Papers by Keyword: Ultrasonic

Abstract: For solving the problems of low bonding strength of anticorrosive layer inside the pressure vessel, the technology of ultrasonic continuous welding applied in aluminum alloy foil is researched in this paper. The technological parameters which affect the welding quality most are analyzed. Through the finite element simulation, the stress and temperature distribution of metal layer and welding head during the welding process are analyzed. The influence of important parameters such as welding pressure and thickness of metal layer on welding quality are studied. The optimal combination of key process parameters such as welding speed, welding pressure and thickness of metal layer are discussed by orthogonal test. The results show that the bonding strength at the weld can reach the tensile strength of the metal itself, and is also qualified to the design expectation.

Abstract: This paper presents the recent studies on the fabrication of magnesium based metal matrix nanocomposites (MMMC) by using ultrasonic assisted stir casting technique. The pure metal and alloys, due to their limited mechanical properties are not suitable for various engineering applications. It has been observed that the addition of suitable reinforcements into metallic matrix improves the specific strength, ultimate tensile strength, porosity and wear properties as compared to the conventional and monolithic engineering materials for aerospace and automotive applications. The effects of ultrasonic vibrations and the resulting uniform dispersion of reinforcements on the mechanical and tribological properties of magnesium based MMCs are specifically highlighted in this paper.

Abstract: Wire electrical discharge machine (WEDM) is non-conventional machining process. It can be used for hard cutting material. The study has been presented the combining WEDM with an ultrasonic machine (USM) with brass and tungsten were used as a wire electrode and workpiece respectively. The experiment was carried out with an ultrasonic transducer at 40, 80 kHz. The results were observed with the material removal rate (MRR) and surface roughness (Ra). This research introduced the method of USM setup and described the effected of vibration with the wire electrode on the displacement of amplitude. The result shows that the WEDM process with USM at 40 kHz can be more improved with the material removal rate and surface roughness than that of USM at 80 kHz. This can be explained that higher frequency affected to vibration displacement which makes lower amplitude.

Abstract: The paper deals with ultrasonically aided micro-electrical discharge machining (μEDM+US) of an advanced material, Co-Cr-Ni-W-Al alloy with multiple utilizations in medicine, automotive, aerospace etc. The high resistance characteristics of this alloy impose thermal concentrated energy machining; μEDM+US is a good response in terms of machining rate, and surface quality. These output performances are proved by the presented experimental and modeling results. Ultrasonic assistance of μEDM augmented the main technological parameters by the synergy created within this hybrid machining.

Abstract: This paper presents the viability of ultrasound in assisting the performance of laser hardening process. A nanosecond pulse laser was employed as a heat source in this study to heat and introduce hardened phase in AISI H13 tool steel. The influences of laser power and traverse speed on surface roughness and case depth of laser-irradiated region were experimentally investigated. The laser processing with the assist of ultrasound can improve the surface roughness of laser-hardened area by 7.5% and also increase the case depth by 7.65% compared to the non-ultrasound condition. Under a suitable processing condition, the laser can harden and polish the metal surface at the same when the ultrasound was incorporated in the process. The implication of this study will broaden the viability of ultrasound in the laser surface hardening/polishing of metals.

Abstract: The organic dye is one of the carcinogenic and toxic substrates that are used as the colorant in industries. Therefore, we have to develop the efficient technique to remove the dye in wastewater. This research aimed to develop the photoelectrocatalytic (PEC) cell with the high efficiency, which offered a simple method to remove dye from the wastewater. The ZnO photoanode electrode was considered for developing to enhance the efficiency of PEC cell for dye degradation. The ZnO electrode was fabricated by cyclic voltammetry method and then was compared the oxidation efficiency to ZnO electrode from dip coating. The film thickness of ZnO was controlled by the number of scan for a cyclic voltammetric method and the deposition time for the dip coating method. The effects of scan rate, the number of scan and calcination temperature were optimized to obtain the highest oxidation efficiency. Absorption properties, photoelectrocatalytic activity and electrochemical impedance spectroscopy (EIS) were measured to confirm the characteristic of the two fabricated electrodes. The results showed that ZnO electrode fabricated by cyclic voltammetry presented higher photoelectrocatalytic activity for water oxidation than that from dip coating. Thus, in this research was development ZnO electrode by cyclic voltammetry to degrade organic dye using the photoelectrocatalytic technique. The efficiency of dye degradation was evaluated by the decreasing absorption of methylene blue dye (5 mg/L) as a function of time. It was found that the photoelectrocatalytic dye degradation efficiency with ultrasonic-assisted was enhanced up to two times with 71% degradation in 1 hour. Therefore, we concluded that the developed ZnO electrode by cyclic voltammetry demonstrated a high photoelectrocatalytic performance with ultrasonic-assisted degradation of organic dyes.

Abstract: This research aim to improve the machining properties of the EDM for cemented carbide. The new methods were designed and proposed to use the ultrasonic vibration technique. Two types of USEDM systems were produced. One had a low frequency of 29 kHz with a large vibration amplitude, while the other had a high frequency of 59 kHz with a small amplitude. The Cu-W tool electrode was synchronized with the devised vibration system, and several discharge generation conditions were carried out on the cemented carbide material. The results showed that the highest machining efficiencies were obtained from the ultrasonic low frequency of 29 kHz with a large vibration amplitude. The MRR, TWR and surface roughness of the ultrasonic low frequency with the large vibration amplitude were better than the high frequency system with the small amplitude system. It was clarified that the ultrasonic vibration with the large amplitude could assist the material removal behavior of the discharge.

Abstract: This work is based on making a comparison of different inspection methods of non-destructive testing (NDT), to detect porosity, bite, undercut, splash, overlap, slag, concavity, lack of fusion and damage to base material, in welds of shielded metal arc welding (SMAW) and flux-cored arc welding (FCAW), made on a steel bridge ASTM-A-588. The main application of non-destructive tests is to evaluate the final state of a welded joint in critical points, in addition the fundamental objective is to ensure that the established acceptance and rejection criteria are met rigorously. For which non-destructive techniques are analyzed, such as the visual testing of welding on the beams of a bridge of length 35000 mm, subsequently, tests of inspection by liquid penetrant were used, based on the AWS D1.5 standard to confirm the failures in welded joints in ABA webs, an ultrasonic is also carried out using an SIUI CTS 602 equipment, finally to issue an acceptance and rejection criterion as determined by ASTM E165 and ASTM E2544-09.

Abstract: Having a robust non-destructive evaluation (NDE) technique for friction stir welded (FSWed) joints is of interest to the processing community. Such a technique has to be sensitive to the different types and shapes of internal weld defects and has to be applicable for both similar and dissimilar material FSW joints. Investigated was the ability of ultrasonic guided waves to detect and assess the quality of FSW joints. The fundamental anti-symmetric (A₀) mode was selected to detect the flaws in FSW joints. Guided waves were excited (using PZT wafers) and received (using a laser Doppler vibrometer, LDV). Implemented was the frequency-wavenumber filtering technique to separate forward propagating wave from any back propagating reflected wave due to the welded joint. Identified was the reflection of the A₀ mode caused by the presence of the interface and/or defects within the joint. The findings indicate little sensitivity to the presence of material interface suggesting this technique to have a promising potential among guided-wave-based techniques in the qualitative and quantitative assessment of FSW joints.

Abstract: Due to the remarkable physical and mechanical properties of graphene, it is considered to be one of the most promising reinforcements for structural ceramics. In this paper, the composite material is compacted by hot pressing and the effects of mechanical stirring and ultrasonic on dispersion of graphene in alumina matrix were investigated, which was believed to have a great influence on the mechanical properties of the hot-pressed composites. It is found that from Scanning electron microscopy (SEM) observation. Compared with ultrasonic, the composite, in which graphene was dispersed by mechanical stirring, showed higher bending strength (555.1MPaVS432.3MPa) and fracture toughness (4.4MPa·m^1/2 VS 4.1MPa·m^1/2). The result is much more promising to be employed in the designing and processing of graphene composites.