Loading...
Search for: ultrasonics
0.005 seconds
Total 245 records

    Experimental-numerical study of AA5754 microstructural evolution under electromagnetic ultrasonic merged fields

    , Article Journal of Materials Processing Technology ; Volume 225 , 2015 , Pages 103-109 ; 09240136 (ISSN) Haghayeghi, R ; Ezzatneshan, E ; Bahai, H ; Sharif University of Technology
    Elsevier Ltd  2015
    Abstract
    The effect of combined electromagnetic-ultrasonic fields evaluated on grain refinement. Cavitation induced by the combination of technologies suggested as major mechanism for grain refinement. A numerical simulation performed predicting the cavitation regions in the molten AA5754 aluminum alloy. It was concluded that the cavitation phenomenon occurs near the electromagnetic and ultrasonic sources. The observed acoustic streaming induced by ultrasonic horn is more intensive than the electromagnetic one. The ultrasonic streaming could transport small bubbles into the bulk rapidly. These micro-bubbles collapsed due to acoustic vibrations where the resulting micro-jets were strong enough to... 

    Grain refinement of AA5754 aluminum alloy by ultrasonic cavitation: Experimental study and numerical simulation

    , Article Metals and Materials International ; Volume 21, Issue 1 , 2015 , Pages 109-117 ; 15989623 (ISSN) Haghayeghi, R ; Ezzatneshan, E ; Bahai, H ; Sharif University of Technology
    Korean Institute of Metals and Materials  2015
    Abstract
    In this work, an experimental investigation was carried out on the grain refinement of molten AA5754 Aluminum alloy through ultrasonic treatment. The cavitation induced heterogeneous nucleation was suggested as the major mechanism for grain refinement in the AA5754 aluminum alloy. A numerical simulation was performed to predict the formation, growth and collapse of cavitation bubbles in the molten AA5754 Aluminum alloy. Moreover, the acoustic pressure distribution and the induced acoustic streaming by ultrasonic horn reactor were investigated. It is suggested that the streaming by ultrasonic could transport the small bubbles formed in the ultrasonic cavitation zone into the bulk of melt... 

    Ultrasonic-assisted grinding of Ti6Al4V alloy

    , Article Procedia CIRP ; Volume 1, Issue 1 , 2012 , Pages 353-358 ; 22128271 (ISSN) Nik, M. G ; Movahhedy, M. R ; Akbari, J ; Sharif University of Technology
    2012
    Abstract
    In conventional grinding of hard to cut materials such as Ti6Al4V alloys, surface burning, redeposition and adhesion of chips to the grinding wheel and workpeice occur visibly unless it is carried out at low speeds and with high volume of cutting fluid. Ultrasonic assisted grinding is an efficient machining process which improves the machinability of hard-to-cut materials by changing the kinematics of the process. In this research, the effect of imposition of ultrasonic vibration on the grinding of Ti6Al4V alloy is studied. Longitudinal vibration at ultrasonic frequency range (20 kHz) is applied on the workpiece and machining forces and surface roughness are compared between conventional... 

    Effect of microstructure on attenuation mechanism of ultrasonic waves in carbon steels

    , Article Materials Science and Technology ; Volume 26, Issue 4 , 2010 , Pages 482-486 ; 02670836 (ISSN) Behjati, P ; Vahid Dastjerdi, H ; Mahdavi, R ; Rasouli, D ; Sharif University of Technology
    Abstract
    In this paper, fundamental concepts of ultrasonics and characteristics of distinctive microstructures have been used to simply explain the effect of microstructure on the attenuation mechanism of ultrasonic waves in carbon steels. In addition, it has been shown that application of the second medium hardness instead of the bulk hardness is more appropriate to correlate the sound velocity and the microstructure  

    Ultrasonic-assisted cylindrical grinding of Alumina-zirconia ceramics

    , Article ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) ; Volume 2 A , Volume 2 A , 2013 ; 9780791856185 (ISBN) Tawakoli, T ; Akbari, J ; Zahedi, A. M ; ASME ; Sharif University of Technology
    American Society of Mechanical Engineers (ASME)  2013
    Abstract
    Due to its vast applications and stochastic nature, grinding has been the subject of investigations and modifications for decades. Applying ultrasonic vibration in grinding has been a successful innovation introducing benefits such as reduced forces and temperature, improved surface quality, and making higher removal rates possible. In this work a set-up is developed for utilizing ultrasonic vibrations in cylindrical grinding. This is done by rotating and simultaneously vibrating the workpiece material. The set-up is used for cylindrical grinding of Alumina-zirconia ceramic as a difficult-to-grind and widely used industrial ceramic. Optimized parameters for efficient grinding and surface... 

    Burr size reduction in drilling of Al/SiC metal matrix composite by ultrasonic assistance

    , Article Advanced Materials Research, 15 December 2011 through 18 December 2011 ; Volume 410 , December , 2012 , Pages 279-282 ; 10226680 (ISSN) ; 9783037853160 (ISBN) Kadivar, M. A ; Yousefi, R ; Akbari, J ; Rahi, A ; Nikouei, S. M ; Sharif University of Technology
    Abstract
    Metal matrix composites (MMCs) have received considerable attention due to their excellent engineering properties. Accuracy and surface finish play an important role in modern industry. Undesired projections of materials, known as burrs, reduce the part quality and negatively affect the assembly process. In this study, reducing burr size in drilling of MMC is performed by adding ultrasonic vibration to the process. Al/SiC p MMC with 5 wt% of SiC particulates in dry drilling operation with HSS drill tools coated with TiN was investigated. The effect of ultrasonic assistance on burr size was studied. The results demonstrate that under suitable ultrasonic vibration conditions, in comparison... 

    An optimization technique on ultrasonic and cutting parameters for drilling and deep drilling of nickel-based high-strength Inconel 738LC superalloy with deeper and higher hole quality

    , Article International Journal of Advanced Manufacturing Technology ; Volume 82, Issue 5-8 , 2016 , Pages 877-888 ; 02683768 (ISSN) Baghlani, V ; Mehbudi, P ; Akbari, J ; Zal Nezhad, E ; Sarhan, A. A. D ; Hamouda, A. M. S ; Sharif University of Technology
    Springer-Verlag London Ltd 
    Abstract
    In this research work, an ultrasonic assisted drilling system is employed to apply both rotation and vibration to drill bits. The transducer horn transfers power very efficiently and changes tools effortlessly. The setup used to conduct drilling tests is Inconel 738LC with depth-to-diameter ratios from 2 to 10 by conventional drilling (CD), ultrasonic assisted drilling (UAD), and electro discharge drilling (EDD). The effects of ultrasonic vibration amplitude, spindle speed, and number of steps to drill each hole on machining force and surface roughness in UAD are investigated. The results demonstrate not only a significant improvement in tool life (by applying ultrasonic vibration to the... 

    Speckle noise reduction of ultrasound images using M-band wavelet transform and wiener filter in a homomorphic framework

    , Article 1st International Conference on BioMedical Engineering and Informatics, BMEI 2008, Sanya, Hainan, 27 May 2008 through 30 May 2008 ; Volume 2 , 2008 , Pages 510-515 ; 9780769531182 (ISBN) Vosoughi, A ; Shamsollahi, M. B ; Sharif University of Technology
    2008
    Abstract
    In this paper we make use of M-band discrete wavelet transform (MDWT) and Wiener filter for speckle noise suppression of ultrasound images. Assuming multiplicative model for speckle noise, by applying logarithmic transform to noisy observation we convert multiplicative noise to additive one. Then, speckle noise can be reduced by taking the M-band wavelet transform of log-transformed observation and employing an adaptive thresholding technique. In order to improve the performance of this denosing approach, we propose a preprocessing stage which exploits Wiener filtering. Through this stage logtransformed observation is separated into two images and then each of these two images is denoised... 

    Ultrasonic-assisted drilling of inconel 738-LC

    , Article International Journal of Machine Tools and Manufacture ; Volume 47, Issue 7-8 , 2007 , Pages 1027-1033 ; 08906955 (ISSN) Azarhoushang, B ; Akbari, J ; Sharif University of Technology
    2007
    Abstract
    Generally in the drilling of modern aviation materials such as nickel and titanium base super alloys, problems frequently occur in terms of burr formation at the cutter exit, tool stress, high heat generation on tool surface as well as low process reliability. A recent and promising method to overcome these technological constraints is the use of ultrasonic assistance, where high-frequency and low-amplitude vibrations are superimposed on the movement of cutting tools. This paper presents the design of an ultrasonically vibrated tool holder and the experimental investigation of ultrasonically assisted drilling of Inconel 738-LC. The circularity, cylindricity, surface roughness and hole... 

    Relationship between young’s modulus and planar density of unit cell, super cells (2 × 2 × 2), symmetry cells of perovskite (catio3) lattice

    , Article Materials ; Volume 14, Issue 5 , 2021 , Pages 1-15 ; 19961944 (ISSN) Rabiei, M ; Palevicius, A ; Nasiri, S ; Dashti, A ; Vilkauskas, A ; Janusas, G ; Sharif University of Technology
    MDPI AG  2021
    Abstract
    Calcium titanate-CaTiO3 (perovskite) has been used in various industrial applications due to its dopant/doping mechanisms. Manipulation of defective grain boundaries in the structure of perovskite is essential to maximize mechanical properties and stability; therefore, the structure of perovskite has attracted attention, because without fully understanding the perovskite structure and diffracted planes, dopant/doping mechanisms cannot be understood. In this study, the areas and locations of atoms and diffracted planes were designed and investigated. In this research, the relationship between Young’s modulus and planar density of unit cell, super cells (2 × 2 × 2) and symmetry cells of nano... 

    Application of ultrasonic models for investigating the properties of the interface between roller compacted concrete (RCC) layers

    , Article NDT and E International ; Volume 124 , 2021 ; 09638695 (ISSN) Ashkar, M ; Toufigh, V ; Ghaemian, M ; Azizmohammadi, M ; Sharif University of Technology
    Elsevier Ltd  2021
    Abstract
    In this paper, a comprehensive set of linear and nonlinear ultrasonic techniques was performed to investigate the properties of the interface between the roller-compacted concrete (RCC) layers. The effect of different time intervals between the pouring of each layer, cement content of concrete and bedding mortar, and various curing periods on RCC specimens were studied in this research. In linear methods, the interlayer led to velocity dispersion and attenuation phenomena except for the inherent inhomogeneity of specimens. The nonlinear parameters showed a general upward at the earlier ages, while the linear methods did not show an apparent regularity. The ultimate strength results were then... 

    Ultrasound Intensity Exposimetry in Physiotherapy Devices using Micro-Bubbles

    , M.Sc. Thesis Sharif University of Technology Rezayat, Ehsan (Author) ; Zahedi, Edmond (Supervisor)
    Abstract
    Routine ultrasound calibration methods have some restrictions such as: low bandwidth, low frequency resolution, limited spatial resolution, the high cost of test and risk of damage to the transducer when exposed to high powers. In this thesis, a new technique based on microbubble resonance is proposed. Non-linear resonating microbubbles produce harmonics;the first harmonic may be masked by reflection from larger microbubbles as well as unwanted reflections which cause ambiguity in the determination of the amplitude of the excited pressure. Therefore, the second harmonic is used, with a single characteristic peak. In order to model the physical phenomenon, the second harmonic generated in the... 

    Applying ultrasonic vibration to decrease drilling-induced delamination in GFRP laminates

    , Article Procedia CIRP, Leuven ; Volume 6 , April , 2013 , Pages 577-582 ; 22128271 (ISSN) Mehbudi, P ; Baghlani, V ; Akbari, J ; Bushroa, A. R ; Mardi, N. A ; Sharif University of Technology
    2013
    Abstract
    Delamination is a major problem in drilling of fiber-reinforced composite materials. Thrust force is an important factor leading to propagation of delamination during drilling process. One of effective methods to reduce machining forces is application of ultrasonic vibrations. In this study ultrasonic assisted drilling is applied to reduce thrust force in drilling of GFRP laminates. In order to conduct experiments a setup is designed and fabricated to apply both vibrations and rotation to drill bits. Using Taguchi method, a set of experiments is conducted with feed rate, spindle speed, and ultrasonic vibration amplitude as control factors. The results show that applying ultrasonic vibration... 

    Ultrasound dosimetery using microbubbles

    , Article IFMBE Proceedings, 20 June 2011 through 23 June 2011 ; Volume 35 IFMBE , June , 2011 , Pages 359-362 ; 16800737 (ISSN) ; 9783642217289 (ISBN) Rezayat, E ; Zahedi, E ; Tavakkoli, J ; Sharif University of Technology
    2011
    Abstract
    In this paper, a new technique based on nonlinear resonance of microbubbles is investigated in order to estimate the amplitude of an ultrasound wave pressure field. First, the existing theoretical model is reviewed. Then, an experimental setup consisting of a bubble generator and transmitting/receiving ultrasound transducers operating in the 1 MHz frequency range is described. The effect of background noise is also taken into account. Results show that the second harmonic oscillations are detectable, paving the way to develop a quantitative method for in vivo calibration of ultrasound waves  

    Design and experimental evaluation of a precise and compact tubular ultrasonic motor driven by a single-phase source

    , Article Precision Engineering ; Volume 48 , 2017 , Pages 172-180 ; 01416359 (ISSN) Dabbagh, V ; Sarhan, A. A. D ; Akbari, J ; Azizi Mardi, N ; Sharif University of Technology
    Elsevier Inc  2017
    Abstract
    A precise and compact tubular ultrasonic motor driven by a single-phase source is proposed and tested in this study. The motor is designed by modeling a motor stator in FEM software. The motor fabricated according to the design is tested experimentally and its working characteristics including speed and torque are measured and presented. The maximum speed and torque of the motor are 59 rpm and 0.28 mN m at 80 Vpp of applied voltage. The proposed motor possesses advantages such as a simple and compact structure with application in the fields of robotics, space, medical devices and high-resolution stages, among others. The proposed motor is a good candidate for applications where accurate... 

    N-doped ZnO-CuO nanocomposite prepared by one-step ultrasonic spray pyrolysis and its photocatalytic activity

    , Article Chemical Physics Letters ; Volume 705 , 2018 , Pages 19-22 ; 00092614 (ISSN) Rahemi Ardekani, S ; Sabour Rouhaghdam, A ; Nazari, M ; Sharif University of Technology
    Elsevier B.V  2018
    Abstract
    Nanocomposite thin film of N-doped ZnO-CuO was deposited on glass substrate using ultrasonic spray pyrolysis method. Zinc acetate, copper acetate and ammonium acetate with different molar ratios were dissolved in water and used as precursors. A crumpled-shape morphology consisting of nanometer-sized particles was observed with FESEM. The elemental composition was evaluated with EDX analysis and the presence of nitrogen, oxygen, copper and zinc was confirmed. XRD analysis revealed the presence of ZnO and CuO crystalline phases with crystallite size of about 18 nm. The prepared nanocomposites exhibited high photocatalytic activity in degradation of methyl orange under UV light irradiation. ©... 

    , M.Sc. Thesis Sharif University of Technology Ghahremani Nik, Mohsen (Author) ; Akbari, Javad (Supervisor) ; Movahhedy, Mohammad Reza (Supervisor)
    Abstract
    In conventional grinding of hard to cut materials such as Ti6Al4V alloys, surface burning, redeposition and adhesion of chips to wheel and workpeice occur visibly unless it is carried out at low speeds and with high volume of cutting fluid. Ultrasonic assisted grinding (UAG) is an efficient machining process for hard-to-cut materials with poor machinability. UAG improves the machinability of such materials by changing the kinematics of the process. In this research, the effect of imposition of ultrasonic vibration on the grinding of Ti6Al4V is studied. Longitudinal vibration at ultrasonic frequency range (20 kHz) is applied on the workpiece and machining forces and surface roughness are... 

    Design and Build an Acoustic Tweezers and Move up the Polystyrene Particles

    , M.Sc. Thesis Sharif University of Technology Ghavidel, Amir (Author) ; Amjadi, Ahmad (Supervisor)
    Abstract
    Ultrasound waves have attracted substantial attention due to their potential for trapping the small particles, which cannot be handled by usual tweezers. The acoustic tweezer is a technology that is able to tarp and control the movement of micrometer to millimeter objects by standing or focused sound waves. Acoustic tweezers are the subject of many researches around the world, due to simplicity, cost-effective, biocompatibility and most important better performance in non-transparent optical environments, compared with optical tweezers.In this project, by using a ring piezoelectric and a power amplifier, an acoustic tweezer was designed and constructed. Moreover, the polystyrene particles... 

    Flaw characterization in ultrasonic non-destructive testing method using exponential modeling

    , Article Conference Record - IEEE Instrumentation and Measurement Technology Conference ; 2013 , Pages 1676-1679 ; 10915281 (ISSN) ; 9781467346221 (ISBN) Ravanbod, H ; Karimi, F ; Amindavar, H ; Sharif University of Technology
    2013
    Abstract
    Determining the shape, area, volume, and direction of flaws using ultrasonic imaging of metallic pieces, is a method estimating the severity of their defects. Different methods are used to process ultrasound images. Among these methods are spectral analyses, statistical, mathematical and intelligent methods. Within each of these, there are some advantages as well as limitations. Prony algorithm, which has been used as a parametric method for extracting exponential components of a signal, has several applications in signal modeling, system identification and classification. In this paper, after simulating pieces of oil pipeline, digital Wavelet transform has been used to reduce the noise of... 

    A comprehensive review on ultrasonic spray pyrolysis technique: Mechanism, main parameters and applications in condensed matter

    , Article Journal of Analytical and Applied Pyrolysis ; Volume 141 , 2019 ; 01652370 (ISSN) Rahemi Ardekani, S ; Sabour Rouh Aghdam, A ; Nazari, M ; Bayat, A ; Yazdani, E ; Saievar Iranizad, E ; Sharif University of Technology
    Elsevier B.V  2019
    Abstract
    Nanostructured materials have attracted much attention in recent decades. Nowadays, there are numerous nanomaterials with several applications. The ultrasonic spray pyrolysis method is a cost-effective and adaptable technique based on an aerosol process for synthesizing nanoparticles and depositing thin films. The technique is capable of synthesizing metal, oxide, and composite nanomaterials with precisely controllable morphologies and chemical compositions using metal salts in aqueous solvents. More importantly, it is popular, as evident from the growing number of studies being conducted on the technique. Here, we review studies conducted on basic principles and applications of the...