Search for: nondestructive-examination
0.005 seconds
Total 24 records

    Configurable ultrasonic flaw classification of oil pipelines

    , Article Nondestructive Testing and Evaluation ; Volume 23, Issue 2 , 2008 , Pages 77-88 ; 10589759 (ISSN) Ravanbod, H ; Jalali, A ; Sharif University of Technology
    These two papers present an innovative method of configurable flaw classification and volume estimation in oil pipelines. In part I, the ultrasonic image acquisition system is introduced and surface and volume of the flaw are estimated with fuzzy image processing. A number of real figures illustrate the system performance. The flops calculation reveals that this fuzzy estimator could be integrated in a real time flaw detection system. In part II, at first, the dynamic detection of interesting points, i.e. as feature points at different levels of images, is proposed using wavelet transform. Furthermore, a guided searching strategy is used for the best matching from the coarse level to a fine... 

    Flaw detection improvement of digitised radiographs by morphological transformations

    , Article Insight: Non-Destructive Testing and Condition Monitoring ; Volume 47, Issue 10 , 2005 , Pages 625-630 ; 13542575 (ISSN) Movafeghi, A ; Kargarnovin, M. H ; Soltanian Zadeh, H ; Taheri, M ; Ghasemi, F ; Rokrok, B ; Edalati, K ; Rastkhah, N ; Sharif University of Technology
    Radiographic inspection is one of the most appreciated techniques among non-destructive testing methods due to the production of a film which acts as a unique fingerprint record. Converting radiographs to a digital format and further digital image processing is the best method of enhancing the image quality and assisting the interpreter on his evaluation. In this research, different algorithms were used for image enhancement and radiograph interpretation in MATLAB environment. A graphical user interface (GUI) was created for implementation of different algorithms. Both spatial and frequency domains techniques were used for image enhancement. The main enhancement technique was a spatial... 

    Improved two-dimensional millimeter-wave imaging for concealed weapon detection through partial fourier sampling

    , Article Journal of Infrared, Millimeter, and Terahertz Waves ; Volume 37, Issue 3 , 2016 , Pages 267-280 ; 18666892 (ISSN) Farsaei, A. A ; Mokhtari Koushyar, F ; Seyed Talebi, S. M. J ; Kavehvash, Z ; Shabany, M ; Sharif University of Technology
    Springer New York LLC 
    Active millimeter-wave imaging based on synthetic aperture focusing offers certain unique and practical advantages in nondestructive testing applications. Traditionally, the imaging for this purpose is performed through a long procedure of raster scanning with a single antenna across a two-dimensional grid, leading to a slow, bulky, and expensive scanning platform. In this paper, an improved bistatic structure based on radial compressive sensing is proposed, where one fixed transmitter antenna and a linear array of receiving antennas are used. The main contributions of this paper are (a) reducing the scanning time, (b) improving the output quality, and (c) designing an inexpensive setup.... 

    THz non-destructive testing for covered defects

    , Article 4th International Conference on Millimeter-Wave and Terahertz Technologies, MMWaTT 2016, 20 December 2016 through 22 December 2016 ; 2017 , Pages 45-47 ; 21570965 (ISSN); 9781509054145 (ISBN) Panahi, O ; Kheyrollahi Kouhanestani, M ; Yahyaei, B ; Mousavi, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2017
    In this paper, a pulsed THz imaging system in normal geometry is presented experimentally and the effect of placing a pinhole in front of a covered sample on image quality has been investigated too. Also, the improvement of image quality by using ray transfer matrix is described theoretically. Finally, by using contour system the results are evaluated and the accuracy of THz imaging system is tested. © 2016 IEEE  

    Damage detection of L-shaped beam structure with a crack by electromechanical impedance response: analytical approach and experimental validation

    , Article Journal of Nondestructive Evaluation ; Volume 39, Issue 2 , 2020 Hamzeloo, S. R ; Barzegar, M ; Mohsenzadeh, M ; Sharif University of Technology
    Springer  2020
    Damage detection and structural health monitoring using the electromechanical impedance method has been accepted as an effective technique between various approaches of nondestructive evaluation. Many efforts have been made on experimental methods for obtaining the impedance of structures. However, expensive experimental methods encourage researchers to develop theoretical models. In this paper, a new theoretical model is developed for damage detection of L-shaped beams, which are basic components in frame structures, with an embedded piezoelectric wafer active sensor. For this purpose, a chirp signal of voltage is used to activate a piezoelectric patch for inducing local strains that lead... 

    Acoustic simulation of ultrasonic testing and neural network used for diameter prediction of three-sheet spot welded joints

    , Article Journal of Manufacturing Processes ; Volume 64 , 2021 , Pages 1507-1516 ; 15266125 (ISSN) Ghafarallahi, E ; Farrahi, G. H ; Amiri, N ; Sharif University of Technology
    Elsevier Ltd  2021
    Ultrasonic Testing (UT) is one of the most common types of nondestructive methods that is being used in various industries, especially in the automotive industry. In this paper, qualitative and quantitative control of resistance spot welds on three-sheet joints was studied. Initially, mathematical model of ultrasonic waves was extracted for triple sheet joints. Then, acoustic simulation of ultrasonic testing on spot welds was performed using Finite Element Method (FEM). Afterwards, A Multilayer Perceptron (MLP) neural network was used to classify spot welds based on their diameter. There was a mean error of 20.9 % between peak amplitudes of numerical and theoretical models which the most... 

    Damage assessment of RC arch structures using fractal analysis of crack patterns

    , Article Nondestructive Characterization and Monitoring of Advanced Materials, Aerospace, Civil Infrastructure, and Transportation XV 2021, 22 March 2021 through 26 March 2021 ; Volume 11592 , 2021 ; 0277786X (ISSN); 9781510640139 (ISBN) Kazemian, A ; Khaloo, A ; Sharif University of Technology
    SPIE  2021
    Surface crack patterns can easily show the behavior of concrete elements and structures. However, visual damage inspection performed by experts is a subjective approach and is prone to inaccuracies. The quantification makes this process objective and more reliable. In that regards, the maximum crack width is used as a practical measurement. It has been shown that the crack width is not a good indicator of damage due to its inherent uncertainties; In fact, it might bounce back after unloading. As such, a dimensionless parameter so-called Fractal Dimension has been introduced as a robust index that can quantify the complexity of crack distribution efficiently. The present study aims to... 

    Application of neuro-fuzzy techniques in oil pipeline ultrasonic nondestructive testing

    , Article NDT and E International ; Volume 38, Issue 8 , 2005 , Pages 643-653 ; 09638695 (ISSN) Ravanbod, H ; Sharif University of Technology
    This paper presents a novel approach to the problem of nondestructive pipeline testing using ultrasonic imaging. The identification of the flaw type and its dimensions are the most important problems in the pipeline inspection. Unlike typical methods, a decision based neural network is used for the detection of flaws. We train a generalized regression neural network to determine the dimensions of the corrosions and generate the whole image of both the internal and external walls of the oil pipeline. As an improvement to the detection algorithm, we introduce fuzzy decision-based neural network algorithms for the detection and classification of the corrosions. The simulation and experimental... 

    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
    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... 

    An appropriate procedure for detection of journal-bearing fault using power spectral density, K-nearest neighbor and support vector machine

    , Article International Journal on Smart Sensing and Intelligent Systems ; Volume 5, Issue 3 , 2012 , Pages 685-700 ; 11785608 (ISSN) Moosavian, A ; Ahmadi, H ; Tabatabaeefar, A ; Sakhaei, B ; Sharif University of Technology
    Journal-bearings play a significant role in industrial applications and the necessity of condition monitoring with nondestructive tests is increasing. This paper deals a proper fault detection technique based on power spectral density (PSD) of vibration signals in combination with K-Nearest Neighbor and Support Vector Machine (SVM). The frequency domain vibration signals of an internal combustion engine with three journal-bearing conditions were gained, corresponding to, (i) normal, (ii) corrosion and (iii) excessive wear. The features of the PSD values of vibration signals were extracted using statistical and vibration parameters. The extracted features were used as inputs to the KNN and... 

    Failure analysis of holding yokes made of investment cast 17-4 PH stainless steel

    , Article Engineering Failure Analysis ; Volume 18, Issue 4 , 2011 , Pages 1242-1246 ; 13506307 (ISSN) Etemadi, A. R ; Behjati, P ; Emami, A ; Motiei, S. M. A. D ; Mirsaeedi, S ; Sharif University of Technology
    Holding yokes made of investment cast 17-4PH stainless steel were too soft (below 20. HRC). Optical microscopy of the parts showed that there is a high fraction of retained austenite after oil quench due to high amount of molybdenum found in parts as an impurity. Subzero treatment in liquid nitrogen after solution heat treating was used to convert retained austenite to martensite but parts became too brittle and fractured during post-heat treating machining. Double and triple aging at 538 °C (1000 °F) after subzero cooling was done on parts. Detailed fractography and tensile testing along with optical microscopy (OM) investigation proved that repeated aging at 538 °C (1000 °F) led to lower... 

    Use of polymer fibres recovered from waste car timing belts in high performance concrete

    , Article Construction and Building Materials ; Volume 80 , April , 2015 , Pages 31-37 ; 09500618 (ISSN) Khaloo, A. R ; Esrafili, A ; Kalani, M ; Mobini, M. H ; Sharif University of Technology
    Elsevier Ltd  2015
    The present paper discusses the possibility of adding recycled polymer fibres to high performance concrete (HPC). Fibres used in this study were recovered from discarded car timing belts. To investigate different characteristics of the concrete specimens several destructive and non-destructive tests, such as compressive strength, modulus of rupture, flexural toughness, ultrasonic velocity and electrical resistance tests were carried out. In addition, slump flow tests were conducted on the fresh concrete. Experimental results from the study showed that the use of low percentages (up to 0.5%) of waste fibres improved the modulus of rupture and flexural toughness. Based on ultrasonic and... 

    A novel method for modeling the magnetizing yoke

    , Article Electromagnetics ; Volume 30, Issue 3 , 2010 , Pages 297-308 ; 02726343 (ISSN) Ravanbod, H ; Norouzi, E
    Magnetic flux leakage is the most widely used method for oil and gas pipeline non destructive testing. The saturation level of the sample under test has a significant effect on its efficiency; therefore, the magnetizing yoke requires an elaborate design. The finite element method is the conventional approach used for this purpose, but it is very time consuming. In this article, a neuro-fuzzy method is presented to model the behavior of the magnetizing yoke. Modeling a few different designs with the finite element method and using the results for training the neuro-fuzzy model eradicates the necessity of modeling a huge number of designs with the finite element method. The acquired... 

    Numerical optimization and manufacturing of the impeller of a centrifugal compressor by variation of splitter blades

    , Article ASME Turbo Expo 2016, Turbomachinery Technical Conference and Exposition, 13 June 2016 through 17 June 2016 ; Volume 8 , 2016 ; 9780791849866 (ISBN) Moussavi Torshizi, S. A ; Hajilouy Benisi, A ; Durali, M ; International Gas Turbine Institute ; Sharif University of Technology
    American Society of Mechanical Engineers (ASME) 
    Design and optimization of centrifugal compressors, based on main blades configuration of impeller have been vastly discussed in open literature, but less researches have addressed splitters. In this research, the impeller of a commercial turbocharger compressor is investigated. Here, profiles of main blades are not changed while the effect of changing the configuration of splitters is studied. An optimization study is performed to find the best configuration using genetic algorithm over a complete operating curve of the compressor. CFD codes with experimental support are used to predict the compressor performance. Quantumetric tests beside destructive analysis of two impellers are... 

    Influence of different types of nano-SiO2 particles on properties of high-performance concrete

    , Article Construction and Building Materials ; Volume 113 , 2016 , Pages 188-201 ; 09500618 (ISSN) Khaloo, A ; Mobini, M. H ; Hosseini, P ; Sharif University of Technology
    Elsevier Ltd  2016
    The aim of this study was to evaluate the effects of applying low replacement ratios (0.75% and 1.50% of the binder weight) of nano-SiO2 particles with different specific surface areas (200 and 380 m2/g) on the properties of high-performance concrete (HPC). Mechanical (compressive and splitting tensile strengths), electrical resistivity, non-destructive (ultrasonic pulse velocity), and microstructural (mercury intrusion porosimetry, X-ray diffraction, and scanning electron microscopy) tests were conducted to investigate the macroscopic and microscopic effects of nano-SiO2 particles on HPC characteristics. The results indicated that the performance of nano-SiO2 particles significantly... 

    Experimental investigation on effects of hybrid fibers on rheological, mechanical, and durability properties of high-strength SCC

    , Article Construction and Building Materials ; Volume 147 , 2017 , Pages 497-509 ; 09500618 (ISSN) Tabatabaeian, M ; Khaloo, A ; Joshaghani, A ; Hajibandeh, E ; Sharif University of Technology
    The aim of the present study is to investigate the effects of using hybrid fibers on rheological, mechanical and durability properties of the high-strength self-consolidating concrete (SCC). For this purpose, two types of fibers including hooked-end steel fibers and polypropylene fibers were used. In this study, a total of eleven mixtures were used: one as a control mix, one containing 0.5% steel fibers, four containing 0.5% hybrid fibers (steel and polypropylene), one containing 1.0% steel fibers and the four containing 1.0% hybrid fibers (steel and polypropylene). For investigating the rheological properties, slump flow, J-ring and V-funnel tests were performed. Mechanical properties were... 

    Fast fourier transform based NDT approach for depth detection of hidden defects using HTS rf-SQUID

    , Article IEEE Transactions on Applied Superconductivity ; Volume 28, Issue 7 , 2018 ; 10518223 (ISSN) Rostami, B ; Shanehsazzadeh, F ; Fardmanesh, M ; Sharif University of Technology
    We present a new approach for depth detection of hidden defects based on the analysis of the frequency spectrum of the output waveform in a nondestructive testing (NDT) system. In our eddy current Superconducting quantum interference device (SQUID) based NDT system, we apply multiple frequencies to its single excitation coil in a magnetically unshielded environment. The excitation coil is a planar D-shaped printed circuit board coil, and a high-Tc gradiometer YBCO rf-SQUID is used as the electromagnetic sensor in this system. An automated two-dimensional nonmagnetic scanning robot is used to test samples with intentional defects at different depths. In this approach, a diagram labeled 'FFT... 

    Optimizing the mixture design of polymer concrete: An experimental investigation

    , Article Construction and Building Materials ; Volume 167 , 2018 , Pages 185-196 ; 09500618 (ISSN) Jafari, K ; Tabatabaeian, M ; Joshaghani, A ; Ozbakkaloglu, T ; Sharif University of Technology
    Elsevier Ltd  2018
    Over the last few decades, polymer concrete (PC) has been finding use in quick repairing of concrete structures. However, there have been only few studies on the mechanical behavior of PC. The aim of this study is to evaluate the mechanical behavior of PC using destructive and non-destructive tests (NDT). The mixtures were prepared with three different polymer ratios (10%, 12%, and 14%) and two different coarse aggregate sizes (4.75–9.5 mm and 9.5–19 mm). The samples were subsequently tested under three different temperatures (−15 °C, +25 °C, and +65 °C). The Taguchi method and analysis of variance (ANOVA) were used to optimize PC mixes based on the compressive, splitting-tensile, and... 

    Assessment of plain and glass fiber-reinforced concrete under impact loading: a new approach via ultrasound evaluation

    , Article Journal of Nondestructive Evaluation ; Volume 38, Issue 4 , 2019 ; 01959298 (ISSN) Soleimanian, E ; Toufigh, V ; Sharif University of Technology
    Springer  2019
    Impact loading leads to micro-crack formation that can compromise the performance of the concrete. The purpose of this paper is to evaluate plain concrete and fiber-reinforced concrete specimens using ultrasound methods under impact loading. These specimens were prepared and subjected to impact loading. Ultrasound tests were performed at different stages of impact loading on each specimen. The loading continued until cracks on the surface of the specimens were observed. Investigations were performed for both plain concrete and fiber-reinforced concrete to establish a correlation between ultrasound response characteristics, and the damage caused by impact loading due to the energy of blows... 

    Electromagnetic attenuation factor based nde approach for depth detection of hidden defects using HTS rf-SQUID

    , Article 27th Iranian Conference on Electrical Engineering, ICEE 2019, 30 April 2019 through 2 May 2019 ; 2019 , Pages 360-363 ; 9781728115085 (ISBN) Rostami, B ; Shanehsazzadeh, F ; Fardmanesh, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    We present a new approach for non-destructive evaluation (NDE) in homogeneous and isotropic metallic objects which contain defects at unknown depths based on single scan and multi frequency excitation. As known, there is an optimum frequency for each depth of defect. Finding the depth of an unknown defect requires us to find the optimal frequency. In conventional single frequency methods, the optimal frequency is obtained by applying a wide range of frequencies to the system separately and comparing the corresponding results in a time-consuming process. Conventional multi frequency inspections were introduced to obtain more information about test specimens. There are two ways to apply...