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In this paper, the simultaneous impacts of using nanofluid and ultrasonic vibrations in a double-pipe heat exchanger are experimentally investigated. The vibrating heat exchanger is designed so that the ultrasonic waves with the power of 60 watts and frequency of 40 kHz are applied to its body at equal length distances in a uniform and effective manner. Water-based Al 2 O 3 nanofluid is used in this research. The available empirical correlation has been used to confirm the accuracy of the measurements and validate the results. The effective thermal parameters have been tested in three cases using water, nanofluids, and ultrasonic-excited nanofluids as the working flow of the double-pipe heat exchanger. These tests have been performed in a relatively wide range of flow rate (113–257 lh −1 ), Reynolds number (3230–7431), inlet hot fluid temperature (40–60 °C), and nanoparticle volume fraction (0.4–0.8%). The results indicate the positive effect of adding nanoparticles and applying ultrasonic vibrations, especially at higher inlet hot fluid temperatures and higher nanofluids concentrations. The nanoparticles are more effective at high-flow rates, whereas the ultrasonic vibration is highlighted at low-flow rates. Also, the effectiveness-NTU analysis carried out for the current heat exchanger shows that using nanofluid and ultrasonic-excited nanofluid instead of water can increase the efficiency of the thermal system up to 18.3% and 42.3%, respectively.

Bone grinding is an essential and vital procedure in most surgical operations. Currently, the insufficient cooling capacity of dry grinding, poor visibility of drip irrigation surgery area, and large grinding force leading to high grinding temperature are the technical bottlenecks of micro-grinding. A new micro-grinding process called ultrasonic vibration-assisted nanoparticle jet mist cooling (U-NJMC) is innovatively proposed to solve the technical problem. It combines the advantages of ultrasonic vibration (UV) and nanoparticle jet mist cooling (NJMC). Notwithstanding, the combined effect of multi parameter collaborative of U-NJMC on cooling has not been investigated. The grinding force, friction coefficient, specific grinding energy, and grinding temperature under dry, drip irrigation, UV, minimum quantity lubrication (MQL), NJMC, and U-NJMC micro-grinding were compared and analyzed. Results showed that the minimum normal grinding force and tangential grinding force of U-NJMC micro-grinding were 1.39 and 0.32 N, which were 75.1% and 82.9% less than those in dry grinding, respectively. The minimum friction coefficient and specific grinding energy were achieved using U-NJMC. Compared with dry, drip, UV, MQL, and NJMC grinding, the friction coefficient of U-NJMC was decreased by 31.3%, 17.0%, 19.0%, 9.8%, and 12.5%, respectively, and the specific grinding energy was decreased by 83.0%, 72.7%, 77.8%, 52.3%, and 64.7%, respectively. Compared with UV or NJMC alone, the grinding temperature of U-NJMC was decreased by 33.5% and 10.0%, respectively. These results showed that U-NJMC provides a novel approach for clinical surgical micro-grinding of biological bone.

Nanofluid minimum quantity lubrication (NMQL) technique has many technological and economic advantages in grinding operation. NMQL can improve grinding performance in terms of cooling and lubrication and is ecofriendly because it consumes a small amount of grinding fluid. Ultrasonic machining can improve grinding performance owing to its reciprocating vibration mechanism and furrow widening. Consequently, the simultaneous utilization of these techniques is anticipated to improve the surface quality, especially for hard brittle materials. In this research, multiangle two-dimensional (2D) ultrasonic vibration is utilized in zirconia ceramic grinding. Results reveal that the adhesion and material peeling phenomenon on the workpiece surface is obviously reduced compared with dry grinding without ultrasonic vibration. The synergistic effect of multiangle 2D ultrasonic and NMQL is also studied. With increased angle, the roughness value is found to initially increase (from 45° to 90°) and then decreases (from 90° to 135°). Moreover, the lubricating effect under 90° is the poorest, with the highest R a and RS m values of 0.703 μm and 0.106 mm, respectively; conversely, the minimum R a value (0.585 μm) is obtained under 45°, and the lowest RS m value (0.076 mm) is obtained under 135°.

Carbon-fiber reinforced silicon carbide matrix (C/SiC) composites are typical difficult-to-cut materials due to high hardness and brittleness. Aiming at the problem of the serious tool wear in conventional milling (CM) C/SiC composite process, ultrasonic vibration–assisted milling (UVAM) and conventional milling tests with a diamond-coated milling cutter were conducted. Theoretical and experimental research on the cutting force during the ultrasonic vibration milling process of C/SiC composites is carried out. Based on the kinematics analysis of tool path during ultrasonic vibration milling process, the cutting force model of ultrasonic vibration milling is established, and the influence mechanism of ultrasonic vibration on the cutting force is revealed. Based on the analysis of the evolution law of tool wear profile and wear curve during the traditional milling and ultrasonic vibration milling of C/SiC, the tool wear forms and mechanism of diamond-coated milling cutters in two processing modes and the influence mechanism of ultrasonic vibration on tool wear are revealed. It is found that the main wear mechanism of the diamond-coated milling cutter is abrasive wear, and the main wear form is the coating peeling. Compared with the traditional milling, the tool wear can be reduced by the ultrasonic vibration milling in machining process. In the range of test parameters, the tool wear decreases first and then increases with the increase of ultrasonic amplitude.

Axial ultrasonic vibration-assisted face grinding (AUVAFG) of SiC has the characteristics of high efficiency and serious damage. With the aim of solving the problem of serious surface damage in AUVAFG of SiC ceramics, a composite ultrasonic vibration-assisted face grinding (CUVAFG) method involving axial vibration and elliptic vibration is proposed, which not only ensures the high efficiency but also maintains high quality of the machined surface. In this paper, the grinding forces and the surface quality were investigated by conducting comparative experiments on axial and composite ultrasonic vibration-assisted face grinding using a single diamond. The effects of ultrasonic vibration amplitude and wheel speed on grinding forces, ground surface roughness, and ground surface morphology were analyzed to reveal the brittle-ductile removal behavior of SiC ceramics during the micro-cutting process caused by elliptic ultrasonic vibration. The results show that CUVAFG can effectively reduce the grinding forces by about 15%, reduce the ground surface roughness by approximately 40.7%, and induce ductile removal to acquire good surface finish with predominantly facets in comparison to AUVAFG. More specifically for CUVAFG, with increased elliptic ultrasonic vibration amplitude along the long axis, the grinding forces are reduced by minor amplitude, but remain constant in the case of major amplitude. When the elliptic vibration amplitude is close to the critical chip thickness of brittle-ductile transition, the number of facets on workpiece surface is the highest, but the grinding forces and the surface roughness are relatively low. Meanwhile, with the increase of wheel speed, the number of facets and the proportion of ductile removal are both increased, but the grinding forces and the surface roughness are decreased. In order to realize low-damage machining of SiC ceramics by CUVAFG, it is suggested to keep the elliptic ultrasonic vibration amplitude around the critical chip thickness of brittle-ductile transition and use minor axial ultrasonic vibration amplitude and high wheel speed to achieve lower grinding forces and good surface quality.

Ultrasonic vibration-assisted grinding (UVAG) is an advanced hybrid process for the precision machining of difficult-to-cut materials. The resonator is a critical part of the UVAG system. Its performance considerably influences the vibration amplitude and resonant frequency. In this work, a novel perforated ultrasonic vibration platform resonator was developed for UVAG. The holes were evenly arranged at the top and side surfaces of the vibration platform to improve the vibration characteristics. A modified apparent elasticity method (AEM) was proposed to reveal the influence of holes on the vibration mode. The performance of the vibration platform was evaluated by the vibration tests and UVAG experiments of particulate-reinforced titanium matrix composites. Results indicate that the reasonable distribution of holes helps improve the resonant frequency and vibration mode. The modified AEM, the finite element method, and the vibration tests show a high degree of consistency for developing the perforated ultrasonic vibration platform with a maximum frequency error of 3%. The employment of ultrasonic vibration reduces the grinding force by 36% at most, thereby decreasing the machined surface defects, such as voids, cracks, and burnout.

The development and application of wire electrochemical micromachining (WECMM) technology have become a research hotspot of non-traditional machining. However, a series of problems cannot be eliminated due to the machining products of micromachining gap, which leads to poor machining performance. This paper proposed a new method named ultrasonic vibration–added wire electrochemical micromachining (UA-WECMM) technology, which can solve the mass transfer problem in WECMM with extremely narrow gap. Firstly, the flow field of machining gap was simulated. The results showed that the pressure range of machining gap was larger and was more conducive to the renewal of electrolyte when ultrasonic vibration was added. Secondly, the effects of ultrasonic amplitude and ultrasonic vibration object on machining accuracy and surface quality were compared by experiments, which illustrated that the machining performance was greatly improved with the increase of ultrasonic amplitude of the workpiece. The slit width can be reduced from 196.2 to 151.2 μm, and the surface roughness can be reduced from R a 0.863 to R a 0.259 μm. Finally, the micro-gear structure with surface roughness of R a 0.263 μm and depth-to-width ratio of 6.7:1 was fabricated, which proved that UA-WECMM technology is an effective technology for fabricating metal microstructures with high aspect ratio and good machining quality.

Carbon fiber-reinforced plastic (CFRP) has been widely used in aerospace equipment due to its exceptional properties, such as light weight, high-temperature resistance, and corrosion resistance. Ultrasonic vibration-assisted drilling (UVAD), a new advanced precision machining technology for CFRP, specifically rotary ultrasonic machining technology, has shown promising machining effects. However, existing research on its cutting characteristics, material removal mechanism, and surface quality research is still insufficient. Therefore, this study conducted finite element simulations and machining tests of UVAD on CFRP, focusing on analyzing the effects of high-frequency vibration on the stress–strain state and damage during CFRP machining, aiming to reveal the material removal mechanism under UVAD, as well as the impact of process parameter changes on cutting force. The results show that the cutting force data from both the finite element simulation and the experiment exhibit good consistency, which verifies the accuracy of the simulation model. Additionally, UVAD enhances the cutting edge with high-frequency impact cutting ability, effectively facilitating the fracture removal of brittle fibers, significantly inhibiting burr damage at the hole edge, reducing the drilling axial force by 5.9 to 15.4%, and decreasing the hole exit stratification factor by 3.6 to 6.2%.

Longitudinal ultrasonic vibration-assisted machining (LUVAM) is a machining technique that offers several benefits such as low cutting force, good surface quality, and prolonged tool life. A new set of LUVAM spindle with high-frequency vibrations was designed to enhance the efficiency of LUVAM and the critical cutting speed of \"tool-workpiece separation.\" The spindle's stepped axial vibration transducer is designed analytically, and its amplitude is amplified. The spindle's performance was assessed by measuring resonant frequencies and amplitudes of tungsten carbide and high speed steel tool at varying lengths. Experimental results showed that the transducer's maximum resonance frequency was around 33.52 kHz, and its maximum amplitude was approximately 24.03 μm. The maximum spindle speed exceeded 20,000 rpm, and the runout error was low during high-speed operations. Additionally, Inconel 718 was machined with the new spindle, and the experimental cutting force, machining temperature, surface morphology, chip, and surface integrity were analyzed under different machining parameters. The test results showed that LUVAM could successfully reduce cutting force and temperature while improving surface integrity when separation conditions are met. Compared to conventional machining, LUVAM reduced cutting force and average cutting temperature by up to 23.3% and 19.8%, respectively. The new spindle design provides a new approach for high-quality, efficient, and eco-friendly machining of difficult-to-cut materials.

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 F x and F y 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.