Ultrasonic Vibration Conditions Research Articles

Optimization of Tool Wear and Cutting Parameters in SCCO2-MQL Ultrasonic Vibration Milling of SiCp/Al Composites

Silicon carbide particle-reinforced aluminum matrix (SiCp/Al) composites are significant lightweight metal matrix composites extensively utilized in precision instruments and aerospace sectors. Nevertheless, the inclusion of rigid SiC particles exacerbates tool wear in mechanical machining, resulting in a decline in the quality of surface finishes. This work undertakes a comprehensive investigation into the problem of tool wear in SiCp/Al composite materials throughout the machining process. Initially, a comprehensive investigation was conducted to analyze the effects of cutting velocity vc, feed per tooth fz, milling depth ap, and milling width ae on tool wear during high-speed milling under SCCO2-MQL (Supercritical Carbon Dioxide Minimum Quantity Lubrication) ultrasonic vibration conditions. The results show that under the condition of SCCO2-MQL ultrasonic vibration, proper control of milling parameters can significantly reduce tool wear, extend tool service life, improve machining quality, and effectively reduce blade breakage and spalling damage to the tool, reduce abrasive wear and adhesive wear, and thus significantly improve the durability of the tool. Furthermore, a prediction model for tool wear was developed by employing the orthogonal test method and multiple linear regression. The model’s relevance and accuracy were confirmed using F-tests and t-tests. The results show that the model can effectively predict tool wear, among which cutting velocity vc and feed rate fz are the key parameters affecting the prediction accuracy. Finally, a genetic algorithm was used to optimize the milling parameters, and the optimal parameter combination (vc = 60.00 m/min, fz = 0.08 mm/z, ap = 0.20 mm) was determined, and the optimized milling parameters were tested. Empirical findings suggest that the careful selection of milling parameters can significantly mitigate tool wear, extend the lifespan of the tool, and enhance the quality of the surface. This work serves as a significant point of reference for the processing of SiCp/Al composite materials.

Study on Surface Characteristics and Work Hardening of SiCp/Al Composites by SCCO2-MQL Combined with Ultrasonic Vibration Milling

This study investigated the milling of SiCp/Al composite materials using Polycrystalline Diamond (PCD) tools under various machining conditions, including dry cutting conditions, supercritical carbon dioxide (SCCO2) conditions, supercritical carbon dioxide cooling with minimum quantity lubrication (SCCO2-MQL) conditions, ultrasonic vibration conditions, and supercritical carbon dioxide cooling with minimum quantity lubrication combined with ultrasonic vibration conditions. The objective was to compare the surface roughness and morphology of the materials under different machining conditions. Furthermore, under dry cutting conditions and SCCO2-MQL combined with ultrasonic vibration, the effects of different milling parameters on the surface roughness and morphology of SiCp/Al composite materials were investigated through a univariate experiment. Microhardness tests were carried out on the machined workpieces to explore the influence of process conditions and milling parameters on work hardening. The experimental results indicate that among all the tested machining conditions, the SCCO2-MQL in combination with the ultrasonic vibration process significantly reduced the surface roughness of the material. When the milling speed was increased from 40 m/min to 120 m/min, both the surface roughness and the degree of work hardening first increased and then decreased. As the feed rate or cutting depth increased, the degree of work hardening also increased. Therefore, under SCCO2-MQL combined with ultrasonic vibration conditions, it is recommended to use a milling speed of more than 60 m/min and avoid using high feed rates and cutting depths in order to optimize the machining performance.

Investigation of the Flow Stress Model for Cr4Mo4V Bearing Steel under Ultrasonic Vibration Conditions

To investigate the mechanisms behind the effect of ultrasonic vibration on the plastic deformation of materials, the flow stress model of Cr4Mo4V was established according to the dislocation dynamics and thermal activation theory, which considers the effect of dislocation density evolution on plastic deformation under ultrasonic vibration conditions. The effect of amplitude and strain rate on the flow stress was analyzed by fitting the stress-strain data obtained from an ultrasonic vibration-assisted tensile (UVAT) single-factor test. To investigate the influence of strain rate and vibration duration on the acoustic effect, comparative tests with and without vibration were performed for various strain rates. The results showed that the flow stress decreased significantly in the tensile test with ultrasound compared to the test without ultrasound, and the degree of reduction increased with increasing amplitude. In addition, the nonlinear relationship between the acoustic softening effect and the strain rate was analyzed. The result demonstrates that the dislocation density absorbs the ultrasonic vibration energy, which results in slip and proliferation. Macroscopically, due to a greater susceptibility to plastic deformation, the dislocation density shows residual hardening at the end of the ultrasound. Finally, the average absolute relative error (AARE) between predicted flow stresses and experimental results under three ultrasonic conditions using the developed model were 4.49%, 1.27%, and 5.64%, which proved the validity of the model.

Experimental analysis of the effect of ultrasonic vibration on porosity suppression in narrow gap laser welding

Abstract The welding process has a wide range of applications in aerospace, military manufacturing, machinery, and other fields, and with the continuous improvement of welding technology requirements, the inhibition of porosity in the welding process is also increasing. This study, through the narrow gap laser welding characteristics and porosity formation mechanism of the depth of analysis, for the existing narrow gap laser welding method exists in the side wall of the weld fusion is poor porosity, poor uniformity of organizational properties and other issues, proposed ultrasonic-based welding method to achieve effective inhibition of porosity. The experimental analysis of ultrasonic vibration on the formation of porosity is carried out based on narrow-gap laser welding. The peak sound pressure of narrow gap welding increases when the ultrasonic current amplitude changes from 24A to 32A. Under different ultrasonic vibration conditions, the number of welds without applied ultrasound was as high as 95, while the number of porosities gradually decreased to 48 with the increase of applied ultrasound amplitude from 12% to 37%. Furthermore, as the ultrasonic amplitude increased, the residual height decreased by 0.45 ml. In addition, at fixed ultrasonic amplitude, with the increase of laser power, the porosity increased from 0.89% to 2.21%, and the average diameter of the porosity increased from 0.29 mm to 0.43 mm. The porosity for the porosity diameter of less than 200 μm was reduced to 0.020%. The percentage of stomata with a diameter greater than or equal to 200μm increased to 2.098%. This study analyzes the inhibition effect of ultrasonic vibration on porosity to a certain extent. Moreover, the inhibition effect of ultrasonic vibration in narrow gap laser welding is significant and the smaller the laser power under the same amplitude, the better the inhibition effect, which provides a valuable reference for the research of the narrow gap laser welding process.

Efficient Charge Separation via MoSe2 Nanosheets with Tunable 1T Phase Contents: Piezoreduction of Cr(VI) to Cr(III) and Piezodegradation of RhB.

Piezocatalysis is a promising technology to address environmental pollution by converting mechanical energy into chemical energy. Herein, MoSe2 nanosheets with different 1T phase percentages (ranging from 30 to 80%) were constructed by adjusting hydrothermal temperature. Moreover, the roles of phase engineering in the piezocatalysis were thoroughly investigated by degrading rhodamine B and reducing Cr(VI) in ultrasonic vibration conditions. In particular, MoSe2 prepared at 220 °C (MoSe2-220) exhibits ultrahigh observed constant kobs and degradation rate k, which is superior to most reported catalysts to date. The experimental results indicate that the introduction of the 1T phase increases the active sites of the material, improves the conductivity, and inhibits the recombination of electrons and holes. Moreover, an internal electric field in the 2H phase induced by piezoelectric polarization is facilitated to separate electron-hole pairs, enabling the degradation and reduction to proceed. The capture experiments and EPR tests further confirm that •O2- and •OH are main reactive species, and a rational mechanism is finally put forward. This study offers a clear understanding of phase engineering in piezocatalysis and provides an efficiency strategy to construct highly efficient piezocatalysts.

Machinability improvement in three-dimensional (3D) ultrasonic vibration assisted diamond wire sawing of SiC

Ultrasonic vibration assisted (UVA) cutting has been proven to be an effective method for improving machining behavior in processing hard and brittle materials. However, there is no investigation on three-dimensional (3D) UVA diamond wire sawing (DWS). In this paper, a novel 3D vibration assisted DWS system is developed. A theoretical model is established for predicating sawing forces. Experiments have been carried out on DWS of silicon carbide (SiC) ceramics. The effects of ultrasonic vibration assistance, input vibration direction and cutting parameters on sawing forces, surface morphologies and tool wear are studied respectively. The simulation results indicate that elliptical motion in 3D space can be obtained for the diamond abrasive. The experimental results reveal that the proposed model has sufficient accuracy to predict sawing forces. It is demonstrated that sawing forces can be reduced by ultrasonic vibration assistance either in vertical direction or in longitudinal direction. However, 3D ultrasonic vibration condition provides the lowest sawing force because of the combined advantages. Due to intermittent cutting mode, sawing forces are decreased by 31%, 40% and 29.8% in X, Y and Z direction, respectively. Because debris can be removed more easily from the contact surface and large ductile smooth area can be obtained, 3D ultrasonic vibration assistance generates higher surface integrity than that of traditional sawing process. Moreover, the wear of diamond wire saw can be effectively decreased.

Material removal profile prediction and experimental validation for obliquely axial ultrasonic vibration-assisted polishing of K9 optical glass

K9 optical glass is one of the typical components in optical systems. However, because of its poor fracture resistance, it is difficult to polish it with ultra-precision and high-efficiency and without any surface damage simultaneously. The emergence of the obliquely axial ultrasonic vibration-assisted polishing (UVAP) method can solve this problem which encounters in polishing efficiency and shape accuracy. However, due to the unclear material removal profile (MRP) mechanism, obliquely axial UVAP is not widely used in the processing field. This paper introduces the obliquely axial UVAP method in research processes, mainly focusing on the fixed point MRP analysis of the obliquely axial UVAP. Based on Hertz's contact theory, polishing pressure, the length of the semi-long axis (LLA) and the length of the semi-short axis (LSA) of the contact area are calculated under ultrasonic vibration conditions. Meanwhile, the relative linear velocity distribution of the oblique polishing tool in the instantaneous contact area is modeled by mathematical geometry method. A novel model of the MRP distribution for obliquely axial UVAP is proposed following the Preston equation. Subsequently, a series of polishing experiments were carried out to verify this model. The results show that the numerical model has good agreement with the experimental results on MRP, LLA, LSA, material removal depth and material removal rate (MRR). In addition, the material removal capability can be significantly improved by larger ultrasonic amplitude and larger oblique angle. This model not only more clearly elucidates the processing mechanism of obliquely axial UVAP, but also provides theoretical support for the polishing of free-form optical lenses.

Theoretical analysis and experimental investigation on a linear ultrasonic motor with a compact slider.

A compact slider for linear ultrasonic motors (LUMs) to improve the ability of LUMs for precision positioning is proposed in this article. The compact slider can avoid the effect of variable stiffness of the traditional slider on ultra-precision positioning, which consists of two pieces of ceramic with little lubricating oil on the sliding interface. Based on contact theory and lubrication theory, the contact mechanism and the lubricating state between the slider and the support plate are analyzed. Subsequently, a dynamic model for LUMs considering the lubricating state and the ultrasonic vibration condition is obtained. Furthermore, the output speed and output force of the motor are analyzed under the influence of film lubrication. Moreover, some experiments are designed to test the feasibility and effectiveness of the compact slider for precision positioning. The results indicate that the compact slider is more effective in inhibiting the fluctuation of the output speed compared to the traditional slider, and it can improve the displacement resolution of LUMs up to 7 nm.

Effect of ultrasonic vibration on cavitation erosion of aluminum oxide in fluid jet machining

Cavitation-induced erosion plays an important role in the material removal process of ultrasonic-assisted fluid jet machining. The influence of the ultrasonic and hydrodynamic parameters on the cavitation features was investigated in the present study. A numerical method was used to model the cavitation involved in the fluid jet flow field under the ultrasonic vibration condition. Experiments were also carried out to evaluate the cavitation erosion in ultrasonic-assisted fluid jet machining. The results indicated that the cavitation intensity has strong relations with the ultrasonic power output and frequency.

Effect of Ultrasonic Vibration Tensile on the Mechanical Properties of High-Volume Fraction SiCp/Al Composite

Silicon carbide particle-reinforced aluminum matrix composite has been widely used in the military and aerospace industry due to its special performance; however, there remain many problems in processing. The present paper introduces an ultrasonic vibration tensile device with a view to investigating an ultrasonic vibration tensile specimen. The results show that there are three major stages in the change in stress of the material under ultrasonic vibration: the ultrasonic stress superposition effect, softening effect, and Hall–Petch strengthening effect, these three effects occupy different proportions in different tensile stages. In addition, increasing the frequency of ultrasonic vibration increased the degree of stress reduction. Increasing the ultrasonic vibration amplitude reduced the fracture strength of the material. Comparison of the fracture morphology shows that the conventional condition was mainly interfacial peeling of SiC particles, and cleavage of the fracture occurred under ultrasonic vibration conditions.

A Temperature Model for Synchronized Ultrasonic Torrefaction and Pelleting of Biomass for Bioenergy Production

Abstract Low-energy and volumetric density of biomass has been a major challenge, hindering its large-scale utilization as a bioenergy resource. Torrefaction is a thermochemical pretreatment process that can significantly enhance the properties of biomass as a fuel by increasing the heating value and thermal stability of biomass materials. Densification of biomass by pelleting can greatly increase the volumetric density of biomass to improve its handling efficiency. Currently, torrefaction and pelleting are processed separately. So far, there has been little success in dovetailing torrefaction and pelleting, which only requires a single material loading to produce torrefied pellets. Synchronized ultrasonic torrefaction and pelleting has been developed to address this challenge. Synchronized ultrasonic torrefaction and pelleting can produce pellets of high energy and volumetric density in a single step, which tremendously reduces the time and energy consumption compared to that required by the prevailing multistep method. This novel fuel upgrading process can increase the biomass temperature to 473–573 K within tens of seconds to create torrefaction. Studying the temperature distribution is crucial to understand the fuel upgrading mechanism since pellet energy density, thermal stability, volumetric density, and durability are all highly related to temperature. A rheological model was established to instantiate biomass behaviors when undergoing various ultrasonic vibration conditions. Process parameters including ultrasonic amplitude, ultrasonic frequency, and pelleting time were studied to show their effects on temperature at different locations in a pellet. Results indicated that the volumetric heat generation rate was greatly affected by both ultrasonic amplitude and frequency. This model can help to understand the fuel upgrading mechanism in synchronized ultrasonic torrefaction and pelleting and also to give guidelines for process optimization to produce high-quality fuel pellets.

Investigation of Indentation Zone on K9 Glass under Ultrasonic Vibration Condition Using an Equivalent Mean Contact Pressure

Ultrasonic vibration-assisted grinding (UVAG) is a promising processing method for parts made of hard-brittle material, as a green machining. The material removal mechanism of hard-brittle material in UVAG is not yet fully understood. The mean contact pressure in the mechanical model of material deformation/fracture that is induced by abrasive grit reveals the deformation/fracture level during the material removal of the indentation of hard-brittle material. To investigate the material removal mechanism of K9 glass in UVAG, a new variable, namely, the equivalent mean contact pressure (EMCP) of glass indentation under ultrasonic vibration was proposed as a corresponding variable for mean contact pressure. A series of indentation experiments with/without ultrasonic vibration was carried out to analyze the material fracture of glass as induced by single random-shaped diamond grits. To obtain the EMCP, an equivalent characteristic size of ultrasonic vibration indentation of K9 glass was defined and measured in the experiments. The vertical load, EMCP and the profile features of the indentation zone, such as the equivalent characteristic size and indentation depth, were investigated in the indentation experiments. Subsurface damage of the K9 glass was also investigated by using UVAG and traditional grinding experiments to analyze the significance of the EMCP on material fracture during machining. The experimental results show the EMCP correlated better with the subsurface damage from UVAG than vertical load. Therefore, compared with the load, the EMCP is a better variable to reveal the difference of material removal mechanism between the UVAG and traditional grinding of glasses.

Ultrasonic Vibration Assisted Cutting of Nomex Honeycomb Core Materials

Nomex honeycomb core materials have been widely used in the aviation industry due to their special structure and performance. Conventional high-speed machining have resulted in the poor machinability of the honeycomb core so that the ultrasonic machining technology was applied. The kinematic characteristics in the ultrasonic vibration assisted cutting process were analyzed according to the movement of the sharp tool. Based on slide effect, a cutting force model was proposed to study the relationship between cutting parameters and cutting force. Ultrasonic vibration assisted cutting and ordinary cutting tests of Nomex honeycomb core material were conducted by considering feed rate, the inclined angle and the deflected angle. Besides, the effects of cutting parameters on machined surface quality of honeycomb core wall were studied. The test results show that slide effect caused by ultrasonic vibrations can reduce cutting resistance compared with ordinary cutting. The developed cutting force model can be applied to evaluated the cutting force in the ultrasonic vibration assisted cutting of Nomex honeycomb core material. The inclined angle has a great influence on the cutting force during ultrasonic vibration assisted cutting. High-speed reciprocating sliding action can effectively cut aramid fibers so that burrs and tearing defects of the incision have been greatly improved under condition of ultrasonic vibration assisted cutting.

Effects of ultrasonic vibration on performance and microstructure of AZ31 magnesium alloy under tensile deformation

Ultrasonic vibration can reduce the forming force, decrease the friction in the metal forming process and improve the surface quality of the workpiece effectively. Tensile tests of AZ31 magnesium alloy were carried out. The stress–strain relationship, fracture modes of tensile specimens, microstructure and microhardness under different vibration conditions were analyzed, in order to study the effects of the ultrasonic vibration on microstructure and performance of AZ31 magnesium alloy under tensile deformation. The results showed that the different reductions of the true stress appeared under various ultrasonic vibration conditions, and the maximum decreasing range was 4.76%. The maximum microhardness difference among the 3 nodes selected along the specimen was HV 10.9. The fracture modes, plasticity and microstructure of AZ31 magnesium alloy also were affected by amplitude and action time of the ultrasonic vibration. The softening effect and the hardening effect occurred simultaneously when the ultrasonic vibration was applied. When the ultrasonic amplitude was 4.6 μm with short action time, the plastic deformation was dominated by twins and the softening effect was dominant. However, the twinning could be inhibited and the hardening effect became dominant in the case of high ultrasonic energy.

Study on the Specific Energy Characteristics of the Ultrasonic Vibration Assisted Sawing Ceramic

Ultrasonic vibration improved the machining performance of a variety of brittle materials, and achieved good results in brittle materials machining applications. In this paper, the experiment about precision sawing engineering ceramic by using a thin diamond blade with and without ultrasonic vibration conditions was investigated. It is aimed to explore the effect of ultrasonic vibration on specific energy. The results show that ultrasonic vibration makes specific sawing energy having a significant reduction during material removal process. Under the ultrasonic vibration condition, the engineering ceramic’s materials removal way is changed. It changed from plastic removal to the removal of brittle fracture, which reduced the energy consumption of material removal.

Study on the Influence of Ultrasonic Vibration on the Specific Energy of Sawing Ceramic

The hard as well as brittle constituents are typically difficult-to-machined materials, and this character upsurges the machining cost. Many non-traditional machining methods were developed to improve its cost-effectiveness. Ultrasonic vibration assisted grinding has been improved the processing performance of a variety of brittle materials, and achieved good results in processing application. In this study, engineering ceramic was precisely sawn using a thin diamond blade with or without ultrasonic vibration conditions. During the sawing process, the specific sawing energy was investigated with the measurement of sawing forces to explore the influence of ultrasonic vibration. The results showed that the ultrasonic vibration made a significant reduction in specific sawing energy. The specific sawing energy decreased with the increase of the maximum undeformed chip thickness in both the sawing conditions; however ultrasonic vibration changed the trend of specific sawing energy in normal cutting mode from exponentially decreasing to a good linear decreasing. Under the ultrasonic vibration assisted sawing condition, the impact of the diamond grain on the engineering ceramic caused to much more material removal in brittle fracture mode. The reducing of the plastic transformation also reduced the energy consumption during the engineering ceramic sawing process.

Analysis of suspension stability for nanofluid applied in minimum quantity lubricant grinding

The nanofluid is usually applied in minimum quantity lubricant (MQL) grinding to decrease grinding temperature and to improve surface integrity of workpiece. However, a large challenge in the application process of nanofluid is the sedimentation of the nanoparticles due to their poor suspension stability in the base fluid. Then, the lubrication and heat conduction characteristics of nanofluid will be deteriorated, and the nanofluid cannot be atomized as expected during grinding. Therefore, the heat transfer performance of nanofluid during MQL grinding severely decreased. In this study, the force state of nanoparticle in base fluid was analyzed and the effect of dispersant on the force state of nanoparticle was researched. The suspension stability of Al2O3 (0.5 wt.%) nanofluid was investigated under different ultrasonic vibration times, pH values, and dispersant concentrations (sodium dodecyl benzene sulfonate, SDBS). It is found that the suspension stability of nanofluid is quite poor under short-time ultrasonic vibration condition, and the nanofluid with good suspension stability can be obtained when the ultrasonic vibration time exceeds 0.5 h. A higher concentration of SDBS will lead to a better suspension stability of nanofluid when the concentration of SDBS is quite low. However, if the concentration of SDBS exceeds 0.5 wt.%, there is oversaturated adsorption on the nanoparticles surface which results in the deterioration of suspension stability of nanofluid with the increase of the SDBS concentration. As pH value is below 7, the suspension stability of nanofluid is significantly improved with the increase of pH value. The sedimentation clearly appeared in the disperse system when pH value is higher than 7. The dispersion morphology of the Al2O3 nanoparticles in disperse system is analyzed by using a scanning electron microscope. It is found that some large aggregates appeared when no dispersant was applied in the disperse system, and the Al2O3 nanoparticles are uniformly dispersed in disperse system with the application of the dispersant.

超音波併用熱圧着における金ボールの変形と合金層の形成過程に関する研究

This study was undertaken to investigate the effect of bonding pressure profiles and ultrasonic vibration triggering timing on the deformation of gold balls and bond intermetallic formation process in Au-Al thermosonic wire bonding. The following results were obtained.Under the condition of ultrasonic vibration triggered after bonding pressure, which makes contact surface of a gold ball flat, small intermetallics are formed dispersively at the flat contact interface of a gold ball and an aluminum pad. They grow in the following two processes. One is the process forming slender islet intermetallics at the middle portion of the bond by micro frictional slip. The other is the process forming intermetallics shaped in arcs at the periphery of the bond by plastic deformation. A dynamic load leads to larger deformation and intermetallics area than a static load during bonding pressure.Under the condition of ultrasonic vibration triggered before bonding pressure, intermetallics are initially formed at the small contact area of spherical surface. They grow rapidly into islet shapes by micro frictional slip and are increased in numbers orthogonally to the direction of ultrasonic vibration. Then, arc-shaped intermetallics are also formed rapidly at the periphery of the bond by plastic deformation. The ultrasonic vibration triggered before pressure causes larger deformation and bond area in a short time than the ultrasonic vibration triggered after pressure. It is effective for reducing bonding time.

Improved Phosphate Ore Leaching with Physical Mutagenized Acidithiobacillus Ferrooxidans Based on Modified Logistic Model

Strains of Acidithiobacillus ferrooxidans (At.f) were separated and purified from water sample collected from a hot spring and bioleaching a low grade phosphate ore. The results indicated that bioleaching phosphorus rate increasing sharply was starting at the ending of pH value decreasing, and ascend velocity had slowed down after linear regression of pH was at its second peak. In the environment of ultraviolet mutagenesis, the initial growth of At.f (r) was decreased by illumination time increased, but the maximum rate of bioleaching phosphate ore (ηm) was increased. In the condition of ultrasonic vibration, r was increased by vibration time added, and ηm was almost increased, except 20 min, owing to the modificatory coefficient was large enough. In circumstances of low temperature treatment, r was decreased by treatment time raised; ηm was more increase than the sample of un-treatment (CK).

Burr Size Reduction in Drilling of Al/SiC Metal Matrix Composite by Ultrasonic Assistance

Metal matrix composites (MMCs) have received considerable attention due to their excellent engineering properties. Accuracy and surface finish play an important role in modern industry. Undesired projections of materials, known as burrs, reduce the part quality and negatively affect the assembly process. In this study, reducing burr size in drilling of MMC is performed by adding ultrasonic vibration to the process. Al/SiCp MMC with 5 wt% of SiC particulates in dry drilling operation with HSS drill tools coated with TiN was investigated. The effect of ultrasonic assistance on burr size was studied. The results demonstrate that under suitable ultrasonic vibration conditions, in comparison with the conventional drilling, the burr height and width could be reduced.