Edge Geometry Research Articles

Structural and electronic properties of novel BeN4/MgN4 nanoribbons

Nanostructures of novel materials are capable of altering the properties of materials quite drastically. Recently discovered Dirac monolayer BeN4 has drawn much attention since this Nitrogen-based material’s electronic structure is very similar to graphene. In this work, we have analyzed various possiblities of nanoribbons structures of MN4 (M=Be, Mg) monolayer materials. We have proposed several possible geometries of BeN4 and MgN4 nanoribbon structures. More specifically, we have proposed armchair nanoribbons with three possible edge configurations as well as zigzag nanoribbons based on edge geometry. Owing to the changes in coordination environment of nanoribbon edge atoms, the resulting bonding characteristics gets altered at the edges, leading to interesting electronic properties. The electronic structures of these nanoribbons are quite different from monolayer and reveal fascinating edge states that exclusively depend on the edge configuration. Though the armchair nanoribbons are found to be metallic, the electronic structure of zigzag nanoribbons exhibits band gap which lead to huge tunability potential of the investigated nanostructures. Therefore, these nanoribbons can function both, metallic as well as semiconducting as required in device applications which can be tuned by modulating the material geometry.

Automated quality evaluation for laser cutting in lithium metal battery production using an instance segmentation convolutional neural network

Separating lithium metal foil into individual anodes is a critical process step in all-solid-state battery production. With the use of nanosecond-pulsed laser cutting, a characteristic quality-decisive cut edge geometry is formed depending on the chosen parameter set. This cut edge can be characterized by micrometer-scale imaging techniques such as confocal laser scanning microscopy. Currently, experimental determination of suitable process parameters is time-consuming and biased by the human measurement approach, while no methods for automated quality assurance are known. This study presents a deep-learning computer vision approach for geometry characterization of lithium foil laser cut edges. The convolutional neural network architecture Mask R-CNN was implemented and applied for categorizing confocal laser scanning microscopy images showing defective and successful cuts, achieving a classification precision of more than 95%. The algorithm was trained for automatic pixel-wise segmentation of the quality-relevant melt superelevation along the cut edge, reaching segmentation accuracies of up to 88%. Influence of the training data set size on the classification and segmentation accuracies was assessed confirming the algorithm’s industrial application potential due to the low number of 246 or fewer original images required. The segmentation masks were combined with topography data of cut edges to obtain quantitative metrics for the quality evaluation of lithium metal electrodes. The presented computer vision pipeline enables the integration of an automated image evaluation for quality inspection of lithium foil laser cutting, promoting industrial production of all-solid-state batteries with lithium metal anode.

PREDICTING THE OPTIMAL PARAMETERS BY MULTI-OBJECTIVE DECISION MAKING WHILE MACHINING AN Al6061 ALLOY USING CBN INSERTS WITH DIFFERENT CUTTING-EDGE GEOMETRIES

The present work aims to investigate the effect of cutting-tool edge geometry on cutting force and surface finish while machining an Al6061 alloy under different conditions. A series of experiments was performed with a custom-fabricated cutting insert of a chamfered edge to observe the effect of feed rate and depth of cut on the cutting forces and surface finish. The results showed that varying the cutting-edge geometry has a significant effect on controlling the cutting forces. Also, as the feed and depth of cut were reduced (at high cutting speeds), the surface roughness was observed to reduce with the geometry effect. Furthermore, in the present work validation of the experimental results were also performed based on a multi-criteria decision-making method called Grey Relational Analysis (GRA). The weighted GRA predicted the optimal combination of machining parameters for two different cutting-tool inserts. Finally, the obtained optimal results were compared with the predicted and experimental values in terms of weighted GRG. The result shows that there was no significant improvement while using the standard cutting tool, whereas a net improvement of 16.9 % was observed while using the chamfered cutting tool for machining the Al 6061 alloy.

Magnetic properties of oxide Mn nanowires on vicinal Au surface

The development of quantum computing or magnetic storage systems requires the search for magnetic nanostructures with multiple magnetic configurations with controllable quantum spin states. The study of the magnetic properties of metal oxide nanowires is of particular importance for the development of these technological implementations. The present work is devoted to an ab initio study of the magnetic properties of Mn and Mn oxide (MnO) nanowires on vicinal Au surfaces with different step edge geometries. The existence of ferromagnetic and antiferromagnetic configurations of Mn and MnO nanowires on vicinal Au surfaces was found. The effect of oxidations and surface geometry on the appearance of ferromagnetic or antiferromagnetic properties of the nanowire was revealed. The ground state of pure Mn nanowires was shown to be dependent on the surface structure. At the same time, the ground state of oxide Mn nanowires is antiferromagnetic on all studied vicinal surfaces and did not depend on the surface structure. We observed an increase in the exchange interaction energy in nanowires under surface oxidation. The exchange interaction between manganese atoms in MnO nanowires is much stronger than in pure Mn nanowires.

Characteristics of the flow-induced noise from rectangular rods with different aspect ratios and edge geometry

The dynamic lift force, wake characteristics and the susceptibility to self-excited acoustic resonance is experimentally investigated for rectangular rods with aspect ratios of l/h=0.5, 1, and 2, where l is the rod length in the flow direction and h is the rod length perpendicular to the flow. The effect of rounding different edges on the flow-sound interaction mechanism is also considered. Rectangular rods with an aspect ratio of l/h=0.5 showed a significant escalation of the acoustic pressure and the dynamic lift force during acoustic resonance excitation. However, when the aspect ratio of the rod increased to l/h=2, an early excitation of the third acoustic mode is observed accompanied with a significant reduction in the dynamic lift force compared to the values observed before the onset of resonance excitation. It is revealed that the wake structure around the rectangular rod with an aspect ratio of l/h=2 has significant dependence on the edge geometry and this results in different shedding modes. The first shedding mode is the typical vortex shedding with a Strouhal value of Stl≈0.16−0.18 and it occurs for rods with aspect ratios of l/h=2 when either all the edges are sharp or the two upstream edges are sharp. Although the vortex shedding is dominant for this case, a masked shear layer instability along the lateral faces of the rectangular rod is what triggers the early excitation of the third acoustic mode. When either all the edges are rounded or the two upstream edges are rounded, the shear layer instability mode becomes dominant with a Strouhal value of Stl≈0.5−0.52 and the dynamic lift force decreases substantially. This mode classically excites the first and the third acoustic modes at their frequency coincidence and no typical single-street vortex shedding is detected downstream of the rod. The work presented in this paper reveals that rounding the upstream edges of a rectangular rod with an aspect ratio of l/h=2 can switch the shedding pattern making the shear layer instability mode dominant and hence a reduction of the dynamic loading and an attenuation of the acoustic energy is obtained.

Estimating splitting capability of modified flax fiber during quality control

The existing problem of cotton import substitution ensures the relevance of modified flax fiber production. Modified flax fiber has potential uses in textile manufacturing when mixed with cotton or similar fibers in order to produce non-woven textile materials, as well as armature for biocomposite materials. As such, it is necessary to alter the existing methods of determining modified flax fiber quality in order to pick new quality metrics corresponding to the changes to fiber's structure during processing. In particular, average thickness and length of the modified flax fiber suffer a degree of reduction during fiber's preparation for spinning, which needs to be measured and taken into account. As the result of the research there was proposed the way to estimate the fractioning quotient of modified flax fiber via sliding bending against rounded edges imitating the effects of actual fiber processing. When working parameters and edge geometry are constant, fiber thickness is reduced by ∆ = Torig - Tres. For fiber with thickness Torig in range of 0.109 to 0.135 micrometers the value of ∆ differes from approximately 0.010 to 0.098 micrometers. It was suggested to estimate the fractioning quotient according to value of D = 100·∆ / Torig. During experimental testing of this method using various quality fiber produced in Tver region and Udmurtia Republic the value of D was varying from 0.10...0.15 % to 7.3...7.7 %. It has been established that the suggested method with the use of standard indicator «fiber thickness» enables to take into account the strength of inter-fiber connections according to the currently accepted theory of their formation. Applying this method makes it possible to differentiate full-scale shipments of modified flax fiber using sliding bending stress performed under identical conditions.

Investigation of Inkjet-Printed Masks for Fast and Easy Photolithographic NIL Masters Manufacturing.

Modern optical systems often require small, optically effective structures that have to be manufactured both precisely and cost-effectively. One option to do this is using nanoimprint lithography (NIL), in which the optical structures are replicated as masters using a stamping process. It would also be advantageous to manufacture the master structures quickly and easily. A master manufacturing process based on a photolithographic image of an inkjet-printed mask is presented and investigated in this paper. An essential element is that a deliberate blurring of the printed structure edge of the mask is used in the photolithographic process. Combined with the use of a non-linear photoresist, this allows for improved edge geometries of the master structure. We discuss the inkjet-printed photomask, the custom photolithography system to prevent imaging of the printing dot roughness and the manufacturing processes of NIL polymer masks as well as their subsequent stamp imprinting. Finally, it was shown that stamp geometries with a width of 1.7 µm could be realised using inkjet-printed photomasks in the master manufacturing process. This methodology opens up the potential of fast and simple master manufacturing for the development and manufacturing of optical elements.

Effect of Wiper Edge Geometry on Machining Performance While Turning AISI 1045 Steel in Dry Conditions Using the VIKOR-ML Approach

AISI 1045 can be machined well in all machining operations, namely drilling, milling, turning, broaching and grinding. It has many applications, such as crankshafts, rollers, spindles, shafts, and gears. Wiper geometry has a great influence on cutting forces (Fr, Ff, Fc and R), temperature, material removal rate (MRR) and surface roughness (Ra). Wiper inserts are used to achieve good surface quality and avoid the need to buy a grinding machine. In this paper, an optimization-based investigation into previously reported results for Taguchi’s based L27 orthogonal array experimentations was conducted to further examine effect of the edge geometry on the turning performance of AISI 1045 steel in dry conditions. Three input parameters used in current research include the cutting speed (Vc), feed (f) and depth of cut (ap), while performance measures in this research were Ra, Fr, Ff, Fc, R, temperature (temp) and MRR. The Vise Kriterijumska Optimizacija Kompromisno Resenje (VIKOR) method was used to normalize and convert all the performance measures to a single response known as the VIKOR-based performance index (Vi). The machine learning (ML) approach was used for the prediction and optimization of the input variables. A correlation plot is developed between the input variable and Vi using the ML approach. The optimized setting suggested by Vi-ML is Vc: 160 m/min; ap: 1 mm and f: 0.135 mm/rev, and the corresponding value of Vi was 0.2883, while the predicted values of Ra, Fr, Ff, Fc, R, temp and MRR were 2.111 µm, 43.85 N, 159.33 N, 288.13 N, 332,16 N, 554.4 °C and 21,600 mm3/min, respectively.

Influence of Cutting Parameters and Tool Geometry on Topography of Hard Turned Surfaces

Three-dimensional topography measurement is a focus area of precision machining because it provides detailed information on the functional behavior of contacting surfaces. The purpose of this study is to analyze how the process parameters and the edge geometry of the cutting insert influence the topographical characteristics of hardened 16MnCr5 steel surfaces and to determine the favorable combinations of technology parameter values based on the analyzed topography parameters (Ssk, Sku, Sz, Sa, Sk, Spk, Svk). A research question is whether the analyzed parameters can be substituted by each other or not. A hard turning experiment was carried out based on a full factorial design of experiments, and the areas of the machined surfaces were scanned and analyzed by analysis of variance, regression analysis (response function), and correlation analysis. It was found that there are strong correlations between the topography parameters that allow the substitution of one with another; the main influencing cutting parameter is the feed rate for both insert types. The contributions of the study are the numerical information with regard to the correlations among the topography parameters, as well as the extent of the influence of cutting parameters.

Wind tunnel measurements on the effects of leading edge geometry on surface pressures and wake flow of finite blunt plate

In this paper, the surface wind pressure distribution and wake flow of finite blunt plates with different leading edge geometries are investigated. Particle image velocimetry and surface pressure measurement are performed on five typical leading-edge plates in a uniform wind. The results show that the wind pressure distribution on the blunt plate surface is largely affected by the leading-edge geometry. Specifically, as the leading edge angle increases from 60° to 180°, the peak values of the mean pressure coefficient and peak suction pressure coefficient decrease by 20.1 % and 11.6 % respectively. Meanwhile, the peak value of the r.m.s pressure coefficient increases from 0.041 to 0.126 and gradually approaches the mid-axis of blunt plate. In addition, larger separation angles lead to an increase in the reattachment length from 0.7d to 5.26d, but monotonically decrease the characteristic frequency of the plate. The analysis of the wake velocity field shows that an increase in leading-edge angle leads to an increase in the length of the low-velocity recirculation zone in the wake from 0.7d to 1.1d, and both the turbulent kinetic energy and Reynolds stress are larger in this region. Meanwhile, the flow streamlines and vorticity distribution become more unstable and complex, exhibiting a faster rate of evolution. Furthermore, the extraction of the wake structure using a proper orthogonal decomposition shows that the aerodynamic shape of leading edge has a limited effect on the large-scale vortex structure, but significantly affects small-scale vortex structure of high-order modes.

State-of-the-art and perspectives of cutting edge preparation and its effect on the cutting performance of titanium alloy

Titanium alloys are commonly used in industrial applications due to their exceptional mechanical and chemical properties. However, their low thermal conductivity and high chemical reactivity pose significant challenges in machining, leading to increased cutting forces, rapid tool wear, and poor surface quality. To overcome these issues, advanced cutting edge preparation techniques have been developed to enhance the machining performance of titanium alloys. This paper provides an overview of state-of-the-art cutting edge preparation techniques for titanium alloy machining and examines their effects on machining performance. It first presents a characterization method for cutting edge geometry and explores how it affects machining performance, demonstrating that strategic cutting edge preparation can significantly enhance performance by reducing cutting forces and improving surface finish. The paper also emphasizes the underlying mechanisms of cutting edge preparation and its impact on machining performance and subsequent cutting edge erosion. Finally, it concludes by discussing future research directions in this field, highlighting the need to develop new cutting edge preparation techniques and optimize existing ones. Overall, this paper serves as a valuable resource for researchers and engineers seeking to improve the cutting performance of titanium alloys in various applications.

Velocity Increment on Incidence Angle near the Leading Edge of the Compressor Cascade

The geometry of a compressor leading edge has an important effect on the aerodynamic performance at an off-designed incidence angle. The current geometric design methods of the leading edge are usually developed based on the flow characteristics at the designed incidence angle. However, few research focuses on the quantitative rules of the leading edge flow characteristics at the off-designed incidence angle in a compressor cascade. This situation restricts the further optimization and development of the leading edge geometry design method. In this paper, starting from the research of a potential cascade theory, the singularity point, where the surface velocity approaches infinity in the leading edge region, is eliminated by applying the characteristic that the ratio of the velocity increasement on the incidence angle in the plate cascade and the isolated plate flow is finite. Secondly, the equivalent pitch lengths based on 1/cos(β) and VI caused by a diffuser deceleration in the cascade passage were employed to correct the effect of the stagger angle. Finally, by introducing the isolated flow around the thick airfoil and considering the influence of the camber line geometry, a model of the variation of the surface velocity near the leading edge under the off-designed incidence angle, named the velocity increment on incidence angle, is derived from any compressor cascade. Hence, the relation between the off-designed incidence angle and the designed incidence angle of the surface velocity in a cascade blade is established, and it depends only on the geometrical parameters. Through a verification using numerical calculations and experimental measurement, the explicit formula for the velocity increment on incidence angle proposed in this paper has high precision near the leading edge.

Generation of vorticity at the open end of acoustic waveguides

It is well-known that high-intensity acoustic fields in narrow open ducts can give rise to shock waves, where the length of the duct is a key factor, but the geometry of the edges at the opening is not. However, the precise geometry of the inner edges of the duct is critical, together with the value of a Reynolds number associated with the boundary layer, in determining whether or not vortices form at the open end of the duct and whether or not they are radiated outwards. The generation and dynamics of these vortical structures are studied experimentally by means of particle image velocimetry, and numerically using Lattice Boltzmann simulations.

Predicting fretting-fatigue endurance of rotating bending shrink-fitted assemblies using a sequential RUIZ-SWT approach: The effect of entrapped debris layer

Fretting-fatigue damage often appears in shaft shrink-fitted assemblies submitted to rotating bending. This paper focuses on the influence of the sleeve edge geometry on such damage. Rotating bending tests have been performed and broken and unbroken specimens have been expertized confirming fretting-fatigue phenomena. A 3D finite element method model was developed to evaluate the sliding and opening lengths. A sequential tribological - fatigue stress analysis strategy allowed the prediction of the maximum crack location ( Ruiz criterion) then the estimation of the fatigue endurance of the assembly using the SWT criterion. The last step of this σSWTXΓmaxapproach considers the presence of a debris layer within the contact to improve the consistency of the service life prediction.

Simulation of Work Hardening in Machining Inconel 718 with Multiscale Grain Size.

Machining nickel-based alloys always exhibits significant work-hardening behavior, which may help to improve the part quality by building a hardened layer on the surface, while also causing severe tool wear during machining. Hence, modeling the work-hardening phenomenon plays a critical role in the evaluation of tool wear and part quality. This paper aims to propose a numerical model to estimate the work-hardening layer for a deeper understanding of this behavior, employing both recrystallization-based and dislocation-based models to cover workpieces with multiscale grain sizes. Different user routines are implemented in the finite element method to simulate the increase in hardness in the deformed area due to recrystallization or changes in the dislocation density. The validation of the proposed model is performed with both literature and experimental data for Inconel 718 with small or large grain sizes. It is found that the recrystallization-based model is more suitable for predicting the work-hardening behavior of small-grain-size Inconel 718 and the dislocation-based model is better for that of large-grain-size Inconel 718. Further, as an important type of cutting tool in machining Inconel 718, the chamfered tools with different edge geometries are employed in the simulations of machining-induced work hardening. The results illustrate that the uncut chip thickness and chamfer angle have a significant influence on the work-hardening behavior.

Manufacturing Analysis of Face Milling Technology by Tool Setting Using the Same Initial Parameters

Abstract The axis of rotation of the tool is perpendicular for the machined surface in case of face milling technology. This technology is applicable for manufacturing of planar surfaces. It can be feasible by conventional or computer numerical controlled (CNC) machines. The aim of this study is the manufacturing analysis of different tool settings that can cause different arc of contacts. The applied manufacturing parameters are the same except the tool position is changed in comparison with the workpiece. The tool is doing rotation motion while we are moving the table under to tool. The edge geometry of the tool can significantly influence the chip separation conditions, the tool wear and the received surface roughness.

The curved uncut chip thickness model: A general geometric model for mechanistic cutting force predictions

The curved uncut chip thickness model is introduced to predict the cutting forces for general uncut chip geometries using the mechanistic approach. Classical geometric models assume that the cutting force is distributed along straight elementary sections of the uncut chip area, which has limited physical validity, but makes mathematical treatments easier for simple cases. The new model assumes that the flow of the material on the contact area of the tool is given by a continuous vector field, according to which the curved uncut chip thickness is measured. The cutting force is distributed along these paths, which leads to a mathematically unique and consistent solution for regular and complex cutting edge geometries. These curved paths can be generated by basic mechanical models, which mimic the more realistic motion of the chip segments along the rake face, without the need of explicit time-consuming cutting simulations. The presented computational procedure generalizes cutting force prediction based on geometric parameters, orthogonal cutting data and the orthogonal to oblique transformations only. The effectiveness of the model for various cutting edge geometries (e.g., thread turning inserts) under extreme cutting conditions is presented in case studies, laboratory and industrial experiments.

Toward accurate measurement of electromagnetic field by retrieving and refining the center position of non-uniform diffraction disks in Lorentz 4D-STEM

Recent advancement in scanning transmission electron microscopy (STEM) allows the use of 4D-STEM, a technique that captures an electron diffraction pattern at each scan point in STEM, to measure electrostatic and magnetic potential and field in materials. However, accurate measurement, separation of the magnetic and electric signals, and removal of artifacts remain challenging, especially in the presence of complex non-uniform diffraction contrast within the disks. Here, based on dynamic simulations of 4D-STEM patterns built upon superstructures consisting of millions of atoms to account for different sample thickness and edge geometries, we show how the shape and intensity distribution of the central disk are affected by multiple scattering. We propose a robust refinement procedure through iteration of the spin-sensitive peak position of the disk-center in the circular Hough transform filtered images from experimental Lorentz 4D-STEM dataset after minimizing the possible artifacts, such as those due to the change of thickness, dynamic scattering, and scanning process. We verify that caution must be taken as in practice the rigid-disk-shift model used to reconstruct induction maps can easily break down due to disk-protrusion when there exists a nonconstant phase gradient or thickness within the width of the probe. Through quantitative analysis and comparing experiment with calculation the effect of the non-spin-related intensity distribution inside the disk as well as that causes the disk shift due to the intensity-protrusion can be removed, and high-quality magnetic field mapping is possible.

Optimization of dead metal zone to reduce cutting forces in micro milling of Inconel 718 using RSM

This study focuses on the mechanism of DMZ (dead metal zone) creation, as well as the impact of cutting edge geometries (sharp, chamfered, double chamfered, and blunt edges), cutting speed, and coefficient of friction on DMZ formation while milling Inconel 718 material (FEM). A non-contact type sensor called a laser doppler vibrometer (LDV) is used to monitor the vibration of rotating surfaces. In current research work, the LDV is used to measure the mill cutter vibration in micro-milling of Inconel 718 in terms of acoustic optic emission signals. A FFT (fast fourier transformer) is used for signals processing in to frequency domain. Design of experiments as per Taguchi, experiments were performed on the alloy at three levels of spindle speeds, depth of cuts, feed rates. Experimental results on the amplitude o vibration of tool along X and Y directions, surface roughness were measured and analysed using response surface methodology. Analysis obtained from the variance was used to recognize the significant parameters which effect the vibration of tool and roughness of surface. RSM was implemented and optimized process parameters for the minimum vibration amplitude and surface roughness.

Safety in Rough Milling of Magnesium Alloys Using Tools with Variable Cutting Edge Geometry

Safety in Rough Milling of Magnesium Alloys Using Tools with Variable Cutting Edge Geometry