Application Of Ultrasonic Vibration Research Articles

Effect of Ultrasonic Vibration in Friction Stir Welding of 2219 Aluminum Alloy: An Effective Model for Predicting Weld Strength

Friction stir welding (FSW) is today used as a premier solution for joining non-ferrous metals, although there are many limitations in its application. One of the objectives of this study was to propose an innovative welding technique, namely ultrasonic-assisted friction stir welding (UAFSW) with longitudinal ultrasonic vibration applied to the stirring head. In this paper, UAFSW mechanical properties and microstructure analysis were performed to demonstrate that the fluidity of the weld area was improved and the strengthened phase organization was partially preserved, due to the application of ultrasonic vibration. The addition of 1.8 kW of ultrasonic vibration at 1200 rpm and 150 mm/min welding parameters resulted in a 10.5% increase in the tensile strength of the weld. The ultimate tensile strength of 2219 aluminum alloy UAFSW was analyzed and predicted using mathematical modeling and machine learning techniques. A full factorial design method with multiple regression, random forest, and support vector machine was used to validate the experimental results. In predicting the tensile behavior of UAFSW joints, by comparing the evaluation metrics, such as R2, MSE, RMSE, and MAE, it was found that the RF model was 22% and 21% more accurate in the R2 metric compared to other models, and RF was considered as the best performing machine learning method.

A mechanistic predictive model for ultrasound guided insertion process of Ø 0.11 mm Z-pins

The insertion of finer Z-pins is a key issue for utilization of their reinforcement potential in Z-pinned composite laminates. This paper aims to reveal the insertion mechanisms of the ultrasound guided insertion process of Ø 0.11 mm Z-pins. Taking into account the fibre deformation, fibre–matrix interface, needle tip cutting and needle-prepreg contact, a new mechanical model is proposed to predict the change of insertion force during the insertion process. It is found that the application of ultrasonic vibration can minimize frictional effect and reduce fibre fracture, thus significantly decreasing the insertion force. The traditional two-phase insertion mechanism is transformed into single-phase insertion mechanism due to ultrasonic vibration. Based on this model, the effects of process parameters (including vibration amplitude, vibration frequency, feed rate and needle geometry) on the insertion force can be determined. Then Z-pin insertion experiments are performed on the prepreg sample to verify the proposed model. Results show that the model can capture the insertion mechanisms during the ultrasound guided insertion and predictions are in excellent agreement with the experimental measurements.

Boosted Charge‐Carrier Transport in Triple‐Cation Perovskites by Ultrasonic Vibration Post Treatment

AbstractUltrasonic vibration imposed on the substrate of a drying perovskite solution film has previously been proposed as a nearly annealing‐free method to improve film quality and thus the photovoltaic performance for perovskite solar cells. However, an in‐depth understanding of the underlying mechanism of the improved film quality via ultrasonic vibration is still lacking. In this work, the effects of substrate vibration post treatment on the carrier lifetime and mobility are studied in triple‐cation perovskite films. With 80 s of annealing‐free vibration, the perovskite film demonstrates much stronger photoluminescence intensity and much longer carrier lifetime up to 2.634 µs, 2 orders of magnitude longer than that of the thermal annealed films. Optical pump terahertz probe spectroscopy reveals that the charge‐carrier mobility increases to 121 ± 44 cm2 V−1 s−1 when subjected to 80 s vibration followed by annealing. Such mobility is about 80 ± 40 cm2 V−1 s−1 higher than that of other polycrystalline organic–inorganic hybrid perovskite thin films of similar composition. The diffusion length is improved to nearly 1.5 times. The new understanding on the vibration‐induced charge‐carrier transport properties paves the way for the application of ultrasonic vibration toward the performance improvement of perovskite‐based electronic devices.

Penetration and microstructure of steel joints by ultrasonic-assisted gas metal arc welding

This work investigates the application of ultrasonic vibration to steel joints formed by gas metal arc welding. Welding is done using a metal active gas welding source with welding current of 120–160 A, 0.8 mm diameter welding wire and 10 l min−1 CO2 flow. The distance from the torch to the ultrasonic horn is 120 mm. Ultrasonic vibration most affects the weld when ultrasonic vibration position is 120 mm from torch and increases the penetration when welding speed is 190 (275) mm/min for a 5 mm thick (10 mm thick) plate. Moreover, weld width increases when welding speed is 190 mm min−1 for 10 mm thick plate. Although ultrasonic vibration does not affect the hardness of welding zones, it modifies the microstructure of the diffusion and welding-pool zones.

A combined multiscale modeling and experimental study on surface modification of high-volume micro-nanoparticles with atomic accuracy

Surface modification for micro-nanoparticles at the atomic and close-to-atomic scales is of great importance to enhance their performance in various applications, including high-volume battery, persistent luminescence, etc. Fluidized bed atomic layer deposition (FB-ALD) is a promising atomic-scale manufacturing technology that offers ultrathin films on large amounts of particulate materials. Nevertheless, nanoparticles tend to agglomerate due to the strong cohesive forces, which is much unfavorable to the film conformality and also hinders their real applications. In this paper, the particle fluidization process in an ultrasonic vibration-assisted FB-ALD reactor is numerically investigated from micro-scale to macro-scale through the multiscale computational fluid dynamics and discrete element method (CFD-DEM) modeling with experimental verification. Various vibration amplitudes and frequencies are investigated in terms of their effects on the fluid dynamics, distribution of particle velocity and solid volume fraction, as well as the size of agglomerates. Results show that the fluid turbulent kinetic energy, which is the key power source for the particles to obtain the kinetic energy for overcoming the interparticle agglomeration forces, can be strengthened obviously by the ultrasonic vibration. Besides, the application of ultrasonic vibration is found to reduce the mean agglomerate size in the FB. This is bound to facilitate the heat transfer and precursor diffusion in the entire FB-ALD reactor and the agglomerates, which can largely shorten the coating time and improve the film conformality as well as precursor utilization. The simulation results also agree well with our battery experimental results, verifying the validity of the multiscale CFD-DEM model. This work has provided momentous guidance to the mass manufacturing of atomic-scale particle coating from lab-scale to industrial applications.

Influence of ultrasonic vibrations on the properties of press-and-sintered titanium

In this study, longitudinal ultrasonic vibration was superimposed during the compaction of titanium powders. Then, specimens were vacuum sintered at 1273 K for 120 min. In order to investigate vibration influence on physical/mechanical properties, density, shrinkage, and compression strength of sintered samples were measured. The influence of powder size, compaction pressure, and aspect ratio also were studied on mentioned physical properties. Improvement of fine powder sintered samples density due to applied ultrasonic is greater than coarse powders, although their compacted density is lower than coarse powders samples. Dimensional stability (in the opposite of shrinkage) in coarse powder is greater than fine powders so that shrinkage in fine powders decreases up to 12%. Compression strength is improved due to the application of ultrasonic vibration up to 64%.

Processing and machining mechanism of ultrasonic vibration-assisted grinding on sapphire

Owing to outstanding mechanical, optical, thermal stability and chemical stability properties, sapphire has widespread use in semiconductors, aerospace and other fields. However, it is difficult to machine it efficiently and precisely because of its brittleness and hardness. In this work, the processing and mechanism of machining sapphire using ultrasonic vibration-assisted grinding technology have been investigated via experiment. The machining factors have been analyzed, including the condition of machined surface, specific grinding energy, force and force ratio. Referring to conventional grinding, the application of ultrasonic vibration reduces the force, force ratio, specific energy, and the reduction ratio is direction dependent. The effect on surface roughness and morphology is also anisotropic. Regarding the smoothness of the surface, the suitable directions were axial and tangential, while there was no noticeable improvement in the radial direction. Our results and insights could be beneficial for the precise machining of brittle materials and quality management.

Effect of simultaneous application of ultrasonic vibrations during laser surface melting on electrochemical properties of 2024 aluminum alloy

In the present investigation, effect of laser melting with and without simultaneous application of ultrasonic vibrations on electrochemical properties of 2024 aluminum alloy is investigated. The electrochemical behavior of the laser melted specimens was studied using open-circuit and potentiodynamic polarization measurements. Subsequently, investigation of the corrosion films was performed using scanning electron microscopy. It was observed that the laser melted specimens exhibited significant improvement in open circuit potential (both with and without simultaneous ultrasonic vibration application). The open circuit potential of the laser melted specimen without ultrasonic vibrations was observed to be more stable compared to the laser melted specimen with ultrasonic vibrations. It was observed that the corrosion mechanism undergoes a transition from pitting to uniform corrosion in the laser treated specimen, particularly in the laser melted specimen without ultrasonic vibrations. However, the extensive agitations due to ultrasonic vibrations in the melt pool appear to restrict Cu migration to grain boundaries that result in porous and relatively inefficient passive layer formation in laser processed samples with application of ultrasonic vibrations. This behavior was also observed in the potentiodynamic polarization studies that showed that the laser melted specimen without ultrasonic vibrations exhibited lower corrosion current and corrosion rate compared to the laser melted specimen with ultrasonic vibrations as well as the as received substrate. Copyright © 2017 VBRI Press.

Structure of the Weld Formed during the Application of Ultrasonic Vibrations

Structure of the Weld Formed during the Application of Ultrasonic Vibrations

Mechanical behavior and microstructure evolution of AZ31 magnesium alloy sheet in an ultrasonic vibration-assisted hot tensile test

Ultrasonic vibration-assisted tensile tests of AZ31 magnesium (Mg) alloy sheets are carried out at different temperatures (150 °C, 200 °C) and amplitudes (0–11.2 µm). The influences of the ultrasonic vibration on the stress-strain responses, microstructural evolution, fracture morphology, dynamic recrystallization (DRX), and dislocation structure of the material during hot deformation are discussed. The results show that both flow stress and elongation of the material are significantly influenced by the temperature and amplitude. The application of ultrasonic vibration delays the occurrence of DRX. However, it accelerates the continuous dynamic recrystallization process, thereby increasing the percentage of the DRX. Furthermore, an evolution of the dislocation structure occurs under the impact of ultrasonic vibration, offering valuable insights into the plasticity improvement of the material. The underlying mechanisms of ultrasonic vibration-assisted hot deformation of AZ31 Mg alloys can be described as below. Ultrasonic vibration affects the motion and distribution of dislocations, which have an effect on the dynamic recrystallization behavior, ultimately leading to changes in mechanical behavior of the material.

Observation on the behavior of ultrasonic micro-hammer and its effects on the deep drawing process: Numerical simulation and experimental study

Combining ultrasonic vibration (UV) with metal forming processes is investigated as a novel technology that has been able to reduce the forming force and enhance this process. This paper attempts to elucidate the effect of Ultrasonically Assisted Deep Drawing (UADD) process on the forming force and thickness distribution of the formed sample. Therefore, a Finite Element (FE) model is developed to simulate this process and further investigate the ultrasonic micro-hammer mechanism in UADD process. Experimental tests were conducted to validate the established numerical model. Accordingly, a robust technological equipment was designed and fabricated, so that by application of ultrasonic vibration, the drawing die will be stimulated in longitudinal mode at the frequency of 20 kHz and thus, remain in the resonant condition. A reasonable congruence was observed when the forming force results and cup configurations from experimental tests and numerical solutions were compared. Therefore, the numerical model was used to evaluate the deformation behavior of the sheet at different amplitudes and frequencies. The results confirmed continuous vibration and ultrasonic micro-hammer conditions exhibit different behavior during the UADD process, and the latter occurs when the ultrasonic die separates from the workpiece surface. Although the UV application under micro-hammer condition significantly reduces the forming force, it has a destructive effect on the thickness distribution of the sheet and causes severe thinning. The current study provides a better understanding of the ultrasonic micro-hammer and its effects on the sheet metal forming process, which is the fundamental step in exploring this process.

Suppression of Bottom Porosity in Fiber Laser Butt Welding of Stainless Steel

The application bottleneck of laser welding is being gradually highlighted due to a high prevalence of porosity. Although laser welding technology has been well applied in fields such as vehicle body manufacturing, the suppression of weld porosity in the laser welding of stainless steel containers in the pharmaceutical industry is still challenging. The suppression of bottom porosity was investigated by applying ultrasonic vibration, changing welding positions and optimizing shielding gas in this paper. The results indicate that bottom porosities can be suppressed through application of ultrasonic vibration at an appropriate power. The keyhole in ultrasound-assisted laser welding is easier to penetrate, with better stability. No obvious bulge at the keyhole rear wall is found in vertical down welding, and the keyhole is much more stable than that in flat welding, thus eliminating bottom porosity. The top and bottom shielding gases achieve the minimal total porosities, without bottom porosity.

Synthesis and characterization of nanocomposite Fe3O4/SiO2 core–shell abrasives for high-efficiency ultrasound-assisted magneto-rheological polishing of sapphire

A functional Fe3O4/SiO2 core–shell abrasive was synthesized via hydrolysis of tetraethyl orthosilicate. A silica shell was successfully coated on a Fe3O4 core, resulting in a core-shell particle with an average diameter of 140 nm. The prepared core–shell abrasives was utilized for ultrasound-assisted magneto-rheological polishing (UAMP) of sapphire substrate. The experimental results showed that the Fe3O4/SiO2 core–shell abrasives exhibited a remarkable polishing performance for the sapphire material, resulting in smooth and detect-free surfaces with a high material removal rate (MRR) compared to mixed abrasives (Fe3O4 and SiO2) and pure Fe3O4 particles. The application of ultrasonic vibration to the sapphire wafer further improved the MRR, which was approximately 3.4 times higher than that of traditional magneto-rheological polishing. The largest MRR (1.974 μm/h) and comparatively low surface roughness (0.442 nm) of the polished sapphire wafer were achieved by UAMP with the Fe3O4/SiO2 core–shell abrasives. The polishing mechanism of the sapphire wafer is discussed in terms of chemical reactions and mechanical polishing.

Study on the Springback Effect and Surface Property for Ultrasonic-Assisted Incremental Sheet Forming of Aluminum Alloy

The effect of ultrasonic vibration on the springback effect and surface property for ultrasonic-assisted incremental sheet forming of aluminum alloy were discussed. A series of experiments were established to explore the ultrasonic vibration on the surface property and springback effect of symmetrical aluminum alloy sheet in order to facilitate analysis of experimental results. It is obtained that the application of ultrasonic vibration can reduce the springback effect. The surface waviness feature aluminum alloy becomes weaker with the continuous increase of ultrasonic amplitude and the surface topography tends to be smoother. In addition, the application of ultrasonic vibration can reduce the surface hardness and promote the surface residual stress distribution to be more uniform. The findings provide an experimental basis for further investigation of the mechanisms of the ultrasonic-assisted incremental sheet forming process.

CALCULATION ON THE STRENGTH OF DEFORMING ELEMENTS AND DEVELOPMENT OF FIRMWARE STRUCTURES FOR ULTRASOUND PROCESSING

The possibility of increasing the efficiency and expanding the technological capabilities of the process of deforming drawing, by studying the contact phenomena and force characteristics of the process of deforming drawing (flashing) with the imposition of ultrasonic vibrations on the tool. The main advantages of deforming drawing with application of ultrasound are noted, among which it is necessary to allocate considerable decrease in force parameters of process, reduction of level of residual stresses, increase of accuracy of the processed details. Also, the application of ultrasound allows you to process parts made of metal and alloys, the processing of which in normal conditions is impossible and requires special techniques. It is noted that it is not possible to use known designs of broaches and firmware when flashing with the application of ultrasonic vibrations, because the firmware must have all the dimensions related to the acoustic parameters and the deforming element must be placed on the mandrel with tension to create good acoustic contact between the mandrel and the element. Prefabricated deforming firmware for processing holes with the imposition of longitudinal ultrasonic vibrations has been developed and a method for calculating their deforming elements for strength has been proposed. The performed calculations showed that the calculated stresses differ from the allowable ones by no more than 15-20 %. From the above calculations it is seen that the deforming element can be destroyed, both under the action of the working load in the process of flashing, and under the action of thermal stresses after the exit of the element from the machined hole. This difference in the results of research can be explained by the fact that the order of tensile strength is a value that has a large scattering zone and in different studies it is different. The results of research on the strength of deforming elements can be used in engineering calculations in the design of prefabricated tools for drawing holes with ultrasound.

Fast and Precise Control for the Vibration Amplitude of an Ultrasonic Transducer Based on Fuzzy PID Control.

This work presents a novel constant frequency ultrasonicamplitude control (CFUAC) method based on fuzzy proportional-integral-derivative (FPID) and amplitude direct feedback. The frequency shift and amplitude nonlinearity of the piezoelectric transducer (PT) are measured to determine the optimal constant control frequency of 19.2 kHz. The FPID controller is designed to adapt to the nonlinear changes in different target amplitudes and loads. A direct PT amplitude feedback method is used to improve the signal's anti-interference ability and accuracy. The 5% settling time and steady-state error of FPID can reach 92.22 ms and [Formula: see text] at the step response under 24 [Formula: see text]. The 5% settling time and steady-state error of FPID are less than 131.44 ms and [Formula: see text] at 10 [Formula: see text] under 150 N. The results confirmthat fast and precise control of the vibration amplitude of an ultrasonic transducer can be realized by the proposed method. The new CFUAC method lays a foundation for revealing the ultrasonic welding and metal processing (UWMP) mechanism and helps to expand the application of ultrasonic vibration in the fields of precision machining and high dynamic ultrasonicmedical equipment.

Acoustic effect on the tensile properties and metallurgical structures of dissimilar friction stir welding joints of Al/Mg alloys

Abstract The joint strength of friction stir welded Al/Mg alloys is a critical factor for the wide applications of dissimilar joints. In this study, dissimilar Al/Mg alloys joints were made by friction stir welding (FSW) and its variant, ultrasonic vibration enhanced FSW (UVeFSW), respectively. The tensile strength, fracture toughness and fracture location of the whole joints and three (upper, middle, lower) parts of the joints were compared by characterizing the macro-, mesoscopic- and micro-structures of the welds. The influence of ultrasonic vibration on the tensile properties of the joints was discussed. The results showed that the lower part of the welds was the weakest part due to the poor materials mixing/interlocking and a large amount of intermetallic compounds, while the upper part of the weld had the best strength. Good material mixing/mechanical interlocking in the welds was the basis for obtaining higher joint strength, and the thinner intermetallic compound layer was the key to the better toughness of the joint. The application of ultrasonic vibration can improve the tensile strength of each part of the welds, but the improvement rate of tensile strength is greater for the middle and lower parts of the welds.

Ultrasound Effect on the Microstructure and Hardness of AlMg3 Alloy under Upsetting.

To date, numerous investigations have shown the beneficial effect of ultrasonic vibration-assisted forming technology due to its influence on the forming load, flow stress, friction condition reduction and the increase of the metal forming limit. Although the immediate occurring force and mean stress reduction are known phenomena, the underlying effects of ultrasonic-based material softening remain an object of current research. Therefore, in this article, we investigate the effect of upsetting with and without the ultrasonic vibrations (USV) on the evolution of the microstructure, stress relaxation and hardness of the AlMg3 aluminum alloy. To understand the process physics, after the UAC (ultrasonic assisted compression), the microstructures of the samples were analyzed by light and electron microscopy, including the orientation imaging via electron backscatter diffraction. According to the test result, it is found that ultrasonic vibration can reduce flow stress during the ultrasonic-assisted compression (UAC) process for the investigated aluminum–magnesium alloy due to the acoustic softening effect. By comparing the microstructures of samples compressed with and without simultaneous application of ultrasonic vibrations, the enhanced shear banding and grain rotation were found to be responsible for grain refinement enhancement. The coupled action of the ultrasonic vibrations and plastic deformation decreased the grains of AlMg3 alloy from ~270 μm to ~1.52 μm, which has resulted in a hardness enhancement of UAC processed sample to about 117 HV.

Microstructure and mechanical properties of parts formed by ultrasonic vibration-assisted laser cladding of Inconel 718

Abstract Laser cladding has shown advantages in metal component forming. However, the accompanying issues, such as inner microstructural defects and poor mechanical properties, require further investigation. In this study, laser cladding technology was combined with ultrasound to improve the performance of the formed parts. Based on the cooperative effect of acoustic streaming and acoustic cavitation during the metal solidification process, the influence of the vibration parameter on the degree of undercooling and nucleation rate of the molten metals was investigated. The experimental results show that the grain size obtained under the application of ultrasonic vibration was finer than that obtained under condition of conventional laser cladding. When the amplitude was 25 μm, the average grain size was 0.522 times of that of non-vibration. The phase structure of the precipitates and the chemical composition changed markedly. In addition, the effects of high-frequency vibration on the mechanical properties of the cladding layer were also analysed through contrast experiments. The results indicate that applying high-frequency vibration can effectively reduce porosity, while improving the microhardness and wear resistance. Quantitatively, the friction coefficient was 0.628 times that without ultrasound and 0.709 times that of conventional processing when the amplitude was 25 μm.

Повышение режущей способности шлифовального круга при обработке заготовок из пластичных сталей наложением ультразвуковых колебаний на заготовку

The study aimed to identify the relations between the sticking intensity and ultrasonic vibrations (UV) used for processing and evaluate the wheels’ performance when grinding ductile materials blank parts. The authors carried out the numerical simulation of local temperatures and the 3H3M3F steel workpiece temperature when grinding by ultrasonic activation. The study determined that the application of ultrasonic vibrations with the amplitude of 3 µm causes the decrease in local temperatures by 13…40 %, and in blank part temperature – up to 20 %. The calculation identified that the activation of ultrasonic vibrations with the amplitude of 3 µm causes the decrease in the glazing coefficient by 33 % for cutting grain and by 7 % for deforming grain. When increasing the longitudinal feed rate or the grinding depth, the glazing coefficient increases to a lesser degree when using the ultrasonic vibration than in the case without ultrasonic activation. The authors carried out the numerical simulation of local temperatures when scratching the 3H3M3F steel specimens by single abrasive grains with ultrasonic activation. The sticking deformation and the stresses resulted from this deformation and affecting the junction points of sticking with grains with and without ultrasonic vibrations application are calculated. The experimental research included the micro-cutting of specimens with single abrasive grains. The experiments identified that the abrasive grains wear out and glaze to a lesser degree when micro-cutting a workpiece with ultrasonic vibrations activation. The lowering of the intensity of sticking of the workpiece material particles to the abrasive grains due to the adhesion causes the decrease in the glazing coefficient when using ultrasonic activation. The study considered the possibility to enhance the efficiency of flat grinding through the use of the energy of ultrasonic vibrations applied to a blank part in the direction with the grinding wheel axis. A workpiece fixed in the device between the vibration transducer and the support is one of the components of a vibration system. The authors performed the experiment when grinding 3H3M3F and 12H18N10T steel workpieces with the wheel face. When grinding with ultrasonic vibrations, the grinding coefficient increases up to 70 %, and the redress life increases twice or thrice.