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In water-guided laser technology, the stability of water jets is crucial to ensure the efficient transmission of laser energy. However, the thermal effects generated when high-power lasers are coupled with water jets are bound to impact the stability of the water jets, thus becoming a critical issue that restricts the development of high-power water-guided laser technology. In addressing this issue, this paper establishes a temperature model for coupling high-power lasers with water jets. Subsequently, with validation of the model's effectiveness through experimental data, simulations are conducted to analyze the temperature distribution within the water jet. During the simulation process, lasers with different parameters were coupled with water jets to analyze the temperature variation law of the water jets. Additionally, the maximum laser power coupled with water jets of different lengths was solved. Based on the calculated temperature values of the water jet, simulate the evolution of its profile over time when it has an initial temperature gradient. Simultaneously, perform a three-dimensional reconstruction of the obtained perturbed profile and conduct ray tracing to analyze the laser's transmission losses within the perturbed profile. Finally, high-speed cameras are utilized to capture the profile of the water jet, validating the laser-induced fragmentation behavior in the water jet. The research findings will provide a significant reference value for selecting laser parameters and controlling thermal effects in water-guided high-power technology. [ABSTRACT FROM AUTHOR]

The challenging machinability of silicon carbide (SiC) ceramic, due to its hardness and brittleness, has traditionally constrained its machined quality and the creation of functional surfaces. Compared to direct laser machining (DLM), waterjet-assisted laser micromachining (WJALM) is an alternative technique for SiC ceramic that is capable of reducing thermal-induced damages. In this paper, high-aspect-ratio (HAR) microchannels are fabricated on silicon carbide ceramic by WJALM, and its effectiveness is verified through comparative experiments with DLM. The effects of the parametric combination of waterjet and laser parameters on machining responses of geometric structural features and sidewall surface quality are investigated by controlled variable experiments. The results revealed that HAR microchannels with almost no recast layers could be obtained when the SiC workpiece was fabricated by a nanosecond laser under the flowing water medium layer, and higher average laser power of 27 W, lower scanning speed of 600 m/s, and medium waterjet velocity of 12/16 m/s contributed to larger aspect ratio, more ablation area and superior sidewall quality of HAR microchannels. [ABSTRACT FROM AUTHOR]

This study introduces an artificial neural network (ANN) model for optimizing process parameters to reduce the chances of delamination in carbon fiber-reinforced polymer (CFRP) materials during abrasive water jet (AWJ) piercing. AWJ is a proper method for cutting CFRP. The initial step in this process is AWJ piercing, which creates entry holes in the material to facilitate further cutting operations. However, AWJ piercing is particularly challenging due to the high energy applied to the material. If it is not properly controlled, this high-energy impact can cause material delamination. Avoiding CFRP delamination is a critical aspect when expensive parts are processed with AWJ, particularly in the aerospace and automotive industries. This can compromise the CFRP workpiece, and this induces extra costs for rework. The ANN model was trained using backpropagation to predict delamination. It features a feed-forward architecture that balances model complexity and performance. Validation showed that the ANN model effectively predicted optimal process parameters, eliminating delamination in machined CFRP parts. This study underscores the potential of ANNs in enhancing AWJ piercing processes and provides a robust and reliable method of improving the quality of CFRP parts. [ABSTRACT FROM AUTHOR]

High-pressure pure water jet has been widely used in breaking soft rocks and medium–hard rocks, but its research on cutting hard rocks is very limited. The cutting depth, as the most important index for evaluating the effectiveness of rock breaking by water jet, is difficult to be predicted accurately because of numerous influencing factors. This article aims to establish a concise and universal prediction model for the cutting depth of hard rock, including all variables that affect the cutting depth. Firstly, four types of granite and sandstone, which are difficult to break in engineering, are selected to investigate their cutting depth under the action of high-pressure continuous water jets. The rock physico-mechanical parameter that has the highest correlation with the cutting depth is found to be the shear modulus through tests. In order to reasonably evaluate the energy utilization rate of cutting depth of rock by water jet, the concept of cutting depth energy index (CDEI) is proposed. The jet pressure corresponding to the maximum value of CDEI is approximately 40–60% of the rock compressive strength. The idea of "moderate nozzle diameter, high traverse speed, multiple cuts" is put forward for cutting hard rock more efficiently using high-pressure water jet. Then, a new prediction model of cutting depth for high-pressure water jet cutting hard rock is established using similarity theory and dimensional analysis method, and the accuracy and reliability of the model are verified through experimental testing. The results of the study can help to improve the breakage efficiency of hard rock, and at the same time, provide a theoretical basis for the rational selection of high-pressure water jet parameters. Highlights: The concept of cutting depth energy index (CDEI) of rock subjected to water jet is proposed. The most effective cutting technology method for cutting hard rock by water jet is proposed taking into account the cutting effect and specific energy consumption. A new prediction model of cutting depth for high-pressure water jet cutting hard rock was established using similarity theory and dimensional analysis method The primary variables affecting the cutting depth of hard rock are the jet pressure and the shear modulus of the rock [ABSTRACT FROM AUTHOR]

Due to their high hardness at elevated temperatures and chemical stability, alumina-based ceramic cutting tools have been successfully applied in the machining of ferrous materials, especially quenched and tempered steels. Their low fracture toughness, however, makes it difficult to finish them by grinding, as cracks and defects can occur. In addition, its application in machining processes demands appropriate edge preparation to avoid tool failure. Within this context, the paper aims to demonstrate the applicability of an experimental Al2O3 + MgO ceramic cutting insert in hard turning. For this, grinding tests were performed to determine the most appropriate conditions to improve its surface and edge quality. The effects of cutting and feed speeds, grinding wheel bonding material, and abrasive grain size were investigated. Moreover, different cutting-edge geometries were prepared in this tool material and tested in turning a hardened AISI 4140 steel (50 HRC) to determine their performance regarding tool life and workpiece roughness. The results demonstrated that a finer grinding wheel (D15) combined with high cutting (60 m/s) and feed (10 mm/min) speeds leads to the lowest surface roughness and edge chipping. In addition, both symmetric (Κ = 1) and asymmetric (Κ = 2) edge roundings led to higher tool lives in hard turning in comparison to a single chamfered tool, as they contributed to better load distribution in the cutting region. The paper provides information for the manufacture and application of alumina-based ceramic cutting inserts in the metalworking industry, as it disseminates good manufacturing practices and recommendations for appropriate cutting-edge geometry. [ABSTRACT FROM AUTHOR]

The preparation of cubic boron nitride (CBN) grinding tools using laser cladding has the advantages of strong bonding, short time consumption and customizable abrasive arrangement. In this paper, a two-step laser cladding method was used to prepare CBN abrasive blocks with the aim of reducing laser damage to CBN grits during the laser cladding process. The cross-sectional morphology of CBN abrasive blocks under different laser power conditions was characterized, and the relationship among laser power, preparation method, and forming quality of Cu–Sn–Ti/CBN cladding layer was investigated. Then, the microstructure at the Cu–Sn–Ti/CBN interface under different laser power conditions was characterized, and the main phase compositions at the Cu–Sn–Ti/CBN interface were analyzed. Finally, the grinding tests were carried out on CBN abrasive blocks. The results show that as the laser power increases from 250 W to 400 W, the fracture ratio of CBN grits increases dramatically from 4.3 % to 17.3 %. TiN, TiB 2 , and TiB compounds are all detected at the Cu–Sn–Ti/CBN interface under different laser power conditions. The mass loss of the TC4 wheel caused by the CBN abrasive block initially increases and then decreases as the laser power increases from 250 W to 400 W. The CBN abrasive block has the optimum material removal performance at the laser power of 300 W using two-step laser cladding. The results provide a theoretical basis for the preparation of high-performance CBN grinding tools using laser cladding. [ABSTRACT FROM AUTHOR]

Vertical water jets present significant challenges for hydraulic structures due to their potential to cause erosion and structural damage. This study aimed to predict the dimensionless pressure coefficient (Cp) of vertical water jets by examining the relationships between experimental parameters, such as Froude number, slope, and the ratio of waterfall height over the product of the Froude number and diameter, referred to as α, using machine learning models. Two hundred forty controlled experiments were conducted, with pressure data collected. To address the problem's non-linearity, six machine learning models were tested: linear regression, K-nearest neighbors, decision tree, support vector regression, random forest, and XGBoost. The XGBoost model outperformed others, achieving an R-squared of 0.953 and a Root Mean Squared Error (RMSE) of 0.191. Residual analysis validated its better performance, demonstrating that it delivered the most accurate predictions with minimal bias. Feature importance analysis revealed the Froude number was the most significant predictor, followed by slope and diameter. This study emphasizes the importance of the Froude number in predicting jet behavior and shows the efficacy of advanced machine learning models in capturing complex fluid dynamics, providing valuable insights for optimizing engineering applications such as water jet cutting and cooling systems. [ABSTRACT FROM AUTHOR]

The goal of this study was to determine the effect of cutting methods on the edges of selected materials applied in structural elements and floor sheathing of unmanned air vehicles. Three cutting methods for MGS L285 epoxy resin composites used for production of unmanned air vehicles manufactured in one of the European companies were presented. Composites reinforced by glass and aramid fibres are approved for certified production of air vehicle elements (AMC-20). Cutting was applied to each material using different technologies, such as: milling, laser cutting and abrasive water jet cutting. The authors focused on the edge quality of the tested specimens cut using various methods. Quality assessment was based on electronic microscopic scanning images and measurement of the specimen maximum damage. In summary, the choice of an appropriate composite cutting method depends on the type of material and its parameters, and it is crucial for the quality of the machined product. The authors focused on determining the selection of parameters for chosen cutting methods and materials used in the military unmanned aerial vehicle industry. Among the conducted tests, the results indicate that better cutting effects are obtained for milling methods in the case of GFRP + L285 (0.143 ± 0.073 µm) and CFRP + L285 (0.072 ± 0.027 µm), and the worst for AFRP + L285 (0.831 ± 0.269 µm). The water jet method gives the worst results in the cutting zone (results above 0.224 μm). [ABSTRACT FROM AUTHOR]

This study presents a comprehensive three-dimensional computational fluid dynamics (CFD) analysis of abrasive fluid flow and its erosive effects on the active components of the WUXI YCWJ-380-1520 water jet cutting machine. The research investigates the behavior and impact of abrasive particles within the fluid, determining the erosion rates for particles with diameters of 0.19 mm, 0.285 mm, and 0.38 mm (dimensions resulting from the granulometry of the experimentally established sand), considering various abrasive flow rates. The methodology includes a detailed granulometric analysis of the abrasive material, identifying critical particle sizes and distributions, with a focus on M50 granulation (average particle size of 0.285 mm). Additionally, the study employs the Wadell method to determine the shape factor (Ψi = 0.622) of the abrasive particles, which plays a significant role in the erosion process. Experimental determination of the abrasive flow rate is conducted, leading to the development of a second-order parabolic model that accurately predicts flow variations based on the control settings of the AWJ machine. The maximum erosion occurs at the entry surface of the mixing tube's truncated zone, with a higher intensity as the particle size increases. For the 0.19 mm particles, the erosion rates range from 1.090 × 10−6 kg/m2·s to 2.022 × 10−6 kg/m2·s and follow a parabolic distribution. The particles of 0.285 mm show erosion rates ranging from 2.450 × 10−6 kg/m2·s to 6.119 × 10−6 kg/m2·s, also fitting the second-order parabolic model. The largest particles (0.38 mm) exhibit erosion rates ranging from 3.646 × 10−6 kg/m2·s to 7.123 × 10−6 kg/m2·s, described by a third-order polynomial. The study concludes that larger particle sizes result in higher erosion rates due to their increased mass and kinetic energy. Therefore, the present investigation demonstrates a significant relationship between particle size, abrasive flow rate, and erosion rate, highlighting critical wear points in the machine's components. The findings contribute to optimizing the design and operational parameters of water jet cutting machines, thereby enhancing their efficiency and lifespan. [ABSTRACT FROM AUTHOR]

Laminated metal‐composite structures, known as fiber metal laminates (FMLs), are modern lightweight materials extensively utilized in diverse industries such as aerospace and automotive manufacturing. These materials offer enhanced impact and fatigue resistance, making them invaluable for various applications. However, machining FMLs poses a challenge due to the occurrence of delamination and heterogenous in nature during conventional methods. Therefore, this study aims to investigate the quality characteristics such as kerf width, surface roughness and kerf taper of Magnesium based FMLs processed with an unconventional machining process namely abrasive water jet cutting (AWJC). These FMLs comprise alternately stacked kevlar/carbon fibers adhesively bonded with epoxy resin matrix filled with varying wt% of reduced graphene oxide (r‐GO), combined with AZ31B alloy sheet as the skin material. AWJC experiments were performed by varying the process parameters including waterjet pressure (275–325 MPa), stand‐off distance (2.5–3.5 mm), and cutting speed (600–800 mm/min) based on the box–behnken experimental design. The findings from the statistical analysis underscore the significant influences of stand‐off distance and waterjet pressure on kerf characteristics, while the inclusion of r‐GO is observed to notably affect the surface quality. In pursuit of enhancing cut quality, a multi‐response optimization was conducted employing the Gorilla Troops Optimization (GTO) algorithm. Comparative analysis with established metaheuristics like the gray wolf algorithm, dragonfly algorithm, and harmony search algorithm reveals GTO's superior performance across various metrics, including rapid convergence, diversity, and spacing values. Further, the cutting‐induced damages such as matrix plowing, fiber‐metal debonding and composite delamination were observed through microstructure analysis. Highlights: Magnesium (AZ31B) fiber metal laminate comprising with various wt% of reduced graphene oxide was fabricated.Abrasive waterjet cutting of FMLs were performed based on box–behnken design experimental approach.Statistical analysis and influence of process parameters on the kerf width, surface roughness and kerf taper were investigated.Multi‐response optimization was carried out using metaheuristic‐based gorilla troops algorithm. [ABSTRACT FROM AUTHOR]

The existence of striations, and scratches in Abrasive waterjet (AWJ) cutting surface necessitates an exploration of these features for enhancing the cutting accuracy of AWJ machining. This article investigates surface roughness and micro-scratch morphology characteristics on brass cutting surfaces. According to the variation law of surface roughness values, the cutting section can be divided into three regions: the initial region, smooth region, and rough region. Numerous micron-scale scratches were observed in the cutting section. The scratch length, width, and depth values all show an increasing trend as the cutting depth increases, with the scratch length experiencing the greatest growth and variability. The influence of position and traverse speed on scratch size was studied using variance analysis. Furthermore, the length and width of the scratches on the cutting surface are significantly influenced by their position, accounting for 89.19% and 81.13%, respectively. Traverse speed had a minor effect on scratch length and width, accounting for 0.01% and 2.64% respectively. The depth of the scratches is influenced by their position on the cutting surface at a rate of 41.12%, while traverse speed had an impact of 38.10%. Finally, a mathematical method based on standard scores was proposed to assess the quality of the cutting section based on micro-scratch dimension. [ABSTRACT FROM AUTHOR]

Highlights The primary factors affecting the geometric accuracy of abrasive water jet (AWJ) machining of ultra‐thick carbon fiber‐reinforced polymer (CFRP) laminates are the cutting front drag and kerf width deviation caused by energy dissipation. Firstly, this study comprehensively analyzes the influence of the coupling relationship between cutting front drag and kerf width deviation on the geometric accuracy of hole machining. Secondly, a gradient distribution theory for jet traverse speed with cutting depth is proposed for taper hole machining characteristics. Finally, a general geometric error model applicable to both straight and taper hole machining of ultra‐thick CFRP laminates using AWJ is established, along with a geometric error compensation method. A series of experiments validate the accuracy of the proposed geometric error model and compensation method. The novelty of this research lies in unifying the geometric error models for straight and taper hole machining of ultra‐thick CFRP laminates by considering the gradient distribution of jet traverse speed. The proposed error compensation method reduces the high degree of freedom required for machine tools. This study provides a general geometric error model and compensation strategy for AWJ hole machining of ultra‐thick CFRP laminates, which has significant engineering value for achieving 3D controllable AWJ machining of complex ultra‐thick CFRP components. The high geometric precision taper holes machining technique is a necessary prerequisite for achieving precise machining of complex trajectories in ultra‐thick CFRP with abrasive water jet. The influence of the coupling relationship between cutting front drag and kerf taper on the geometric accuracy of hole processing is comprehensively analyzed. A model considering the gradient distribution of traverse speed during taper holes machining was established, and a geometric error model considering this gradient distribution of traverse speed was developed. A taper holes machining geometric error compensation method with high engineering applicability was proposed. Geometric error prediction experiments and error compensation experiments were conducted, and the results proved the accuracy of the geometric error model and error compensation method. [ABSTRACT FROM AUTHOR]

This work investigates the piercing of microholes in turbine shroud rings (Inconel-625) using the Abrasive Waterjet Cutting process. The concern with the hole piercing is the kerf angle caused by the attenuation of the jet energy and stand-off distance, which seriously impacts the processing precision of abrasive water jet piercing. The effects of piercing parameters like machining time (40, 60 and 80 s), abrasive mesh size (80 mesh and 120 mesh), stand-off distance (1, 2, 3 and 4 mm), abrasive jet pressure (100, 125, 150 and 175 MPa) are studied to reduce the kerf angle. The kerf angle increased linearly with a stand-off distance increase at different machining times. By piercing for 60 s and 80 s, the lowest values of kerf angle are obtained (0.03∘ and 0.02∘). The optimum conditions for making a pierced hole with a minimum kerf angle of 0.02∘ were achieved with a machining time- of 60 s, abrasive mesh size- of 20 mesh, and abrasive jet pressure- of Scanning electron microscope (SEM) images and visual measuring system (VMS) images are used to identify the surface characteristics in kerf zone. The features, including ploughing, particle embedment, lip impression and wear path due to the ductile mode of erosion caused by high energy impact, is also discussed. [ABSTRACT FROM AUTHOR]

As a machining tool with great potential, abrasive water jet (AWJ) has been used extensively in cutting many types of difficult-to-cut materials. Actually, using AWJ to trim workpieces is another important application. Unlike other traditional machining tools, which do not make much difference in machining surface through cutting or trimming, the AWJ, a soft knife, would lead to a different shape profile on the machining side in the trimming process other than cutting. To explore the trimming process of AWJ, a specific method of modeling the shape profile of the machining side trimmed by AWJ is proposed in this paper. Firstly, a criterion has been built to classify whether it is a cutting task or an edge trimming task. After that, a series of experiments have been carried out to obtain how the AWJ cutting parameters affect the trimming process. Based on the experimental results, the key parameters affecting the trimming process have been found. Further, a mathematical model for trimming process has been built and its effectiveness has been verified through actual trimming. With this model, the shape error of the machining side trimmed by AWJ can be further reduced by adjusting the compensation parameters. [ABSTRACT FROM AUTHOR]

This study investigates the effects of a water-guided laser on the cutting performance of AISI 1020 steel sheets of various thicknesses by comparing the results with respect to a conventional laser. For this purpose, a novel nozzle design has been devised enabling the delivery of laser beams to the workpiece conventionally as well as through water guidance. Diverging from prior literature, a fiber laser is used with a high wavelength and a laser power output of 1 kW. Experiments are conducted on steel sheets with thicknesses ranging from 1.5 mm to 3 mm using three different cutting speeds and laser power levels. Analysis focuses on assessing surface roughness, burr formation and heat effects on the cut surfaces for both conventional and waterjet-guided cutting. Surface roughness is evaluated by using a 3D profilometer and cut surfaces are examined through SEM imaging. The results showed that the waterjet-guided laser system greatly reduced surface roughness and minimized problems associated with traditional laser cutting such as kerf, dross adherence and thermal damage. The study revealed that cutting speed had a greater effect on surface roughness reduction than laser power, with the most noticeable differences occurring in thinner sheets. Furthermore, the investigation suggests that the waterjet-guided laser cutting system demonstrates superior performance relative to conventional methods, particularly in surface quality. [ABSTRACT FROM AUTHOR]

Precision machining using a premixed abrasive water jet is an important problem to solve. The establishment of predictive mathematical models, physical model analyses, experimental research, and experimental verification are relatively mature. However, there has been little research on the cutting surface roughness of premixed abrasive water jets, so comprehensive studies and theoretical systems are scarce. Consequently, in this study, Q235 carbon structural steel, which is widely used in the industry, was selected for preliminary research. First, based on dimensional analysis, four key influencing parameters on the cutting surface roughness (Ra) of the premixed abrasive water jet were determined—that is, the water jet working pressure (P), feed rate (v), target distance (h), and nozzle outlet diameter (d). A full-factor premixed abrasive water jet cutting experiment L81(34) was then designed and conducted for Q235 carbon structural steel based on the four key influencing parameters. Moreover, based on an analysis of polarity variance, significant relationships between the four key influencing parameters were obtained, with d > v > P > h, and the optimal parameter combinations were obtained—that is, P = 28 MPa, v = 50 mm/min, h = 4 mm, and d = 1.14 mm. Under this parameter combination, the Ra was at its smallest (0.760 µm). Finally, based on multiple nonlinear regression analysis, a predictive mathematical model for the cutting surface roughness of Q235 carbon structural steel was developed, with an arithmetic mean error of 3.811% and a standard deviation of 1.499%. The predictive model exhibited good reliability and predictive effect. [ABSTRACT FROM AUTHOR]

Preconditioning of rock for drilling operations is a potential method to facilitate the mechanical breakage and mitigate the tool wear. This paper numerically investigates one such preconditioning technique, namely, the thermal jet assisted rock cutting. For this end, a numerical method for solving the governing thermo‐mechanical problem is developed and validated. The continuum approach is chosen to describe the rock failure, being based on a damage‐viscoplasticity model with the Drucker–Prager yield surface and the modified Rankine surface as the tensile cut‐off. In the damage part, separate scalar damage variables are employed for tension and compression. The cutters are modelled as rigid bodies and their interaction with the rock is modelled by imposing contact constraints by the forward increment Lagrange multiplier method, which is compatible with the chosen explicit time integration scheme. A damage‐based erosion criterion is applied to remove the contact nodes surrounded by heavily damaged elements. The thermal jets are modelled with a moving external heat flux boundary condition. The global thermo‐mechanical problem is solved with a staggered approach explicitly in time while applying mass scaling to increase the critical time step. The novel 3D numerical simulations involving two cutters demonstrate the capabilities of the method with a special emphasis on cutter‐thermal jet configurations. Therefore, the present method provides a potential tool for the bit design in thermal jet assisted drilling. [ABSTRACT FROM AUTHOR]

When tunnel boring machines (TBMs) tunnel in extremely hard rock, it is difficult for the cutter to penetrate the rock, resulting in an excessive cutting load, severe wear, and a short lifespan. The rock-breaking mode of synchronous cutting by an abrasive water jet (AWJ) and a disc cutter is expected to improve the rock-breaking performance. To investigate the cutting features of the new method, a synchronous cutting model is established. The results demonstrate that synchronous cutting can significantly enhance the rock-breaking efficiency and reduce the cutting load compared to single-cutter cutting. Moreover, synchronous cutting results in superior rock-breaking effectiveness compared with precutting kerf cutting, attributed to the overlapping of stress waves. The influence of the AWJ kerf depth and the spacing between the disc cutter and the jet on the rock-breaking performance is studied. As the depth of the AWJ kerf increases and the spacing decreases, the cutting load decreases, while the range of rock damage and stress-wave propagation initially increase and then decrease. When the penetration depth of the cutter, kerf depth and spacing are 6 mm, 15 mm, and 30 mm, respectively, the cutting performance of the synchronous cutting is better than that under other conditions. Highlights: A simulation model of the synchronous cutting of granite by an AWJ and a disc cutter is constructed based on the SPH–FEM coupled algorithm. The dynamic process of rock damage and stress-wave propagation is studied for synchronous cutting by an AWJ and a disc cutter. The rock-breaking characteristics of the single-cutter cutting mode, the precutting kerf mode, and the synchronous cutting mode are comprehensively compared. The influence of the AWJ kerf depth and the spacing between the disc cutter and the jet on the rock-breaking performance are investigated. [ABSTRACT FROM AUTHOR]

This paper presents a numerical simulation study on the coupling of lasers and waterjets, focusing on the distribution of the spot power density. The analysis utilized a laser wavelength of 532 nm, chosen for its minimal energy attenuation in water. The key conditions for successful coupling were identified, including the necessity for the spot diameter of the laser beam to be smaller than the nozzle diameter of the waterjet fiber, the numerical aperture of the laser beam to be lower than that of the waterjet fiber, and the divergence angle of the laser to be smaller than the critical angle for total internal reflection. Using the ZEMAX simulation software, various coupling cases were explored, revealing that the radial displacement of the waterjet fiber relative to the laser axis has the most significant impact on the output power density, followed by angular deflection, whereas the axial displacement has the minimal effect. This study also investigates the combined effects of different influencing factors on the peak distribution of the output power density, uncovering distinct characteristics resulting from these deviations. Overall, the research findings provide theoretical insights for achieving effective coupling between fine waterjets and lasers as well as for the design of water-guided laser coupling devices. [ABSTRACT FROM AUTHOR]

Cutting edge preparation is an established approach in the field of machining technology for optimizing the performance of cutting tools. However, the potential of asymmetric geometries has not yet been sufficiently utilized for filigree micromilling tools. In this regard, the study presents investigations on the adjustment of asymmetric microgeometries through the design of the pressurized air wet abrasive jet machining (PAWAJM). The study features results regarding the design of the preparation process as well as subsequent application tests in a hard micromilling process of the hardened high-speed steel AISI M3:2. The application tests focus on the effect of the conditioned cutting edge on the process forces and the surface quality as well as the tool life. The results show that asymmetrical microgeometries with small average cutting edge rounding and a form-factor of K > 1.2 can be achieved by PAWAJM. Machining tests revealed a potential reduction of the wear development and process forces for modified tools with low cutting edge rounding and asymmetrical microgeometry. [ABSTRACT FROM AUTHOR]

In order to improve the performance of high-pressure abrasive water jet cutting extremely hard rock, research on the cutting effect and mechanism of abrasive water jet was carried out. The research focused on cutting depth, and one-factor tests were devised to cut hard rock using key parameters of high-pressure abrasive water jets. The cutting performance of the process parameters was assessed using both the cutability index and the energy-consumption index. The mechanism of abrasive water jet cutting hard rocks was examined using a stereomicroscope. The governing relationships of key parameters influencing the effectiveness of abrasive waterjet in breaking extremely hard rocks were investigated. The results indicate a linear correlation between the cutting depth of the abrasive water jet and pump pressure. Additionally, there is a power function relationship with traverse speed and target distance, a quadratic function relationship with abrasive flow, an exponential function relationship with nozzle diameter, and a logarithmic function relationship with cutting times. Under high traverse speed conditions, the removal mechanism of the abrasive water jet on hard rock involves brittle fracture and plastic shear, while on extremely hard rock, it encompasses plastic shear and a minimal amount of brittle fracture. These research findings can serve as a valuable reference for choosing construction parameters for abrasive water jet-assisted TBM cutting of hard rock. [ABSTRACT FROM AUTHOR]

The study aims to analyze the strength properties obtained from three-point bending tests of epoxy-glass composite samples modified by adding rubber recyclate. A pure epoxy-glass composite is used as a comparative variant. The tested materials, which varies in the percentage of rubber recyclate and distribution, are cut through waterjet cutting to minimize the influence of temperature. The results undergo statistical analysis, and the microstructures are examined using scanning electron microscopy. The decreasing bending strength of the composites is observed, as the content of rubber recyclate in the material increased. However, adding rubber recyclate directly into the resin subtly decreases in bending strength compared to adding in the layers between the glass mat layers. Composites with rubber recyclate exhibits lower deflection under load compared to pure composites. The most favorable bending test parameters are obtained for the material containing 5% rubber recyclate distributed in three layers. [ABSTRACT FROM AUTHOR]

This article presents the effect of the conditions of abrasive compounds on the wear of samples made by different methods. The 28MnB5 steel was used, which is intended for agricultural components, to which two arc and laser coatings were applied. The study included the analysis of microstructure, microhardness, roughness, and tribological experiments on a dedicated stand. The arc coating was found to significantly improve the tribological properties compared to the samples without the coating. Varied wear results were obtained for the laser coating depending on the parameters of the abrasive compound. Studies of the surface roughness of the samples showed that the concentration and pH of the abrasives have a significant effect on the changes in the surface parameters after the tribological tests. The results of the tribological experiments indicated that wear resistance for some of the abrasive mass conditions was improved by the application of heat-applied coatings. In addition, it was found that the power consumption on the stand was the highest for abrasive mass conditions of a 10% moisture content and a pH of 10. For these test conditions, the mass loss was four times higher than for the parameter with W0% and pH7. The energy consumption of the stand was 60 kWh lower for this variant than for the parameter with W10% and pH10. The results of the study have important practical applications that can help in the selection of materials for agricultural machinery components, depending on the abrasive mass conditions. [ABSTRACT FROM AUTHOR]

The reliability of GIS (gas-insulated switchgear) circuit breakers significantly depends on the condition of the insulated pull rods, with micro-defects on their surface posing a potential risk for micro-discharges and breakdown incidents. Experimentally investigating these micro-discharges is challenging due to their minute nature. This study introduces a framework to examine the linkage between micro-defects and micro-discharges, coupled with numerical simulations of the micro-discharge process in insulated pull rods afflicted by surface infiltration flaws under operational conditions. Initially, samples containing micro-defects were sectioned via water jet cutting for microstructural analysis through white light interferometry. Subsequently, a two-dimensional axisymmetric model simulating positive corona discharge from a needle to a plate electrode was employed to derive the relationship between charged particle density and the electric field in SF6 and air. Building on these observations, a micro-discharge model specific to micro-defects was developed. Comparative analysis of micro-discharge behaviors in SF6 and air for identical defect types was conducted. This research framework elucidates the discharge dynamics of charged particles in SF6 and air during micro-discharge events, shedding light on the mechanisms underpinning micro-discharges triggered by insulation rod defects. [ABSTRACT FROM AUTHOR]

The traverse speed influences the exposure time of the target to the cutting energy and the number of abrasive particles that impact the target. The number of abrasive particles that are confined within the effective jet diameter is identified as the areal number density. These particles suffer collisions and interference, resulting in energy loss. In this study, the effects of the water and abrasive flow rates and standoff distance on the performance of multi-cutting were evaluated, with the traverse speed as the main variable for rock cutting, by using the areal number density concept. The results showed that a higher traverse speed in single cutting increased the optimal abrasive flow rate, indicating that a greater number of abrasive particles effectively removed the target rock owing to reduced collision and interference. In multi-cutting, in which the same cutting energy is applied within the same operational time, an increase in the number of repetitions results in an increased cutting depth. It was found that a higher areal number density caused higher energy losses and decreased the efficiency, highlighting the effectiveness of a higher traverse speed in repetitive cutting. A partial dependence analysis and gradient boosted regression tree-based predictive model showed the high relative importance of the water flow rate and number of repetitions. This research proposes an economical strategy based on multi-cutting and suggests that the areal number density concept can be used to evaluate the cutting efficiency. [ABSTRACT FROM AUTHOR]

Cutting simulations via the Finite Element Method (FEM) have recently gained more significance due to ever increasing computational performance and thus better resulting accuracy. However, these simulations are still time consuming and therefore cannot be deployed for an in situ evaluation of the machining processes in an industrial environment. This is due to the high non-linear nature of FEM simulations of machining processes, which require considerable computational resources. On the other hand, machine learning methods are known to capture complex non-linear behaviors. One of the most widely applied material models in cutting simulations is the Johnson–Cook material model, which has a great influence on the output of the cutting simulations and contributes to the non-linear behavior of the models, but its influence on cutting forces is sometimes difficult to assess beforehand. Therefore, this research aims to capture the highly non-linear behavior of the material model by using a dataset of multiple short-duration cutting simulations from Abaqus to learn the relationship of the Johnson–Cook material model parameters and the resulting cutting forces for a constant set of cutting conditions. The goal is to shorten the time to simulate cutting forces by encapsulating complex cutting conditions in dependence of material parameters in a single model. A total of five different models are trained and the performance is evaluated. The results show that Gradient Boosted Machines capture the influence of varying material model parameters the best and enable good predictions of cutting forces as well as deliver insights into the relevance of the material parameters for the cutting and thrust forces in orthogonal cutting. [ABSTRACT FROM AUTHOR]

This paper introduces an Acoustic Emission (AE)-based monitoring method designed for supervising the Abrasive Waterjet Cutting (AWJC) process, with a specific focus on the precision cutting of Carbon Fiber-Reinforced Polymer (CFRP). In industries dealing with complex CFRP components, like the aerospace, automotive, or medical sectors, preventing cutting system malfunctions is very important. This proposed monitoring method addresses issues such as reductions or interruptions in the abrasive flow rate, the clogging of the cutting head with abrasive particles, the wear of cutting system components, and drops in the water pressure. Mathematical regression models were developed to predict the root mean square of the AE signal. The signal characteristics are determined, considering key cutting parameters like the water pressure, abrasive mass flow rate, feed rate, and material thickness. Monitoring is conducted at both the cutting head and on the CFRP workpiece. The efficacy of the proposed monitoring method was validated through experimental tests, confirming its utility in maintaining precision and operational integrity in AWJC processes applied to CFRP materials. Integrating the proposed monitoring technique within the framework of digitalization and Industry 4.0/5.0 establishes the basis for advanced technologies such as Sensor Integration, Data Analytics and AI, Digital Twin Technology, Cloud and Edge Computing, MES and ERP Integration, and Human-Machine Interface. This integration enhances operational efficiency, quality control, and predictive maintenance in the AWJC process. [ABSTRACT FROM AUTHOR]

Vibroacoustic metamaterials represent an innovative technology developed for broadband vibration reduction. They consist of an array of local resonators and are able to reduce vibrations over a wide frequency range, commonly referred to as a stop band. Vibroacoustic metamaterials may be a promising strategy to reduce out-of-plane vibrations of thin-walled, disk-shaped structures, such as saw blades. However, their behavior in rotating systems has not yet been fully understood. In this study, a vibroacoustic metamaterial integrated into a circular disk for the reduction of out-of-plane vibrations is experimentally investigated in the rotating and non-rotating state. Derived from the predominant frequency range of noise emitted by saw blades, a vibroacoustic metamaterial with a numerically predicted stop band in the frequency range from 2000 Hz to 3000 Hz, suitable for integration into a circular disk, is designed. The resonators of the metamaterial are realized by cutting slots into the disk using a waterjet cutting machine. To experimentally examine the structural dynamic behavior, the disk is excited by an impulse hammer and observed by a stationary optical velocity sensor on a rotor dynamics test stand. The results of the rotating and the non-rotating state are compared. The measurements are carried out at two different radii and at speeds up to 3000 rpm. A distinct stop band characteristic is shown in the desired frequency range from 2000 Hz to 3000 Hz in the rotating and non-rotating state. No significant shift of the stop band frequency range was observed during rotation. However, adjacent modes were observed to propagate into the stop band frequency range. This work contributes to a better understanding of the behavior of vibroacoustic metamaterials in the rotating state and enables future applications of vibroacoustic metamaterials for vibration reduction in rotating, disk-shaped structures such as saw blades, brake disks or gears. [ABSTRACT FROM AUTHOR]

The bevel cutting of large-thickness plates is a key process in modern industries. However, traditional processing method such as air-arc gouging bevel cutting or laser bevel cutting may cause serious deformation and rough surface quality due to the defects of the thermal cutting method. In order to improve the quality and efficiency of bevel processing, the abrasive waterjet cutting method is used in this research to overcome the challenge for bevel machining of high-strength DH40 steel plates with a large thickness. For different kinds of beveled structures, a 3D camera is used to measure the reference points defined on the workpiece and the SVD registration algorithm is adopted to transform the theoretical coordinate system to the actual coordinate system. Furthermore, the distance between the nozzle and the workpiece surface is also measured and compensated for to ensure the consistency of the bevel width. Finally, experiments are carried out for different kinds of bevels to verify the feasibility of the proposed method for high precision processing for beveled structures. The developed method has been effectively applied in the actual shipbuilding industry. [ABSTRACT FROM AUTHOR]

Fiber lasers, the latest laser-cutting technology, are notable for their high process efficiency, cutting precision, and high cutting quality for thin materials. However, the quality of the cut significantly decreases when machining thicker materials. For now, this is a challenge for the metalworking industry. This study investigated the effects of laser power, cutting speed, and auxiliary gas pressure on the fiber-laser cutting quality of 4 and 6 mm thick S355JR steel plates. To evaluate the influence of cutting parameters on cutting quality, surface roughness, dimensional accuracy and cut taper were measured. A microscopic analysis of the laser cuts was performed, revealing the heat-affected zone, transition zone and unaffected base-material zone. Research results show that laser cutting is a complex process, and the correct choice of cutting parameters greatly influences the cutting performance and final quality. An artificial neural network was created and trained using the results from measuring the quality characteristics to achieve optimum cutting quality. The accuracy of the optimization model was assessed by control samples, which were cut using calculated optimum parameters. The actual values of the quality characteristics only slightly differ from the predicted values, showing that the optimization model is suitable for selecting cutting parameters. [ABSTRACT FROM AUTHOR]

Metamaterials are artificial materials with properties depending mainly on their designed structures instead of their materials. Pentamode metamaterials are one type of metamaterial. They have solid structures with fluid-like properties, which can only withstand compressive stresses, not shear stresses. Two-dimensional pentamode metamaterials are easier to manufacture than three-dimensional models, so they have received wide attention. In this review, the properties, manufacturing, and applications of two-dimensional pentamode metamaterials will be discussed. Their water-like properties are their most important properties, and their velocities and anisotropy can be designed. They can be processed by wire-cut electrical discharge machining, waterjet cutting, and additive manufacturing techniques. They have a broad application prospect in acoustic fields such as acoustic stealth cloaks, acoustic waveguides, flat acoustic focusing lenses, pentamode acoustic meta-surfaces, etc. [ABSTRACT FROM AUTHOR]

Austempered ductile iron (ADI) is a hard-to-cut material used for a variety of purposes, including flanges in power plants, oil fields and railway sectors. This article aims to establish a correlation between the surface quality (Ra), the kerf angle (KTa), and the erosion rate and four critical process variables such as traverse speed (NS), abrasive flow rate (AFR), water jet pressure (WJP), and standoff distance (SoD). All of the inferences from the experiments were made using the RSM-CCD response surface methodology and the central composite design. An analysis of variance (ANOVA) was employed to identify which WJP factors had the greatest impact. WJP was shown to be the most influential parameter in the outcomes. The Ra and KTa both fell by 56.7 and 33% when the WJP reached a value of 360 MPa, whereas the MRR increased by 35.46 %. In order to fine-tune the abrasive water jet machining settings of the ADI sample, the desirable analysis is taken to optimize the parameter. Surface morphology and erosion processes of AWJM are studied using a scanning electron microscope and 3D surface roughness analysis. [ABSTRACT FROM AUTHOR]

The research aimed to study the impact of changing the stand-off distance (SOD) and traverse speed (TS) on the results of abrasive water jet (AWJ) machining on brass surfaces. The study specifically evaluated the kerf width (KW), cutting quality (CQ) and surface roughness (Ra). For this purpose, Abrasive Water Jet Machining (AWJM) was used, and adjustments were made to the SOD and TS to obtain the best cutting quality for 0.8-mm-thick brass sheets. The results showed that to achieve high cutting quality, it was necessary to reduce the SOD and increase the TS to minimize the KW. Conversely, higher TS and Ra resulted in decreased cutting quality. The largest KW was recorded at an SOD of 5 mm and TS of 90 mm/min, measuring 6.537 mm. Fine-tuning the SOD by 1 mm at the same TS produced the best machining outcomes, with a minimum KW of 1.706 mm, indicating superior cut quality. Lower cutting quality was observed at higher traverse speeds and surface roughness. The optimal Ra was achieved at 90 mm/min with an SOD of 5 mm, measuring 1.1 µm, while the maximum Ra was observed at 150 mm/min with an SOD of 1 mm, measuring 8.15 µm. [ABSTRACT FROM AUTHOR]

The process of roughing surfaces by sandblasting before the coating is essential to obtain consistently high tensile strength between coating and substrate, for carbon-deposit elimination, and to remove some flaws such as piston cracks and minor chips in the top crown. This work aims to investigate the effect of sandblasting pressure and alumina volume on the roughness of the AK12MMgN alloy substrate and the roughness of the deposited galvanic plasma modification (GPM) coatings after blast cleaning, and the adhesion strength of these coatings. Many technological factors, such as grain size, pressure and time of blasting, distance to the abrasive, angle of blasting, and the hardness of the surface parts subjected to blasting, determine the magnitude and nature of surface roughness. Thus, the sandblasting process must be controlled appropriately in order to obtain a high GPM coating with a high coating-to-substrate adhesion value. More importantly, the process parameters must be optimized. The results indicate the importance of the roughness of the base after sandblasting of the AK12MMgN alloy and the roughness of the subsequently applied coatings in determining the bond strength value. [ABSTRACT FROM AUTHOR]

It has been confirmed that the passive obstacles would substantially depress the leading-edge cavitation in a waterjet pump. Combined with the experiments and numerical simulations, this work revisits blade cavitation evolutions to demonstrate the stabilizing effects of obstacles on cavitation unsteadiness. The multiscale proper orthogonal decomposition (mPOD) and ensemble empirical mode decomposition (EEMD) are adopted to study the energy contributions regarding the cavitation-induced loading and thrust. The mPOD modes illuminate that the leading-edge loading oscillations of the obstacle blade are consequently eliminated where the cavitation is completely depressed and the obstacle cavitation wakes greatly contribute to loading excitation. The thrust statistics demonstrate that the thrust extremes and standard deviation in some revolutions can be well reduced as the large-scale leading-edge cavity depression. The adaptive spectra obtained by EEMD further illuminate that both the tonal and broadband components of blade thrust would be reasonably degraded to some degree. The pump with only one obstacle implementation, as an improvement strategy, is comparatively studied and indicates that single obstacle configuration presents positive effects on the leading-edge cavity depression owing to the pressure-raising effects and can reduce the un-necessary energy loss compared with two obstacles. [ABSTRACT FROM AUTHOR]

The latest technological advance in weaving machinery and preparation at 2022 China International Textile Machinery Exhibition & ITMA Asia were summarized. The structure and performance of weaving machinery were continuously optimized, the development was closer to the market demand. The manufacturing level of domestic rapier, air jet and water jet looms had developed rapidly, which improving the core competitiveness of household equipment. With the explosive growth of artificial intelligence, the digital transformation of weaving machinery was accelerated, the application of advanced information technology and automation tools were making the weaving machinery present a new trend of personalized, intelligent, green development. It is considered that weaving machinery has made remarkable progress in high speed, automation and greening in recent years. [ABSTRACT FROM AUTHOR]

This document is an editorial for a special issue of the journal Processes on the topic of Computational Fluid Dynamics (CFD) applications in energy engineering research and simulation. The editorial highlights the significant progress made in CFD over the past few decades, with advancements in numerical methods, physical models, and computer technology. CFD is now widely used in both industry and academia, with a range of applications in energy engineering, such as power generation, wind energy, and fuel cells. The special issue covers various topics, including rotating machinery, oil and gas applications, and novel technologies. Contributions come from 22 countries, with notable contributions from China, the USA, Korea, Mexico, and Spain. The editorial concludes by mentioning specific research articles that have the potential to further advance CFD in energy engineering applications. [Extracted from the article]

Using a simple and cost-effective water jet process, silicon etch depth limitations are overcome to realize a 6 mm deep atomic vapor cell. While the minimum silicon feature size was limited to a 1.5 mm width in these first generation vapor cells, we successfully demonstrate a two-chamber geometry by including a ∼ 25 mm meandering channel between the alkali pill chamber and the main interrogation chamber. We evaluate the impact of the channel conductance on the introduction of the alkali vapor density during the pill activation process and mitigate glass damage and pill contamination near the main chamber. Finally, we highlight the improved signal achievable in the 6 mm silicon cell compared to standard 2 mm path length silicon vapor cells. [ABSTRACT FROM AUTHOR]

Electrical steels are widely used in the electrical industry in the construction of many devices, e.g., power transformer cores and distribution transformers. An important parameter of electrical components that determines the efficiency of devices is energy loss during remagnetization. These losses are influenced, among other factors, by steel cutting processes. The common techniques for cutting electrical materials on industrial lines are mechanical cutting and laser cutting. High-pressure abrasive water jet (AWJ) cutting, unlike the technologies mentioned above, can ensure higher quality of the cut edge and limit the negative impact of the cutting process on the magnetic properties of sheet metal. However, the correct control of the process and the conditions of its implementation comprise a complex issue and require extensive scientific research. This work presents a new approach to cutting electric sheets, involving bundle cutting, which significantly increases the processing efficiency and the dimensional and shape accuracy of the cut details. The tests were carried out for bundles composed of a maximum of 30 sheets, ready to be joined in a stator and rotor in a motor. The influence of processing conditions on the quality of the cut edges of sheet metal, the width of the deformation zone, and the burr height were analyzed. The detailed analysis of the quality of the cut edges of electrical bundled sheets creates new possibilities for controlling the AWJ cutting process in order to obtain a product with the desired functional and operational properties. [ABSTRACT FROM AUTHOR]

This study aims to predict machinability and high performance optimum surface roughness (Ra) by developing multiple regression models and artificial neural network (ANN) model for abrasive water jet cutting (AWJC) of Aluminum 7068 alloy. Important basic processing parameters such as pump pressure (3500-4000 Bar), nozzle distance (2-5 mm), abrasive flow rate (200-350 g/min), abrasive grain size (100-110 mesh), and nozzle traverse speed (240-300 mm/min) were selected in the study. To examine the effects of these parameters on Ra, 32 experiments were conducted using the L32 orthogonal array, and data was collected. Additionally, the most important factors and interactions affecting Ra were determined using multiple regression analysis and analysis of variance (ANOVA). The Artificial Neural Network (ANN) model was designed to have multiple hidden layers using MATLAB. The model was trained and evaluated using experimental data, and its performance was measured using mean squared error (MSE) and mean absolute error (MAE). The model was optimized using hyper parameter tuning and cross-validation techniques. As a result, it was determined that the best R2 value of 95.65% from the multiple regression models created to estimate the surface roughness could be obtained from the linear regression model. While selecting the optimum process parameters for AWJC, it was determined that nozzle rotation speed, abrasive grain size and flow rate had the greatest effect by 35.5%, 25.4% and 21.9%, respectively. The optimized ANN model showed high accuracy in predicting Ra for different input parameter combinations. This study provides a reliable and efficient tool for predicting Ra in AWJC, which can contribute to improving process planning and control. [ABSTRACT FROM AUTHOR]

To investigate the rail repair process based on high-pressure abrasive water jet, simulation analysis of its machining process is carried out based on smoothed particle hydrodynamics with finite element method (SPH-FEM). First, through the water jet cutting experiment, analysis of simulation data and experimental results are compared, and the results are basically the same in terms of values and trends. The depth of cut decreases with the increase of transverse speed, increases with the increase of abrasive flow, and tends to increase and then decrease with the jet pressure and target distance. Then, the rail top surface is repaired by high-pressure abrasive water jet technology, and the experimental results show that the repaired rail surface fully meets the rail grinding and repair standards. The repaired rail surface roughness of 2.648 μm is better than the rail milling train repair index value of 56.2%, which verifies the feasibility and effectiveness of rail repair based on high-pressure abrasive water jet technology. [ABSTRACT FROM AUTHOR]

The waterjet-assisted laser processing (WJALP) technology has a significant effect in reducing the damage to the workpiece caused by laser ablation. While, due to the limitation of the depth-of-field (DOF) of the microscopic magnification system, the processing quality and features of the material surface cannot be accurately identified during processing. In multi-focus image fusion (MFIF) according to different DOF images, the conventional wavelet transform in the condition of waterjet cannot accurately provide detailed features of microscopic images. In this work, in order to overcome the shortcomings of traditional wavelet transform, the method of discrete wavelet transform (DWT) based on the human vision principle (HVP) was proposed, and stretched the detail part while fully retained the source image information. Based on morphological theory and defogging algorithm, the waterjet interference was excluded by image pre-processing as much as possible. The approximate component and detailed component were obtained by DWT, and the detailed components were stretched utilizing HVP according to the brightness and darkness provided by the approximate component. Finally, the image brightness was adjusted using an adaptive gamma correction. According to the experimental results, in the case of complex flowing water films, SD, E(F), AG, and SF can reach 75.45%, 95.38%, 73.60%, and 77.45% of the ideal fusion, respectively, which indicated that the proposed method can achieve a better fusion effect in different waterjet situations. [ABSTRACT FROM AUTHOR]