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Grinding is an effective method for precision machining of difficult-to-machine hard and brittle materials such as carbon/carbon (C/C) composites. Research on grinding force and machined surface quality is crucial for the precision machining process and practical applications of C/C composite components. However, there are currently few studies on ultrasonic-assisted grinding of needle-punched C/C composites, and the material removal mechanism during the grinding process remains unclear. Additionally, a suitable method for evaluating surface quality specifically for needle-punched C/C composites has not yet been established. To address these issues, this paper conducted experiments on both conventional and ultrasonic-assisted grinding for precision machining of needle-punched C/C composites. The influences of ultrasonic assistance and machining parameters on grinding force and machined surface morphology were investigated. The feasibility of using 3D surface roughness parameter Sa to evaluate the surface quality of needle-punched C/C composites was analyzed. The results indicated that the increase spindle speed could effectively reduce grinding force and improve surface quality, while feed rate and grinding depth were inversely proportional to changes in grinding force and surface quality. Compared to conventional grinding, ultrasonic-assisted grinding could significantly reduce grinding force and enhance surface quality. Furthermore, a standardized sampling area of 4 × 4 mm2 for measuring the 3D surface roughness of needle-punched C/C composites was proposed. Additionally, the ratio of the apparent pit area on the surface was introduced as a quantitative measure for analyzing surface damage caused by machining. [ABSTRACT FROM AUTHOR]

Hard and brittle materials, represented by silicon carbide, single-crystal silicon, and ceramic-based composites, possess excellent mechanical, physical, and chemical properties. They have various applications in aerospace, aviation, microelectronics, medicine, and other fields. However, the hardness, brittleness, and weak rigidity of thin wall parts made of hard and brittle materials pose challenges to their processing. In this paper, considering the processing efficiency and quality, an optimization strategy of variable thickness ultrasonic assisted machining of thin-walled parts of hard and brittle materials is proposed. Under the condition that the volume of the material removed in each process is constant, the shape of the workpiece is optimized based on the finite element method to minimize the maximum stress, reduce the deformation of the workpiece during the machining process, and improve the machining efficiency. The results showed that compared with traditional machining, the maximum stress was decreased by 39.02 %–47.72 %, and the maximum deformation of planes A and B was reduced by 19.61 % and 60.97 %, respectively. Furthermore, optimal machining is verified by experiments, revealing that it effectively mitigated the deformation of thin-wall parts while enhancing processing efficiency by 41.16 %. Finally, this optimization strategy was applied to machining off-axis aspheric mirrors on single-crystal silicon. The measured surface shape accuracy PV is 60.895 μm, and RMS is 11.221 μm. The research has specific technical guidance for improving the high efficiency and high-quality precision machining of weak, rigid, thin-walled mirrors. [ABSTRACT FROM AUTHOR]

Microstructures in glass materials have important applications in fields such as aerospace, MEMS, and medicine. Current non-traditional machining methods used for micro-slit fabrication suffer from poor sustainability, large slit widths, and poor surface quality. To analyze the transformation relationship between the electrical energy and the heat energy from the discharge plasma point of view, a new method of electrochemical-assisted discharge plasma machining of glass microstructures by ultrasonic vibrating wire electrode is proposed. Firstly, the electrothermal energy conversion is studied through simulation and modeling, and the mechanism of improving machining quality by ultrasonic is illustrated. Then, the influence of the key machining parameters on the quality of the slit is studied. The experimental results show that when ultrasonic vibration is applied to the wire electrode, the optimum amplitude is 7.5 μm. The average slit width is reduced by 20.99% and the surface roughness is reduced by 54.23%. Finally, the micro-star structure with a slit width of 64.94 μm and surface roughness of 0.35 μm was successfully machined by selecting the optimum parameters. It is shown that the electrochemical-assisted discharge plasma machining of glass microstructures by ultrasonic vibrating wire electrode can effectively improve the machining quality and stability, providing the feasibility for further machining of more complex microstructures of non-conductive hard brittle materials. [ABSTRACT FROM AUTHOR]

The application of ultrasonic longitudinal-torsional (LT) machining in the field of machining brittle and hard materials such as ceramics and titanium alloys has been increasingly emphasized. Aiming at the existing ultrasonic LT shank, mainly using piezoelectric materials resulting in low power density, overheating failure, and small torsional vibration components, a new ultrasonic LT shank based on giant magnetostrictive materials is designed. The conical transition hollow horn and giant magnetostrictive ultrasonic LT transducer are designed by theoretical analysis method, and the effects of different spiral groove parameters on the resonant frequency and torsion-longitudinal ratio of the horn are analyzed by using finite element software, and the modal analysis is carried out for the shank. Finally, the ultrasonic LT shank is subjected to experimental studies on impedance characteristics, frequency amplitude response, and voltage amplitude response, and the simulation and experimental results show that the designed shank has a resonant frequency of 19.12kHz, a maximum longitudinal amplitude of 14.5μm, a maximum torsional amplitude of 6.1μm, and a maximum torsion-to-longitudinal ratio of 0.46, which is suitable for most of ultrasonic machining, and verifies the correctness of the design methodology. [ABSTRACT FROM AUTHOR]

Post-processing of selective laser melted (SLMed) Ti6Al4V alloy with poor surface quality and low dimensional accuracy is a necessary operation to better achieve its operational performance. Considering the principle and advantages of ultrasonic vibration–assisted machining (UVAM) and textured tools, the synergistic application of UVAM and textured tools is expected to improve the micro-machining performance of SLMed Ti6Al4V alloy. The micro-machinability and machining mechanism of the SLMed Ti6Al4V alloy are investigated by a series of micro-machining with different scanning strategies, different ultrasonic vibration modes, different micro-texture tool types, and different elliptical trajectories. Multifaceted comparisons of machining results are presented in terms of cutting force, cutting temperature, equivalent stress and strain, temperature field, stress field, strain field, and chip formation. The machining results showed that the cutting forces of UVAM are reduced by 56.5 ~ 66.8% compared with conventional machining (CM). The differences in the cutting forces and temperatures of SLMed Ti6Al4V alloys with different scanning strategies are dependent on the microstructures and mechanical properties. The stress and strain fields are significantly affected by the coupled impact effect of cutting motion and ultrasonic vibration, and the UVAM processes improve serrated chip fracture properties. The dual effect of ultrasonic elliptical vibration and textured tools produces better machining performance, especially for the semi-elliptical micro-texture tools. The differences in machining response for different elliptical trajectories are attributed to the effects of tool vibration impact angle and the dynamic cutting thickness, and the machining response with a phase difference of φ = 45° is better. [ABSTRACT FROM AUTHOR]

This study uses molecular dynamics simulations to examine how varying frequencies and amplitudes of ultrasonic vibration affect the temperature and pressure of cavitation bubbles at the atomic scale. A three-dimensional model of water, gas molecules, and metal atoms was developed using LAMMPS code. The microcanonical ensemble (NVE) and isothermal-isobaric ensemble (NPT) were employed to track the evolution of cavitation bubble temperature and pressure in response to tool head vibrations. The findings show that cavitation bubbles experience significant temperature and pressure increases during oscillation, with these parameters varying noticeably across different vibration amplitudes and frequencies. At lower amplitudes, pressure fluctuations are more intense and erratic, while at higher amplitudes, pressure peaks are higher but exhibit smoother changes. Further analysis indicates that a specific combination of amplitude and frequency can optimize pressure and temperature outputs, highlighting the mechanisms of thermal and mechanical softening in ultrasonic cavitation. This study offers valuable atomic-scale insights into the cavitation effects that occur in ultrasonic machining. [ABSTRACT FROM AUTHOR]

The current study aimed at the optimization of process parameters for microchannel fabrication on thermal sprayed carbide coatings using rotary ultrasonic machining (RUSM). Rare earth oxides (REOs) such as La₂O₃, CeO₂, and Er₂O₃ have been incorporated into WC-Co-Cr coatings to enhance machinability and improve coating characteristics. The research has demonstrated that La₂O₃ doped coatings have significantly increased the material removal rate (MRR), with a 15 % improvement when compared to undoped coatings. Additionally, surface roughness has been reduced by 20 %, resulting in a smoother and more uniform finish. The inclusion of REOs has refined the microstructure of the coatings, yielding denser and more compact layers, which has reduced defects and improved the overall surface quality. Furthermore, the hardness of the coatings has been enhanced by 45 %, with La₂O₃ doped coatings achieving a maximum hardness value of 1313 ± 11 HV. The findings have highlighted the potential of REO doping to enhance the performance and efficiency of microchannel fabrication on WC-Co-Cr coatings using RUSM, contributing valuable insights to industrial applications. [ABSTRACT FROM AUTHOR]

Ultrasonic vibration-assisted machining is a widely used method in recent times to improve the tribological performance by lowering the friction coefficient and increasing the wear resistance of sliding components. The present study experimentally investigates the tribological performance of longitudinal ultrasonic vibration-assisted milling (LUVAM) and conventional milling (CM) surfaces in starved lubrication environments. During the LUVAM process, high-frequency vibration (40.4 kHz) with a low vibration amplitude (≈1.2 µm) was applied on the milling tool to generate uniform surface textures on the surface. The introduction of surface texture using the LUVAM process makes the surface hydrophobic in nature as compared to the corresponding CM surface. The LUVAM surfaces showed improved friction behavior as compared to the CM surfaces when machined at high feed rate values and under high applied load and sliding speed conditions. In addition, the LUVAM surface had a lower specific wear rate at high sliding speed and high applied load conditions for the surfaces generated at high feed rate values. The retention of lubrication oil in between surface textures and the flow back of this lubricant oil into the contact area because of hydrodynamic pressure produced by the applied load turned out to be the main reason for the improved tribological behavior of LUVAM surfaces at high applied load and sliding speed conditions. [ABSTRACT FROM AUTHOR]

This study examined the impact of abrasive slurry assisted Rotating Ultrasonic Machining (RUM) using Boron Carbide (B 4 C) powder of three mesh sizes: 400 Mesh, 600 Mesh, and 800 Mesh. The effects of abrasive size, feed rate, and tool rotation on Material Removal Rate (MRR) and Surface Roughness (SR) were investigated. The highest MRR of 3.454 mm³/min was achieved with 400 mesh, 30 mm/min feed rate, and 1250 rpm due to larger abrasive size, medium feed rate, and medium tool rotation velocity, while the lowest MRR of 0.284 mm³/min was noted with 600 mesh, 30 mm/min feed rate, and 1500 rpm, attributed to intermediate abrasive size and high tool rotation. The lowest SR of 1.16 μm was observed at 800 mesh, 15 mm/min feed rate, and 1500 rpm, resulting from smaller abrasive size and higher tool rotation facilitating polishing action and vibrational dampening. The highest SR of 3.71 μm occurred at 400 mesh, 45 mm/min feed rate, and 1500 rpm, due to larger abrasive size, higher feed rate, and tool rotation, increasing surface corrosion. ANOVA and regression analyses highlighted mesh size as the most significant parameter for both MRR and SR, with strong model-experimental value correlations. The findings demonstrate the suitability of abrasive slurry assisted RUM for fabricating micro-channels in X-Ray, optoelectronic, and semiconductor applications. [ABSTRACT FROM AUTHOR]

Aramid fiber–reinforced polymer composite (AFRPC) is popular in aerospace and defense industries owing to its superior thermal and mechanical properties. However, its intricate hexagonal cellular structure and the material's heterogeneous, soft, and brittle characteristics lead to significant surface defects, such as burr formation, wall tearing, roughness, dimensional inaccuracies, and uncut fibers during traditional machining. Such poor machining quality issues notably affect the operational lifespan and functional performance of its sandwich structural components. To address these issues, the rotary ultrasonic assisted machining (RUSAM) process has been introduced. To thoroughly investigate the RUSAM of AFRPC using various cutting tools, a 3D finite element model was developed and validated. This paper mainly investigates the effect of various machining parameters such as vibration amplitude (VA), cutting width (CW), feed rate (FR), and spindle speed (SS) on the cutting force, surface morphology, burr formation, and burr height during RUSAM of AFRPC structure by plane and toothed disc cutters. The burr height was found to decrease with the increase of spindle speed (60.82% and 71.00%) and vibration amplitude (78.15% and 82.32%), whereas increase with cutting width ( 149.81 % and 321.16%) and feed rate (156.53% and 314.83%) during RUSAM by plane and toothed disc cutters, respectively. The pattern of variation of burr height with machining parameters was found similar to that of the cutting force. Significance analysis based on 4 levels, 4 factors orthogonal L 16 ( 4 4 ) experiments revealed the cutting width to be the most influential parameter on the burr height and cutting force followed by the spindle speed, feed rate, and vibration amplitude during RUSAM of the AFRPC core by the disc cutters. Up to 62.54 % reduction in burr height was realized by rotary ultrasonic assisted machining compared to the conventional machining. Under specified operating conditions, the disc cutter generates a higher but less number of burr as compared to the toothed disc cutter without any tearing defects. 3–10% and 5–20% burrs were observed during rotary ultrasonic assisted machining compared to 20–50% and 40–70% burrs during conventional machining of AFRPC structure by plane and toothed disc cutters, respectively. This experimental research will be extremely useful to comprehend the burr formation mechanism and optimize the machining parameters for enhanced surface morphology of AFRPC structures. [ABSTRACT FROM AUTHOR]

SiCp/Al composites are widely used in the aerospace field due to their excellent properties. However, the huge difference in the properties of silicon carbide and aluminum matrix materials can easily lead to machining defects. Ultrasonic vibration-assisted machining is an effective method to deal with difficult-to-machine materials. In this study, ultrasonic elliptical vibration is applied to the helical milling of SiCp/Al composites. Firstly, the ultrasonic elliptical vibration-assisted helical milling (UEVHM) cutting-edge trajectory is modeled, and the equation of the UEVHM tool-chip separation condition is established, which lays a foundation for the analysis of the cutting mechanism. Then, the influence of ultrasonic elliptical vibration on the removal mechanism of SiCp/Al composites was investigated by finite element simulation. It was found that UEVHM can reduce the tearing of aluminum matrix and reduce the hole damage by changing the direction of the cutting velocity and the relative position of the cutting edge and particles. Finally, the single-factor experiment was carried out, and the surface morphology and roughness of HM and UEVHM were compared. The influence of process parameters on the surface roughness of UEVHM was analyzed. The experimental results show that compared with HM, UEVHM can reduce surface defects and exit damage, to obtain better surface roughness and exit edge quality. The increase in cutting speed can reduce the roughness, and the increase in pitch and revolution speed will increase the surface roughness. [ABSTRACT FROM AUTHOR]

Carbon fiber-reinforced polymers (CFRPs) are widely used in biomedical, optical and tissue engineering applications. Nevertheless, machining these materials significantly differs from other materials and faces special challenges. In recent years, ultrasonic drilling as a new technique was introduced in the field of composites' machining. This study evaluates the effects of nano-graphene incorporation and machining parameters including feed rate, tool type in both conventional and ultrasonic vibration assisted drilling. Besides, statistical analysis is conducted in order to identify contribution of the parameters. The results suggest that feed rate is the most influential factor on cutting force and hole quality including delamination and hole roundness. In addition, in order to acquire the best optimal process parameters, desirability method was established. That was indicated the best hole quality is achieved in CFRP samples at the least feed rate by the HSS-8% cobalt tool (M42 tool) and in presence of the ultrasonic vibration. [ABSTRACT FROM AUTHOR]

A new method of machining ultrasonic cavitation abrasive flow based on phase control technology was proposed for improving the machining efficiency of the inner wall of TC4 (Ti-6Al-4V) titanium alloy tubes. According to ultrasonic phase control theory and Hertzian contact theory, a model of ultrasonic abrasive material removal rate under phase control technology was established. Using COMSOL Multiphysics 6.1 software, the phase control deflection effect, acoustic field distribution, and the size of the phase control cavitation domain on the inner wall surface were examined at different transducer frequencies and transducer spacings. The results show that the inner wall polishing has the most excellent effect at a transducer frequency of 21 kHz and spacing of 100 mm. In addition, the phased deflection limit was explored under the optimal parameters, and predictive analyses were performed for voltage control under uniform inner wall polishing. Finally, the effect of processing time on polishing was experimented with, and the results showed that the polishing efficiency was highest from 0 to 30 min and stabilized after 60 min. In addition, the change in surface roughness and material removal of the workpiece were analyzed under the control of the voltage applied, and the experimental results corresponded to the voltage prediction analysis results of the simulation, which proved the viability of phase control abrasive flow polishing for the uniformity of material removal of the inner wall of the tube. [ABSTRACT FROM AUTHOR]

A giant magnetostrictive transducer is a highly integrated device that facilitates the conversion of magnetic energy into mechanical energy, enabling the generation of motion or force during actuation. However, the energy efficiency of giant magnetostrictive materials (GMM) is hindered by several factors, resulting inless-than-optimal performance. To improve energy conversion efficiency, a magnetic circuit control strategy for optimizing the transducer is proposed, focusing on increasing magnetic flux density and enhancing magnetic field uniformity. Theoretical derivations demonstrate the positive correlation between magnetic circuit parameters, flux density, and uniformity. The impact of various magnetic circuit parameters on magnetic field strength is then analyzed using COMSOL software, which identifies optimal parameters for the stacked structure, resulting in a 9% improvement in magnetic field uniformity. Impedance analysis experimentally validates these results. The optimized stacked magnetic circuit for GMM shows a larger impedance circle diameter, an improved mechanical quality factor, and 95% magnetic field uniformity. By appropriately arranging the bias magnetic field and fine-tuning the magnetic circuit structure, magnetic flux density and uniformity along the GMM rod's central axis are enhanced, reluctance is reduced, and magnetic flux leakage is minimized in the closed magnetic circuit, which ensures high energy conversion efficiency in high-power ultrasonic vibration systems. The study provides essential guidance for optimizing system design and offers valuable insights to improve system efficiency and performance significantly. [ABSTRACT FROM AUTHOR]

AbstractPlant-based food consumption has increased substantially owing to its positive effects on human and global health. However, ensuring the quality and safety of plant-based foods remains a challenge. Diagnostic ultrasonic technology is widely used for rapid and nondestructive determination owing to its ability to penetrate optically opaque materials, strong directivity, rapid detection capabilities, low equipment costs, and ease of operation. This review provides a comprehensive understanding of diagnostic ultrasonic technology by summarizing the principles of food characterization, factors that influence detection accuracy and methods to mitigate their impact, composition of ultrasonic machine systems, and application of diagnostic ultrasound for monitoring plant-based foods. The detection principle of ultrasonic technology is based on empirical equations that establish a relationship between the ultrasonic and physicochemical indicators of food. To improve the detection accuracy, a compensation mechanism for the temperature and pressure should be established, measurement distances should be set in the far-field region, and liquid samples should be degassed. Furthermore, the sample platform design and the choice of detection mode depend on the nature of the food. Combining ultrasonic technology with machine learning techniques presents promising prospects for real-time process monitoring in the food and beverage industries. [ABSTRACT FROM AUTHOR]

In the field of gesture recognition technology, accurately detecting human gestures is crucial. In this research, ultrasonic transducers were utilized for gesture recognition. Due to the wide beamwidth of ultrasonic transducers, it is difficult to effectively distinguish between multiple objects within a single beam. However, they are effective at accurately identifying individual objects. To leverage this characteristic of the ultrasonic transducer as an advantage, this research involved constructing an ultrasonic array. This array was created by arranging eight transmitting transducers in a circular formation and placing a single receiving transducer at the center. Through this, a wide beam area was formed extensively, enabling the measurement of unrestricted movement of a single hand in the X, Y, and Z axes. Hand gesture data were collected at distances of 10 cm, 30 cm, 50 cm, 70 cm, and 90 cm from the array. The collected data were trained and tested using a customized Convolutional Neural Network (CNN) model, demonstrating high accuracy on raw data, which is most suitable for immediate interaction with computers. The proposed system achieved over 98% accuracy. [ABSTRACT FROM AUTHOR]

Small-hole components of Inconel 718 are widely used in aerospace engineering, medical devices, and other fields. Limited by material properties, its machining efficiency seriously restricts its wide application. The objective of this study is to investigate a novel machining technique for Inconel 718 that integrates ultrasonic machining (UM) and hydrogen embrittlement (HE) treatment. Accordingly, the technique is designated as hydrogen embrittlement-enhanced ultrasonic machining (HEUM). Prior to machining, a stress layer is formed on the surface of the workpiece. To ascertain the fundamental characteristics of Inconel 718, the influences of ultrasonic amplitude, HE time, and HE voltage on the specific material removal rate and surface roughness in the presence of HE were empirically examined. To investigate the material removal process for HEUM, the nanoscratch test and nanoindenter were also conducted with HE samples. Further, the subsurface for HEUAG samples were obtained with SEM. The specific material removal rate under experimental conditions of 10 min and 5 V HE increased by 27.4%. Finally, HEUM is proposed to be used for a 1 mm through-hole with Ra 0.318 μm. A precision hole with a diameter as small as 0.5 mm has been manufactured. [ABSTRACT FROM AUTHOR]

Anti-fatigue design in the machining process of aviation material requires advanced processes to enhance the surface integrity and a holistic model which can optimize the process aiming at maximum fatigue life. In the present study, the axial ultrasonic assisted milling process was utilized to machine the Inconel 718 while the process executes the thermomechanical cutting and peening action simultaneously. To optimize the process factors, a hybrid model using a combination of regression analysis and an analytical model was developed to correlate the machining factors, i.e., vibration amplitude, cutting velocity and feed rate to fatigue life. Herein, the former was used to map the process inputs to surface integrity aspects (SIAs), viz. roughness, hardness and residual stress; then, the SIA was mapped to fatigue life through a stress-based approach. The obtained results revealed that there is close agreement between the measured and predicted values of fatigue life where the prediction error is less than two times the dispersion. On the other hand, applying ultrasonic vibration at the highest amplitude together with the maximum feed rate and cutting velocity yield significant improvement in fatigue life, i.e., three times the same condition without ultrasonic vibration in light of the enhancement of compressive residual stress and work hardening of the surface layers. [ABSTRACT FROM AUTHOR]

Dimensional distortion and instability in the milling process of aluminum alloy parts can significantly increase production costs and result in defective parts. Therefore, distortion mitigation has long been a central focus of aerospace industry researchers. This article aims to investigate the effect of axial ultrasonic-assisted milling on distortion. In this study, the machining parameters effect in conventional milling (CM) and ultrasonic assisted milling (UAM) were experimentally and statistically investigated on distortion and milling force, and the results were subjected to a comparative analysis. Experiments provided compelling evidence of the technical advantages offered by axial ultrasonic-assisted milling, demonstrating its efficacy in reducing both milling force and distortion when compared to conventional milling. Furthermore, our study established a direct relationship between milling force and distortion. Applying the axial ultrasonic-assisted vibration resulted in a notable 29% reduction in cutting force compared to conventional milling. Additionally, UAM exhibited a reduction in distortion by approximately 21%. These findings have significant implications, particularly in improving the flatness tolerance of the workpiece, thereby yielding components free from waves and warpages.

The use of advanced brittle composites in engineering systems has necessitated robotic rotary ultrasonic machining to attain high precision with minimal machining defects such as delamination, burrs, and cracks. Longitudinal–torsional coupled (LTC) vibrations are created by introducing helical slots to a horn's profile to enhance the quality of ultrasonic machining. In this investigative research, modified ultrasonic horns were designed for a giant magnetostrictive transducer by generating helical slots in catenoidal and cubic polynomial profiles to attain a high amplitude ratio ( T A / L A ) and low stress concentrations. Novel ultrasonic horns with a giant magnetostrictive transducer were modelled to compute impedances and harmonic excitation responses. A structural dynamic analysis was conducted to investigate the effect of the location, width, depth and angle of helical slots on the Eigenfrequencies, torsional vibration amplitude, longitudinal vibration amplitude, stresses and amplitude ratio in novel LTC ultrasonic horns for different materials using the finite element method (FEM) based on the block Lanczos and full-solution methods. The newly designed horns achieved a higher amplitude ratio and lower stresses in comparison to the Bezier and industrial stepped LTC horns with the same length, end diameters and operating conditions. The novel cubic polynomial LTC ultrasonic horn was found superior to its catenoidal counterpart as a result of an 8.45 % higher amplitude ratio. However, the catenoidal LTC ultrasonic horn exhibited 1.87% lower stress levels. The position of the helical slots was found to have the most significant influence on the vibration characteristics of LTC ultrasonic horns followed by the width, depth and angle. This high amplitude ratio will contribute to the improved vibration characteristics that will help realize good surface morphology when machining advanced materials. [ABSTRACT FROM AUTHOR]

Performance of rotary ultrasonic machining (RUM) system greatly influences by appropriate design of ultrasonic horn. Ultrasonic stepped horn gives high amplitude of vibration and better cutting efficiency but design and integration of horn with RUM system is highly intricate. Therefore, systematic study on design and implementation of ultrasonic stepped horn was needed in order to achieve better efficiency of RUM process. This paper focuses on design aspects of ultrasonic stepped horn by theoretical, FE simulations and modeling techniques. The designed horn was integrated with RUM system, performance was measured in terms of ultrasonic resonant frequency through FE simulations and modeling on ANSYS workbench. Finally, fabricated ultrasonic stepped horn was validated by performing experiments on rotary ultrasonic machine tool for Nomex honeycomb composites (NHCs). FE simulations and experimental results prove that the designed ultrasonic stepped horn achieves reasonable vibration amplitude at desired resonant frequency to perform RUM process on NHCs materials. [ABSTRACT FROM AUTHOR]

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Dimensional distortion and instability in the milling process of aluminum alloy parts can significantly increase production costs and result in defective parts. Therefore, distortion mitigation has long been a central focus of aerospace industry researchers. This article aims to investigate the effect of axial ultrasonic-assisted milling on distortion. In this study, the machining parameters effect in conventional milling (CM) and ultrasonic assisted milling (UAM) were experimentally and statistically investigated on distortion and milling force, and the results were subjected to a comparative analysis. Experiments provided compelling evidence of the technical advantages offered by axial ultrasonic-assisted milling, demonstrating its efficacy in reducing both milling force and distortion when compared to conventional milling. Furthermore, our study established a direct relationship between milling force and distortion. Applying the axial ultrasonic-assisted vibration resulted in a notable 29% reduction in cutting force compared to conventional milling. Additionally, UAM exhibited a reduction in distortion by approximately 21%. These findings have significant implications, particularly in improving the flatness tolerance of the workpiece, thereby yielding components free from waves and warpages. [ABSTRACT FROM AUTHOR]

This article presents a review on some important recent research, development, and innovations related to the nonconventional machining of glass material. Nonconventional machining processes were identified suitable for machining of glass, years ago, and from then to now various technological developments have made nonconventional machining a viable alternate to the conventional machining of glass material. In this article, we have mainly focused on three important nonconventional machining processes, namely, last cutting, ultrasonic machining, and electrochemical discharge machining (ECDM). Novel aspects, effects of process parameters, and salient features are discussed. Mainly, previous five years' work is reviewed. This review finally ends with a conclusion and important future research directions. [ABSTRACT FROM AUTHOR]

Carbon fiber reinforced polymers (CFRP) are increasingly used in aerospace, military, and automotive applications due to their high specific strength and corrosion resistance. CFRP components usually require small-hole machining before assembly. CFRP parts are susceptible to defects such as tears and uncut fibers during hole machining. Ultrasonic-assisted drilling (UAD) contributes to the suppression of their defects. However, preliminary experiments revealed that the effect at different diameters is not the same. Therefore, this paper innovatively compares the effect of ultrasonic-assisted machining on the suppression of defects under different hole diameters and investigates the mechanism. The effects of machining parameters such as ultrasonic power, feed rate, and rotational speed on burr and tear defects of holes under different hole diameters are experimentally studied and theoretically analyzed. It was shown that the lowest defective machined holes were obtained at 50% (4 μm) ultrasonic power for all hole diameters, while higher ultrasonic power would result in an increase in machining defects. Compared with small hole diameters, there are relatively fewer uncut fibers at large hole diameters, but the tearing defects are more severe. The defect suppression effect of ultrasound is more pronounced at larger holes. The change in cutting force due to ultrasound is an important reason for the difference in machining defects. At a diameter of 6 mm, the longitudinal cutting force decreased by 58.7%, while uncut fibers and tearing defects decreased by 45.1% and 12.6%, respectively. This study can provide a theoretical basis for the selection of ultrasonic power and other parameters when machining holes of different diameters. [ABSTRACT FROM AUTHOR]

Freeform micro-structures can exhibit advanced and useful functions of optical components by guiding beam path. Growing interest has been shown in fabricating large-scale 3D freeform micro-structures on hard-to-cut materials as mould for mass production. Currently, ultrasonic vibration-assisted diamond turning is a feasible and efficient technique to fabricate these structures made of steel. However, the tool path linear error increases significantly with the increase in workpiece dimension in fast tool/slow slide servo diamond turning of microstructures with sharp edges. In this research, using Mirrax 40 steel as the mould material and applying a high-frequency ultrasonic tooling system (UTS2) to ease the machining of steel workpiece. To reduce linear error in machining large-scale 3D microstructures, diamond sculpturing instead of diamond turning was applied. This machining technology is called ultrasonic vibration-assisted sculpturing (UVAS). The principle of UVAS, tool path determination, surface generation, tool parameter selection as well as linear error of the tool path and form error induced by ultrasonic vibration kinematics, were comprehensively investigated, in order to fabricate an aspheric microlens array and a freeform microlens array with small theoretical error and reliable slide dynamic response. Furthermore, a large-scale freeform microlens array was fabricated and a measurement method was used to evaluate the machining accuracy. UVAS achieved a form error of less than 0.5 μm and an arithmetic surface roughness Sa of 5 nm for the large-scale freeform microlens array. • Ultrasonic vibration-assisted diamond sculpturing was used to reduce linear error in machining large-scale microstructures. • Form error induced by kinematical overcut in ultrasonic vibration-assisted sculpturing was theoretically clarified. • Tool vibration was eliminated to cut aspheric and freeform microlens arrays by various tool path modification methods. • A method based on finding structural peaks was used to evaluate 3D global form accuracy of large-scale 3D microstructures. [ABSTRACT FROM AUTHOR]

In this work, the effect of multi-walled carbon nanotubes (MWCNT1, MWCNT2, and MWCNT3) with different outer diameters and specific surface areas on the mechanical and electrical properties of cement mortar have been investigated. Various concentrations of MWCNTs were used (0.05, 0.10, and 0.15%), the effective dispersion of which was carried out by an Ultrasonic machine (for 40 min with 160 W power and a 24 kHz frequency) using a surfactant. Composites have been processed with a biosilica content of 10% by weight of cement and without it. Compressive strength tests were carried out on days 7 and 28 of curing. The 7-day compressive strength of samples prepared without biosilica increased compared to the result of the control sample (6.4% for MWCNT1, 7.4% for MWCNT2, and 10.8% for MWCNT3), as did those using biosilica (6.7% in the case of MWCNT1, 29.2% for MWCNT2, and 2.1% for MWCNT3). Compressive strength tests of 28-day specimens yielded the following results: 21.7% for MWCNT1, 3.8% for MWCNT2, and 4.2% for MWCNT3 in the absence of biosilica and 8.5%, 12.6%, and 6.3% with biosilica, respectively. The maximum increase in compressive strength was observed in the composites treated with a 0.1% MWCNT concentration, while in the case of 0.05 and 0.15% concentrations, the compressive strengths were relatively low. The MWCNT-reinforced cement matrix obtained electrical properties due to the high electrical conductivity of these particles. The effect of MWCNT concentrations of 0.05, 0.10, and 0.15 wt% on the electrical properties of cement mortar, especially the bulk electrical resistivity and piezoresistive characteristics of cement mortar, was studied in this work. At a concentration of 0.05%, the lowest value of resistivity was obtained, and then it started to increase. The obtained results show that all investigated specimens have piezoresistive properties and that the measurements led to a deviation in fractional change in resistivity. [ABSTRACT FROM AUTHOR]

Nomex honeycomb composites are widely recognized for their advanced structural applications in the aerospace, automotive and defense industries. These materials are distinguished by exceptional characteristics such as thin cell walls and a hexagonal structure, as well as layers made of phenolic resins and aramid fibers. However, complex machining and the maintenance of high quality at a large scale presents considerable challenges. This study provides a comprehensive review of the literature on the processing of Nomex composites, highlighting the design challenges related to processing technologies, the impact of conventional and ultrasonic processing methods, and the associated mechanical properties and microstructural topographies. Moreover, it reviews research advances in machining techniques, current challenges, and future perspectives, thereby providing valuable guidance to ensure the optimal cutting of Nomex honeycomb composite structures (NHCs). [ABSTRACT FROM AUTHOR]

The surface roughness of mechanical parts plays an important role in evaluating the machining performance. However, achieving fine surface finishes on small-diameter shafts through traditional lathes poses challenges due to low cutting speed and workpiece stiffness. To address this issue, in the present work, we applied ultrasonic-assisted vibration aligned with the cutting speed direction to enhance the turning process of small shafts made of C40 Carbon steel or 201 stainless steel. The workpieces were machined by Ultrasonic Assisted Turning (UAT) at three different cutting speeds, ranging from 15 to 36 m/min, while maintaining a constant feed rate and depth of cut. To facilitate comparison with conventional turning (CT), the cutting parameters remained consistent, and both methods were performed for the same duration. UAT necessitates the use of a specialized turning inserts' fixture known as a horn to transmit ultrasonic vibrations from the generator to the tooltip. This study also presents the design methodology and the performance evaluation of the horn. Surface roughness was assessed using the arithmetical mean height, Ra. In UAT, the roughness Ra exhibited the most significant reduction for C40 Carbon steel, reaching a decrease of 308% at a cutting speed of 15 m/min, whereas for 201 stainless steel, Ra did not vary by more than 23% across different cutting speeds. [ABSTRACT FROM AUTHOR]

In the field of power ultrasonic vibration processing, the thin liquid layer nestled between the tool head and the material serves as a hotbed for cavitation shock wave emissions that significantly affect the material's surface. The precise manipulation of these emissions presents a formidable challenge, stemming from a historical deficit in the quantitative analysis of both the ultrasonic enhancement effect and the shock wave intensity within this niche environment. Our study addresses this gap by innovatively modifying the Gilmore-Akulichev equation, laying the groundwork for a sophisticated bubble dynamics model and a pioneering shock wave propagation model tailored to the thin liquid layer domain. Firstly, our study investigated the ultrasound enhancement effect under various parameters of thin liquid layers, revealing an amplification of ultrasound pressure in the thin liquid layer area by up to 7.47 times. The mathematical model was solved using the sixth-order Runge–Kutta method to examine shock wave velocity and pressure under different conditions. our study identified that geometric parameters of the tool head, thin liquid layer thickness, ultrasonic frequency, and initial bubble radius all significantly influenced shock wave emission. At an ultrasonic frequency of 60 kHz, the shock wave pressure at the measurement point exhibited a brief decrease from 182.6 to 179.5 MPa during an increase. Furthermore, rapid attenuation of the shock wave was found within the range of R0-3R0 from the bubble wall. This research model aims to enhance power ultrasonic vibration processing technology, and provide theoretical support for applications in related fields. [ABSTRACT FROM AUTHOR]

Carbon fiber reinforced silicon carbide ceramic matrix composites (C f /SiC composites) have a wide range of applications in aerospace, nuclear energy, braking systems owing to its excellent mechanical performance. Nevertheless, the hardness, brittleness, heterogeneity, and anisotropy of C f /SiC composites give rise to difficulties in machining them. In addition, the characterization and formation mechanism of surface damage in the grinding of C f /SiC composites have not been fully elucidated. The purpose of this paper is to provide a characterization method for surface damage of C f /SiC composites and an evaluation index for surface edge chipping damage (SECD) through conventional scratching (CS) / ultrasonic vibration assisted scratching (UVAS) tests with single abrasive. Towards revealing the surface damage behavior of C f /SiC composites during scratching, as well as the impact of fiber orientation on surface damage. The findings indicate that main forms of surface damage of C f /SiC composites in single abrasive scratching are fiber breakage, fiber fracture-shedding, fiber fracture, fiber-matrix interface debonding, interface fragmentation, matrix cracking, and matrix microcracks. Further, ultrasonic vibration could help to suppress the SECD, and the SECD factor was smallest when scratching along the perpendicular fiber. Furthermore, the fiber orientation can significantly affect the scratching force and cross-sectional area of scratches on C f /SiC composites via single abrasive scratching. The tangential scratching force was usually smaller as compared to the normal scratching force, and the cross-sectional area of scratches in UVAS is smaller than that in CS. Based on the above findings, this study elucidates the formation and evolution of surface damage after scratching under different fiber orientations, filling the research gap in surface damage under ultrasonic assisted machining of C f /SiC composites and providing technical guidance for the machining. [Display omitted] [ABSTRACT FROM AUTHOR]

Exploring advanced green processing technology is the way to achieve efficient precision manufacturing of difficult-to-machine materials and carbon-neutral development. Thus, the design and manufacture of a large-amplitude longitudinal ultrasonic vibration-assisted milling (LALUVAM) toolholder is conducted in this work. For validation of the developed toolholder a TC4 titanium alloy milling experiment is carried out. Multifaceted analysis are presented in terms of milling force, surface roughness, and residual stress. The results indicate that the LALUVAM toolholder exhibits excellent performance in milling TC4 materials. What's more, the disordered tool feed trajectory is eliminated when using the LALUVAM toolholder in milling TC4. Moreover, resultant forces F is reduced 36.61%. The minimum surface roughness and a smaller range of compressive residual stress can be obtained under LALUVAM condition. Meanwhile, a scaled texture can be generated on the surface of TC4 by using harmonic movement of end mill. In the future, LALUVAM toolholder will be able to meet the 10 μm to 20 μm ultrasonic machining and provide better results in terms of reduced milling forces and surface roughness. [ABSTRACT FROM AUTHOR]

Ultrasonic vibration-assisted machining is a promising technique for improving the removability of materials, especially for difficult-to-machine materials, but the material removal mechanism under ultrasonic vibration status is still far from clear. Scratch testing is generally employed to study the material removal mechanism, but currently, there is a lack of instruments capable of performing scratch testing under ultrasonic vibration. To address this gap, this study developed an ultrasonic vibration scratch tester that can perform quantitative ultrasonic vibration-assisted scratch (UVAS) testing of materials. A prototype was designed and fabricated, followed by characterizing its performance parameters. Comparative experiments of conventional scratch (CS) testing and UVAS testing were performed on AL1050 to investigate the effects of ultrasonic vibration on scratch characteristics, such as the scratch depth and coefficient of friction. It was found that compared to CS testing, UVAS testing, with an amplitude of 1.45 µm and a frequency of 20 kHz, achieved a maximum reduction in the coefficient of friction of approximately 22.5% and a maximum increase in the depth of the residual scratch of approximately 175%. These findings confirm the superiority of ultrasonic vibration-assisted machining and demonstrate the requirement for the development of ultrasonic vibration scratch testers. [ABSTRACT FROM AUTHOR]

Ultrasonic Machining (USM) has broad applicability in numerous industrial fields. Accurate capture of ultrasonic vibration signals is pivotal to the functioning of USM, making them areas of significant research interest. However, the nonlinear and non-stationary nature of the USM vibration signal makes it unsuitable for analysis with conventional methods such as Fast Fourier Transform. Despite current methodologies like Discrete Wavelet Transformation (DWT) yielding valuable insights, they involve manual parameter selection and could lead to sub-optimal results. This paper presents a novel method, using Variational Mode Decomposition (VMD) to automatically decompose USM vibration signals into intrinsic mode functions (IMFs). This method is complemented by Particle Swarm Optimization (PSO) algorithm to optimize the number of IMFs and penalty factor, with Sample Entropy (SE) serving as a fitness function. The innovative SE-PSO-VMD method is validated in ultrasonic metal welding and demonstrates a notable ability in predicting the pull force of welding materials with a high coefficient of determination R2 value of 0.78.

The Foreign Object Damage problem is considered as the damage tolerance statement for consecutive loading tests, which include the shock-wave loading (by explosive generator) of massive planar targets (aluminum alloy AlMg6) to provide a billet for the specimen machining with controlled damage that is the analogous material of the fan blades subjected to high-speed collision with solid particles. These samples were used to perform high cycle fatigue and very high cycle fatigue tests with the ultrasonic testing machine, which allows fatigue loading for 108–1010 cycles with an amplitude of up to several tens of micrometers and a frequency of 20 kHz. It is shown that the fatigue strength of AlMg6 alloy specimens pre-loaded by shock in the 109 cycle regime reduces by 24%. The fatigue damage-failure transition and crack initiation were studied by the amplitude–frequency analysis of higher harmonics associated with the influence of defects on the effective elastic properties. The structural study of the fracture surface for the specimens after consecutive loading was conducted using the profilometry data to identify the roughness scale invariants induced by defects for corresponding areas responsible for the staging of fatigue damage-failure transition. The scale invariants and corresponding lengths were used for the formulation of the generalized Paris law for the crack advance in the damaged material. [ABSTRACT FROM AUTHOR]

Infrared thermal imaging camera as a non-contact monitoring of the object to be measured is widely used in fire detection, driving assistance and so on. Although there are many related studies, there is a lack of research on the influence of fog or smoke on infrared imaging under different environmental temperatures. To address this shortcoming, The temperature of both the environment and the target in this experiment is controlled by PID technology. The smoke or fog environment is generated using a smoke cake or an ultrasonic fog machine. The temperature of the target was measured by infrared thermal imaging camera. It was observed that as the temperature of the environment increases, the measured temperature of the target also increases. However, the change in temperature is more pronounced in the fog environment compared to either the smoke environment or the normal environment. It has been found through research that environmental radiation causes temperature changes in fog droplets. Therefore, Infrared radiation is less affected in the smoke environment and more affected in the fog environment. Additionally, when the environmental temperature is close to the target's temperature, the infrared image becomes blurred. [ABSTRACT FROM AUTHOR]

Nomex honeycomb composite core (NHC) is characterized by thin walls and complex hexagonal cells, giving it specific characteristics. However, this particularity generates significant challenges during its shaping, requiring the use of cutting tools of the particular geometry. In this study, experimental tests were conducted on the milling of NHC structure assisted by RUM technology using the UCSB cutting tool which is a toothed milling cutter. However, the experimental procedure fails to follow the cutting process, which complicates the visualization of the chip formation process due to the rapid movement of the cutting tool and the inaccessibility of the surface between the part/tool. Therefore, in order to effectively follow chip formation, a 3D numerical approach to the milling process of the NHC structure, using RUM technology, is developed using Abaqus Explicit software. On the basis of this model, the study focused on the components of the cutting force, the quality of the machined surface, and the accumulation of chips in front of the cutting tool. The numerical simulation results corroborate the experimental test findings, demonstrating the effectiveness of RUM technology in reducing cutting force components by up to 63%. An exhaustive analysis of the impact of the feed component Fy on the quality of the surface obtained was carried out, highlighting that the quality of the generated surface improves when the values of this component are low. In addition, the effectiveness of ultrasonic vibrations in reducing the accumulation of chips in front of the cutting tool is particularly accentuated, especially when large amplitudes are involved. Thus, the simulated results complemented the experimental results by offering coherent theoretical explanations. [ABSTRACT FROM AUTHOR]

High-volume fraction silicon carbide particle-reinforced aluminum (SiCp/Al) has a promising application for its high specific strength, wear resistance, and thermal conductivity. However, SiCp/Al components with a high-volume fraction are prone to poor surface quality and defects such as fractures, cracks, and micro-pits. It has been reported that ultrasonic-assisted grinding machining (UAG) helps to improve the quality of SiCp/Al machined surfaces. However, the differences between SiCp/Al with different volume fractions obtained by UAG machining are not clear. Therefore, a comparative study of surface roughness, morphology, and cutting force was carried out by UAG machining on SiCp/Al samples with volume fractions of 45% and 60%. Compared to the 45% volume fraction SiCp/Al, the 60% volume fraction SiCp/Al has a higher cutting force and roughness under the same machining parameters. In addition, experiments have shown that cutting forces and surface roughness can be reduced by increasing the tool speed or decreasing the feed rate. UAG machining with an ultrasonic amplitude within 4 μm can also reduce cutting forces and surface roughness. However, more than 6 μm ultrasonic amplitude may lead to an increase in roughness. This study contributes to reasonable parameter settings in ultrasonically-assisted grinding of SiCp/Al with different volume fractions. [ABSTRACT FROM AUTHOR]

Ultrasonic assisted machining is an eco-friendly surface texture fabrication method with low machining cost, high-accuracy precision, and efficiency. This study analyzes the surface texture formation in feed direction ultrasonic vibration assisted milling (FUVAM) and elliptical ultrasonic vibration assisted milling (EUVAM). The trajectories of the single and adjacent tool tips in FUVAM are analyzed. Furthermore, the tool–workpiece separation mechanism in EUVAM is discussed. Moreover, a 3D surface topography model of EUVAM is applied to study the influences of machining parameters on the ultrasonic machining topography. The experiments of conventional milling (CM) and EUVAM are carried out and different types of surface textures are successfully fabricated on Ti-6Al-4V using EUVAM. The results of the response surface indicate that the surface roughness shows an increasing trend with higher spindle speed, but decreases with improved feed speed and cutting depth. Compared with CM, the chips generated in EUVAM have the characteristics of small width and low bending degree. This work is expected to provide some guidance for the selection of machining and vibration parameters during ultrasonic assisted milling. [ABSTRACT FROM AUTHOR]

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Titanium alloy milling is prone to burrs at the edges of the workpiece, which can negatively affect surface integrity and dimensional accuracy, and even lead to part scrap. Ultrasonic vibration–assisted milling technology can effectively inhibit burr generation and improve machining quality. However, the research of ultrasonic vibration–assisted milling on burr inhibition is not clear, so this paper establishes a mathematical model of ultrasonic vibration vertical milling titanium alloy top burr size based on the chip deformation process and specifically analyses the effect of ultrasonic machining parameters on burr through experiments. The experimental results show that the depth of cut has the greatest influence on the burr size, and the ultrasonic vibration has the second greatest influence on the burr. The cutting force and the burr size on both sides of the groove show a trend of "decrease and then increase" with the increase of ultrasonic amplitude. When the ultrasonic amplitude was 3 µm, the cutting forces Fx and Fy were reduced by 34.42% and 31.36%, respectively, and the heights and widths of the burrs on the up milling side and on the down milling side were reduced by 75.49%, 44.33% and 89.16%, 47.82%, respectively, when comparing with no ultrasonic machining. The longitudinal-torsional ultrasonic vibration converted the large piled-up, rolled-up, and serrated burrs into intermittent, small-sized flocculent burrs, which significantly improved the burr morphology and weakened the serrated characteristics of the chips. [ABSTRACT FROM AUTHOR]

The ultrasonic vibration-assisted polishing (UVAP) method, a recently developed advanced processing technology, is widely used in the processing of brittle materials. This study uses molecular dynamics (MD) simulations to investigate the polishing behavior of diamond grits on SiC workpieces during the UVAP process. The frequency (fz), amplitude (Az), and dimensions of the vibration are varied to investigate various aspects of the material removal process. In the low-frequency region, the UVAP processing method exacerbates taper slips and dislocations in the workpiece. In the high-frequency region, fz and Az can improve the MRR by more than 32% and reach 2–4 times higher than that of traditional scratching, respectively. The surface morphology obtained using MD simulation is consistent with the experimental results. In the ultrasonic elliptical vibration assisted polishing (UEVAP) method, fy not only causes a periodic and stable increase in temperature, which helps to transform atoms into an amorphous structure, but it also increases material removal rate (MRR) while decreasing friction factor and surface roughness. Appropriate increase of fz reduces forces and improves stress distribution. Az significantly increases MRR but results in a rough surface. In comparison to the UVAP process, the UEVAP method further improves MRR and produces smoother machined surfaces. This study uses molecular dynamics (MD) simulations to investigate the polishing behavior of diamond grits on SiC workpieces during the UVAP process. The frequency (fz), amplitude (Az), and dimensions of the vibration are varied to investigate various aspects of the material removal process. [ABSTRACT FROM AUTHOR]