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With the advancement of ultrashort pulsed-laser processing technologies, greater control of processing conditions has come into demand. A factor which particularly complicates ablation situations is "damage incubation," a phenomenon in which the intrinsic optical properties of the processed material change due to accumulated defects from repeated laser excitation. Damage incubation can induce striking changes in the observed morphology during ablation and should be an important factor governing processing results. However, only a few studies have incorporated these effects into multiple-pulse ablation models due to its complexity. Here, in order to quantify the effects of damage incubation in a practical processing setting, we study ablation morphologies of shallow grooves formed on the surface of sapphire (α -Al 2 O 3) with varying laser pulse number and energy in a purpose-made experiment. We observe clear evidence of incubation-induced changes in ablation phase and nonlinear dependence of depth on the incident total energy density. To understand the results, we create a simple empirical model for material energy absorption by characterizing interpulse absorption changes and analytically derive solutions for two limiting cases in which the material has either a very low (quasistatic absorption) or very high (accumulative absorption) damage incubation characteristic. By following the energy absorption characteristics predicted by the latter model, we were able to derive universal relations between ablated depth and incident energy density for sapphire. This work serves to highlight the effects of damage incubation on multiple-pulse ablation situations and provides a simple and practical method to predict such morphological characteristics of an arbitrary material. [ABSTRACT FROM AUTHOR]

The article focuses on grooved axes of exceptional workmanship from east Tennessee, southwest Virginia and some from western North Carolina. It mentions specimens now in the author's collection are herein pictured in vivid colored detail and further described as follows. It also mentions South Carolina are known to have fashioned well-developed grooved stone axes many with exceptional surface polish.

In recent years, the grooving method in the form of "externally bonded reinforcement on groove" (EBROG) has been introduced as an alternative method of the conventional externally bonded reinforcement (EBR) for strengthening concrete structures using fiberreinforced polymer (FRP) materials. This paper is a first attempt to develop an FRP-concrete bond strength model based on nonlinear regression on the experimental results. The agreement of the model to the data is verified using different statistical tools and analysis of variance. One hundred and fifty-four single lap-shear tests are conducted on 136 specimens made through the EBROG method and 18 specimens through the EBR method. The design of experiments techniques in the form of response surface methodology and I-optimality criteria are used to design and optimize the test layouts. The effects of groove dimensions, concrete compressive strength, and FRP sheet width and stiffness on the EBROG bond strength and its efficiency are investigated and compared with those on similar EBR specimens. Although debonding failure is observed to occur in all of the specimens, the results obtained confirm the superiority of the EBROG over the EBR specimens, as evidenced by an average enhancement of 31% achieved in bond strength and the postponed debonding. A bond strength model for the EBROG method was proposed by modifying the well-known Chen and Teng model, originally used for EBR. [ABSTRACT FROM AUTHOR]

The main objective of this study is strengthening of flat slabs in punching shear with a new model. For this purpose 15 numerical samples include a control and 14 strengthened defined and nonlinearly analyzed up to failure. The strengthening method is new method of grooving in two orthogonal direction (x and y axes of slab plan) and then mounting the external bars (sticking) in one direction and FRP in EBROG (externally bonded reinforcement on groove) method in another direction. The results showed the great efficiency of the method so that the punching shear capacity of strengthened samples increased between 28 and 62% compare to control one. Also the mode of failure changed in strengthened specimens from shear to flexure-shear and the punching critical area was broader and developed from the loading point. In the grooving method the sticking bars yielded in all specimens and the FRP tensile strain was closer to rupture strain compared to EBR. [ABSTRACT FROM AUTHOR]

The flow development in a groove-modified channel consisting of flat and grooved walls was investigated by direct numerical simulations based on the Navier–Stokes equations at a Reynolds number of 5×103 based on the full channel height and the bulk velocity. Simulations were performed for highly disturbed initial flow conditions leading to the almost instantaneous appearance of turbulence in channels with flat walls. The surface morphology was designed in the form of profiled grooves aligned with the flow direction and embedded in the wall. Such grooves are presumed to allow development of only the statistically axisymmetric disturbances. In contrast to the rapid production of turbulence along a flat wall, it was found that such development was suppressed over a grooved wall for a remarkably long period of time. Owing to the difference in the flow structure, friction drag over the grooved wall was more than 60 % lower than that over the flat wall. Anisotropy-invariant mapping supports the conclusion, emerging from analytic considerations, that persistence of the laminar regime is due to statistical axisymmetry in the velocity fluctuations. Complementary investigations of turbulent drag reduction in grooved channels demonstrated that promotion of such a state across the entire wetted surface is required to stabilize flow and prevent transition and breakdown to turbulence. To support the results of numerical investigations, measurements in groove-modified channel flow were performed. Comparisons of the pressure differentials measured along flat and groove-modified channels reveal a skin-friction reduction as large as DR ≈ 50% owing to the extended persistence of the laminar flow compared with flow development in a flat channel. These experiments demonstrate that early stabilization of the laminar boundary layer development with a grooved surface promotes drag reduction in a fully turbulent flow with a preserving magnitude as the Reynolds number increases. [ABSTRACT FROM AUTHOR]

Grain-boundary migration, void formation as well as associated hillock formation are important mechanisms which lead to the failure of interconnects in the microelectronic packages. An understanding of the underlying physics of each of the phenomena can allow better design of interconnects. In this paper, we formulate a new phase-field model based on a grand-potential formalism for studying the phenomena of grain-boundary grooving under the combined influence of pure diffusion controlled transport, electric current and thermal gradient. We separately investigate the contributions of each of the stimuli towards the process of grain-boundary migration and hillock formation, by performing phase-field simulations as well as comparing with analytical theories. Additionally, we qualitatively reproduce the phenomena observed in experiments on polycrystalline metals, wherein electromigration and thermomigration may act in unison or against each other towards their contributions in grooving, hillocking and void growth. [ABSTRACT FROM AUTHOR]

Hierarchical assembly of nanoparticles (NPs) is of interest for omniphobic surfaces in the way that hierarchical scale roughness possibly provides effective liquid repellency and also it is relatively easy to build large-area coatings via the bottom-up assembly process. However, all NP assemblies often lacks mechanical robustness. Hence, the development of the effective fabrication method to make well-deposited hierarchical NPs assembly is demanded. In this report, we have demonstrated an all-NP three-dimensional hierarchical surface that is omniphobic yet highly transparent and mechanically robust. By taking advantage of sublimation and recondensation of smectic A liquid crystals (LCs) in a simple thermal annealing process, we patterned NP aggregates in one-dimensional grooves directed by LCs. The resultant groove-like NP-assembled surface showed omniphobicity, repelling water, glycerol, ethylene glycol, and olive oil (with contact angle of 156.5°, 147°, 136.5°, and 123.2°, respectively) because of the low surface energy of the fluorinated NPs and dual roughness. The coating is highly transparent with ∼90% transmittance in the visible wavelength. We investigate the mechanical robustness of the all NP coatings by sand abrasion, which shows nearly identical omniphobicity and transparency after the sand abrasion. [ABSTRACT FROM AUTHOR]

In the strengthening of existing deficient structures using the near-surface mounted (NSM) FRP method, a group of parallel NSM FRP strips are usually needed to meet the capacity enhancement requirement. When the groove spacing (i.e., the net distance between grooves) is relatively small, the bond behaviour of each NSM FRP strip is detrimentally influenced by the adjacent grooves/FRP strips, and such detrimental effect should be taken into account for a safe design of the NSM FRP strengthening system. All the existing models, however, have been proposed for NSM bonded joints with a single FRP strip and thus cannot consider the effect of groove spacing on the bond behaviour, due to the insufficiency of data from tests or numerical simulations. Against this background, a numerical parametric study, was conducted to clarify the effect of groove spacing on the bond strength of such bonded joints; the numerical parametric study involved the use of a three-dimensional meso-scale finite element model developed in the present study for NSM bonded joints with two FPP strips separately embedded in two parallel grooves. Based on the results from the parametric study, a reduction factor to account for the detrimental effect of insufficient groove spacing on the bond strength is proposed and extended to NSM bonded joints with three or more evenly-spaced FRP strips. By combining the proposed reduction factor and the bond strength model previously developed by the authors for NSM bonded joints with a single FRP strip, a bond strength model for NSM bonded joints with multiple FRP strips is proposed and the accuracy of the proposed model is verified with test results. [ABSTRACT FROM AUTHOR]

We have used a phase field model to study destabilization of cylindrical pores in a polycrystalline membrane; a key feature in the model is that it incorporates surface diffusion as the mechanism for mass transport. Using a model system in which a cylindrical pore runs through a material in which all the grain boundaries (GBs) are perpendicular to the pore axis, we identify two elementary mechanisms for pore failure. The first one is based just on grain boundary (GB) grooving, which causes a circular trench at the groove, and a constriction of the pore on either side of the GB; as the groove deepens, the constriction narrows, and eventually closes the pore. Pore closure through this mechanism is possible only when the grain size exceeds a critical size (below which the open pore surface acquires an inverse-bamboo morphology), and therefore, it is controlled by grain growth kinetics. In the second mechanism, the groove profiles of unequal sized grains is such that the curvature differences trigger a coarsening-like process in which atoms from the surface of smaller grains are transported to that of larger grains, causing an ever-narrowing constriction there. A simplified model that incorporates these two mechanisms acting in parallel is used to rationalize our observations of pore failure in polycrystalline systems. [ABSTRACT FROM AUTHOR]

The interactions at the interface between planar Ag 3 Sn and liquid Sn under ultrasonic irradiation were investigated. An intensive thermal grooving process occurred at Ag 3 Sn grain boundaries due to ultrasonic effects. Without ultrasonic application, planar shape of Ag 3 Sn layer gradually evolved into scalloped morphology after the solid-state Sn melting, due to a preferential dissolution of the intermetallic compounds from the regions at grain boundaries, which left behind the grooves embedding in the Ag 3 Sn layer. Under the effect of ultrasonic, stable grooves could be rapidly generated within an extremely short time (<10 s) that was far less than the traditional soldering process (>10 min). In addition, the deepened grooves leaded to the formation of necks at the roots of Ag 3 Sn grains, and further resulted in the strong detachment of intermetallic grains from the substrate. The intensive thermal grooving could promote the growth of Ag 3 Sn grains in the vertical direction but restrain their coarsening in the horizontal direction, consequently, an elongated morphology was presented. All these phenomena could be attributed to the acoustic cavitation and streaming effects of ultrasonic vibration. [ABSTRACT FROM AUTHOR]

Application of fiber-reinforced polymer (FRP) composites to enhance the flexural strength of members in the expected plastic hinge regions of ductile reinforced concrete (RC) moment frames for resisting seismic loads are stipulated in the current construction codes and guidelines. The main issues of concern in these documents include provisions for appropriate anchorage details for FRP composites at the beam-column interface, debonding of FRP composites off the concrete substrate, and the effect of cyclic load reversal on FRP reinforcement. The present experimental study was conducted to gain insight into the effectiveness of an innovative FRP anchor fan at the beam-column joint interface flexurally strengthened with carbon FRP (CFRP) sheets. To avoid any likely debonding of FRP composites off the concrete substrate, surface preparation of the test specimens was performed according to a recently developed grooving method (GM) in the form of externally bonded reinforcement on grooves (EBROG). For the purposes of this study, seven half-scale RC beam-column subassemblies, including a control specimen and six rehabilitated ones, were tested under constant axial and reversal cyclic lateral loadings. The primary test variables were the FRP sheet length along the beam and fiber volume in the CFRP anchor fan. The results indicated that the adopted rehabilitation strategy enhanced the lateral strength of RC joints up to 80% compared to the control one. It was also found that deformation-controlled classification action could be justified for strengthened specimens under specific circumstances. [ABSTRACT FROM AUTHOR]

This paper numerically studies the wind effect on grooved and scallop domes. The introduction of a groove on a spherical dome causes abrupt change on its wind pressure coefficient (Cp) in the vicinity of the groove. The sharpness of indentation varies with the position angle of the axis of the groove to wind direction and obtains its highest effect at 90°. This paper develops equations for the distribution of Cp on the surface of spherical, grooved and scallop domes with rise to span ratios [0, 0.7]. The results of the equations agree reasonably well with that of CFD. [ABSTRACT FROM AUTHOR]

Both buried contact solar cells (BCSC) and laser doped selective emitter (LDSE) solar cells have achieved considerable success in large-scale manufacturing. Both technologies are based on plated contacts. High metal aspect ratios achieved by BCSC allow low shading loss while the buried metal contacts in the grooves provide good contact adhesion strength. In comparison, although the LDSE cell achieves significantly higher efficiencies and is a much simpler approach for forming the selective emitter region and self-aligned metal plating, the metal adhesion strength falls well short of that achieved by the BCSC. Recent studies show that plated contacts based on the latter can be more durable than screen-printed contacts. This work introduces a new concept of laser doping with grooving to form narrow grooves with heavily doped walls in a simultaneous step, with the self-aligned metal contact subsequently formed by plating. This process capitalizes on the benefits of both BCSC and LDSE cells. The laser-doped grooves are only 3–5 µm wide and 10–15 µm deep; the very steep walls of these grooves remain exposed even after the subsequent deposition of the antireflection coating (ARC). This unique feature significantly reduces the formation of laser-induced defects since the stress due to the thermal expansion mismatch between the ARC and silicon is avoided. Furthermore, the exposed walls allow nucleation of the subsequent metal plating. This novel structure also benefits from greatly enhanced adhesion of the plated contact due to it being buried underneath the silicon surface in the same way as the BCSC. Cell efficiencies over 19% are achieved by using this technology on p -type Czochralski (Cz) wafers with a full area aluminum (Al) back surface field (BSF) rear contact. It is expected that much higher voltages and consequently higher efficiencies could be achieved if this technology is combined with a passivated rear approach. [ABSTRACT FROM AUTHOR]

The bond behavior of carbon fiber–reinforced polymer (CFRP) sheets attached to concrete surface subject to mixed-mode I/II loading through single lap-shear tests is assessed. A 63 concrete prism specimens of 150 × 150 × 330 mm were prepared through externally bonded reinforcement (EBR) and externally bonded reinforcement on grooves (EBROG) techniques, using CFRP sheets of constant width and 100=150-mm bond lengths. To instigate mode I loading, 31 of the specimens were tested in a manner that the loaded end of FRP sheets were angled inward -6.0 to -2.3 degrees; while in 24 of the specimens, the FRP strips were angled outward 2.4–4.7 degrees. By applying a noncontact digital image correlation (DIC) technique, load-slip responses of both EBR and EBROG joints were obtained and are discussed in detail. The failure criteria for CFRP sheets attached to a concrete substrate applying different bonding techniques subject to mixed-mode I/II loading are developed based on the experimental results. In general, it was observed that the EBROG technique in mixed-mode I/II loading improves the FRP-concrete bond strength by delaying or fully eliminating the inappropriate debonding failure mode. [ABSTRACT FROM AUTHOR]

Uniformity of crystallographic texture in rods of niobium (Nb) is one of the most important microstructural parameter determining the quality of rods. In this work, we perform a quantitative texture uniformity study in rods of high purity Nb, which were manufactured by rolling using square-to-round shaped rolling die assembly and oval-to-round shaped rolling die assembly. After rolling, the rods were annealed under the same condition. Texture characterization was carried out using electron backscatter diffraction (EBSD). We observe that the oval-to-round die assembly produced a more uniform ⟨110⟩ fiber texture in the rod cross-section compared to the square-to-round die assembly. To confirm the observation, texture in the rods processed in the two different dies were quantitatively compared through the calculations of two suitably defined metrics: texture difference index (TDI) and pole figure difference (PFD). The calculations verify that rolling of Nb in the oval-to-round shaped die assembly produces rods of superior texture uniformity. Strain fields developed in the rods during the two processes were predicted using finite element (FE) analysis. The strain distribution in the rod made using the oval-to-round shaped dies was determined to be more uniform than in the rod made using the square-to-round shaped dies. In particular, the simulations reveal that the square-to-round rolling dies create highly localized strains that are detrimental towards achieving uniform final microstructure in the rods. [ABSTRACT FROM AUTHOR]

A major cause underlying the collapse of reinforced concrete (RC) moment-resisting frames observed in past earthquakes is the shear failure of nonseismically detailed exterior beam-column joints. A number of studies have investigated the external application of fiberreinforced polymer (FRP) composites for the seismic rehabilitation of these members. However, the main challenge facing this technique is the premature debonding of FRP composites off the concrete substrate posed. The grooving method (GM), as an alternative to the conventional externally bonded reinforcement (EBR) technique, has yielded promising results in postponing, or in some cases eliminating altogether, the undesirable debonding failure mode in the flexural/shear strengthening of beams. The present experimental study was conducted to investigate the effects of GM in the seismic behavior of exterior RC beam-column deficient joints strengthened with carbon-FRP (CFRP) sheets taking advantage of the special technique of externally bonded reinforcement on grooves (EBROG). Another facet of the study is the investigation of the performance of FRP fans in preventing the splitting failure of the concrete cover. For the purposes of this study, six halfscale RC beam-column subassemblies with no transverse reinforcement in the joint region were constructed. Results revealed that the EBROG technique, coupled with FRP fans at the termination point of FRP sheets, was able to eliminate altogether the debonding. It was, further, able not only to delay the brittle shear failure of the beam-column joints but also to relocate the beam plastic hinge away from the column interface under specific circumstances. Moreover, it was found that application of CFRP composites via the EBROG method was able to produce a significant enhancement in the seismic capacity of the test specimens in terms of their strength, stiffness, ductility, pinching width ratio, and energy dissipation. [ABSTRACT FROM AUTHOR]

A one-step multiplex real-time reverse transcription polymerase chain reaction (RT-qPCR) based on TaqMan probes was developed for the simultaneous detection of Apple mosaic virus (ApMV), Apple stem pitting virus (ASPV) and Apple stem grooving virus (ASGV) in total RNA of pome trees extracted with a CTAB method. The sensitivity of the method was established using in vitro synthesized viral transcripts serially diluted in RNA from healthy, virus-tested (negative) pome trees. The three viruses were simultaneously detected up to a 10−4 dilution of total RNA from a naturally triple-infected apple tree prepared in total RNA of healthy apple tissue. The newly developed RT-qPCR assay was at least one hundred times more sensitive than conventional single RT-PCRs. The assay was validated with 36 field samples for which nine triple and 11 double infections were detected. All viruses were detected simultaneously in composite samples at least up to the ratio of 1:150 triple-infected to healthy pear tissue, suggesting the assay has the capacity to examine rapidly a large number of samples in pome tree certification programs and surveys for virus presence. [ABSTRACT FROM AUTHOR]

Amorphous nickel phosphorus (Ni-P) alloy is a suitable mold material for fabricating micropatterns on optical elements for enhancing their performances. Ultra-precision cutting is preferred to be used to machine the mold material for high precision in a large workpiece. However, burrs and chippings always form and are detrimental especially when fabricating micropatterns. The formation mechanisms of burrs and chippings have not yet been revealed precisely in the cutting processes of amorphous alloys, because their cutting behavior is more complex and less discussed in existing researches than that of crystalline metals. In the present study, the burr formation process of amorphous Ni-P is defined and a three-dimensional cutting model using energy method is proposed to predict and minimize burrs and chippings. Microgrooving experiments were conducted with different undeformed chip geometries using three types of cutting tools to observe burr formation processes. Large burrs and chippings were formed when cutting with a tapered square tool and a tilted triangle tool. These large burrs and chippings were found to be induced by large slippages that are unique to amorphous alloys. It was revealed that burrs and chippings appear when the angle between the chip flow direction and the groove edge is less than a critical value. Energy method was used to predict the chip flow directions and the calculated results agree with the experimental ones, which proved that the energy method is valid for designing an appropriate undeformed chip geometry to reduce burrs and chippings in ultra-precision grooving. [ABSTRACT FROM AUTHOR]

Purpose This study aims to improve the performance of hydrodynamic journal bearings through partial grooving on the bearing surface.Design/methodology/approach Bearing performance analysis is numerically carried out using the thin film flow physics of COMSOL Multiphysics 5.0 software. Initially, the static performance analysis is carried out for hydrodynamic journal bearing system with smooth surface, and the results of the same are validated with results from the literature. In the later part of the paper, the partial rectangular shape micro-textures are modeled on bearing surface. The effects of partial groove pattern on the bearing performance parameters, namely, fluid film pressure, load carrying capacity, frictional power loss and frictional torque, are studied in detail.Findings The numerical results show that the values of maximum fluid film pressure, load carrying capacity, frictional power loss and frictional torque are considerably improved due to deterministic micro-textures. Bearing surface with partial groove along 90°-180° region results in 81.9 per cent improvement in maximum fluid film pressure and 75.9 per cent improvement in load carrying capacity as compared with smooth surface of journal bearing, with no increase in frictional power loss and frictional torque. Maximum decrease in frictional power loss and frictional torque is observed for partially grooving along 90°-360° region. The simulations are supported by proof-of-concept experimentation.Originality/value This study is useful in the appropriate selection of groove parameters on bearing surface to the bearing performance characteristics. [ABSTRACT FROM AUTHOR]

We present a theory of thermal grooving, i.e. surface motion due to surface diffusion, based solely on geometrical and energetic arguments and a variational approach involving a thermodynamic extremal principle. The theory is derived for a fully three-dimensional setting. All interface and contact conditions at junction lines and points of the material aggregate are derived rigorously and without ambiguity. A finite element implementation of the model is employed. Numerical examples are presented and compared with experimental results from the literature. [ABSTRACT FROM AUTHOR]

A multiple integration technique of the integral-balance method allowing solving high-order diffusion equations is conceived in this note. The new method termed multiple-integral balance method is based on multiple integration procedures with respect to the space co-ordinate and is generalization of the widely applied heat-balance integral method of Goodman and the double integration method of Volkov. The method is demonstrated by a solution of the linear diffusion models of Mullins for thermal grooving. [ABSTRACT FROM AUTHOR]

Creating grooves in the surface of grinding wheels for the purposes of modifying their performance properties has been a subject of academic interest since the late 1970s. Recently, this area of investigation has increased in popularity, with around half of all papers on the subject being published in the last decade. The advantages of grooved grinding wheels over conventional wheels have been well documented across the literature: decreased specific energy of machining, decreased process forces, and decreased process temperatures. However, there remains some debate over the disadvantages of grooved wheels over conventional wheels, namely, increased wheel wear and increased surface roughness. This paper presents a literature review of state-of-the-art grinding wheel grooving processes for vitrified bond grinding wheels, along with a proposed update to the nomenclature surrounding grinding wheel grooves. The advantages and disadvantages of several grooving methods are then discussed and areas of future research are suggested. [ABSTRACT FROM AUTHOR]

This study used a molecular dynamic (MD) method to study the grooving behaviors of single crystal of copper cut with a rigid diamond tool. The crystallographic orientation effects on cutting force and groove morphology are discussed by metallurgical viewpoint. The grooving crystal planes and directions included $$ (001)\left[\overline{1}00\right] $$ , $$ (101)\left[\overline{1}01\right] $$ , and $$ (101)\left[0\overline{1}0\right] $$ . The MD simulation results showed that crystal orientation significantly affected the grooving behaviors of single crystal copper. The cutting along different orientations led to the number of slip system difference. The simulation results showed that grooving on (101) along $$ \left[0\overline{1}0\right] $$ direction with a rectangular tool can obtain the suitable rectangular slot but get a groove with 'V' shape cross section in $$ (101)\left[\overline{1}01\right] $$ grooving. [ABSTRACT FROM AUTHOR]

Disc milling strategy has been applied in grooving for decades for its capacity to provide huge milling force on the difficult-to-cut material. The processing efficiency of machined components thus can be tremendously improved with the application of disc milling. However, the fundamental research of the mechanisms of disc milling on cutting metal materials, especially on titanium alloys, is lacking in the literature. In this study, the milling force and temperature were inspected in disc milling grooving experiment, and the effect of thermal-mechanical coupling on surface integrity of titanium alloy, including surface roughness, surface topography, surface and subsurface residual stress, microstructure, and microhardness, was analyzed. The results showed that a better surface quality can be obtained at the center of the surfaces compared to the marginal regions on the same machined surface. Residual compressive stress was generated on the machined surface and subsurface and gradually reduced to zero with an increase in depth. The microstructure of lattice tensile deformation was emerged along feed direction, while the phase transition was not produced. A hardened layer was found on the machined surface and subsurface, mostly causing by the mechanical loads and oxidation reaction. [ABSTRACT FROM PUBLISHER]

The molded interconnected devices (MID) technology is vastly growing as an important innovative technology in the field of electronics production. The laser direct structuring (LDS) method is one of the most common available technologies for building up MID's products. The current existing knowledge in industry and in research about the standards in the respective manufacturing processes and process parameters is up to now not fully comprehensive in terms of mutual influencing and dependencies on each other. This is particularly the case for the three-dimensional applications and micro products. In the present contribution, a new simulation procedures based on a three-dimensional finite element model (FEM) has been developed. The effect of each of latent heat of fusion and temperature on the material properties as well as the 3D Gaussian heat source for the laser beam has been considered in this work. The used material was a polymer plate poly ether ether ketone (PEEK). The effect of the process parameters including laser power, speed, frequency, hatching percent or overlap between the laser lines, the laser incident angle, and the focal length have been investigated in experiments and simulations. The present simulation can be used to predict, temperature distribution, maximum temperature, groove dimensions, and groove profile at different process parameters setup. The theoretical and the experimental results can show a good accordance. It can be concluded that the FEM simulation can be used efficiently for predicating, analyzing, and optimizing the 2D/3D laser parameters for the LDS process. [ABSTRACT FROM AUTHOR]

This paper presents the optimization work of 355 nm ultraviolet (UV) laser diode ablation process for CMOS 45 nm Copper (Cu) low-k semiconductor wafer. The micromachining parameters included laser power, laser frequency, feed speed, and defocus amount were optimized via design of experiment (DOE). Package reliability stressing tests were carried out as part of the efforts to validate the robustness. The results show that high repetition rate, low laser pulse energy and a high pulse overlap produced zero dicing defects. The laser groove depth increased as the laser pulse energy increased. It is shown that, laser grooving is one of the best solutions to choose for dicing quality, throughput and yield improvements for CMOS 45 nm Cu low-k wafer dicing. [ABSTRACT FROM AUTHOR]

This paper investigates the ability of circumferentially grooved grinding wheels to create parallel ridges on a workpiece providing a textured surface that may be advantageous for certain applications. In this paper, the effect of wheel speed, workpiece feed rate, grinding direction, and groove factor on the height, spacing, and angle of these ridges were investigated. In addition, an analytical model based on the kinematics of grinding with circumferentially grooved wheels, as well as a corresponding simulation method to predict the patterns on the resulting ground surface were developed. A wide range of workpiece textures predicted by the analytical and simulation results were compared with experimental results. When comparing the experimentally measured texture angles on the workpiece, the angles predicted by both the analytical model and the simulation model had an average difference within 3.4 %. When comparing the experimentally measured spacing between ridges on the textured workpiece, the spacing predicted by both the analytical model and the simulated model had an average difference within 2.4 %. Finally, when comparing the experimentally measured heights of the ridges on the textured workpiece, both the analytical and simulation models differed from experiments by, on average, only 2.3 μm. [ABSTRACT FROM AUTHOR]

Milling technique was proposed to fabricate close-loop hydrophilic groove (CLHG) patterns on superhydrophobic Al alloy surface. On account of the pinning force that derives from the milled smooth grooves, water can be trapped and stretched into thin water films with different shapes on the superhydrophobic substrate. The contact angle of 13 μL water film trapped by a circular CLHG with an outer diameter of 10.3 mm was only 5.8°. Water films trapped by the CLHGs are similar to those hydrophilic/superhydrophilic patterns and have great water trapping capacity. The critical water trapping volume (CWTV) and sliding resistance of droplets on the circular CLHGs versus outer diameters and groove widths of the CLHGs were investigated. The results indicate that both the CWTV and sliding resistance are independent of the groove widths but closely related to the CLHG outer diameters. Compared with plasma-treated superhydrophilic dots, the circular CLHGs have equal CWTV and sliding resistance. This water-film patterning method has advantages like high efficiency and less liquid loss in liquid shifting processes, and therefore can possibly find such applications as large-area liquid patterning and water storage on superhydrophobic substrates. [ABSTRACT FROM AUTHOR]

A pretreatment of micro grooving was applied before the MAO process on the surface of aluminum. The influence of micro grooves on oxide ceramic coating was characterized by XRD, SEM, EDS and micro-hardness tester. The experiment shows that the micro groove could significantly increase the partial growth rate (from 0.66 to 1.0 μm min −1 ) and hardness of oxide ceramic coating; the parameter of current and process time have a big influence on coating thickness and smoothness; the micro groove can be completely filled with the products of ejection under the appropriate process parameter and continuous smooth with the coating out of the grooves. [ABSTRACT FROM AUTHOR]

This technical paper deals with high temperature dry sliding wear behavior and its mechanism of Inconel 718 and Hastelloy X alloys. The sliding wear behavior of the Inconel 718 alloy and Hastelloy X was investigated using a pin on disc equipment at 500 °C with varying normal load. Hastelloy X has shown the higher coefficient of friction in comparision to IN718. SEM features of worn samples reveal that delamination, ploughing and deep grooving are the dominant wear mechanisms for IN718, while for Hastelloy X, it is shear band, cleavage formation, debris generation. [ABSTRACT FROM AUTHOR]

Stall margin improvement (SMI) curve is a function of a single groove location for a low-speed axial compressor and is investigated numerically and experimentally in this paper. SMI curve illustrates that good grooves are located in a fairly wide region approximately from 30% C to 80% C aft of the rotor leading edge. The narrow region that contains bad grooves is near 20% C aft of the rotor leading edge. The initial selection of groove location combination for multi-groove casing treatments is proposed based on the SMI and efficiency improvement data generated by a series of single-groove and multi-groove casing treatments. The grooves should be set in the 'wide region' of the SMI curve. The grooves located near the 'narrow region' and the rotor trailing edge should be avoided. The 'narrow region' can be identified by the axial momentum distribution of the tip leakage flow or the circumferentially averaged axial shear stress on the casing using the simulation results of the smooth casing at the near-stall point. [ABSTRACT FROM AUTHOR]

Potential of fiber laser grooving in silicon has been investigated with continuous wave beam and modulated beam of micro-second durations. Though silicon shows considerably high transparency for the utilized laser wavelength (1.07 μm), due to the increase of absorption coefficient with temperature its micro-machining is feasible with good precision by laser. A co-axial water-jet has been employed for ejecting out the molten silicon effectively and simultaneously for rapid cooling. This in turn, overcomes the limitation of micro-machining of silicon with laser pulses of relatively longer durations and alleviates the oxidation problem also. It has been observed that with increasing water-jet speed at constant laser parameters, spatter and recast are reduced. Grooves of controlled depth in 14–520 μm range, free from micro-cracks and thermal damage could be obtained by controlling the laser and process parameters. Compared to argon-jet assisted laser grooving this technique produced grooves of relatively better quality in terms of lesser micro-cracks, spatter and thermal damage. [ABSTRACT FROM AUTHOR]

In the present study, application of carbon-fiber-reinforced polymer (CFRP) composites with fibers aligned along the column's axis to improve compressive strength of reinforced concrete (RC) columns has been investigated. Global buckling of fiber-reinforce polymer (FRP) composite with fibers along the column's axis may result in debonding of FRP from the column's surface, and thus, the compressive load carrying capacity of the strengthened column would not be increased considerably. To limit the global buckling of composite under compression, a newly introduced strengthening method, named as grooving method (GM), was utilized in the present study and compared with externally bonded reinforcement (EBR) method using conventional surface preparation and near surface mounted (NSM) method. For this purpose, 22 circular RC columns with 150-mm diameter and 500-mm height were tested under uniaxial compression. Two techniques of GM named as externally bonded reinforcement on grooves (EBROG, to be pronounced as / ebrΛg/) and externally bonded reinforcement in grooves (EBRIG, to be pronounced as /ebrIg/) were used in the present study. Experimental results showed that grooving method considerably enhanced the columns' maximum loads. It was also observed that the maximum compressive stress capacity of CFRP based on average compressive stresses of fibers in the composite was impressively increased when grooving method was used. The results showed that in the columns strengthened by EBROG method, nearly 80% of the fibers' tensile strength in direct shear test could be utilized as compressive stresses in fibers of longitudinal composite; this value was about 13% and 16% when EBR and NSM techniques were used, respectively. [ABSTRACT FROM AUTHOR]

In ball-cratering wear tests, two abrasive wear modes are commonly observed, grooving abrasion and rolling abrasion, which act in distinct areas. Observing this tendency, the aim of this article is to discuss the characterization of an intermediate condition, in which the superposition of the grooving and the rolling abrasive wear modes is observed. This phenomenon is referred to as microrolling abrasion due to the following particular characteristic: the rolling abrasion was found to act on the grooving abrasion. Additionally, in a defined sliding distance range and normal force range, microrolling abrasion is qualitatively observed to be proportional to the sliding distance and inversely proportional to the normal force. [ABSTRACT FROM PUBLISHER]

A three-dimensional finite element model of evaporative laser grooving process has been developed for ceramic materials. The laser is assumed to be a continuous wave and approximated as Gaussian beam. The model can predict three-dimensional temperature distribution inside the specimen as well as resultant groove depth. By comparing the predicted groove depths with experimental data from literature, it was found that the effect of multiple reflections in deep grooves is significant. The computational model can be calibrated for deep grooves by increasing absorptivity for deeper cuts. The calibrated model was used to develop a fuzzy expert system (FES) which can reliably predict groove depth at relatively low computational costs. Fuzzy logic (FL) methodology, on the other hand, is a capable modeling tool which performs extremely robust in a nonlinear complex field with least trial data. In the fuzzy expert system, the goodness of fit was found to be 0.991, and the mean relative error was 4.714 % compared to goodness of fit of 0.897 and mean relative error of 10.675 % in finite element method (FEM). FES could successfully increase the accuracy of FEM without taking the complex phenomena of multiple reflections into computation. [ABSTRACT FROM AUTHOR]

An approach to simulate the behaviour of steel stiffened plates subjected to weld-induced grooving corrosion using nonlinear finite element modelling is proposed. The model includes the effects of different initial geometric imperfections and weld-induced residual stresses. The influence of corrosion damage on the load shortening curves and ultimate strength is investigated. It is shown that grooving corrosion depth has a greater influence on structural performance as compared with corrosion width for the same volume loss. Such corrosion damage could cause a significant reduction in the ultimate strength of a plate panel. Considerations of weld-induced deflection and residual stresses further enhance the corrosion influence on the strength capacity. [ABSTRACT FROM AUTHOR]

Effects of grooving in a porous faced hydrostatic circular step thrust bearing are investigated using a mathematical model based on the narrow groove theory (NGT). It is shown that enhancement of load capacity by grooving the step is possible at moderate level of permeability of the porous facing. Load capacity drops sharply with the increase of porous facing thickness. However, this drop in load capacity occurs mostly within a small thickness of the porous facing. Considering the coupled effects of permeability and inertia, it is recommended that the dimensionless step location should be 0.5-0.8 and the dimensionless step height should be less than five to take advantage of grooving. The groove geometric parameters such as groove inclination angle, fraction of grooved area and groove depth corresponding to the maximum load capacity are found to be the same for both with and without porous facing. However, with porous facing, the sensitivity of the load capacity on the groove parameters reduces. At high level of permeability, the effects of grooves may become insignificant because of high seepage flow through the porous facing. [ABSTRACT FROM AUTHOR]

The grooving technique was employed for manufacturing a self-standing curved Ge crystal. The crystal focuses hard X-rays with high efficiency by diffraction in Laue geometry through asymmetric bent planes. The sample was tested at the Institut Laue-Langevin (Grenoble, France), undergoing two types of characterization. A monochromatic and low-divergence γ-ray beam was used to test the curvature of asymmetric planes, showing a diffraction performance better than for any mosaic crystal under equal conditions. Then, the focusing capability of the crystal was probed through a polychromatic and fine-focus hard X-ray beam. Asymmetric (220) planes were chosen for analysis because of the impossibility of obtaining a curvature along this family of planes via any symmetric configuration in focusing crystals. A method for calculating the curvatures induced in any family of lattice planes is also presented. [ABSTRACT FROM AUTHOR]

The formation of stable back beads in a root pass weld during one side multi-layer welding is important to achieve high quality welded metal joints in MAG welding. The authors employed the switch back welding method for V groove joints without backing plates. In this switch back welding method, the torch moves forward and backward with an oscillation frequency of 2.5 Hz. In order to achieve this welding, personal computers control the conventional welding robot, the power source characteristic and the wire feeder unit. During the forward, the torch is weaving on the V groove gap without the weld pool. If the weaving width becomes wider than the proper width, the tip of the wire becomes high and a good back bead cannot be obtained. The weaving width is adjusted so as to get the proper width in the switch back welding. The suitability of the welding conditions for each root gap was verified by observation of the arc, the weld pool and the external appearance of back beads. A good back bead was obtained under V groove welding in 2–4 mm gap. [ABSTRACT FROM AUTHOR]

A thin layer of Ge (1 nm) deposited between a 30 nm Ni film and a (100)Si substrate was used as a marker for the diffusing species during Ni silicide formation. In situ X-ray diffraction heat treatments with temperatures ranging from 150 to 400 °C were performed to show the specific steps of silicide formation. Atom probe tomography (APT) enabled the diffusing species during the Ni deposition and during the formation of δ-Ni 2 Si and NiSi phases to be determined. APT measurements of the redistribution of Ge during the stress relaxation of δ-Ni 2 Si and during the formation of NiSi highlighted the mechanisms of stress relaxation and morphological degradation of NiSi. [ABSTRACT FROM AUTHOR]

We report the feasibility of assembling rear-irradiated flexible dyesensitized solar cells employing a transparent Ni-Se alloy counter electrode along with a groove stored TiO2 and liquid electrolyte. The flexible device with the NiSe counter electrode and anode at a groove depth of 36 µm yielded a maximum efficiency of 7.35%. [ABSTRACT FROM AUTHOR]

The influence of side grooving on the parameters, m and β, in the calculation of fracture toughness for self-healing composites is investigated with 3D tapered double cantilever beam models. The impact of side grooving is elucidated through investigation of both specimen compliance and stress intensity factors along the crack front for models differing in crack length and groove ratio, the ratio of specimen thickness to crack width. The models exhibit a linear change in compliance ( C ) with crack length ( a ), allowing for a crack-length-independent determination of fracture toughness owing to a constant m value. However, dC / da increases by ∼20% as the groove ratio changes from 1 to 6 showing that the parameter m is groove ratio dependent. This influence on m has not been accounted for in previous studies on self-healing composite fracture toughness. Stress intensity factors were also found to depend on groove ratio. Those at the specimen mid-plane were exponentially fitted as a function of groove ratio and the determined exponent agrees with the analytical form of β that is suggested by ASTM. Stress intensity factors at the intersection of the crack front with the side groove give a higher exponent due to the local stress concentration. Exponents from both simulation and experimentation fall within the theoretical bounds set forth by Freed and Krafft while the value currently used in self-healing literature falls outside these bounds. In the light of these findings, an alteration to the current method of calculating fracture toughness for self-healing material is suggested. [ABSTRACT FROM AUTHOR]

Abstract: A method for accurate, low-cost, lab-scale determination of the optimal collision angles and velocities for collision welding of a given combination of materials has been introduced. 0.508mm thick grade 2 CP Ti sheets were launched at various velocities toward a Cu 110 target with grooves of angles ranging from 8° to 28°, machined on the collision side. Capacitor bank-driven aluminum vaporizing foil actuators operated at input energy levels up to 12kJ and currents up to 140kA were used to launch the flyer sheets. Velocity was measured with high temporal resolution using a photonic Doppler velocimetry (PDV) system. Collision velocities ranged from 440m/s to 860m/s. The welded assemblies were sectioned and the weld interfaces were observed via scanning electron microscopy. For each collision angle there were certain collision velocities which yielded a wavy interface. Welding velocity for transition from smooth to wavy interfaces for each collision angle was used to determine the corresponding transition Reynolds number and was compared to existing results in literature. The uniqueness of this process lies in its small scale and ease of implementation. [Copyright &y& Elsevier]

Highlights: [•] A cold forging mechanism for the inner race with six skew-angled cross ball grooves was proposed. [•] To realize the inner race, six-segmentalized skewed ball grooving dies were introduced and applied to the numerical and experimental investigations. [•] Structural integrity evaluation was performed to prevent the fracture of the skewed and segmentalized grooving die. [•] The simulated and forged inner races were compared with the target geometries. [•] The dimensional accuracy of the forged inner race was achieved within the variation of about 2.0%. [Copyright &y& Elsevier]

In this paper, a new grinding wheel grooving system is proposed that is able to both groove as well as re-groove a grinding wheel using a single-point diamond dressing tool. The re-grooving capability of the new system is achieved by synchronizing the grinding wheel angular position with the dressing tool translational position. This position synchronization enables the diamond dressing tip to repeatedly engage the grinding wheel at the same angular position around the wheel and then proceed to trace the existing groove pattern along the wheel surface to, for example, refresh a worn groove geometry. Furthermore, the proposed system can be mounted on either a non-CNC or a CNC conventional grinding machine and can groove and re-groove the grinding wheel without the need to remove it from the grinding wheel spindle. The novel wheel grooving system was experimentally validated by creating helically shaped circumferential grooves on the grinding wheel surface. The resulting maximum differences in groove width and depth were found to be 0.015 and 0.013 mm, respectively, for ten consecutively cut grooves. These small discrepancies are believed to be primarily due to the brittle fracture mechanism of the abrasive grits. Furthermore, the new wheel grooving system was shown to be able to create a wide range of different groove patterns on the wheel surface. A wear study was then carried out to compare the performance of both grooved and non-grooved grinding wheels. For the conditions used in this research, the results of this wear study showed that a grooved wheel not only exhibits less wear than a non-grooved wheel but also can remove approximately twice as much workpiece material before failure occurs. [ABSTRACT FROM AUTHOR]

The advantages of profile connections are considered in the article. The possibility to produce this type of connection on the grooving equipment is described. The question concerning tool grinding is considered. The program, which allows to obtain vector image of adjusted sectional shape of a form cutter, is suggested. It allows to obtain base profile of cutting edge during overlapping of cutting work angle by means of grinding on the standard tool grinding machinery. [ABSTRACT FROM AUTHOR]

This paper investigates the combined effect of mechanical grooving and porous silicon (PS) on the front surface reflectance and the electronic properties of crystalline silicon substrates. Mechanical surface texturization leads to reduce the cell reflectance, enhance the light trapping and augment the carrier collection probability. PS was introduced as an efficient antireflective coating (ARC) onto the front surface of crystalline silicon solar cell. Micro-periodic V-shaped grooves were made by means of a micro-groove machining process prior to junction formation. Subsequently, wafers were subjected to an isotropic potassium hydroxide () etching so that the V-shape would be turned to a U-shape. We found that the successive treatment of silicon surfaces with stain-etching, grooving then alkaline etching enhances the absorption of the textured surface, and decreases the reflectance from 35% to 7% in the 300-1200 nm wavelength range. We obtained a significant increase in the overall light path that generates the building up of the light trapping inside the substrate. We found an improvement in the illuminated I-V characteristics and an increase in the minority carrier lifetime τeff. Such a simple method was adopted to effectively reinforce the overall device performance of crystalline silicon-based solar cells. [ABSTRACT FROM AUTHOR]