رضوان عابدینی

This study investigated damage initiation in the microstructure of DP1000 dual-phase steel under ultrasonic very high cycle fatigue (VHCF) conditions. The microstructure of this steel consists of ferrite and martensite phases, a combination of which provides outstanding mechanical properties such as high strength and fatigue resistance. In this study, a precise heat treatment method was employed to optimize the steels microstructure, resulting in a uniform distribution of 50% soft ferrite and 50% hard martensite. Additionally, the design of hourglass-shaped specimens for ultrasonic fatigue testing (20 kHz) and the implementation of a novel combined cooling system enabled stable temperature control during testing. This temperature control method allowed very high cycle fatigue testing to be conducted for the first time without the influence of thermal stresses, yielding results with greater accuracy and reliability compared to previous research. During the test, the displacement of the specimens free end was measured using a laser sensor and the S-N diagram was constructed. The results demonstrated that the optimized microstructure delayed damage initiation and reduced the crack growth rate, whereas an improper phase’s distribution accelerated crack growth

High-power ultrasonic transducers emit high-frequency waves in a liquid environment, creating intense sound fields that cause the phenomenon of cavitation inside the liquid tank. The explosion of small bubbles, known as cavitation, results from intense sound fields, as well as physical and chemical phenomena. This process is used to remove contamination from the surface of sensitive and complex parts. Determining the acoustic field of the ultrasonic transducer within the tank can assist in identifying the required number of transducers, the optimal distance between them, and the appropriate dimensions of the tank. Given the high cost of experimental tests, the finite element method is a suitable tool for predicting the behavior of the vibrating assembly and determining the ultrasonic acoustic field within the liquid inside the tank. In this research, the resonance frequencies of the vibrating assembly and the acoustic wave propagation field were investigated using COMSOL finite element analysis software. After fabricating the components and assembling the tank, the acoustic field resulting from ultrasonic vibration was measured in different positions of the tank using a high-frequency hydrophone during the experimental test phase. Based on the experimental mapping data and its comparison with the simulation results, both harmonic and superharmonic frequencies were observed simultaneously in the water environment. The consistency between the simulation results and the experimental tests demonstrated that the simulation method is a suitable tool for predicting the behavior of the liquid inside the tank under high-power ultrasonic vibrations.

The joining of thermoplastic composites by continuous ultrasonic welding results in the creation of a fast joint with high load-bearing capability. This method falls into the category of fusion welding. The viscoelastic behavior of polymeric materials becomes dominant at temperatures higher than their glass transition temperature. Under these conditions, the application of ultrasonic vibrations induces viscoelastic losses in the material, generating sufficient heat to melt the polymer matrix of the composite. In this study, the continuous ultrasonic welding of polypropylene reinforced with woven glass fibers was investigated experimentally. Composite plates were fabricated and cut into dimensions of 101.6 × 140 mm. Subsequently, lap joints were welded using the continuous ultrasonic welding method while considering welding parameters such as power, speed, and welding pressure. Various welding modes were applied to the composite plates. The shear strength of the resulting joints was calculated based on existing standards, and the fracture surfaces along the welding line were examined to evaluate the effect of different welding modes on the uniformity and shear strength of the welds. Finally, by properly setting the process parameters—100% power, a speed of 30 mm/s, and a pressure of 0.83 MPa—an uniform weld with 4 MPa lap shear strength was achieved.

Ultrasonic shot peening (USP) is used as a surface treatment to create work-hardening on the surfaces of the parts. In this process, spherical shots with a certain size, type and number are moved by a vibrating object (horn) and hit the surface of the workpiece. On the other hand, stainless steel plays an important role in the development of manufacturing technologies due to its high strength and oxidation resistance. Therefore, in this research, the USP process was performed on 316L stainless steel, and the effect of ultrasonic power and shot peening duration on the cross-sectional microhardness of the samples was evaluated at two depths of 75 and 250 microns. The results showed that by applying the USP, the microhardness of the cross section at the depths of 75 and 250 microns increases by a maximum of 43.37% and 18.5% compared to the raw sample, respectively. Therefore, by increasing the depth from the shot-treated surface, the effect of the USP decreased by 57.34%. The ANOVA results also showed that the ultrasonic power in both depths is known as the most effective input variable and in the depth of 250 microns, the effect of the ultrasonic power is greater than the duration of shot peening. Also, dual-objective optimization was done to achieve the maximum hardness in both depths using the desirability method, and the optimal values of the ultrasonic power and shot peening duration were equal to 100% and 195 seconds, respectively, with a desirability value of 87%.

Continuous ultrasonic welding is one of the new and very fast methods for joining thermoplastic composites, in which by using high power ultrasonic waves with a frequency of 20kHz and transferring it to the interface of the composite plates that have a certain overlap, the viscoelastic heat produced leads to the melting of the polymer and at the same time as the pressure is applied, the welding process of the composite plates in the desired direction is done continuously. In this research, the effect of three main parameters of this process, i.e., welding power, welding speed and pressure, on the lap shear strength of continuous ultrasonic welding is investigated by making glass-polyamide 6 composite plates and planning continuous ultrasonic welding experiments. To justify the effect of each parameter on the welding strength, The images of the fracture surface of the weld joint were used by optical and scanning electron microscopes. Finally, it was found that the power parameter has a direct relationship and the speed and pressure parameters have an inverse relationship with the lap shear strength of continuous ultrasonic welding glass-polyamide6 composite.additionally, power has the greatest effect and pressure has the least effect on weld strength.

New surgical technologies are continuously being developed to enhance control during operations and mitigate injuries resulting from surgical procedures. One such advancement is the ultrasonic laparoscopic surgical tool known as the ultrasonic scalpel, which is designed to minimize surgery-related injuries when used alongside conventional tools. Establishing optimal input parameters for this ultrasonic instrument not only enhances operational reliability but also decreases the risk of resultant injuries. Ongoing research investigates the impact of varying power and duration of ultrasonic vibrations, along with the equivalent energy input into the blood vessel during surgery, on tissue mechanical characteristics and thermal effects. This study assesses the ability of sheep carotid artery tissues to withstand blood pressure within the vessel and examines thermal damage through pressure testing and optical imaging. Findings indicate that maintaining constant time at specific power yields maximum pressure tolerance at optimal power levels. However, varying the time at specific power settings produces different effects. For instance, the highest blood pressure resistance, at 1100 mmHg, was observed at 44 Watt of power over a 10 second duration at 10 newton. Furthermore, results demonstrate that increased energy input correlates with heightened thermal damage to surrounding tissues during the operation.

In the current research, finite element simulation and experimental tests have been used to design, manufacture and evaluate the performance of a high-power ultrasonic radiator. The two main goals in the design are to achieve a nominal resonance frequency of 20 kHz in longitudinal mode shape of the transducer and booster assembly and the flexural mode shape of the radiator plate and to remove the disturbing modes from the frequency range of the main mode shape. After designing and manufacturing the sample based on the simulation results, experimental tests of modal analysis, impact test and impedance analysis were performed to evaluate the performance characteristics of the ultrasonic radiator. In order to verify the accuracy, the simulation results, including the resonance frequency and position of the node and anti-node, were compared with the experimental test results. The results of the experimental tests to determine the resonance frequency and compare it with the simulation results (error less than 0.5%), indicate the accuracy of the prediction of the results and the matching of the resonance frequency with the designed nominal value. Also, the disturbing mode shapes were at an acceptable distance from the main flexural mode shape of the radiator. Finally, the vibration amplitude measurement test results show that the position of the node and anti-node points in the experimental test match with the finite element simulation results.

Composites of continuous fibers have higher mechanical performance than short fibers, which is why they are produced and used significantly in the aviation industry. One of the new methods of joining composites is ultrasonic welding. In this process, by applying high power (100 to 2000 watts) and high frequency (15 to 100 kHz) vibrations to the joint of two parts, heat is generated in the joint and causes the two parts to stick together. In this research, the parameters of the ultrasonic welding of polyamide 6 glass composite, the effect of the interlayer film, and the direction of the fibers on the strength of the connection have been investigated. Ultimately, the ultrasonic welding connection has been compared with the adhesive bond. In examining the connection as an edge-to-edge connection, the samples were cut according to ASTM D5868 standard and subjected to a tensile-shear test after ultrasonic welding. Considering the average input parameters for time, pressure, and power, it was observed that using a pure polymer film layer as the interlayer film increases the welding strength. By changing the direction of the fibers of all layers by 90 degrees, the welding strength decreased a little. The amount of polymer and fiber protrusion increased, and the appearance quality decreased. In comparing the welding connection with the adhesive bond, the value of the welding strength was higher than the strength of the adhesive connection. Also, the time spent on the welding connection was much less than on the adhesive bonding.

Material cutting is one of the most widely used industrial processes, which is always accompanied by challenges. One of these challenges is the ability to cut materials with high elasticity such as rubber or soft and crispy materials such as cake. In order to increase the life of the tool and achieve a suitable and accurate cutting surface and achieve a high cutting speed, the technology of high power ultrasonic vibrations is used in the modern industries of tire and rubber production and food industries. The proper design of the ultrasonic cutting tool, guarantees the proper performance and the tool life. The design and manufacture of ultrasonic cutting horns is complicated due to the influence of various factors on the shape and dimensions of the part. In this article, the effect of the dimensional parameters of the horn design on two important output factors, namely the resonance frequency of longitudinal vibration mode and the uniformity of the vibrations of the front surface of the ultrasonic cutting horn made of titanium alloy, have been investigated and analyzed. The results have shown that by using design improvements in finite element software, it is possible to achieve a cutting horn with a frequency close to the nominal design frequency and with the highest uniformity of the vibration amplitude on the front surface of the horn.

Superimposing high power ultrasonic vibration on metal forming processes changes the mechanical behavior of the material and reduces its flow stress. These phenomena improve the ductility of material and reduce forming forces. To investigate the influence of ultrasonic vibration on various materials, standard compression and tensile tests under ultrasonic vibration could be performed. This research investigates the compression behavior of Ti-6Al-4V alloy under superimposed ultrasonic vibration. For this purpose, a special set-up was designed, fabricated and tested. Ultrasonic vibration is transmitted from the ultrasonic transducer to the booster and then guided by horn (punch) to apply to test sample. Horn geometry, vibrational mode shape and ultrasonic power were selected as input variables. The effect of specimen position in system vibrational mode shape was studied by using different ultrasonic transmitters, which allowed the specimen to place at node and anti-node positions. It is found that ultrasonic vibrations reduced the formability of this alloy. Acoustic hardening phenomena do not observe in this material. Also, flow stress of the material reduced under ultrasonic vibration up to 17.63% which has direct relation to ultrasonic power. In addition, the most efficiency was observed when the specimen placed in the node position.

Identifying piezoelectric defects and ultrasonic transducers failure based on electromechanical impedance is one of the methods to assess their health. In a healthy piezoelectric, the electromechanical impedance is determined based on the piezoelectric properties, shape and size. In order to identify and predict the failure of piezoelectric, in this paper, a practical and effective method for evaluating the quality and health of piezoelectric used in high power ultrasonic transducers is presented. The basis of this procedure is to study the change in electric impedance characteristics of the piezoelectric disc, which can be measured according to the standard. This method can be used by researchers and manufacturers of piezoelectric. The results of experimental tests have shown that by analyzing the impedance diagram of piezoelectric, it is possible to identify faults and defects in them; even before they are visible to the naked eye. It is also possible to compare the quality of different piezoelectric manufacturers and to evaluate the performance of a healthy worked piezoceramic compared to a new component.

Today, ultrasound technology has found a special place in medical surgery. In recent years, researchers have tried to upgrade this technology to perform various surgeries. The most important features of ultrasound surgical equipment compared to traditional models are accurate cutting and no damage to surrounding tissues, less bleeding, reduced tissue healing time, Easier operation of the surgeon and, also the possibility of affecting some tissues in a non-invasive way. Due to the importance and many applications of this issue, this article examines the applications of ultrasound technology in medical surgery, the parameters affecting the equipment used in this field and, the mechanisms of the effect of ultrasound in the body. In addition, ways to advance this technology in medical surgery, challenges and, the future of scientific and industrial research in this field are also presented. challenges and, the future of scientific and industrial research in this field are also presented.

Ultrasonic welding as a new technology in many industries has replaced the usual methods of joining such as welding, brazing, sewing and etc. In this technology, ultrasonic energy is generated by the ultrasonic transducer and transmitted to the joining area through the booster and horn. Ultrasonic energy is dissipated and absorbed in the joining area and generates heat. Simultaneous application of static force / pressure and heat causes the involved parts to join with each other. In this process, various parameters such as power, frequency, static force / pressure, time, material and shape of parts and etc affect the joining properties and the resulting sample. In this paper, with the aim of acquainting researchers with the principles and applications of this technology, scientific and industrial research in the field of ultrasonic welding has been reviewed. Due to the major application and different effective mechanisms, this paper is divided into two main parts of metal welding and plastic welding. Considering the importance and application of the subject, the principles and methods of applying ultrasonic vibrations, different mechanisms of ultrasonic, the parameters of the ultrasonic welding process and the important applications of this technology have been studied. Finally, a perspective on the application of high power ultrasonic vibrations in new manufacturing and joining technologies in the future of the industry is presented.

Electronic tiltmeter is used as a tool of setting the accurate angles in advanced equipment. The accuracy and precision of tiltmeter should be evaluated by means of precise calibration equipment. This study aimed to calibrate and evaluate the accuracy of a precise dual axis electronic tiltmeter. To this end, a calibration setup with accurate positioning capability was designed and constructed. Then the calibration setup was employed to investigate linear and nonlinear behavior of electronic tiltmeter and extract the corresponding equations. In order to assess the reliability of the tiltmeter sensor, nonlinearity error and repeatability of the tiltmeter at different angles were obtained. Afterwards in an analytic way, arithmetic and geometric means were compared and the factors which affect the calibrator output error were identified to obtain that how much the accuracy and measurement error of each of those factors affect the uncertainty of angle measurement in the calibration process. The results indicate that both introduced methods of averaging can be used to derive relationship of uncertainty propagation accurately. Uncertainty analysis of the constructed base and calibration process demonstrate that the employed equipment correspond with the evaluation of a precise electronic tiltmeter.

Hot pressing of metal powders is used in production of parts for similar properties to wrought materials. Since residual porosity, inhomogeneous properties, dimensional and geometrical instability and therefore reduction in mechanical strength are the main problems in powder metallurgy components which are due to friction between powder particle interfaces and powder compact and die walls. Because of this, access to parts with high density and homogeneous structure is the great object in powder metallurgy. One of the remedies can be employment of ultrasonic vibrations which is thought to result in increased rates of densification and therefore higher efficiency of the process in increase of part density and strength. To evaluate this solution, this paper deals with the effects of high power longitudinal ultrasonic vibrations on the densification of AA1100 aluminum and Ti-6Al-4V titanium alloy powder under constant applied stress and different temperatures. The effects of powder type and process temperature on the densification behavior and ultrasonic efficiency are discussed. For experimental tests, setup of ultrasonic assisted hot pressing of powders were designed and fabricated. The results show that applying ultrasonic vibrations leads to obtaining higher relative density. In addition, it is found that the effect of ultrasonic vibrations is greater for Ti-6Al-4V powders. However, the temperature has different effects on the ultrasonic vibrations efficiency in two types of powders.

Metal forming is a conventional manufacturing process that a material with simple form is subjected to plastic deformation and emerged to industrial end products. Reduction of forming forces and improving of products quality have been a promising object for investigators and artisans. To accede this purpose, primary methods such as increasing material temperature and modern methods such as use of high power low amplitude ultrasonic vibrations were introduced. In ultrasonic assisted forming, high power ultrasonic transducer produces low amplitude high frequency mechanical vibrations which transmitted to material subjected to deformation and contacting surfaces of tool/workpiece. Results show reduction of forming forces and tool wear as well as improving surface integrity and dimensional stability that lead to increasing production rate and process efficiency. By regarding to importance and capability of ultrasonic assisted metal forming, this paper is concerned with application of ultrasonic vibration on metal forming processes. To this purpose, fundamental and mechanisms of application of high power ultrasonic were introduces and discussed. Also, industrial future of this technology as well as its advantages, range of application and its restriction were mentioned.