Longitudinal Ultrasonic Vibration Research Articles

Ultrasonic vibration-assisted single point incremental forming of hemispherical shaped component using AA3003 material

ABSTRACT Ultrasonic vibration-assisted single point incremental forming is a recent hybrid process variant of the single point incremental forming process. In this process, longitudinal ultrasonic vibration is used as an assistance in the conventional forming process. In this paper, the effect of amplitude of vibration in the ultrasonic vibration assisted single point incremental forming process have been researched. For the same, experimental work has been carried out by forming the hemispherical shaped components using multistage forming strategy. Moreover, numerical simulation work has been carried out using the LSDYNA solver and the results have been discussed in the light of depth of forming and strain distribution. The experimental fracture forming line is also developed for the AA3003 material for single point incremental forming process. High amplitude of vibration of 12 micron with 20 kHz frequency leads to poor formability; however, the lower amplitude of vibration of 8 micron with 30 kHz frequency leads to good formability.

Determination of the absorbed acoustic power of longitudinal vibrations by measuring their amplitude in a chosen area of the waveguide system outside the load

The way of determining the acoustic power of longitudinal ultrasonic vibrations going into the load by measuring the amplitude of longitudinal displacements using an electrodynamic sensor installed near the surface of the waveguide rod is considered. Two possibilities of using the developed method of measurement are analyzed in detail. One of them is based on the registration of the value of longitudinal displacements at the constant position of the electrodynamic sensor in two different states of the ultrasound system: with the load disconnected and after the load is connected, i.e. it uses two measurements at different moments of time, when the states of the system differ from each other. Another way uses two measurements of the amplitude of longitudinal oscillations at two chosen points of the oscillatory system, made at the same time. Formulas have been obtained that make it possible to determine the power entering the load from the measured values and other known values of the system parameters. The role of errors, both in the readings of the sensor and in determining its location on the oscillating system, on the accuracy of calculating the value of the power of the ultrasonic oscillations that went into the load is analyzed.

Understanding the mechanisms behind ultrasonic vibration in resistance spot welding of aluminum and steel

An ultrasonic-assisted resistance spot welding process, which can improve the quality of aluminum/steel spot-welded joints, has been developed. However, the mechanism of the thermal-electrical-mechanical behavior caused by the ultrasonic longitudinal vibration to welding process has not been clarified. In this study, the role and impact mechanisms of ultrasonic longitudinal vibration during the welding process to form joints were confirmed by combining the microstructural characterization of the formed joints with the signal analysis of the process, as well as the analysis of the independent finite element numerical calculation results. Additionally, the interface metallurgical reaction behavior, welding defects, fracture behavior, and joint strength characteristics of ultrasonic-assisted aluminum/steel resistance spot welding joints were comprehensively analyzed, and the results indicated that the sizes of the aluminum/steel nuggets decreased. It could be attributed to the competition among multiple ultrasonic effects. Specifically, ultrasonic vibration decreased the contact resistance between the aluminum/steel sheets, whereas the acoustic cavitation and acoustic streaming effects increased the electrical conductivity of molten steel and thermal conductivity of molten aluminum, respectively. Moreover, ultrasonic vibration promoted the radial creep of molten and near-molten aluminum, which expanded in the effective bonding area between the two workpieces. Furthermore, ultrasonic vibration effectively reduced the thickness of the intermetallic compound layer (<3.0 µm), concurrently inhibited the formation of interfacial welding defects. Finally, the peak tensile-shear load of aluminum/steel joints is significantly increased under multiple ultrasonic optimization mechanisms.

Characteristics of 2D Ultrasonic Vibration Incremental Forming of a 1060 Aluminum Alloy Sheet.

Currently, 1060 aluminum alloy is widely applied in the electronics industry, construction, the aerospace field, traffic engineering, decorations, and the consumer goods market for its good chemical, physical, and mechanical properties. In general, excellent processing property is necessary and important for the manufacturing of complicated panels. In this paper, a special 2D ultrasonic vibration incremental forming method is designed to improve its plasticity and mechanical properties. Three kind of processing methods, including traditional single-point incremental forming, longitudinal ultrasonic vibration incremental forming, and 2D ultrasonic vibration incremental forming, are used for the flexible manufacturing of cones and cylindrical cups of 1060 aluminum alloy sheet. Then, micro-hardness tests, residual stress tests, and scanning electron microscopy tests are carried out to probe the changes in micro-structure and mechanical properties and to analyze the effects of different types of ultrasonic vibration on the plasticity and fracture characteristic of 1060 aluminum alloy. It is proven that 2D ultrasonic vibration facilitates the improvement of plasticity and surface qualities of 1060 aluminum alloy better than the other two processing methods. Therefore, the novel 2D ultrasonic vibration incremental forming process possesses substantial application value for the flexible and rapid manufacturing of complicated thin-walled component of aluminum alloy.

A comprehensive study of ultrasonic-assisted gas metal arc welding of high-strength steel

The present study investigated longitudinal ultrasonic vibrations applied uniformly perpendicular to the weld line as an efficient approach in the ultrasonic-assisted gas metal arc welding (U-GMAW) of high-strength steel. The penetration depth, microstructure, microhardness, mechanical properties, and corrosion of welded joints produced from GMAW and U-GMAW were experimentally explored at different welding conditions to evaluate their performance. The experimental findings show that welded joints produced by U-GMAW have a maximum ultimate tensile strength (UTS) of 18.7 %, while showing 35.4 % elongation and 57.4 % toughness compared to the GMAW-welded joints at optimal conditions. The surface morphology analysis of the welded joints emphasizes that the dendritic microstructures generated by U-GMAW are finer than the dendritic microstructures generated by GMAW. Moreover, the microhardness of welded joints produced by U-GMAW method is higher than the GMAW-welded joints. The results of the polarization test also confirm that the corrosion rate of GMAW-welded and U-GMAW-welded joints are 360 and 1.60 µm/year, respectively with a power of 30 %. These results show that the corrosion rate of welded joints produced by GMAW is much higher than the one produced by U-GMAW.

Longitudinal ultrasonic vibration effects on grinding mechanism in side and end grinding of 2.5D Cf/SiC composites

Longitudinal ultrasonic vibration effects on grinding mechanism in side and end grinding of 2.5D Cf/SiC composites

Investigation on cutting forces and tool wear in high-speed milling of Ti-6Al-4V assisted by longitudinal torsional ultrasonic vibrations

Investigation on cutting forces and tool wear in high-speed milling of Ti-6Al-4V assisted by longitudinal torsional ultrasonic vibrations

Precision Grinding Technology of Silicon Carbide (SiC) Ceramics by Longitudinal Torsional Ultrasonic Vibrations.

Silicon carbide (SiC) ceramic material has become the most promising third-generation semiconductor material for its excellent mechanical properties at room temperature and high temperature. However, SiC ceramic machining has serious tool wear, low machining efficiency, poor machining quality and other disadvantages due to its high hardness and high wear resistance, which limits the promotion and application of such materials. In this paper, comparison experiments of longitudinal torsional ultrasonic vibration grinding (LTUVG) and common grinding (CG) of SiC ceramics were conducted, and the longitudinal torsional ultrasonic vibration grinding SiC ceramics cutting force model was developed. In addition, the effects of ultrasonic machining parameters on cutting forces, machining quality and subsurface cracking were investigated, and the main factors and optimal parameters affecting the cutting force improvement rate were obtained by orthogonal tests. The results showed that the maximum improvement of cutting force, surface roughness and subsurface crack fracture depth by longitudinal torsional ultrasonic vibrations were 82.59%, 22.78% and 30.75%, respectively. A longitudinal torsional ultrasonic vibrations cutting force prediction model containing the parameters of tool, material properties and ultrasound was established by the removal characteristics of SiC ceramic material, ultrasonic grinding principle and brittle fracture theory. And the predicted results were in good agreement with the experimental results, and the maximum error was less than 15%. The optimum process parameters for cutting force reduction were a spindle speed of 22,000 rpm, a feed rate of 600 mm/min and a depth of cut of 0.011 mm.

A comparative study of limit diagram of ultrasonic-assisted and conventional hot incremental forming of Ti-6AL-4V alloy

Electric hot incremental forming (EHIF) technique is a novel sheet metal forming method for low-formability materials like Mg and Ti-6Al-4V alloys. There are some defects in EHIF including low surface quality, unexpected sheet tear, and oxidation of the fabricated workpieces. These defects limit its widespread use. In this article, longitudinal ultrasonic vibrations of forming tools are used for Ti-6Al-4V sheets in the EHIF process. This technique led to a significant reduction of friction coefficient and improvement of workpieces’ surface quality. Also, a combination of mechanical vibrations and heat reduced the phase transformation temperature of α phase (HCP structure) to the more formable β phase (BBC structure) at 600 °C. It improved Ti-6Al-4V sheets’ formability. In this study, various tensile and compressive strains were created by manufacturing different geometries such as cone, frustum, torispherical, and five-lobe. These strains are used to compare the forming limit diagram of the ultrasonic-assisted and conventional hot incremental forming. The design of the experiment and analysis of variance were employed to identify the optimum condition for creating the largest strains. Also, effective parameters were optimized by response surface methodology. Then major and minor strains for both techniques were compared. Achieved strains in all types of geometries for ultrasonic-assisted technique were higher than those achieved by a conventional process.

Optimizing Processing Parameters and Surface Quality of TC18 via Ultrasonic-Assisted Milling (UAM): An Experimental Study.

This study conducted longitudinal ultrasonic-assisted milling (UAM) tests and optimized a combination of milling technological parameters to achieve high-quality machining of TC18 titanium alloy. The motion paths of the cutter under the coupled superposition states of longitudinal ultrasonic vibration and end milling were analyzed. Based on the orthogonal test, the cutting forces, cutting temperatures, residual stresses, and surface topographical patterns of TC18 specimens under different UAM conditions (cutting speeds, feeds per tooth, cutting depths, and ultrasonic vibration amplitudes) were examined. The differences between ordinary milling and UAM in terms of machining performance were compared. Using UAM, numerous characteristics (including variable cutting thickness in the cutting area, variable cutting front angles of the tool, and the lifting of the cuttings by the tool) were optimized, reducing the average cutting force in all directions, lowering the cutting temperature, increasing the surface residual compressive stress, and significantly improving the surface morphology. Finally, fish scale bionic microtextures with clear, uniform, and regular patterns were formed on the machined surface. High-frequency vibration can improve material removal convenience, thus reducing surface roughness. The introduction of longitudinal ultrasonic vibration to the end milling process can overcome the limitations of traditional processing. The optimal combination of UAM parameters for titanium alloy machining was determined through the end milling orthogonal test with compound ultrasonic vibration, which significantly improved the surface quality of TC18 workpieces. This study provides insightful reference data for subsequent machining process optimization.

Modeling of grinding force in longitudinal ultrasonic vibration–assisted grinding alumina ceramics and experimental evaluation

Modeling of grinding force in longitudinal ultrasonic vibration–assisted grinding alumina ceramics and experimental evaluation

Groove bottom material removal mechanism and machinability evaluation for longitudinal ultrasonic vibration–assisted milling of Al-50wt% Si alloy

Groove bottom material removal mechanism and machinability evaluation for longitudinal ultrasonic vibration–assisted milling of Al-50wt% Si alloy

Surface Mechanical Properties and Micro-Structure Evolution of 7075 Aluminum Alloy Sheet for 2-Dimension Ellipse Ultrasonic Vibration Incremental Forming: A Pretreatment for Laser Shock Peening

In this paper, a composite technique of ultrasonic incremental forming and laser shock peeing is proposed. The former process is mainly used for the manufacturing of complex-shaped sheet and strengthening coating that is prepared for subsequent laser treatment. The latter is applied for secondary surface reinforcement with ultra-high energy. This work focused on the novel ultrasonic incremental forming method and its effects on surface mechanical properties and micro-structure of a 7075 aluminum alloy. First, a kind of 2-dimension ellipse ultrasonic vibration incremental forming process and the unique double-mechanism method of sectionalized cooperative control of plastic deformation and mechanical performance were designed. Second, the single-point incremental forming, the longitudinal ultrasonic vibration incremental forming, and the 2 dimension ellipse ultrasonic vibration incremental forming were performed for the manufacture of conical components of 7075 aluminum alloy. Third, the Vickers micro-hardness testing results and images of the fracture morphology of the machined part for the novel technique confirm that softening mechanisms become dominant inside the metal sheet. Furthermore, a strengthening coating with excellent mechanical properties and a residual compressive stress field were created on its surface simultaneously. In a word, the research shows potential values of the proposed technique for the manufacture of aircraft panels of complex shape and excellent surface properties.

Experimental study on longitudinal-torsional ultrasonic vibration drilling of carbon fiber–reinforced plastics/titanium alloy stacks

Carbon fiber–reinforced plastics (CFRP)/titanium alloy (Ti) stacks are extensively applied in the aerospace industry due to their excellent mechanical properties. However, their poor machinability poses great challenges. In this study, longitudinal-torsional ultrasonic vibration drilling (LT-UVD) is innovatively introduced to improve the quality of CFRP/Ti drilling. First, the separation mode of LT-UVD is analyzed by kinematic equations. Then, an experimental platform is built based on the LT-UVD vibration actuator to perform CFRP/Ti drilling experiments. The thrust force, interface temperature, hole wall quality, hole defects, Ti chip morphologies, and tool wear in LT-UVD are experimentally compared against conventional drilling (CD) and longitudinal ultrasonic vibration drilling (L-UVD). The experimental results show that, compared with CD and L-UVD, the thrust force of CFRP in LT-UVD decreases by 20.36–40.55% and 2.04–14.61%, while the thrust force of Ti decreases by 19.08–24.83% and 1.95–9.34%. Moreover, a relatively low maximum interface temperature is achieved in LT-UVD. In addition, the hole size accuracy, surface roughness for the hole’s inner surface, and delamination factor are improved in LT-UVD. Fiber pullout defects, chip-breaking performance, and tool wear of CFRP are improved due to torsional vibration in LT-UVD. Finally, according to the high-speed camera, damage forms of the interface area are different when drilling CFRP/Ti stacks with various drilling sequences.

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.

Modeling and Simulation Study of Dry Ultrasonic Vibration-Assisted Grinding of Tool Steel With Single Alumina Abrasive Grit

Abstract In the precision fabrication industries, ultrasonic vibration-assisted grinding is widely utilized for the finishing of “difficult-to-cut” materials due to its intermittent cutting mechanism and brittle-to-ductile mode machining. In this study, a two-dimensional finite element model (FEM) of single grit ultrasonic vibration-assisted dry grinding (UVADG) and conventional dry grinding (CDG) of AISI D2 steel has been developed, which taken into account the influence of longitudinal ultrasonic vibration on the workpiece with variable downfeed. The effects of ultrasonic vibration and downfeed on the chip formation mechanism, temperature field, grinding force, and equivalent stress and strain were evaluated by analytical and simulation methods. The results show that the formation of the grinding chips under UVADG is much shorter and straighter than CDG mode at all respective downfeed. The validation experiment compared the simulated and experimental grinding force in both grinding modes to verify the reliability of the FEM results. The validation results demonstrate that the FEM model can accurately describe the single grit UVADG and CDG grinding. At each downfeed, the CDG mode has generated a larger equivalent plastic strain than the UVADG mode, resulting in a higher thermomechanical load on the workpiece. According to the findings, UVADG mode has the least plastic damage on the ground surface, which may improve the surface integrity of the ground component.

Experimental Study on Ultrasonic-Assisted End Milling Forces in 2195 Aluminum-Lithium Alloy.

To achieve high-quality machining of the 2195 aluminum-lithium alloy, this paper presents an experimental study on the effect of milling processing parameters on milling forces and surface topography, during which conventional milling and longitudinal-torsional ultrasonic vibration milling of the 2195 Al-Li alloy were performed. The characterization of the tool tip trajectory illustrates some of the advantages of ultrasonic machining, which include variable depth of cut and tool chip pulling. The differences in milling forces between conventional milling and longitudinal-torsional ultrasonic vibration machining were compared using orthogonal tests, and the effect of ultrasonic vibration on milling forces was investigated in detail. The maximum reduction of milling force Fy in the feed direction under the influence of torsional vibration is 62% and 54% for larger feed per tooth and cutting depth, respectively. The high-frequency impact generated by the longitudinal vibration not only reduces the chip accumulation on the surface, but also smooths out the tool-tooth scratches and creates a regular surface profile. In addition, the characteristics of the milling force signals of the two machining methods were analyzed, and the analysis of the spectrum of the collected milling forces revealed that the ultrasonic vibration caused the high-frequency components of the milling forces Fy and Fz. The orthogonal result analysis and single-factor result analysis verified the superiority of ultrasonic machining, provided parameter selection for subsequent aluminum-lithium alloy machining, and bridged the gap of longitudinal torsional ultrasonic vibration machining of 2195 aluminum-lithium alloy in the study of milling force.

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%.

Study of Features of the Diffraction of X Rays in a Quartz Crystal Modulated by Longitudinal and Transverse Ultrasonic Vibrations

Study of Features of the Diffraction of X Rays in a Quartz Crystal Modulated by Longitudinal and Transverse Ultrasonic Vibrations

Research on cutting force and surface integrity of TC18 titanium alloy by longitudinal ultrasonic vibration assisted milling

In order to study the influence of spindle speed and amplitude on the surface integrity, TC18 titanium alloy samples were milled by the process of conventional milling and longitudinal ultrasonic vibration assisted milling. The experimental data were obtained by dynamometer, thermometer, scanning electron microscope, X-ray diffractometer, and three-dimensional surface topography instrument for observation and analysis. The results show that the spindle speed has a significant effect on the cutting force, cutting temperature, surface morphology, and surface residual stress. Compared with conventional milling, the surface micro-texture produced by longitudinal ultrasonic vibration assisted milling is more regular, and the cutting force and cutting temperature can be reduced by 34.1% and 19.5%, respectively. Then, the surface residual compressive stress and surface roughness can be increased by 50.9% and 163.88%, respectively. In addition, a certain depth of plastic deformation layer can be formed under the surface of ultrasonic vibration machining, and the depth of deformation layer increases with the increase of amplitude, and when the amplitude is 4 μm, the depth of plastic deformation can reach about 5.2 μm. This study lays a theoretical foundation for further research and optimization of ultrasonic milling technology for difficult machining materials.