Ultrasonic Vibration Frequency Research Articles

Experimental Evaluation and Kinetic Analysis of Direct-Contact Ultrasonic Fabric Drying Process

Abstract Over the past two decades, due to the rising energy prices and growing awareness about climate change, significant efforts have been devoted to reducing the energy consumption of various home appliances. However, the energy efficiency of clothes dryers has little improvement. Recent innovations in the direct-contact ultrasonic fabric drying technique offer new opportunities for energy saving. In this technique, high-frequency mechanical vibrations generated by the ultrasonic transducer are utilized to atomize water from a fabric in the liquid form, which demonstrates great potential for reducing energy use and drying time of the fabric drying process. Here, for the first time, fabric drying kinetics under different direct-contact ultrasonic drying conditions were investigated experimentally and analytically. The drying processes of four kinds of fabrics were experimentally tested under different ultrasonic transducer vibration frequency (115, 135, and 155 kHz) and input power (1.2, 2.5, and 4.4 W) conditions. According to the experimental data, five different kinds of models were applied to quantify the drying kinetics of fabrics during direct-contact ultrasonic drying. The models not only incorporated the transducer parameters but also the parameters related to the nature of fabric. Our evaluation results of model prediction performance demonstrated that the two empirical models, i.e., the Weibull model and the Gaussian model, were superior to the three semi-theoretical models for anticipating the drying kinetics of fabrics under direct-contact ultrasonic drying. Furthermore, the Weibull model is more suitable for practical energy-efficient direct-contact ultrasonic fabric drying applications compared with the Gaussian model.

Investigation of the effects of ultrasonic assisted drilling on tool wear and optimization of drilling parameters

In this study, ultrasonic-assisted drilling was performed on different heat-treated (T6, T1) AA6061 to investigate the effects of cutting parameters on forces, surface roughness, and tool wear. TiN-coated and uncoated HSS-G drill bits were used in the experiments. The results obtained in the experiments were evaluated according to the general full factorial design and the effect graphs of different drilling parameters were generated. In addition, ANOVA tables were created to evaluate the results. SEM and OM micrographs were used to investigate the tool wear and chip formation. Finally, a multi-response optimization was performed to optimize drilling parameters for minimum cutting force and surface roughness. According to, optimum drilling parameters were determined as AA6061-T6 for material, uncoated HSS-G for a drill bit, 1520rpm for spindle speed, and highest ultrasonic vibration frequency at 22.5kHz. In addition, it was observed that ultrasonic vibration has the effect of reducing built-up edge formation on the drill bit.

Study on the Sensitivity of Bare Fiber Bragg Grating for Ultrasonic Frequencies Response Under Various Temperature

This work presents a study on the sensitivity of bare fiber Bragg grating (FBG) to detect ultrasonic frequencies under various temperature. Two infrared (IR) laser with excitation wavelength, λ=1310nm and λ=1550nm were employed. Various types of FBG with operating wavelength of 1546nm, 1550nm and 1554nm were used to identify the optimum design of sensor in detecting range of ultrasonic frequencies between 5kHz until 30kHz under various surrounding temperature from 20°C until 30°C. The principle of FBG vibration detection lies in the fact that spectral shift would occur due to the acoustic-induced variations in the medium. In this study, the ultrasonic signal had been investigated by monitoring the amplitude of optical output power. At 30°C, the bare FBG with operating wavelength of 1554nm using 1310nm light source exhibits the optimum performance in detecting ultrasonic vibration frequency, in which its sensitivity was obtained as ∆P=0.10dBm. We believe that the sensitivity of the proposed sensor can be enhanced by introduce nanomaterials onto the FBG or by altering the physical structure of FBG.

The Effect of Ultrasonic Vibration Frequency on Double Pipe Heat Exchangers During the Cooling Process

The Effect of Ultrasonic Vibration Frequency on Double Pipe Heat Exchangers During the Cooling Process

Исследование процесса сушки шиповника в поле действия ультразвука

Introduction. Rose hips are rich in macro- and micronutrients. Unfortunately, heat treatment destroys most nutrients. Ultrasonic technologies make it possible to reduce the drying time and lower the temperature regime. The research objective was to adjust ultrasound technology to rose hip production in order to reduce the loss of vitamins and improve the quality indicators of the dried product.
 Study objects and methods. The research featured rose hips of the Rosa canina species collected in the south of Kazakhstan. This subspecies of wild rose is poor in vitamin C. Nevertheless, this shrub is extremely common in Russia and other countries of the Commonwealth of Independent States. The raw material was dried according to standard methods. One group of samples was treated with ultrasound, while the other served as control. Both groups underwent a sensory evaluation and were tested for moisture and vitamin C.
 Results and discussion. The rose hips were dried in a combination steam oven with a built-in ultrasonic wave generator. The research revealed the following optimal parameters of the ultrasound drying process: frequency of ultrasonic vibrations – 22 kHz, processing time – 2.5 h, temperature in the combination steam oven – +56°C, initial moisture content – 30%. The resulting product met the requirements of State Standard. The loss of moisture was 57%. According to State Standard 1994-93, the initial moisture content should be 15% or less. Time decreased from 360 min to 160 min, and the initial moisture was 13%. The experiment confirmed the initial hypothesis that ultrasonic treatment improves the drying process by improving quality indicators and preserving vitamin C in raw materials using.
 Conclusion. Ultrasound treatment during moisture removal from rose hips provides a resource-saving technology that fulfills an economically and socially important function.

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.

Experimental Research on Hole Wall Integrity of TiBw/TC4 Based on Ultrasonic Vibration Assisted Drilling

Titanium Matrix Composites (TMCs) are widely used in aerospace because of their excellent mechanical properties, but it is accompanied by the difficulty of machining. Ultrasonic Vibration Assisted Drilling (UVAD) can effectively reduce the axial force in the drilling process and improve the integrity of machined surface. In this paper, the discontinuous titanium matrix composite TiBw/TC4 was developed by preparation method of in situ. In order to obtain the machining parameters of TiBw/TC4 and guide the application of UVAD in TiBw/TC4, the contrast experiments between conventional drilling (CD) and UVAD were carried out to analyze the variation law of axial force. In this experiment, the frequency and amplitude of ultrasonic vibration were set as 35 kHz and 2.5 μm respectively, and the drilling conditions were that the spindle speed was (1500/1600/1700/1800/1900) r/min and the feed speed was (6/7/8/9/10) mm/min. The surface integrity of hole wall such as roughness, residual stress and white layer was discussed. The experimental results show that the yield strength of TiBw/TC4 developed by in situ is 51% higher than that of pure TC4. Compared with CD, the axial force of TiBw/TC4 in UVAD is significantly reduced, and the formation of continuous chips and winding cutters is effectively reduced. Besides, the wear rate of the cutters is reduced. The number and size of hole wall defects, such as scratches, delamination and tearing, are obviously reduced. As well as the residual stress, white layer thickness and hole wall roughness are reduced by 4.67–16.31%, 42.48% and 5.98–29.27% respectively. Within the limits of the experiment, when the spindle speed is 1700 r/min and the feed speed is 8 mm/min, UVAD can obtain better hole wall surface integrity parameters.

РАСЧЕТ ЗАВИСИМОСТИ ЗВУКОКАПИЛЛЯРНОГО ЭФФЕКТА ОТ ЧАСТОТЫ УЛЬТРАЗВУКА НА ОСНОВЕ КРИТЕРИЯ ПОРОГОВОЙ КАВИТАЦИИ

The possibility of calculating parameters of the ultrasonic capillary effect depending on frequency of acoustic vibrations in liquid is considered. According to known experimental data, the intensification of fluid motion in the capillary is mainly associated with the formation and collapse of cavitation bubbles at the capillary end. Therefore, it is assumed that the ultrasonic capillary effect occurs as a result of cavitation processes at the entrance to the capillary channel, while cavitation processes depend on the frequency of ultrasonic vibrations. The threshold pressure at cavitation, leading to the rise of fluid, for a given ultrasound frequency is determined by the criterion of incubation time of cavitation. The size and number of cavitation bubbles at the considered threshold pressure depend on ultrasound frequency. The number of bubbles in the cavitation area is determined by solving the problem of packing equal circles in a larger circle, taking into account the distance the influence of the bubbles on each other. The height of the liquid rise is calculated based on the assumption that during one cycle of oscillation of the cavitation region, the sound capillary pressure performs the work on lifting the liquid column to a certain height due to the energy of collapsed bubbles. This approach makes it possible to determine the threshold amplitude of acoustic vibrations and evaluate the corresponding behaviour of sound-capillary pressure in the frequency range of 7-62 kHz. The specified range is determined by the frequency requirements for the ratio of the size of the cavitation process zone and the capillary diameter. Thus, the obtained model of the ultrasonic capillary effect takes into account the diameter of the capillary and allows to determine the frequency range over which this effect can be realized. The calculation results show good agreement with the known experimental data in water. The results of calculations using the model showed that the highest sound capillary pressure is reached in the range of 10-20 kHz.

Machining performance study in Radial Ultrasonic-Assisted Rolling Electrochemical Micromachining

Surface texturing is an attractive approach for improving the friction, tribological and heat transfer performance in the equipment. Ultrasonically assisted electrochemical micromachining (USEMM) is a promising method for generating micro dimples as it can reduce the overcutting and enhance electrolyte renewal to improve the machining localization and increase the material removal. Considering the micro dimple array fabrication on smooth and rotary workpiece, the radial ultrasonic rolling electrochemical micromachining (RUREMM) is presented in this paper. With the cathode revolving and ultrasonic vibration in the interelectrode gap, the electrolyte renewal and the machining stability improves, micro dimples array with good performance could be obtained. Detailed discussions were done based on the machined micro dimples on 304 stainless steel plate at different conditions. Results show that the machining efficiency of micro dimple in RUREMM is better than in (electrochemical micromachining) EMM and the existing ultrasonic vibration in the interelectrode gap is more effective to enhance the machining performance. Then, effects of gap pressure on the material removal rate, machining accuracy and roughness are studied and discussed in detail. Experiments denote that the width of the micro dimples is decreased by 14.6%, the depth of the micro dimples is increased by 19.2%, the cross-sectional area is expanded by 31.2 %, the roughness of the bottom is decreased by 23.9% and better surface quality for the side wall could be obtained by using the selected parameters, 10 % NaNO3, 50 μm machining gap, 0.8 r/min rotation speed, 28 kHz Ultrasonic vibration frequency, 10μm amplitude in RUREMM.

Ultrasonic Vibration-Induced Shape Memory Polymer (Polyurethane)/Graphene Nanoplatelets Composite

Ultrasonic vibration (UV)-induced shape memory polyurethane (PU) and composite containing 1 phr (part per hundred) graphene nanoplatelets (GNPs) were prepared through ex situ polymerization by using microcompounder. Atomic force microscopy and field emission scanning electron microscopy were used for the characterization of surface morphology, surface roughness, and graphene nanoplatelets dispersion in the polyurethane matrix. The thermomechanical properties (storage modulus, loss modulus, energy dissipation factor, and glass transition temperature) were determined by using the dynamic mechanical analyzer. The thermomechanical properties, shape memory stretch and recovery strength, shape fixity, tensile strength, and UV-induced shape recovery are enhancing for a composite having 1 GPU (1 phr GNPs in PU matrix). Shape memory and mechanical properties were improved for composite sample as compared to pure polyurethane. 1 GPU composite sample shows ultrasonic vibration-induced shape recovery, whereas pure polyurethane sample has no shape recovery. The UV-induced shape recovery strongly depends on the dispersion of GNPs and frequency of ultrasonic vibration. For composite sample (1 GPU), embedded GNPs in the PU matrix may absorb the UV frequency and converted into heat energy (lattice vibration of GNPs and heat is transfer through conduction) which is responsible for shape recovery. With increase in the frequency of UV, the shape recovery also increases for the composite. Glass transition temperature (Tg) was influenced with the addition of GNPs into neat polyurethane matrix. UV-induced shape recovery test was carried out in an ultrasonic vibration transducer with variable frequency (0–40 kHz).

Experimental study of ultrasonic rolling processing

The ultrasonic vibration device and the rolling pressure measurement device are added on the ordinary rolling equipment, which form the ultrasonic rolling equipment. Due to the ultrasonic impact, ultrasonic rolling processing can obtain better surface quality and surface reinforcement than ordinary rolling processing. The experimental results show that the process parameters such as rolling pressure, rolling speed and feed volume effects obviously on the surface roughness and surface micro-hardness of the work piece ultrasonic rolled. In ultrasonic rolling processing, a relatively small rolling pressure can be used to obtain satisfactory processing results, avoiding the surface defects caused by large rolling pressure. Ultrasonic vibration frequency is generally 20kHz. And the vibration amplitude is generally 20 μm. The right combination of process parameters and the use of coolant provide the best process results.

Intensification of pectin obtaining from apple pomace

This study is devoted to the problem of improving the methods of pectin obtaining from apple pomace. The relevance of the study is dictated by the fact of formation of a large amount of waste when receiving apple juice. The output of apple juice at the enterprises of the processing industry is from 50 to 75%, therefore, 25-50% is waste. In our studies we used 42 KHz frequency of ultrasonic vibrations. The powers of ultrasound waves were 30 and 50W. The output of pectin depends on the sample exposure time, and with time passing this growth decreases and eventually stops, which may indicate that a certain amount of destruction has been reached at a given power. The maximum increase in the output of pectic substances is observed when the ultrasonic treatment time is 15 minutes and it is 26%. Capacity also affects pectin output. With power increasing from 30 to 50 W, the amount of pectin released increases by an average of 10%. It is shown that the use of separation at the stage of solution partitioning from pectin allows one to increase the speed of the process by a factor of two.

Close-to-process strain measurement in ultrasonic vibration-assisted turning

Abstract. The application of ultrasonic vibration assistance in machining offers many benefits over conventional machining. In some machining processes, like the generation of geometrically defined microstructures by cutting, the interaction of the system components and the machining process can be particularly crucial with respect to the production result. Monitoring of ultrasonic vibration-assisted machining in terms of the in-process measurement of frequency and amplitude is currently realized by measurement inside the actuator; thus, measurement is presently undertaken relatively far away from the cutting process. In this paper an in-process measurement set-up based on strain gauges positioned close to the cutting edges is presented. It is used to investigate the induced vibration in the ultrasonic horn. Experiments on machine samples with and without ultrasonic vibration assistance are performed using the in-process measurement set-up described. The results of the strain gauges are analysed in comparison to internal feedback signal and surface measurements. The experiments show the high sensitivity of the measurement set-up presented and a huge gain of information compared with the conventional measurement approach. This enables improved controllability of the excited mode shapes as well as in-process adjustment of the ultrasonic vibration frequency and amplitude for the manufacturing of defined microstructures.

The effect of ultrasonic activation on the formation of polytetrafluoroethylene modified by detonation nanodiamonds

The article discusses the influence of low-frequency ultrasonic vibrations on the structure and tribological properties of the synthesized polymer composite material based on polytetrafluoroethylene, modified by detonation nanodiamonds. As a result of researches it is established that the effect of low frequency ultrasonic vibrations and entered a modifier of detonating nanodiamonds leads to changes the supramolecular structure of the polymer composite, expressed in the increasing the blocks size and degree of crystallinity. Studies of the elemental composition and chemical state of the atoms indicate the improvement of the composite structure, which has a better structure and contains no defects as a C-H, C-C and C-CFn ties and contains mainly of the –CF2 and –CF3 chemical bonders. Detonation nanodiamonds are introduced in the process of forming material, prevent the formation of unwanted C-H, C-C due to the absorption of excess carbon, whereby the surface of the composite material has a more perfect structure. Low frequency ultrasonic vibrations lead to the improvement of wear resistance by 13.6% and to reduce the coefficient of sliding friction is 15% of the studied composite material.

Rotary ultrasonic machining of carbon fiber–reinforced plastic composites: effects of ultrasonic frequency

Rotary ultrasonic machining (RUM) is effective and efficient in cutting carbon fiber–reinforced plastic (CFRP) composites. With ultrasonic vibration assistance, both machining efficiency and machining effectiveness can be improved. Ultrasonic vibration has two major variables (including ultrasonic amplitude and ultrasonic frequency), which play important roles in RUM processes. Other intermediate variables, such as ultrasonic power and indentation depth, are directly related to these two variables. Effects of ultrasonic vibration amplitude have been extensively investigated in RUM hole making and surface machining processes. However, the effects of ultrasonic frequency in RUM have not been reported. The effects of ultrasonic frequency under different combinations of tool rotation speed, feed rate, and depth of cut on output variables, including cutting forces, surface roughness, and machined surface characteristics, are investigated, for the first time, in this study. The critical frequency is analyzed for the RUM process. Three different levels of ultrasonic frequencies are generated and applied to the RUM process. The kinematic motions of abrasive grains in RUM with different frequencies are analyzed and discussed. The results show that RUM with higher frequency of ultrasonic vibration is a more effective machining process, leading to cutting force reduction and the machined surface quality improvement.

Effects of ultrasonic vibration on resistance spot welding of transformation induced plasticity steel 780 to aluminum alloy AA6061

A newly developed joining technique, ultrasonic resistance spot welding (URW), where high frequency ultrasonic vibration is effectively integrated into resistance spot welding (RSW) process, has been applied for joining transformation induced plasticity (TRIP) steel 780 to aluminum alloy Al 6061. Comparing URW with traditional RSW, up to 300% increase in strength and more than 150% increase in displacement to failure is achieved. Light optical microscopy (LOM) and scanning electron microscopy (SEM) revealed cracks and wide interfacial debonded regions in conventional RSW AlFe welds. With the assistance of ultrasonic vibrations, these interfacial cracks are effectively removed and a thin AlFe intermetallic layer (IMC) of around 3 um thickness is formed. SEM images of the fractured surface revealed that ultrasonic waves eliminated the eggcrate morphology generally observed in RSW welds fractured surface, which is a typical representative of solidification cracking. In situ high speed videos showed that ultrasonic vibration can help break off surface contamination and oxides as well as improving wetting of melted aluminum over the AlFe interface.

Sensorless control of a three-degree-of-freedom ultrasonic vibration tool holder

Piezoelectric actuators are commonly used to deliver vibrations with an amplitude range of (5 μm–25 μm) at ultrasonic frequencies (≥15 kHz) in machining applications. The natural frequencies of ultrasonic vibration actuators vary under the varying cutting force disturbances during machining. Consequently, the amplitudes of delivered vibrations deviate from the desired reference values. As opposed to using vibration sensors, this paper presents a sensorless method to track and control the frequency and amplitude of ultrasonic vibrations during machining. The dynamic model of the actuator is first modeled to obtain a transfer function between the supply voltage and driving current. An observer with Kalman filters per actuator direction is designed to estimate the vibration velocity amplitude and the phase between the supply voltage and current. The estimated vibration amplitude is used as a feedback in a proportional integral (PI) controller to maintain at the desired level during machining. The estimated phase is also kept at the desired reference level by pushing the excitation frequency towards resonance with another PI controller. The proposed control method has been digitally implemented in controlling a three degree of freedom rotary ultrasonic vibration actuator, and the crosstalks between the axes have been compensated when generating elliptical vibrations. The system has been experimentally tested in unidirectional turning and drilling, as well as two directional milling with elliptical vibrations.

Energy efficient piezoelectrically actuated transducer for direct-contact ultrasonic drying of fabrics

Current clothes drying technology is an energy-intensive process that involves blowing hot air across tumbling wet fabrics to evaporate water. To address the relatively low energy efficiency of this drying technique, a new cloth drying technology was proposed in our prior study. This technology utilizes high frequency ultrasonic vibrations to extract water from a fabric in the liquid phase, resulting in a dramatical reduction in energy consumption and drying time. A piezoelectrically actuated transducer was designed and fabricated. The transducer design was based on a piezoelectric actuator that excites axisymmetric resonant modes in a thin circular metal mesh. The device was constructed by bonding a piezoelectric ring to a thin metal mesh with a hole diameter of 120 µm. Test results demonstrated that the new ultrasonic transducer efficiently dried clothes at an order of magnitude lower resonant frequency compared with the previous commercial devices, 23 kHz versus 135 kHz. Also, the power consumption per area of the new transducer was an order of magnitude less than the commercial devices. Depending on operating conditions, the device was 3–24 times more efficient compared to the commercial ultrasonic transducers utilized in our prior ultrasonic clothes drying studies.

Analytical modeling of ultrasonic surface burnishing process: Evaluation of residual stress field distribution and strip deflection

Ultrasonic surface burnishing (USB) process is a promising surface enhancement technique that improves fatigue life of components by exerting work hardening and compressive residual stress of the surface layers. However, USB is a complex process in practice, and there is not an analytical model published to facilitate the design and comprehension of the process. In the present paper an analytical elastic-plastic model was developed to correlate USB process factors to residual stress field (RSF). Also, deformation of strip samples was determined in the analytical approach. Parameters such static force, ultrasonic vibration amplitude, ball material and its diameter as well as ultrasonic vibration frequency were included in the model to find how they influence the residual stress variation and strip deflection. Two types of material constitutive equation i.e. Johnson-Cook (JC) that is sensitive to strain rate as well as Chaboche hardening that is influenced by cyclic loading were considered to find which material behavior is more consistent with experimental results. The experiments have been carried out on two different materials with various initial state of residual stress field (IRSF). It was obtained from the results that residual stress field variation and strip deflection obtained by experiments are consistent well with the values derived from analytical model. Therefore, the model was comprehensively used to find how the USB process factors influence the RSF and strip deflection.

Increase of aggregative and sedimentation stability of slag suspensions by ultrasound

The paper discusses the relevance of the use of metallurgical wastes crushed to a fine state in the production of building materials. Domain granulated slag (DGS) was used as a research object. A method for introducing fine ground slag (FGS) into the cement composition in the form of a slag suspension instead of mixing water has been developed. To establish the uniform distribution of FGS particles in the cement matrix, the behavior of slag particles in an aqueous dispersion medium was previously studied. The optimal parameters of ultrasonic dispersion of slag suspensions are established: the frequency of ultrasonic vibrations is 44 kHz; temperature of dispersion - 25±2°C; dispersion time - 15 min. It has been established that the application of UST to slag suspensions with the observance of optimal dispersion parameters can increase the aggregative and sedimentation stability of the FGS suspension by 2–3 times as compared with mechanical mixing, accelerate the micelle formation process, and enhance the electrostatic factor of aggregative stability.