direction, motivating much of the present analysis. For lead force, the analytical procedure yielded values which were confirmed by finite element computation methods described previously by Engel (1990). Fatigue tests were performed on both J- and gullwing leads. Solder joints failed in the former, while lead failures occurred in the latter.

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

A simple modification of a standard laboratory saw and the work bench surface enhances the saw's overall usefulness for sectioning casts. When using these modifications, the operator has a clear view of the preparation margin and the saw blade at all times, thereby permiting accurate, controlled cuts to be made from the underside of a removable pinned die section.

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

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

Vertical liquid-filled cylindrical shells which are subjected to horizontal seismic loads can fail by buckling in shear. One example where this might arise in the nuclear industry is with the primary vessel in a fast breeder reactor (LMFBR) and design criteria are, therefore, needed to prevent its occurrence. In the present paper, the static analogue of the foregoing problem is considered and experimental results on the plastic buckling of short, steel cantilevered cylindrical shells subjected to transverse edge shearing loads are presented. In addition, a simple quadratic equation is suggested for predicting the plastic shear buckling loads. The agreement between the experimental shear loads at the inception of buckling and the predictions of the proposed design equation is excellent for the limited range of geometries investigated.

The crack propagation that occurs in corrugated board in connection with die cutting is analysed in order to identify the most crucial liner and fluting parameters and clarify their relative importance. Based on an energy approach and the brittleness concept — Lc-1(m-1) — for the liner, a formula is derived. This formula is then verified exeprimentally for a large number of corrugated board qualities of different thicknesses and flat crush strengths as well as for liners with widely differing mechanical properties. The correlation can be regarded as very good. The analysis shows that crack propagation is dependent on three material parameters —the brittleness of the liner, the compression strength of the fluting in relation to the tensile strength of the liner and the breaking strain of the liner. It is shown that crack propagation increases proportionally with increasing liner brittleness, provided that the other material parameters remain unchanged. The compression strength of the fluting layer contributes somewhat more than proportionally — by a power of 1.33. The crack propagation decreases with increased breaking strain, the relation is almost inversely proportional. In practice, none of the above mentioned liner parameters car. be chosen independently of the others. The same applies to the fluting parameters. When estimating the expected crack propagation in a particular corrugated board quality, it is necessary to consider the contribution from all the mentioned parameters according to the formula.