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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]

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]

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]

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]

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]

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]

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]

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]

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.

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]

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]

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]

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]

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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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.

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]

This review article presents the current status of various micromachining techniques used to create microfeatures in alumina ceramic. Alumina has emerged as an advanced substrate in various radio-frequency communication and automotive packaging applications due to its superior electrical resistivity, lower dielectric loss, higher wear resistance, and dimensional stability at high temperatures. However, creating complex-shaped microfeatures in alumina is challenging due to its hard and brittle nature. Traditional contact-based methods fail to create microsized shapes in alumina; thus, the researchers are exploring novel machining methods, like abrasive, thermal, chemical, and hybrid micromachining processes. This review article comprehensively summarizes various micromachining methods used to create microfeatures in alumina ceramics. The mechanism, unique features, pros/cons, novelty, and applications of ultrasonic machining, laser ablation, electrochemical discharge machining, abrasive-jet machining, etc., are presented. The associated processing challenges in various alumina micromachining and the potential remedies to produce high-quality alumina microparts for microelectronics applications are discussed. [ABSTRACT FROM AUTHOR]

Nomex honeycomb composites (NHCs) are commonly used in various industrial sectors such as aerospace and automotive sectors due to their excellent material properties. However, when machining this type of structure, problems can arise due to significant cutting forces and unwanted cell vibrations. In order to remedy these shortcomings, this study proposes to integrate RUM (rotary ultrasonic machining) technology, which consists of applying ultrasonic vibrations along the axis of rotation of the cutter. To fully understand the milling process by ultrasonic vibrations of the NHC structure, a 3D numerical finite element model is developed using Abaqus/Explicit software. The results of the comparative analysis between the components of the simulated cutting forces and those from the experiment indicate a close agreement between the developed model and the experimental results. Based on the developed numerical model, this study comprehensively analyzes the influence of the ultrasonic vibration amplitude on various aspects, such as stress distribution in the cutting zone, chip size, the quality of the machined surface and the components of the cutting force. Ultimately, the results demonstrate that the application of ultrasonic vibrations leads to a reduction of up to 50% in the components of the cutting force, as well as an improvement in the quality of the machined surface and a reduction in the size of chips. [ABSTRACT FROM AUTHOR]

This study aims to investigate the application and machining characteristics of brittle conductive ceramics using ultrasonic vibration-assisted powder-mixed electrical discharge machining (UV-PMEDM) technology. Titanium nitride (TiN) ceramics are widely used in aerospace, biomedicine, and electronics due to their excellent properties. However, the conventional mechanical machining methods of these materials result in severe tool wear, high costs, and low efficiency. Although electrical discharge machining (EDM) can overcome some limitations, it typically exhibits a low material removal rate and poor surface quality. This study utilizes the UV-PMEDM technology to process TiN ceramics. Single-factor experiments are conducted to analyze the effects of processing parameters, including ultrasonic amplitude, powder concentration, pulse-on time , and pulse-off time , on the material removal rate, surface roughness, and relative electrode wear rate, which indicate the EDM processing performance. With the assistance of ultrasonic vibration and mixed powders, the material removal rate of TiN ceramics using UV-PMEDM reaches 0.50 mm3/min, while maintaining a relative electrode wear rate below 1 % and surface roughness lower than 4.2 μm. The synergistic combination of ultrasonic vibration and mixed powders significantly enhances the processing efficiency and reduces surface roughness of TiN ceramics. These findings contribute to a better understanding of machining strategies for brittle conductive ceramics. [ABSTRACT FROM AUTHOR]

This study introduced a new ultrasonic vibration–assisted short electric arc machining method to improve the machining quality of workpieces. This method mitigated abnormal discharge phenomena such as short circuits, partial discharge, and secondary discharge caused by particle bridges formed between electrodes and workpieces owing to ineffective chip removal in conventional short electric arc machining. After both standard short electric arc and composite processing, the macroscopic characteristics and microscopic morphology of the workpiece were compared through experiments. Moreover, the surface morphology, roughness, and elemental energy spectrum of the workpiece were examined and analyzed through ultra-depth-of-field microscopy, electron scanning, and other methods. The results revealed changes in the surface morphology of the workpiece after the integration of a short electric arc machining and ultrasonic vibration. With the introduction of ultrasonic vibration, the workpiece surface exhibited disorder and uniformity, along with a significant reduction in the number of electrical corrosion pits and surface microcracks. Consequently, the thickness of the recast layer decreased by half, and the surface roughness decreased by over 16%, achieving a maximum reduction of more than twice the original state. Additionally, the surface elements of the material were modified. This study introduces a new method for advancing short electric arc technology to improve processing quality, material modification, and technological coupling. [ABSTRACT FROM AUTHOR]

The unique microstructures of bulk metallic glasses (BMGs) provide them with excellent mechanical, physical, and chemical properties, having important applications in the fields of medical devices, military equipment, aerospace, etc. However, the superb mechanical properties also contribute to poor machinability of the BMGs. Currently, researchers have proposed to improve the machinability by single-point diamond turning, laser-assisted machining and ultrasonic vibration-assisted machining, but their plasticity and viscous flow remain unchanged, thus restraining further enhancement of surface quality. Atmospheric pressure cold plasma jet (APCPJ), which is rich in active particles, can effectively ameliorate material machinability by modulating material properties. In this paper, we propose to use the APCPJ to regulate the properties of BMGs, and carry out nanoindentation, nanoscratching, and micro-milling experiments to investigate the influence mechanisms of APCPJ on the material properties and cutting process. The results demonstrate that after modified by APCPJ, plastic deformability of the BMGs is improved due to the increase of free volume content; meanwhile, the viscous flow is inhibited. The micro-milling experiments indicate that under the conditions of feed rate V f = 500 μm/s, spindle speed n = 30,000 rpm, and cutting depth a p = 5 μm, the improvement effect of APCPJ on the cutting process is relatively optimum. The surface roughness Ra of the Zr-based BMG and Ti-based BMG obtained by APCPJ are respectively 0.076 μm and 0.081 μm, which can be reduced by 37.7 % and 38.2 % compared with dry micro-milling. The cutting forces F z in the direction of cutting depth are also reduced by 30.9 % and 23.3 %, respectively. The APCPJ-assisted micro-milling method proposed in this work may ameliorate the machining quality of BMGs and promote the application of BMGs and APCPJ-assisted machining technology in aerospace and precision machining. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries are essential for electrochemical energy storage, yet they undergo progressive aging during operational lifespan. Consequently, precise estimation of their state of health (SOH) is crucial for effective and safe operation of energy storage systems. This paper investigates the viability of ultrasound-Based methods for assessing the SOH of prismatic lithium-ion batteries. In the experimental framework, a designated prismatic lithium-ion battery was subjected to numerous charging and discharging cycles using a battery cycling system. Subsequently, ultrasonic detection experiments were conducted to record the waveforms of the transmitted and received signals. These signals were then processed through wavelet transforms to extract signal amplitude and time-of-flight data. To analyse these data, we applied four algorithms: linear regression, support vector machines, Gaussian process regression, and neural networks. The predictive performance of each algorithm was evaluated through extensive experimentation and analysis. The combination of ultrasonic signals with computational models has emerged as a robust technique for precise battery degradation assessment, suggesting its potential as a standard in battery health evaluation methods. [ABSTRACT FROM AUTHOR]

A study on machining CFRP composites by rotary ultrasonic machining (RUM) has been carried out to explore the influence of process parameters on machining performance and to determine the optimal cutting force value. The design approach was used to determine the effects of each of these characteristics independently and the effects of their interactions. A novel hybrid manufacturing technique, RUM, involves the use of a rotating tool vibrated at ultrasonic frequencies. The results obtained show that every residue point exhibits a strong alignment, as they are all in close proximity to the regression line. Nevertheless, subtle distinctions emerge between the calculated and observed response values, evident in the slight vertical gaps between the points on the regression line. The residual standard deviation offers a mean estimation of these disparities. Therefore, we can deduce that the choice of feed rate holds a higher degree of importance in carbon fiber-reinforced plastic (CFRP) machining operations when compared to the other parameters. [ABSTRACT FROM AUTHOR]

Metallic glass has been widely used in aviation, medical, military, and other fields because of its excellent performance. In view of the poor processability of metallic glass, the introduction of ultrasonic vibration provides a unique idea for it. In order to further explore the influence of ultrasonic vibration on trajectory and machining effect, this paper focuses on the theoretical feasibility of generating a unique type of tool path under different parameter combinations and studies the machining effect of metal glass under this condition. The experimental results show that the frequency coefficient, amplitude, and phase difference are all important parameters that affect the characteristics of tool path and the machining effect of metallic glass. The tool path formed by the appropriate phase difference and frequency coefficient will greatly improve the surface morphology, and the separation characteristics formed under the appropriate parameters can reduce the cutting force by about 50%. In addition, the effect of ultrasonic vibration machining with a frequency coefficient of 2 is the best, the cutting force generated is similar to that of elliptical ultrasonic vibration machining, and the roughness is reduced by nearly 50%. Choosing the appropriate parameters will get the ultrasonic vibration tool path with a positive effect, and will greatly improve the machining quality of metallic glass. [ABSTRACT FROM AUTHOR]

Particle-reinforced titanium matrix composites (PTMCs) are extensively utilized in key aerospace structural components due to their low density, high ductility, oxidation resistance, excellent wear, and high temperature properties. However, the quality of machining is significantly impacted by macro-fracture and pull-out of the reinforcing particles. In order to address the aforementioned issues and elucidate the material removal mechanism of cubic boron nitride (cBN), this study introduces ultrasonic machining technology into conventional single cBN grain grinding and conducts comparative experiments. The impact of machining parameters on material removal ratio, abrasive wear, and surface quality is the primary focus of the investigation. Findings indicate that the implementation of radial ultrasonic vibration-assisted grinding (RUAVG) can effectively reduce the pile-up ratio from 17.3 to 58.3%. Due to the impact of ultrasonic vibration on abrasive grains and their interference with reinforced particles, cBN abrasive grains undergo continuous micro-fracturing, resulting in superior self-sharpening capabilities and sustained sharpness and processing performance of the grinding edge. Compared to conventional grinding, RUVAG achieves material removal via cutting and micro-fracture mechanisms, which effectively prevents reinforcement pull-out and significantly enhances machining quality. [ABSTRACT FROM AUTHOR]

SiCf/SiC ceramic matrix composites are widely used in high-tech fields such as aerospace and usually processed by grinding methods. In the conventional machining (CON-M), the cutting force during machining is increased due to the hard and brittle characteristics of the material, which affects the surface topography after machining. As a new machining method, longitudinal-torsional coupled rotary ultrasonic machining (LTC-RUM) can effectively reduce the cutting force and improve the surface topography after machining. The machining characteristics of SiCf/SiC ceramic matrix composites in LTC-RUM was investigated to improve the service performance of the material, and reduce the energy consumption. However, relatively few studies have been performed on the machinability of SiCf/SiC ceramic matrix composites by LTC-RUM. This paper studies the cutting force and surface topography during machining by experimental methods. Firstly, the motion characteristics of a single abrasive grain during LTC-RUM are analyzed, and the cutting characteristics of the abrasive grain under the both machining conditions are obtained. Secondly, the effects of spindle speed, feed rate, cutting depth, and ultrasonic amplitude on cutting force and surface roughness were obtained by experimental exploration of CON-M and LTC-RUM. Compared with CON-M, the cutting force is reduced by 64.4%, the surface roughness is reduced by 44.5% under LTC-RUM, and the surface topography is significantly improved. The results of this study provide a theoretical and experimental basis for machining SiCf/SiC ceramic matrix composites. [ABSTRACT FROM AUTHOR]

In order to study the influence of machining methods and parameters on the surface quality of carbon fiber reinforced composites (CFRP) in the cutting process, the finite element simulation model of ultrasonic-assisted cutting CFRP was established, the simulation results show that the introduction of ultrasonic reduces the damage degree of CFRP in the cutting process, and the tool attached torsional ultrasonic vibration effect is the most significant. The ultrasonic-assisted torsion and longitudinal cutting tests of CFRP disc were carried out respectively, and compared with the ordinary cutting process, the experimental results show that the introduction of ultrasonic changes the fracture mode of fiber and effectively reduces the surface roughness. The fiber cutting angle (the angle between the cutting speed direction and the fiber direction) is the main factor affecting the surface roughness of CFRP, the effect of ultrasonic is better in the low-speed area, and the direction of fiber can be weakened by high-speed processing. When the amplitude is in the range of 0 ~ 6 μm, with the increase of amplitude, the advantage of ultrasonic is more obvious, and the inhibition of the influence of fiber directivity is more obvious. The results show that large amplitude and small cutting speed can achieve better ultrasonic machining effect; large vibration amplitude and high cutting speed can effectively suppress the influence of fiber directivity. The results are helpful for the high-quality processing of CFRP and other composite materials. [ABSTRACT FROM AUTHOR]

The aluminum alloy Al7075-T6 finds extensive application in the aviation and automotive industries, where machining plays a pivotal role. Emerging techniques such as Ultrasonic Vibration-Assisted Machining (UVAM) and Minimum Quantity Lubrication (MQL) hold promise for enhancing machining efficiency. In this study, the combined use of UVAM and MQL for slot milling of Al7075-T6 was investigated. The results demonstrate that UVAM reduced cutting forces by an average of 10.87% in MQL and 8.31% in Conventional Cutting Fluid (CCF) conditions when compared to Conventional Machining (CM). In addition, UVAM yielded significantly improved surface finishes, characterized by an average reduction in surface roughness of 41.86% in MQL and 32.11% in CCF conditions relative to CM. Furthermore, surfaces subjected to UVAM exhibited fewer instances of burn marks and tool-induced markings, reduced chip splashing, and more uniform surface integrity compared to those manufactured with CM. Lastly, chips generated through UVAM exhibited distinct characteristics, notably shorter length, curvier shape, and a distinctive half-turn morphology when compared with the irregular chips produced through CM. In conclusion, our findings underscore the potential of UVAM in synergy with MQL to augment the machining of Al7075-T6 alloy, thereby yielding superior-quality machined components with enhanced operational efficiency. [ABSTRACT FROM AUTHOR]

The material removal in the ultrasonic machining process is due to the fracture of the workpiece material. The fracture is due to energy transfer by vibrating abrasive particles. The vibration energy is induced by a tool oscillating at a frequency of more than 20 kHz. The vibrating particles not only impact the workpiece surface but also impact the oscillating tool, and it leads to the fracture of the tool, which is of interest to understand to guarantee efficient machining with accuracy and precision. In the current investigation, the tool wear during the ultrasonic machining of Inconel 718 super alloy is attempted. An acoustic emission sensor is integrated with the machining setup, and signal information is extracted in the time and time-frequency domains. The features and process parameters are input to a support vector regression model to estimate tool wear. The model developed for tool wear prediction yields an accuracy of 96.13% compared to the model developed with only process parameters, which delivers an accuracy of 84.89%. The developed model can be beneficial for the real-time monitoring of tool wear during the ultrasonic machining process for industrial and remote applications. [ABSTRACT FROM AUTHOR]

Purpose: Utilization of advanced hard and brittle materials in engineering applications has led to the need of non-conventional machining techniques such as rotary ultrasonic machining (RUM) to achieve high dimensional accuracy and low machining defects (delamination, burr and cracks formation, etc.). RUM performance greatly depends on vibration amplitude at tool end which is achieved through appropriate ultrasonic horn design. Longitudinal–torsional coupled (LTC) vibrations, generated by incorporating helical slots in horn design, improve ultrasonic machining quality of hard and brittle materials. In present investigative work, modified ultrasonic horns were designed and analyzed for RUM by producing helical slots in quadratic and cubic Bezier horn profiles to achieve high amplitude ratio ( T A / L A ) within safe stress limits. Methods: Modal and harmonic analyses were performed to investigate the influence of depth ( D s ), width ( W s ), angle ( θ s ) and location ( L sp ) of helical slots on the modal frequencies, vibration amplitudes, torsional to longitudinal amplitude ratio and stresses in ultrasonic LTC Bezier horns using FEM. Modified ultrasonic horns were tested for three different materials: steel, aluminum, and titanium after validation with available literature. Results: Presently designed horns were found to attain high amplitude ratio and low stresses as compared to the commercial step LTC horn for same end diameters and length. Different stresses (shear, von Mises, radial, tangential and axial) were also computed and plotted along horn axial length for optimum designs and were found well below the endurance limit. Conclusions: For the same end conditions and length, cubic Bezier LTC ultrasonic horn is preferable to its quadratic counterpart due to 19.91 % higher amplitude ratio. However, stresses are 24.78 % less in quadratic Bezier LTC ultrasonic horn. The amplitude ratio attained by both types of LTC Bezier horns was found to be significantly greater than that in the commercial LTC step horn, with additional advantage of low stresses. Achievement of high amplitude ratio will help in reduced cutting force and improved surface quality of advanced hard and brittle materials as compared to standard LTC horn design. [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.

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]