Papers by Keyword: Ultrasonic Vibration

Abstract: Al-5.0Cu-0.6Mn-0.6Fe alloy was obtained for the first time using ultrasonic vibration and squeeze casting simultaneously. The effect of ultrasonic vibration and applied pressure on the microstructures and hardness of Al-5.0Cu-0.6Mn-0.6Fe alloy were studied. The results indicated that the ultrasonic vibration and applied pressure promoted the formation of smaller α-Al globular grains. In particularly, with the treatment of ultrasonic vibration or applied pressure during solidification, the brittle Fe-rich imtermetallic compounds in Al-5.0Cu-0.6Mn-0.6Fe alloy became more refined and changed from Chinese script shape to polyhedral shape, which improved the mechanical property. Furthermore, these effects on the grain refinement and Fe-rich intermetallic compounds became more significant by using ultrasonic vibration and applied pressure concurrently during solidification. This process technology is helpful for the development of high performance aluminum alloys with low cost as well as for green casting.

Abstract: Based on the understanding of Friction Stir Welding (FSW) and the effect of ultrasound, the purpose of the paper is trying to find the effective access to reduce the welding resistance and improve the quality of weld during FSW. The best vibration point was first determined through the vibration test system. Then, the thermal cycling, three-force and torque were tested by using paperless recorder and mechanical sensor in heat-power test bench for 4mm thick AZ31 magnesium alloy. The results showed that the periodic vibration took place at the weld under the excitation of ultrasonic vibration, and the frequency of this vibration was as same as the frequency of ultrasonic vibration. The best tracking distance of ultrasonic vibration was 40 mm, and its optimal incident angle was 45°. By applying ultrasonic vibration to FSW, the forward resistance, the axial force and the torque of the tool can be significantly reduced. In addition, the distribution of temperature field was basically consistent with the two conditions, presenting “asymmetrical, non-linear” distribution characteristic. The heating effect of ultrasonic vibration was not obvious, but it was able to make the temperature field of the welding seam become more uniform.

Abstract: The paper presents a review on the current situation of diamond tool ultrasonic vibration cutting ferrous metal. The key technology of diamond tool ultrasonic vibration cutting ferrous metals is presented in this paper and the influence of the processing environment of the presence of carbon atoms protective gas, the presence of carbon particles coolant of temperature control technology, ultrasonic vibration, workpiece material surface pretreatment or without on diamond tool wear rate and workpiece surface quality, the relationship between diamond tool wear rate, the workpiece surface quality and the ultrasonic vibration technology, processing environment, workpiece material surface pretreatment technology factors is given. Propose research direction and research emphasis on reducing diamond tool wear rate and improve workpiece surface quality.

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

Abstract: Inconel 718 has high yield strength, corrosion resistance, heat resistance and fatigue resistance, and possesses a lower thermal conductivity, leading to high grinding force and heavy wheel damage in grinding of this material. Against these problems, ultrasonic assisted grinding (UAG) can be the potential candidate for high efficiency processing of Inconel 718. The current work is, hence, to clarify the fundamental UAG characteristics of Inconel 718 by experimentally investigating the effect of vibration amplitude on grinding force, actual material removal and work-surface roughness under different process parameters such as the wheel rotational speed, wheel depth of cut and vibration amplitude. Summarizing the obtained results revealed that the grinding forces and the actual material removal in UAG are significantly smaller and larger, respectively, than those in conventional grinding. It is also found that ultrasonic vibration can improve the work-surface finish even at deep wheel depth of cut.

Abstract: The work presents recommendations related to the selection and installation of high power piezo ceramic rings dedicated to simultaneous power supply and data transmission for the purpose of extending life in their operation. Mechanical and electrical defects in piezoceramic elements of conical actuators were presented. The issue is important in the case when energy and information are transmitted at the same time using upper acoustic waves to autonomic wireless measurement nodes (WMN) in mechanical construction elements. A laboratory ultrasonic actuator was made and used to test ceramic rings. Additionally a dedicated vibration sensor was made and a measurement system for determination of frequency response of high power actuators was developed. Identification of the material used to make the ceramic rings and feeding electrodes was conducted. Next calibration tests of conical piezoelectric actuators were conducted and their defects were tested.

Abstract: This work is based on investigation of the influence of electromagnetic fields and ultrasonic vibrations and their combination on the resulting microstructure of an AA7449 aerospace aluminium alloy. The results demonstrate the application of the compound electro-magnetic and ultrasonic fields under optimum conditions delivers not only a refined microstructure but also consistent distribution of chemical composition. It suggests an alternative method for producing high strength aerospace alloys which could not be refined through conventional addition of chemical grain refiners.

Abstract: In common hypereutectic high Si-Al alloy, the properties and applications of high Si-Al alloy was influenced by the thick multi-triangle shaped primary silicon seriously. In this paper, the fine hypereutectic Al-Si alloy was fabricated with ultrasonic vibration aided casting technology and the influence of ultrasonic vibration on the alloy structure is investigated as well as the influence of the silicon content on the wear volume and hardness with the comparison of microscopic structures. The results show that the increase of silicon content ascends the hardness of the high Si-Al alloy. However, along with increase of silicon content, the wear loss decreases initially and increases when the silicon content is larger than 22%.

Abstract: The research of improving thermal properties of cool storage medium using nanocomposite technology is proposed in this paper. The nanocomposite cool storage material was prepared by the method of mixing directly. The effect of dispersant, ultrasonic time and concentration of dispersant were deeply researched. The optimizing concentration of dispersant and the optimizing dispersion process conditions are confirmed. The results show that thermal conductivity of TiO₂ /HS-6 nanofluids is noticeably enhanced to compare base fluid HS-6, the increasing extent is 21.5%. The results provide the basic data for the application research of TiO₂ nanoparticles in PCM for air-conditioning system.

Abstract: In order to study the states of oxide layer under different pre-dressing process conditions in ultrasonic vibration and electrolytic in-process dressing combined grinding. The effects of electrical parameters, wheel speed, ultrasonic vibration on the oxide layer are investigated with indicators of oxide layer surface morphology and thickness characteristics. The results indicate that the oxide layer thickness increases with the decrease of inter-electrode gap and the increase of duty ratio with pre-dressing time. The effect of ultrasonic vibration cause thinning of the oxide layer. Oxide layer surface morphology allowing processing requirements are obtained by duty cycle of 5μs: 5μs, electrode gap of 0.3mm, wheel speed of 3200 r/min.