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Micro-cutting edges are often used for the die cutting of functional films and paper containers. A hardening process is needed here because the ridgelines of micro-cutting edges require not only we...

Fast machining is essential for mass production of composite structures, and out-of-plane shearing, also known as die cutting, is appropriate for trimming. Nevertheless, little is known about shearing of polymer-matrix composites. This study was done to investigate the damaging impact of shearing conditions on carbon fiber reinforced plastic (CFRP) laminates. The clearance and temperature affected the damage progress, while the cutting speed in the tested range had negligible effect. In cross-ply laminates, delamination and matrix cracks first appeared in a narrow shearing zone, and with further loading longitudinal plies broke at the dies’ edges. Although delamination occurred only in a narrow shear-stress concentrated zone in the case of a small clearance, it was significant for a large clearance, owing to the local bending deformation. A temperature slightly lower than the glass transition temperature narrowed the delamination area, owing to the increase in the interlaminar fracture toughness as well as insignificant strength degradation of the matrix.

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.

To form the required shapes from advanced high strength steels sheets, such as dual-phase (DP) steel, shearing processes are commonly used. In general, although good cut-edge characteristics can be often achieved by setting a small shearing clearance, a scar still remains a major defect on the cut-edge. Therefore, in the present study, the mechanism of scar formation of a DP steel sheet, grade SPFC980Y (JIS) subject to a shearing process was investigated and clarified based on the microstructural evolution, fracture mechanism, and a stress distribution analysis. The microstructural evolution in both tensile test specimens and sheared workpieces were observed to identify the fracture mechanism. The angle between the shear band and the elongated grain flow direction during tensile testing was examined and used to predict the angle of initial fracture and its propagation during the shearing process. With the stress distribution analysis of the shearing zone during the shearing process, the fracture could not propagate into the shearing zone and be directed to the die tip, resulting in the formation of a smooth region again. This feature occurred as a cyclic loop as the punch stroke proceeds and resulted in scar defects in the case of SPFC980Y. However, when the fracture propagation remained in the shearing zone, the fracture was not delayed and fracture was completely generated on the cut-edge in the case of a baseline SPCC steel.

Polytetrafluoroethylene (PTFE) has been studied as a low friction surface coating since its discovery. The high wear-rate of PTFE reduces the usefulness of the polymer for mechanical purposes; however, combining PTFE with polydopamine (PDA) has been shown to greatly reduce the film wear-rate. During rubbing tests involving PDA/PTFE thin films, a tenacious layer of PTFE remains intact after substantial testing even though pure PTFE film layers are destroyed quickly. Understanding the interface mechanics that allow PTFE and PDA to adhere so well during experimental rubbing tests is necessary to improve the wear-rate of PDA/PTFE thin films. In this study, we use density functional theory (DFT) and molecular dynamics (MD) simulations to investigate the adhesive properties and interface deformation mechanisms between PDA and PTFE molecules. Steered molecular dynamics (SMD) is then performed on isolated pairs of PDA and PTFE molecules to investigate different modes of deformation from equilibrium. PDA trimer oligomers were identified as the most adhesive to PTFE and selected to use in a PDA/PTFE thin film, where nano-indentation and scratch tests are performed. Our results indicate that a combination of the unique deformation mechanisms of PDA molecules and the penetration of PTFE molecules into the PDA substrate provide the PTFE/PDA interface with its wear resistance.

The aggregation behavior and the subsequent deposition behavior of wax crystals own undesirable effects on the production and transportation of waxy crude oil. The understanding and prediction of these behaviors are essential to ensure economic and uninterrupted flow of waxy crude oil when the oil temperature decreases below the wax appearance temperature (WAT). In this paper, a novel method of fractal dimensional analysis was introduced to elucidate the aggregation behavior of wax crystals in different shear flow fields. The fractal methodology for characterizing wax crystal aggregation was then developed, and a blanket algorithm was introduced to compute the fractal dimension of the aggregated wax crystals. Considering the flow characteristics of waxy crude oil in a pipeline can be correlated with the shearing stress work, a modified wax deposition model focusing on shearing energy analysis was established. The results indicate that a quantitative interpretation of the wax crystal aggregation behavior can be realized using the fractal methodology. The aggregation behavior of the wax crystals is closely related to the temperature and shearing experienced by the waxy crude oil. The aggregation behavior will be intensified with decreasing temperature and shearing effect, and a wider fractal dimension distribution appears at lower temperatures when the same shear rate range is used. Furthermore, the improved model provides a method for discussing the effects of the operating conditions on wax deposition. The average relative deviation between the improved model prediction results and experimental results from the literature is 3.01–5.32%.

Anisotropic textiles are commonly used in wearable applications to achieve varied bi-axial stress-strain behavior around the body. Auxetic textiles, specifically those that exhibit a negative Poisson’s ratio (v), likewise exhibit intriguing behavior such as volume increase in response to impact or variable air permeability. Active textiles are traditional textile structures that integrate smart materials, such as shape memory alloys, shape memory polymers, or carbon nanotubes, to enable spatial actuation behavior, such as contraction for on-body compression or corrugation for haptic feedback. This research is a first experimental investigation into active auxetic and shearing textile structures. These textile structures leverage the bending- and torsional-deformations of the fibers/filaments within traditional textile structures as well as the shape memory effect of shape memory alloys to achieve novel, spatial performance. Five textile structures were fabricated from shape memory alloy wire deformed into needle lace and weft knit textile structures. All active structures exhibited anisotropic behavior and four of the five structures exhibited auxetic behavior upon free recovery, contracting in both x- and y-axes upon actuation (v = −0.3 to −1.5). One structure exhibited novel shearing behavior, with a mean free angle recovery of 7°. Temperature-controlled biaxial tensile testing was conducted to experimentally investigate actuation behavior and anisotropy of the designed structures. The presented design and performance of these active auxetic, anisotropic, and shearing textiles inspire new capabilities for applications, such as smart wearables, soft robotics, reconfigurable aerospace structures, and medical devices.

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 tool life becomes one of the critical manufacturing issues in the metal forming process of advanced high-strength steel as the material strength continually increasing. In this paper, an evaluation method on trim die chipping damage was developed. This method is based on the measurement of chipped volume, which is achieved from the area measurement on two chipped die surfaces on front and top views, to construct a missing metal triangle, which is further integrated along the die cutting edge line to obtain the loss metal volume. 18 dies made of three different materials (Caldie, AISI D2, and Vanadis 4) and six trim uphill angles were received and measured with the known total trimming cycles (hits). The measurement was achieved with two methods using two combinations of camera view directions. The die materials and trim uphill angle effect on the die performance (chipping resistance) were obtained based on average chipping rate, defined as the loss metal volume per hit. For AISI D2 dies, wide scattering of the chipping rates was seen. And it was identified that the unfavorable carbide/grain orientation relative to the trim die cutting edge line is responsible to the obtained unusual low cycle to failure. Furthermore, a simple in-line real-time die damage monitoring and measurement system is proposed, and the favorable die machining orientation relative to the rolling coordinate is suggested.

Journal bearings of high torque diesel engines are used to cater for high combustion loads which are applied intermittently. A lubrication layer is provided between journal (crankshaft) and bearing to avoid contact between them. The relative velocity between crankshaft and journal bearing results in viscous shear heating among the different layers of lubricating oil. The shear heating reduces the viscosity of the lubricant that ultimately reduces the load carrying ability of the journal bearing. It offers a physical contact and reduces the designed life of crankshaft. In this study the 2-D transient numerical lubrication model is developed by employing the Reynolds equation to calculate the pressure and film thickness profiles as a function of crankshaft speed. The shear heating effects are determined by coupling the energy equation with lubrication model. The finite difference method is used and an appropriate numerical scheme is employed to simulate the conduction and convection based thermal energy transfer in transient and steady state journal bearing lubrication model. The lateral displacement of crankshaft is incorporated in the thermal model to analyze the effect of secondary dynamics of crankshaft. The viscosity and temperature relationship are used to ascertain its variation with temperature. The characteristic of three different viscosity-grade lubricates are incorporated separately in the model to carry out the comprehensive comparative analysis. The results are simulated for particular application where low operating speed and length to width ratio of journal bearing is fixed and analyzed the results for complete 720 degrees of crankshaft in its two revolutions. The results show that the oil with high viscosity produces high hydrodynamic pressures as compared to the oil that have low viscosity. The viscous shearing temperature reduces the hydrodynamic pressures but still the high viscosity lubricating oil have enough pressures to uplift the shaft after incorporating the shear heating effects. This study determines the hydrodynamic pressure, and variation of density, viscosity and thermal-conductivity with temperature for three different lubricating oils. These analyses will facilities towards the selection of appropriate lubricant for high torque low speed diesel engine in order to enhance the life of crankshaft.

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.

Die-cutting tools have been widely applied in industrial production. However, different forms of failure on a blade, such as wear and fracture, can greatly reduce its service life. In this research, the die-cutting tool was selected as the object, a mixture of high speed steel powder and 304 stainless steel powder was coated as a gradient cladding layer onto the surface of AISI/SAE 1045 steel by laser cladding. The central composition design of the response surface methodology was adopted to establish a mathematical model between the pore area of the multi-layer, multi-track cladding, and its processing parameters: Laser Power (LP), Scanning Speed (SS), Gas Flow (GF), and Overlapping Rate (OR). This model was validated by variance analysis and inspection indicators. The actual experiment value by processing parameters optimization for achieving the smallest pore area showed a 4.41% error compared with the predicted value. The internal structure of the cladding layer is uniform. The defects, such as pores and cracks, meet the requirements. The wear resistance on the cutting edge is about 4.5 times compared with the substrate. The results provide a theoretical guidance for the controlling and prediction of the laser cladding forming quality on a two-dimensional gradient material and the optimization of the processing parameters.

During the micromachining processes of particle-reinforced metal matrix composites (PMMCs), matrix-particle interface failure plays an important role in the cutting mechanism. This paper presents a novel analytical model to predict the cutting forces in micromilling of this material considering particle debonding caused by interface failure. The particle debonding is observed not only in the processed surface but also in the chip. A new algorithm is proposed to estimate the particles debonding force caused by interface failure with the aid of Nardin–Schultz model. Then, several aspects of the cutting force generation mechanism are considered in this paper, including particles debonding force in the shear zone and build-up region, particles cracking force in the build-up region, shearing and ploughing forces of metal matrix, and varying sliding friction coefficients due to the reinforced particles in the chip-tool interface. The micro-slot milling experiments are carried out on a self-made three-axis high-precision machine tool, and the comparison between the predicted cutting forces and measured values shows that the proposed model can provide accurate prediction. Finally, the effects of interface failure, reinforced particles, and tool edge radius on cutting forces are investigated by the proposed model and some conclusions are given as follows: the particles debonding force caused by interface failure is significant and takes averagely about 23% of the cutting forces under the given cutting conditions; reinforced particles and edge radius can greatly affect the micromilling process of PMMCs.

This paper proposes a new approach that combines the cutting processes for extruding a billet. A trough is laid on the die, and the ram module is used to press the billet before extrusion. The diameter of the punch does not need to be equal to that of the die. It can have two situations: negative clearance (extrusion) and zero as well as positive clearances (blanking). In this approach, a cutting process is combined with a high hydrostatic stress produced from the trough on the die cutting edge, and this can substantially eliminate fracture in the shear zone. A series of experimental tests for forming the shapes of a cylinder and spur and cycloid gears were performed. The results indicate that this approach can extrude a billet with an excellent burnished surface. The test ranges of the surface roughness for the burnished surface were 0.03–0.12 μm, and the tolerance band for the diameter ranged from IT3 to IT6. This new approach provides the precise sizes higher than those obtained using conventional extrusion.

To convert a corrugated fiberboard (Cfb) into a couple of unfolded formed-cut sheets for making a container box, since the raw Cfb is cut off by using a combination of center-bevelled (wedge) blade and its counter faceplate, the cutting edge of blade dynamically and repeatedly collides on the faceplate. Therefore, the edge profile of blade and the contact zone of faceplate plastically deform and abrasively removed with respect to the repeated cutting times. When the cutting times of raw Cfb increase and reach a certain number, the occurrence probability of string-like dust empirically increases due to the variation of edge profile of blade and dent of faceplate. When such the string-like dusts become larger and adhere to the product object, they become foreign matter. Therefore, in order to reduce the occurrence of string-like dusts, any countermeasures are required. Nagasawa et al. (J Jpn Soc Technol Plast (SOSEI-TO-KAKOU) 43(498):624–628, 2002, [3]) had reported about the effects of blade tip thickness on string-like dust occurrence in the case of white-coated paperboard of basis weight 350 (a thickness of 0.45 mm) and the correlation between room humidity and dust occurrence probability. However, any generation mechanism of string-like dusts and its applicability of occurrence estimation to a Cfb are not sufficiently discussed in the past. When the Cfb is subjected to a pressure cutting of flatbed die cutter, a stacked collection of three raw fiber sheets, upper liner, medium, and lower liner sheets, is fasten and cut off by a wedge indentation. These raw sheets have a thickness of 0.18–0.22 mm, which is relatively thinner than that of widely known white-coated paper of 0.45 mm, and these three raw sheets have different mechanical properties for each layer. Synthetically, the occurrence probability of string-like dusts in the Cfb cutting appears to be partially different from that of the white-coated paperboard. The authors experimentally investigated the relationship between the blade tip thickness and geometrical features of string-like dusts and the corresponded cutting load responses, in order to reveal the mechanical condition for causing the string-like dusts.

Components of forming tool dies such as draw ring, ejector pin use AISI 4140 as material for their manufacturing. The integrity of the die cutting tools is essential to achieve adequate product quality. In present study, the influence of plasma nitriding (PN) on the wear behav-iour of AISI 4140 steel was investigated. Full factorial experimental design technique was used to study the main effects and the interaction effects between operational parameters and the response variable. The control factors at their two levels (-1 and +1) were: applied load (4.905N and 14.715N), sliding speed (3.14 m/s and 5.23 m/s), and sliding distance (500m and 1000m).The parameters were coded as A, B, and C, consecutively, and were investigated at two levels (-1 and +1). Response selected was Wear Volume Loss (WVL). The effects of in-dividual variables and their interaction effects for dependent variables, namely, WVL were determined. The process of selecting significant factors, based on statistical tools, is illustrat-ed. Analysis of Variance (ANOVA) was performed to know the impact of individual factors on the WVL. Untreated and PN treated AISI 4140 specimens were investigated using field emission Scanning Electron Microscope (SEM) equipped with Energy Dispersive X-ray (EDX) analyzer. Finally diagnostics tools were used to check adequacy of the model in terms of assumptions of ANOVA. ‘Design Expert-7’ and ‘Minitab 17’ softwares were used in the study. Results of statistical analysis indicate that the most effective parameters in the WVL were load and sliding speed. The interaction between load and sliding speed was the most influencing interaction. Results of regression analysis indicate regression coefficient (R2) to be above 90% which suggests good predictability of the model. ‘Predicted-R2’ and ‘Adjusted-R2’, found to be in good agreement with R2, for both the materials under investigation. More-over, results of SEM microscopy suggest PN to be an effective technique to reduce wear.

Electromagnetic perforation is a method of producing holes in a workpiece based on electromagnetic effect. It overcomes the disadvantages of conventional shearing processes like, the formation of burrs and slivers. Electromagnetic manufacturing is one of the well-known technologies for forming aluminium alloys. In this study, a novel approach for modelling the electromagnetic punch-less perforation has been used to study the shearing mechanism, optimum energy, and pressure required for the perforation. The complete FE analysis is conducted in two steps. Firstly, a coupled simulation model is developed in LS-DYNA software for the calculation of transient magnetic pressure generated in the process. This pressure causes the expansion of the tube, resulting in crack initiation near the die cutting edge and subsequent perforation of the tube. In the second step, to study the detailed shearing mechanism involved during the EM perforation process, obtained transient pressure is used for 2D FE analysis in Abaqus/explicit.

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.

The runnability and convertibility of biopolymer dispersion–coated paperboard were determined using a novel adjustable packaging line equipped with a tray-pressing mould. Commercial paperboard was dispersion barrier coated on the back-side using a dual polymer system containing both a synthetic and a renewable biopolymer, of which the latter was the main component in the dispersion. The effect of the addition of a high-aspect-ratio platy pigment and synthetic polymer on both the grease resistance and the convertibility of the product was evaluated in addition to the evaluation of runnability and crack resistance in tray pressing and die cutting. The addition of synthetic polymer into bio-based dispersion improved the elastic properties, plasticity and, subsequently, mechanical convertibility of the product. Moderate additions of the synthetic polymer provided improved grease resistance for the biopolymer coatings. It revealed that the addition of synthetic polymer was sufficient in providing improved barrier properties, although the chemical compatibility and process window for the convertibility need to be considered. In addition to mechanical stability, the heat stability of the substrate needs to be investigated. Copyright © 2013 John Wiley & Sons, Ltd.

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.

Investigated the technological process of cutting of printed sheets. For the evaluation of the products were established indicators of quality such as cleanliness, roughness, waviness of the edges, the accuracy of the geometric dimensions and the absence of skew in length and width, the magnitude of asperities of slices. For an objective assessment of these indicators, the proposed corresponding method. From the obtained research results we can see that the quality of cut is affected by the direction of the fibers and the thickness of the material, namely, it can be noted that when cutting in the longitudinal direction of the fibers in the cut quality is much higher.As a result of researches it is established that the most important factors that affect the quality of die cutting are: the geometrical parameters cutting knife (sharpening angle and shape of knife-edge); the thickness of the material that is processed; the pressure of die cutting; square die; the total length of the cutting and creasing knives; the duration of the cutting tool.The result of experimental studies it was determined that the cutting pressure is in direct proportion to the die area and the total length of the cutting and creasing knives. Consequently, the influence of the area of the cutting die and the total length of the die-cutting and blanking knives on the value of the applied pressure, leads to an increase in the cutting pressure with an increase in the area of die-cutting plates. Increasing the perimeter of die-cutting and blanking knives also requires increased cutting pressure.The results of research have shown that the quality of the die-cut is influenced by the direction of the fibers. It is also established a general tendency to improve the quality of the cut when die-cutting in the longitudinal direction of the fibers.

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.

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.

Asymmetric plunge cutting by using grooved knife edge plate was proposed for advanced die cutting of a polycarbonate (PC) sheet. By varying the tip angle U and the tip thickness wU 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 investigated and also that deformation was observed by a CCD camera. Through this works, the followings were found: 1) there were two deformation modes of sheared profile. 2) The tip thickness wU was a primary factor, compared to the tip angle of U. 3) The equivalent wedge angle effect was revealed with respect to the upper/lower angles  and U, while the PC sheet was bent up by the lower knife indentation.

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.

The corrugated carton as a common packaging tool is usually produced in production line including feeding unit of corrugated boards, printing unit, slotting unit, die cutting unit, and gluing unit. Among them, the die cutting unit is a very important device in this line, which has a large influence on the accuracy of cutting position. So it is crucial to design the structure of die cutting unit. First, both main structure and motion of rotary die cutting unit are analyzed. It is explained that die cutting unit is mainly composed of two rollers, rubber roller and die roller. Both the rollers rotate synchronously. In order to promote the cutting quality, adjustments of rubber roller and die roller are necessary, such as roller position, rotating speed, so adjusting structure in detail and its principle of die cutting unit are illustrated in this paper.

Research has shown that the interfacial shear strength in an asperity contact is generally a linear function of the asperity pressure with a maximum value below the shear strength of the substrate material. Research further suggests that the properties of the surface-film materials in the micro-contact largely govern the shear-strength-pressure relation and the maximum attainable interfacial shear strength. This paper studies the effect of boundary films on the frictional behavior of rough-surface contacts in incipient sliding. Two parameters are used to describe the shearing properties of the boundary film. One is the shear-strength-pressure proportionality constant and the other, the ratio of the maximum interfacial shear strength to the substrate shear strength. The study uses an asperity-based mathematical model for frictional sliding-contact of nominally flat elastic-plastic rough surfaces incorporating the above interfacial shearing properties in the asperity contacts. A sequence of parametric studies is carried out to study the frictional behavior of the contact system. The parameters include surface plasticity index, contact load, and boundary film properties. More details of the results along with literature studies and references are presented in a full paper [1].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.

Electrically-driven rapid vaporization of thin conductors produces a high-pressure pulse which can be used to accelerate thin metal sheets to high velocities. Recently, vaporizing foil actuators (VFA) have been applied toward a variety of impulse-based metalworking operations such as collision welding, closed-die forming, embossing, and shearing. To better apply VFA to different purposes, it is necessary to develop an understanding of how variations in the characteristics of the foil actuator affect its mechanical impulse generation. In this work, actuators made out of 0.0508, 0.0762, and 0.127 mm thick full hard temper AA1145 foil were used to launch 0.508 mm thick AA2024-T3 sheets toward a photonic Doppler velocimeter (PDV) probe. Launch velocities ranging between 300 and 1000 m/s were observed over a distance of less than 3 mm, and repeated trials demonstrated repeatable results. Velocity, current and voltage traces were used to examine the effect of deposited energy on average pressure and resulting velocity for foil actuators of various thicknesses. Experiments with annealed foil actuators showed that foil temper had no effect on the evolution of flyer velocity for the given electrical energy input of 8 kJ.Copyright © 2014 by ASME

Cropping is a cutting process whereby opposing aligned blades create a shearing failure by exerting opposing forces normal to the surfaces of a metal sheet or plate. Building on recent efforts to quantify cropping, this paper formulates a plane strain elastic–plastic model of a plate subject to shearing action by opposing rigid platens. Shear failure at the local level is modeled by a cohesive zone characterized by the peak shear traction and the energy dissipated by shear failure process at the microscopic level. The model reveals the interplay between shear cracking and the extensive plastic shearing accompanying the cutting process. Specifically, it provides insight into the influence of the material’s microscopic shear strength and toughness on the total work of cropping. The computational model does not account for deformation of the cropping tool, friction between sliding surfaces, and material temperature and rate dependence.

The influence of harmonic normal loads on sliding friction is investigated through analysis of contacts consisting of conical and spherical sliders of hard materials on softer metal surfaces. Friction for such contacts is assumed to result from a plowing component and a shearing component. Calculations and experiments show that the coefficient of friction is essentially independent of normal load for contacts with conical sliders. However, for spherical sliders the relation between the coefficient of friction and normal load is highly nonlinear. In the presence of harmonic variations in normal load, this non-linearity causes a shift in the average coefficient of friction. For ideal lubricated contacts, the shearing component of friction is very small and for this case, it is shown that the maximum average reduction in the coefficient of friction is ten percent. When the shearing component is more significant, as with dry contacts, the shift is less. For example, when the shear strength is one-sixth the hardness of the softer material, the maximum average reduction in the coefficient of friction is five percent.

Temperature-distribution measurements in cutting tools during the machining process are extremely difficult and remain an unresolved problem. In this paper, cutting temperature distributions were measured by thin film thermocouples (TFTCs) embedded into polycrystalline cubic boron nitride (PCBN) cutting inserts in the immediate vicinity of the tool-chip interface. The embedded TFTC array provides temperature measurements with a degree of spatial resolution (100 μm) and dynamic response (150 ns) that is not possible with currently employed methods due to the micro-scale junction size of the TFTCs. Using these measurements during hard turning, steady-state, dynamic, as well as chip morphology and formation process analyses were performed based on the cutting temperature and cutting force variations in the cutting zone. It has been shown that the temperature changes in the cutting zone depend on the shearing band location in the chip and the thermal transfer rate from the heat generation zone to the cutting tool. Furthermore, it became evident that the material flow stress and the shearing bands greatly affect not only the chip formation morphology but also the cutting temperature field distributions in the cutting zone of the cutting insert.

Nanometer-thick liquid lubricant films are useful for the lubrication of miniaturized mechanical systems, such as hard disk drives or microelectromechanical systems. However, there are no established methods for measuring the mechanical properties of such thin films, which can be an obstacle to the optimal design of lubrication systems. We previously developed a highly sensitive method for measuring shear forces, which we called the fiber-wobbling method (FWM). In the FWM, we used a ball-ended optical fiber to probe shear and we measured the friction force acting on the probe tip by detecting the deflection of the fiber. By this means we succeeded in measuring friction forces in nanometer-thick liquid lubricant films. However, we could not evaluate the mechanical properties of the films quantitatively because the contact area between the probe tip and lubricant film was unknown. Here, we developed a method for measuring the contact area during shearing of nanometer-thick liquid lubricant films in the FWM.Copyright © 2012 by ASME

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.

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.

The antiplane strain problem of a unidirectional fiber composite consisting of a doubly periodic rectangular array of fibers containing interfacial cracks in an infinite matrix is considered. The interfacial cracks are assumed to exhibit the same periodicity as the fibers. The periodicity of the geometry allows the use of a unit cell in the formulation of the problem. The governing weakly singular integral equation of the mixed boundary value problem permits an explicit solution which contains a set of unknown constants. The unknown constants are then determined by satisfying the boundary conditions on the external surfaces of the unit cell through the method of least squares. The stress intensity factor is calculated for various crack lengths, fiber volume fractions, and fiber spacings. Unlike the plane strain or plane stress deformation, the oscillations in stress and displacement around the interface crack tip are absent in the current antiplane strain problem.

This paper describes a study of the process of deposition of RTV dispersion on electronic components placed on substrates. The objective was to develop a technique for the consistent manufacture of encapsulant coating of a desired thickness and extent. In addition, it was desired to obtain an understanding of the phenomenon of run-over, or wicking, of the RTV dispersion onto external leads of circuits being encapsulated, and of means to control it. In this paper physical properties of the RTV dispersion which influence the deposition process were determined using a novel drop test method. These properties allow building of a physical model of the deposition process, and its analysis. The results of drop tests show that the RTV dispersion behaves like a plastic “false body” material which possesses yield stress after a long rest, and which retains residual yield stress after shearing. Part I of this paper is concerned with building of the physical model of the encapsulant deposition process. It also deals with the derivation of an equation relating the wall shear stress to the encapsulant volumetric flow rate.

In this part of the paper the drop test method is used to show that RTV dispersions are in fact plastic “false body” materials, and to determine the magnitudes of the residual yield stresses after shearing for different RTV dispersion lots. With the aid of the equation for the wall shear stress derived in Part I of this paper [1], a correlation equation between the residual yield stress and the deposition variables is obtained, and analysis is made of the drop spreading phenomenon. It is shown that the drop spread, which is responsible for the run-over, or wicking, of external leads of electronic circuits, can be decreased by decreasing the deposition rate of the encapsulant. Finally, a method is developed to determine the required deposition flow rate and deposition time to produce a drop having required final diameter and cured skin thickness.

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

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 friction of a sliding tactile contact was measured in an apparatus which simulated a keyboard. Results were taken for several materials. The friction coefficient was found to decrease with increasing load and with increasing speed. Experiments at varying humidity and surface roughness helped to define the friction mechanisms. It is concluded that tactile friction is predominantly adhesive, but modified by liquid bridging between the ridges of the skin and the counterface. Increased bridging due to higher humidity causes increased friction from viscous shearing effects, while increased roughness allows fewer bridges to form, decreasing the friction.

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

Piercing of brittle sheets, which is difficult to achieve by conventional shearing or drilling, is achieved using a new manufacturing process utilizing the impact compression of a viscoplastic pressure medium, recently proposed by the authors. The impact pressure is analyzed with a linear viscoelastic model to determine optimum working conditions. Under a specific condition the process is shown to be successful in piercing a circular hole through various brittle materials; for example, inorganic glasses, glassy-carbon carbon composite and alumina ceramic sheets. The hole formation process in a glass sheet is examined experimentally and theoretically.

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

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

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

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