Cut Shape Research Articles

Circular Spline Tooth Longitudinal Modification Design and Contact Analysis for Harmonic Drives with Short Flexspline

Harmonic drives (HDs) with short flexspline (FS) always suffer from small meshing areas and severe stress concentration caused by large cone angles when a short FS is assembled and loaded. To address this issue, a tooth longitudinal modification method for the circular spline (CS) with a double circular arc common-tangent tooth profile (DCTP) is proposed. Using neutral layer and envelope conjugation theories, a mathematical model of the conventional straight CS tooth was developed. A shaping cutter for this tooth profile was then designed through coordinate transformation and meshing principles. The proposed longitudinal modification for the CS was achieved by adjusting the cutter’s trajectory. A precise finite element model of the HD was developed, revealing that tooth longitudinal modification can reduce the maximum contact pressure by 69.6% and significantly increase the contact area for HDs with short FS. This work provides valuable technical references for improving the contact state of HDs with short FS.

EXPERIMENTAL INVESTIGATION ON THE SHEAR RESISTANCE OF I-SHAPED PERFORATED CONNECTORS IN COMPOSITE BEAMS

Introduction: Steel-concrete composite girders have been widely used in bridges, with the stability of the interface being crucial. Shear connectors and reinforced concrete slabs play a key role as interfaces. Understanding the interaction between the composite beam and slab is essential for predicting the overall system response. It is necessary to optimize the connection between steel beams and reinforced concrete slabs in steel-concrete composite girders and facilitate their assembly and installation on-site, emphasizing their pivotal role in upholding the structural integrity of composite systems. The purpose of the study was to conduct an experimental investigation and a numerical simulation using the finite element method. During the study, the following methods were used: examining the behavior of IPE and IPN perforated shear connectors using push-out tests. The main objective was to analyze how the I-shaped perforated connector, concrete slab, steel beam, and rebar affect the measured slip between the steel beam and concrete slab. To achieve that, specimens with IPE80 or IPN80 shear connectors having circular or long cut holes containing 8 mm or 6 mm diameter steel bars were used to enhance the connector’s resistance against uplift forces. The test setup follows Eurocode 4 guidelines, focusing on hole shape and anti-lift rebar diameter parameters. The predominant failure modes were mainly dictated by the crushing of the concrete slab. As a result, it was found that the hole geometry of IPE and IPN perforated shear connectors significantly impacts shear load capacity and ductility. The long cut hole shape in IPE and IPN perforated shear connectors exhibits superior ultimate load capacity but less interfacial slip compared to the circular hole. The IPE and IPN perforated shear connectors demonstrated satisfactory ductility for all tested hole shapes, and the 3D finite element models are consistent with the test results.

A novel time-varying mesh stiffness model for orthogonal face gear drives considering EHL

PurposeThis study aims to research the time-varying mesh stiffness (TVMS) model for orthogonal face gear drives considering elastohydrodynamic lubrication (EHL) and provide a theoretical basis for understanding the dynamic characteristics of face gear drives.Design/methodology/approachConsidering EHL, a novel model is proposed to calculate the TVMS of orthogonal face gears using the deformation compatibility condition. First, the tooth surface equations of orthogonal face gears are derived according to the tooth surface generation principle. Then, the oil film thickness on the tooth surface of face gears is obtained by solving the governing equations of EHL. Furthermore, the proposed model is used to calculate the TVMS of face gears along the mesh cycle and is verified. Finally, the effects of module, tooth number of shaper cutter and pressure angle on mesh stiffness are analyzed.FindingsThe results indicate that when the contact ratio is greater than 1 and less than or equal to 2, the TVMS of face gears exhibits a phenomenon of double-single tooth alternating meshing where sudden changes occur. As the module increases, the overall mesh stiffness of face gears increases, and the magnitude of the sudden change at the moment of single-double tooth alternating meshing gradually increases. As the tooth number of shaper cutter and pressure angle increase, so does the TVMS of face gears. When the effect of oil film is considered, the calculated TVMS of face gears slightly increases overall and the increase in average oil film thickness leads to a rise in the TVMS. This study provides a theoretical basis for understanding the dynamic characteristics of face gear drives.Originality/valueThis study’s originality and value lie in its comprehensive approach, which includes conducting analysis based on loaded tooth contact, considering the influence of elastohydrodynamic lubrication, proposing a novel analytical–finite–element model, calculating TVMS of face gears, verifying the proposed model and analyzing the effects of typical structural parameters and oil film thickness.

Investigation on rock-breaking characteristics of hard sandstone by non-planar PDC cutters under high confining pressure

Due to high hardness, strong heterogeneity, and low drillability in deep formations, conventional Polycrystalline Diamond Compact (PDC) bits with planar cutters usually get bit worn, short drilling footage, and low rate of penetration (ROP) when drilling into such formations. To improve the aggression and the impact resistance of PDC bit, a series of non-planar PDC cutters have been proposed and developed by scholars and oil & gas industries. However, the in-situ stress and hydrostatic pressure significantly weaken the rock-breaking performance of PDC cutters, which is a paucity in related studies. Consequently, this paper conducts rock-cutting experiments in hard sandstones by planar cutters and three types of ridged cutters under confining pressure and atmospheric conditions. The influences of cutting parameters on the rock-breaking performances of different cutters are investigated, focused on the changes in cutting force, mechanical specific energy, and rock cuttings distribution. Additionally, visual cutting experiments are conducted to compare the differences in the rock-breaking mechanisms of different cutters. The results indicate that in-situ stress and hydrostatic pressure exert a noticeable inhibitory effect on rock fragmentation, resulting in smaller cuttings and lower rock-breaking efficiency than those under atmospheric conditions. Furthermore, compared to the three types of ridge cutters, planar cutters exhibit a lower rock-breaking efficiency. Ridged cutters, which leverage the efficient stress concentration caused by their ridges, demonstrate a higher rock-breaking performance by effective and efficient rock failure near the ridges. Additionally, under different cutting parameter conditions, each cutter have a corresponding optimal rock-breaking efficiency range. Specifically, for the triple-ridged concave cutters, the highest rock-breaking efficiency is achieved when the cutting angle is approaching 20°. As the cutting angle increases, the axe-shaped cutter exhibits the highest rock-breaking efficiency. In addition, the triple-ridged concave cutter and the axe-shaped cutter possess unique rock-breaking advantages, with the former being more stable and the latter producing larger volumes of cuttings. The selection of appropriate cutter parameters can enhance the service life and the drilling speed of PDC bits. The experimental results and optimization charts have significant implications for selection on cutter shapes and the design of hybrid-cutter parameters in deep hard formation drilling.

Analisis Preferensi Konsumen Daging Ayam Broiler di Pasar Tradisional Kabupaten Jember Jawa Timur

Broiler chicken meat or usually known as broiler chicken, is easy to find in traditional markets and modern markets in Jember Regency. Consumers see a product as a collection of attributes that will determine a preference. A person's preferences can be formed through a person's behavior patterns which are based on several reasons, namely, previous experience and hereditary beliefs. The existence of people who still choose traditional markets amidst the rise of modern markets has become a social phenomenon. The aim of the research is to find out what attributes of broiler chicken meat are consumer preferences and what attributes are most considered by consumers. The research method used is descriptive. The data collection methods in this research are primary and secondary data. The analytical methods used are Chi Square analysis and Fishbein Multiattribute analysis. The results of the research show that all the attributes observed in this study, namely meat color, meat aroma, meat parts and cut shape, are significantly different within the 95% confidence level, meaning that there are differences in consumer preferences for the existing attributes (color, aroma, part and shape of the cut). on broiler chicken meat. Broiler chicken meat which is the consumer preference in traditional markets in Jember Regency is broiler chicken meat with attributes of choice including yellowish white color, non-fishy aroma, chicken thigh meat, and even cut shape. The attributes that are most considered and those that are least considered are color, aroma, part of the meat, shape of cut.

The time evolution of the mother body of a planar uniform vortex moving in an inviscid fluid

The time evolution of the mother body of a planar, uniform vortex that moves in an incompressible, inviscid fluid is investigated. The vortex is isolated, so that its motion is just due to self-induced velocities. Its mother body is defined as the part internal to the vortex of the singular set of the Schwarz function of its boundary. In the present analysis, it is an arc of curve (branch cut), starting and ending in the two internal branch points of this function, across any point of which the Schwarz function experiences a finite jump. By looking at the mother body from the outside of the vortex, it behaves as a vortex sheet having density of circulation given by the jump of the Schwarz function. Its name (mother body) is taken from Geophysics, and it is here used due to its property of generating, outside the vortex and on its boundary, the same velocity as the vortex itself. The shape of the branch cut and the jump of the Schwarz function across any point of it change in time, by following the motion of the vortex boundary. As it happens for a physical vortex sheet, the mother body is not a material line, so that it does not move according to the velocities induced by the vortex. In the present paper, the cut shape, the above jumps, as well as the cut velocities are deduced from the time evolution equation of the Schwarz function. Numerical experiments, carried out by building the branch cut and calculating the limit values of the Schwarz function on its sides during the vortex motion, confirm the analytical calculations. Some global quantities (circulation, first and second order moments) are here rewritten as integrals on the cut, and their conservation during the vortex motion is analytically and numerically verified. Indeed, the numerical simulations show that they behave in the same way as their classical contour dynamics forms, written in terms of integrals on the vortex boundary. This proves that the shape of the cut, as well as the limit values of the Schwarz function on its sides, are correctly calculated during the motion.

Phenotyping Wheat Kernel Symmetry as a Consequence of Different Agronomic Practices

The use of instrumental methods of analysis in the assessment of indices that record changes in symmetry in the structure of grains to evaluate the quality of durum and soft wheat grain is currently considered a search tool that will allow us to obtain previously unavailable data by finding correlations associated with differences in the shape and ratio of starch granules in conditionally symmetrical and asymmetrical wheat fruits (kernels) formed in different field conditions and with different genotypes. Indicators that had previously shown their effectiveness were used to analyze the obviously complex unique material obtained as a result of growing under critically unique sowing conditions in 2022, which affected the stability of grain development and filling. For the evaluation, a typical agronomic comparative experiment was chosen, which was used to evaluate the soil tillage practices (fallow, non-moldboard loosening, and plowing) and sowing dates (early and after excessive rainfalls), which made it possible to analyze a wider range of factors influencing the studied indices. The soil tillage methods were found to affect the uniformity of kernel fullness and their symmetry, and the sowing dates did not lead to significant differences. This study presents detailed changes in the shape of the middle cut of a wheat kernel, associated with assessing the efficiency of kernel filling and the symmetrical distribution of storage substances under the influence of external and internal physical factors that affect the formation of the wheat kernel. The data obtained may be of interest to breeders and developers of predictive phenotyping programs for cereal grain and seeds of other crops, as well as plant physiologists.

Study on Microstructure, Mechanical Properties, Tribological Properties and Service Performance of CrAlN and CrAlBN Coatings Deposited on Powder Metallurgy High-Speed Steel (PM-HSS) and Shaper Cutter by Arc Ion Plating Technique

CrAlN and CrAlBN coatings were prepared on the surface of high-speed steel and shaper cutter by physical vapor deposition (PVD) technique using arc ion source. In the process of coating preparation, the adhesive layers were deposited by low bias voltage (−40 V) and the working layers are deposited by high bias voltage (−130 V). The effects of the addition of B element on the microstructure, hardness, elastic modulus and wear resistance of CrAlBN coating were studied. The results show that B element and its compounds exist in amorphous form in the coating, resulting in lattice distortion of the coating, increase of coating hardness to 37.1 GPa, and decrease of elastic modulus to 406.2 GPa. The addition of B element increases the uniformity of the columnar structure distribution and decreases the width of the columnar structure and grain size. The resistance to elastic deformation and plastic deformation of CrAlBN coating is improved, the wear resistance is improved. The performance of CrAlN and CrAlBN coatings on shaper cutter was studied. It was found that the main failure mode of shaper cutters is boundary wear and the wear mechanism of coatings had changed obviously. CrAlBN coating is mainly due to fatigue induced failure, accompanied by some diffusion wear. The addition of B element makes the CrAlBN coating have excellent resistance to oxidative wear, abrasive wear and diffusion wear during cutting. The results show that the addition of B element can improve the microstructure and mechanical properties of CrAlN coating, and the preparation of CrAlBN coating on the surface of the shaper cutter can significantly improve the service life of the coated shaper cutter, which has significance for the development of the shaper cutter industry.

Investigation on the rock-breaking performance of specially-shaped PDC cutter under confining pressure conditions

Cutter shape has a significant influence on the rock-breaking performance of drill bit. Compared with conventional Polycrystalline Diamond Compact (PDC) cutter, the emergence of specially-shaped PDC cutters (SSPCs) with different geometric shapes is of great benefit to solve the problems of low rate of penetration (ROP) and rock-breaking efficiency in deep hard and hot dry rock formations. However, the high confining pressure and high in-situ stress (HCHS) have a significant influence on the rock-breaking performance of PDC cutter which cannot be ignored. Given that the above facts, this paper selects five kinds of PDC cutters with different cutter shapes, and implements a series of cutting experiments of granite under confining pressure conditions (CPCs) and atmospheric pressure condition (APC) using a true triaxial rock cutting device. The influence of cutter profile on the rock-breaking performance of PDC cutter was studied from the perspective of cutting force, mechanical specific energy (MSE), cuttings, coarseness index (CI) and fractal dimension. The results show that the rock breaking under CPC is more difficult than that under APC, resulting in the increased cutting force and MSE. Moreover, the cuttings obtained under CPC are smaller in size and the cutting grooves are smoother. Cutter shape has a great influence on the rock-breaking efficiency of PDC cutter, the rock-breaking efficiency of axe-shaped cutter is higher, while that of stinger cutter is lower. Moreover, PDC cutters with different shapes have different sensitivities to confining pressure, and stinger cutter has the lowest sensitivity to confining pressure, in other words, confining pressure has little influence on the rock breaking process of stinger cutter. What is more, the distribution of cuttings is characterized by the fractal dimension and particle size distribution parameter from the perspective of cuttings morphology and size respectively, and they present completely opposite changing trends. The obtained results are of great significance to the optimization of cutter profile, the design of bit cutter arrangement and the drilling of deep formation.

A particle finite element method approach to model shear cutting of high-strength steel sheets

AbstractShear cutting introduces residual strains, notches and cracks, which negatively affects edge-formability. This is especially relevant for forming of high-strength sheets, where edge-cracking is a serious industrial problem. Numerical modelling of the shear cutting process can aid the understanding of the sheared edge damage and help preventing edge-cracking. However, modelling of the shear cutting process requires robust and accurate numerical tools that handle plasticity, large deformation and ductile failure. The use of conventional finite element methods (FEM) may give rise to distorted elements or loss of accuracy during re-meshing schemes, while mesh-free methods have tendencies of tensile instability or excessive computational cost. In this article, the authors propose the particle finite element method (PFEM) for modelling the shear cutting process of high-strength steel sheets, acquiring high accuracy results and overcoming the stated challenges associated with FEM. The article describe the implementation of a mixed axisymmetric formulation, with the novelty of adding a ductile damage- and failure model to account for material fracture in the shear-cutting process. The PFEM shear-cutting model was validated against experiments using varying process parameters to ensure the predictive capacity of the model. Likewise, a thorough sensitivity analysis of the numerical implementation was conducted. The results show that the PFEM model is able to predict the process forces and cut edge shapes over a wide range of cutting clearances, while efficiently handling the numerical challenges involved with large material deformation. It is thus concluded that the PFEM implementation is an accurate predictive tool for sheared edge damage assessment.

PROFILING OF CUTTING TEETH OF A GEAR SHAPING HEAD

This paper investigates a possibility of the use of the mathematical model of the cutting edge profile developed for turning form cutter in the profiling the cutting edge of the tooth of a gear gushing head. The corresponding cutting tooth of the gashing head was carried out with Mathcad commercial software package accounting for the rake and clearance angles. The use of the same mathematical model increases the degree of automation of the design of various types of form cutting tools, which is the goal of many research work in the field of tool design and its manufacturing. In order to apply the mathematical model of the tuning form tool during the profiling of cutting teeth of a gear gashing head, arrays of coordinates of the points of the involute profile of the tooth are formed accordingly. This was carried out accounting on the difference in the motions of cutting edge of the tuning form tool and that of a gear gushing head. Moreover, the obtained results allow to conclude that the developed generalized mode can be used not only for great gushing tools but also for gear generating tools as gear shaper cutters.

Rock-breaking performance of specially-shaped PDC cutters from a new insight into the damage beneath cutting groove

Deep formation drilling ushers in a new direction of exploration due to the advantages of specially-shaped polycrystalline diamond compact (PDC) cutters which conventional PDC cutters cannot provide. To clarify the rock-breaking mechanism of specially-shaped PDC cutters, experiments using single-cutter cutting tests and secondary cutting tests were carried out to reveal the influence of cutter shape on the ability to remove rocks and affect grooves. This paper compared and analyzed the mechanical cutting performance, cuttings shape, and groove damage ability of four specially-shaped PDC cutters. And proposed two new concepts (the damage impact factor and the damage intensity factor) based on the rock-breaking behavior of secondary cutting to evaluate the ability of specially-shaped PDC cutters to affect grooves. The experimental results show that the aggressiveness, representing the difficulty of the rock-cutting process, was significantly influenced by the cutter's shape, and its value increased with the increase of depth of cut (DOC). The experimental results show that the cutter's shape significantly influences the aggressiveness, representing the difficulty of the rock-cutting process, and its value increased with the increase of DOC. Axe Cutter and Tri-Plane Cutter shows a higher aggressiveness and a lower MSE during the rock-cutting process, but they produce a strong compression around the grooves. In contrast, the Stinger Cutter and Wedge Cutter exhibit low aggressiveness and high MSE, with lower compression and increased damage around the groove. The experimental results further improve the understanding of the rock-breaking mechanism of specially-shaped PDC cutters, which offers valuable insights for selecting and arranging PDC cutters in deep formations.

Tunable Acoustic Properties in Reconfigurable Kerf Structures

Freeform structures are appealing in architecture owing to their ability to combine pleasing aesthetics and functionality. Regarding architectural functionality, freeform structures have the potential to meet desired acoustic requirements in indoor architecture through the proper design of materials and geometries. Kerfing is one of the practical methods to generate reconfigurable freeform structures from rigid planar construction materials. This study aims to explore tunable room acoustic characteristics through the use of kerf structures. In this study, we investigate acoustic responses of kerf structures made out of a medium density fiber board having a hexagon spiral kerf pattern with varying cut densities. Experiments are conducted to measure the acoustic properties (e.g., absorption coefficient) of the kerf unit cells with different cut densities. We then design kerf patterns using the parametric design method and explore the flexibility of kerf structures with different kerf cut densities. We model the kerf structures of varying kerf cut density and shape reconfigurations and use a ray-tracing simulation to study their impacts on the acoustic performance, i.e., reverberation times, of a small office space. Overall, this study leverages the unique attributes of kerf structures such as different cut densities and shape reconfigurations to tune the room acoustics in addition to their usage in indoor architectures due to their pleasing aesthetics.

Mixed Reality for Safe and Reliable Human-Robot Collaboration in Timber Frame Construction

In the field of construction, human-robot collaboration and mixed reality (MR) open new possibilities. However, safety and reliability issues persist. The lack of flexibility and adaptability in current preprogrammed systems hampers real-time human-robot collaboration. A key gap in this area lies in the ability of the robot to interpret and accurately execute operations based on the real-time visual instructions and restrictions provided by the human collaborator and the working environment. This paper focuses on an MR-based human-robot collaboration method through visual feedback from a vision-based collaborative industrial robot system for use in wood stereotomy which we are developing. This method is applied to an alternating workflow in which a skilled carpenter lays out the joinery on the workpiece, and the robot cuts it. Cutting operations are instructed to the robot only through lines and conventional “carpenter’s marks”, which are drawn on the timbers by the carpenter. The robot system’s accuracy in locating and interpreting marks as cutting operations is evaluated by automatically constructing a 3D model of the cut shape from the vision system data. A digital twin of the robot allows the carpenter to previsualize all motions that are required by the robot for task validation and to know when to enter the collaborative workspace. Our experimental results offer some insights into human-robot communication requirements for collaborative robot system applications in timber frame construction.

Changes in the Design Shape of Two-Block Asymmetrical Cuts According to the Head Shape Division, Angle, and Slice Line

Purpose: In this study, the weight line is the right (diagonal) line and the shape line is the asymmetrical cut of the left (diagonal) line rendered in the form of two blocks. In addition, it is meaningful to provide basic data on haircuts by demonstrating the design and length changes according to head area division, angle, and slice line.Methods: It is divided into upper and lower parts starting from golden back medium point, back point, and back nape medium point. 10 cm at the upper point, diagonal (V) line on the left, diagonal (A) line on the right, celestial axis of 0°, and a head angle of 20°, and 40° were used.Results: LGBM1 and LB1 were observed as two-block asymmetrical cuts, expressing rhythm, mystery, liveliness, dynamic, and freshness. However, LBNM1 was observed only asymmetrically. Since the asymmetrical cut is different from left to right, a heterogeneous phenomenon appeared. Regular asymmetry is thought to provide dynamism, liveliness, rhythm, and freshness expressed as harmonious beauty of order and balance. In addition, since the slice line is started from the side, it is considered that the slope is less than that starting from the back. One length symbolizes smoothness, orderliness, and heaviness, and the gradation has both a smooth texture and rough texture.Conclusion: Asymmetrical cuts can provide freshness, mystery, dynamism, liveliness, and rhythm through imbalance. In other words, the asymmetrical cut can be balanced and harmonized with creative effects. In future studies, it is expected that studies on the mixed form of gradation and uniform layer cut, volume cut, and design form of the front of the head and the temporal area of the head will be conducted.

Morphological features of stab–cut wounds of the skin of the trunk and limbs inflicted by kitchen knives

Examination of injuries caused by sharp objects is a complex process that requires the application of a whole range of knowledge not only in the field of forensic medicine, but also in human anatomy. Among all sharp objects, stab–cut objects are the most common, namely the kitchen knife. Researching the peculiarities of the morphology of injuries to various anatomical parts of the human body with this subject would improve the quality of forensic research. The purpose of the study is to analyze the morphological features of stab–cut wounds to the skin of the trunk and limbs caused by kitchen knives. A forensic examination of 93 stab–cut wounds of corpses, which were inflicted by kitchen knives with one-sided sharpening and a straight butt, was carried out. Wounds in the chest ranged in size from 1.7×0.2 cm to 4.3×0.6 cm; wounds in the abdomen ranged in size from 1.8×0.4 cm to 3.3×0.7 cm; wounds in the lumbar region had sizes from 1.7×0.2 cm to 4.0×0.6 cm; wounds on the upper extremities – from 1.5x0.9 cm to 3.0×0.6 cm and wounds on the lower extremities from 1.5x0.2 cm to 3.2x0.6 cm. In all cases, the wounds had even edges and a smooth surface of the walls. Wounds located along Langer's line have a linear shape, and those located across Langer's lines have an oval shape. In addition, a different shape of the butt section was found, depending on the localization and the force of immersion. In this way, characteristic differences in the shape of the butt cut were revealed and the existence of differences in its morphology in different anatomical parts of the body was proved. Taking into account the location of the injury according to the location of Langer's lines should be standard procedure in forensic investigations of injuries caused by sharp objects.

Testing and predicting the response of reinforced conrete shear walls retrofitted for recentering

Laboratory tests were conducted to investigate the feasibility of a new retrofit method for reinforced concrete shear walls to enable self-centering and to evaluate strength and drift capacity prediction methods for pre- and post-retrofit walls. The proposed retrofit method involved cutting the base of a wall, adding external post-tensioning, and providing additional confinement at wall toes. Three shear walls, one benchmark and two retrofitted specimens, were tested under quasi-static cyclic lateral loading. The two retrofitted specimens differed in the initial post-tensioning force, external confinement plate size, and base cut shape. The benchmark specimen exhibited both flexure and shear damage, whereas the governing displacement mechanism for the retrofitted walls was rocking at the wall-to-foundation interface. As intended, the strengths of the retrofitted walls were 80% to 100% of that of the benchmark specimen. The retrofitted walls had larger drift capacities, fewer cracks, smaller areas of concrete crushing, lower residual drifts, and sufficient energy dissipation. The existing methods predicted the strength and drift capacity of the pre-retrofit specimen reasonably well, yet overestimated the strength and underestimated the drift capacity of the post-retrofit specimens.

Micro-macro fracture mechanism of heterogeneous granite in percussive drilling

The conventional rotary rock breaking method faces a technical bottleneck in improving the rate of penetration (ROP) in deep hard formations. Percussive drilling is the most potential approach to increase rock-breaking efficiency and ROP. However, the rock-breaking mechanism of percussive drilling is still unclear enough, especially the micro-fracture mechanism of rock under confining pressure (under lateral pressure and hydraulic pressure). In this paper, the impact rock breaking experiments by four kinds of Polycrystalline Diamond Compact (PDC) cutters are carried out using a drop-weight impact testing machine and an acoustic emission (AE) recording system, the influence of parameters such as cutter shape, rake angle, and impact energy on rock-breaking are systematically analyzed. This study includes a numerical simulation to examine the process of crack initiation, propagation, and cuttings formation during the impact process with the consideration of confining pressure. The results show the conical-shaped cutter is the most aggressive with high breaking efficiency. The penetration depth of the cutter is mainly influenced by the impact energy and cutter shape than the rake angle of the cutter. There exists critical impact energy makes the rock breaking efficiency the highest. The critical impact energy is about 40 J when using the conical-shaped cutter with a rake angle of 15°. The rock mainly failed in tensile mode, and the inter-grain crack is the main crack. Hydraulic pressure can inhibit the formation of horizontal cracks, while lateral pressure can inhibit the formation of vertical cracks and reduce the proportion of tensile cracks. The research results can provide some reference and basis for improving the rock-breaking efficiency in deep hard formations.

Vibration chiseling: A backward-moving cutting for the high-efficiency fabrication of short metallic microfibers

This study proposes a rapid process for fabricating metallic microfibers: vibration chiseling. A parallelogram-shaped vibration is superimposed on the tool using a two-dimensional non-resonant vibration device, while the tool moves backward relative to conventional cutting. In this way, the material can be chiseled out from the surface as a chip during each vibration cycle to form a microfiber. Increasing the tool vibration frequency allows the short fibers to be produced rapidly. The tool vibration trajectory, tool shape, backward-moving velocity, and depth of cut (DoC) are the crucial parameters that control the microfiber’s geometries. Machining tests have been conducted on copper under different tool-moving velocities and DoC to verify the efficacy of the proposed process. Copper microfibers with a length of tens to hundreds of microns and a diameter of 2 ∼ 4 µm have been successfully fabricated, demonstrating that vibration chiseling has good reproducibility, controllability, and efficiency.

Beef Quality Classification with Reduced E-Nose Data Features According to Beef Cut Types.

Ensuring safe food supplies has recently become a serious problem all over the world. Controlling the quality, spoilage, and standing time for products with a short shelf life is a quite difficult problem. However, electronic noses can make all these controls possible. In this study, which aims to develop a different approach to the solution of this problem, electronic nose data obtained from 12 different beef cuts were classified. In the dataset, there are four classes (1: excellent, 2: good, 3: acceptable, and 4: spoiled) indicating beef quality. The classifications were performed separately for each cut and all cut shapes. The ANOVA method was used to determine the active features in the dataset with data for 12 features. The same classification processes were carried out by using the three active features selected by the ANOVA method. Three different machine learning methods, Artificial Neural Network, K Nearest Neighbor, and Logistic Regression, which are frequently used in the literature, were used in classifications. In the experimental studies, a classification accuracy of 100% was obtained as a result of the classification performed with ANN using the data obtained by combining all the tables in the dataset.