A Nondestructive Testing Method of Incremental Permeability Based on Permanent Magnet Movement Magnetization

Modern requirements for the quality of manufactured and operated metal products are largely ensured by non-destructive testing methods, among which ultrasonic testing is the most advanced one. One of the promising ultrasonic quality assessment methods is the electromagnetic-acoustic (EMA) method, as it does not require special surface preparation of the object under test (OUT), does not imply the use of contact liquids, and offers high testing productivity. However, it is generally believed that the EMA method has low sensitivity. Some specialists suggest that the sensitivity of the EMA method can be increased by using pulsed magnetization of the OUT. Nevertheless, a comprehensive approach to address the technical and technological challenges has not been found in the existing publications. Therefore, the authors of this paper conducted relevant studies and analysed modern information sources, which only partially address some solutions related to the development of methods and measuring instruments, testing, and diagnostics using ultrasonic electromagnetic-acoustic transducers (EMATs) with pulsed magnetization. These developments potentially allow increased EMAT sensitivity by improving the signal-to-noise ratio of the ultrasonic signal. As a result of the analysis, a new EMA method of non-destructive ultrasonic testing was developed. It defines the operations, parameters, and sequence of actions required during pulsed magnetization of the OUT. The necessity to determine optimal relative timing between the magnetizing pulses and the short high-frequency pulses supplying the EMAT coil was established, which makes it possible to significantly (up to 40%) improve the efficiency of the transducer when assessing the quality of ferromagnetic materials. To study the potential of the new EMA method, a special test bench was created. It included an EMAT, a generator of powerful high-frequency current pulses, a generator of powerful magnetizing current pulses, an amplifier for received ultrasonic pulses (with parameters adjustable over wide ranges), and a digital dual-beam oscilloscope. Experimental results using this test bench demonstrated that the new EMA method and its supporting equipment improve the signal-to-noise ratio of the received ultrasonic signals compared to traditional EMATs based on permanent magnets. In other words, the efficiency of the EMAT has been enhanced.

Cemented Paste Backfill (CPB) has become a useful practice in many modern operations around the world. This method is an innovative tailings disposal and underground mine backfilling scheme that returns much of this material to the underground stope field. Thus, it is of great interest for financial and security reasons to fully comprehend the mechanical performance of such underground CPB. Uniaxial compressive strength (UCS) is one of the most commonly used parameters for evaluating the mechanical performance of CPB. Electrical resistivity (ER) measurement, which is a method of nondestructive testing, can also be used to determine the mechanical properties of CPB. This study was undertaken to suggest a nondestructive testing method that would permit prediction of the UCS of a CPB within 90 days. Five CPB samples were prepared at different cement-to-tailing ratios (1/4, 1/6, and 1/8 by weight) and solid content (65 and 70 wt. %), and a curing period of 3–90 days was used for ER measurement. Seventy-five CPB samples were prepared with the same cement content as those used in the pastes for UCS tests cured for 3, 7, 28, 56, and 90 days. The results of the ER measurement show that the ER versus curing periods of 3–90 days first drop to a minimum value and then gradually increase with time. The greater ER values of CPB are reached when the greater cement-to-tailing ratio and solid content is used. A logarithmic relationship is established between the UCS and the ER of CPB at 90 days. It is possible that a nondestructive method could be developed to evaluate the strength of underground CPB based on the obtained logarithmic relationship with ER at 90 days.

This paper dedicated to electromagnetic acoustic (EMA) inspection of boiler tubes in the process of regular maintenance for prevention of tube rupture. This non-destructive testing method is developed to replace commonly used ultrasonic method of inspection which is costly and very labor intensive. During proposed EMA inspection surface of tubes does not require sandblasting and special coupling between measuring tool and tube wall. Commonly used ultrasonic method, based on detection of the wave generated by a piezoelectric effect of a crystal transducer, provides accurate but sparse data and takes long time to inspect healthy boiler condition. Electromagnetic acoustic transducer EMAT generates such wave directly in tube material by electromagnetic method. EMAT technology is well known and used in many nondestructive testing situations. This method relies on generating ultrasound wave directly in the metal in the form of elastic wave with ultrasonic velocity, characteristic for a given metal. There are two ways that EMATs can generate elastic energy directly in the boiler water-wall. The first is via the “Lorentz force” mechanism where interaction between an applied magnetic field and induced eddy currents produces an elastic wave. The second is through magnetostriction (MS), where an alternating magnetic field generates an alternating elastic force. Developed and fabricated with high energy Neodymium-Iron-Boron permanent magnets with magnetic energy over 56 MGsOe by M. Bergander [1] transducer is able to generate strong elastic wave using magnitostrictive properties of tube material for prediction of the tube thickness. In the special conditions of coal-fired boiler inside and outside surfaces of the tube are covered by erosive and corrosive layers. Those corrosive and erosive layers have good magnitostrictive properties which allow making water-wall thickness measurement without sand blasting and without necessity to have coupling between measurement tool and the tube material surface. This method allows inspecting boiler tubing much faster with the high quality of assessment. To make process of inspection faster claiming robot has been designed. This robot is able to deliver sensor of the measuring device to the surface of the tube and provide stable data reading. Using such robotic device it is possible to do automation of the inspection procedure.

The search of a durable and low cost fiber reinforced cement concrete for construction works is an empirical challenge in developing countries. Economic scarcity have confined the use of carbon fibers in cementitious composites on a commercial level. Jute fiber has the potential to be used in reinforcement to surpass the inherent deficiencies in cementitious materials. In this research, jute fiber reinforced concrete is used to find out which test method is more reliable among destructive and non-destructive test methods. In recent years, one of the most challenging scientific method is intelligent defect detection. Non Destructive Testing (NDT) techniques are the most useful and the easiest methods due to their efficiency and low cost. The experimental process using Ultrasonic Pulse Velocity and Schmidt Rebound Hammer as Non-destructive Tests (NDT) are used in this paper to set up a correlation between the compressive strengths of compression tests and NDT values. These two tests have been used to find out the concrete quality by applying regression analysis models between compressive strength of jute fiber reinforced concrete and tests values. The relationship between compression strength of concrete collected from destructive test method and estimated results from NDT’s records using regression analysis are compared together to assess their reliability of prediction of concrete strength. The test results show that destructive test methods are the most reliable way to find out the original strength of test specimens. After destructive test methods, the rebound number method is more efficient in predicting the strength of concrete under certain conditions. Schmidt Hammer rebound tests is recommended to estimate the strength of concrete to reduce the number of cores taken from the structures in practical cases.

A comparative analysis between Rebound Hammer and Pullout method in testing concrete was conducted in this study. Experimental analysis were carried out to compare the correctness between the two testing method in estimating the strength of concrete. Different cube (cubes of 175 x 175 x 175) samples were prepared using two mix designs of 1:2:4 and 1:3:6 with a constant w/c ratio of 0.45 and were tested at 7, 14, 21 and 28 days. The rebound hammer readings had a correlation coefficient of 0.695 while the pullout had a correlation coefficient of 0.725 for the 1:2:4 mix and the rebound hammer readings for 1:3:6 was 0.724 and that for the pullout was 0.675. From the results obtained, it is observed that the non-destructive testing methods were correlated with the compressive strength results which showed that a higher correlation existed between the Rebound Hammer and the compressive strength than the Pullout. Statistical analysis of the results obtained showed that there was no significant difference between the means of the two methods for both mix at a 0.05 level of significance. However, Rebound hammer method can be recommended as it provides a quicker, less-expensive means of checking the uniformity of concrete even though it shows less sensitivity as concrete matures, unlike the Pullout test in which measuring strength is affected by the arrangement of the embedded insert, the dimensions of bearing ring, the depth of embedment, the concrete age and the type of aggregates uses in concrete.

Non-destructive methods have many advantages over traditional test methods, especially since it does not damage the specimen, it can be used multiple times on the same specimen. These advantages also provide a great benefit in terms of following the property development in concrete as the same specimens are used which eliminates the variations related to the specimens. In this study, it is aimed to determine the damaged amount of concrete produced with different binders by electrical bulk resistivity, resonance frequency, and ultrasonic pulse velocity methods. Firstly, concretes containing different binders were produced, and along with the mechanical properties, ultrasonic wave velocity, resonance frequency, and electrical resistivity values of the produced concrete were determined at the 7, 28, and 90 days. Besides, the specimens were subjected to gradually increase compressive loads and non-destructive methods were used to estimate the extent of damage on specimens. It was attempted to establish a relationship between the damage on concrete specimens and the results obtained by non-destructive methods. Consequently, the compressive strength, electrical resistivity, ultrasonic pulse velocity and resonance frequency values of all specimens increased with the advancing age. It was concluded that the resonant frequency method is more successful than other methods in estimating the amount of damage in concrete.

Various non-destructive test methods have been developed for the detection of cracks in metallic structures. Electromagnetic non-destructive testing (NDT) is one of the widely used non-destructive methods used for the detection and characterization of cracks. Utilizing the principle of electromagnetic induction, this technique is used in the areas of nuclear, aerospace, power, transport, petroleum and other industries to inspect defects in metallic sheets, plates and tubes that have good electrical conductivity.;Aircraft structures and wings are made of aluminum sheets riveted together. Cracks are often found emanating from the edge of the rivet holes which are covered by the rivets and are difficult to be detected. Electromagnetic NDT, which involves flow of electrical current and a resultant magnetic field, can be applied to detect these cracks.;In this research, a finite element model was developed which utilizes the principle of electromagnetic NDT. Electrical current density analyses were carried out on aluminum plate with cracks of various shapes and sizes, and demonstrated how electromagnetic NDT can help detect cracks emanating from edge of rivet holes.

Eddy Current Array Inspection of Zlin 142 Fuselage Riveted Joints

The engineering risk of pressure equipment is closely related on the structure and material of equipment as well as the parameters such as pressure, temperature, medium environment, etc., which it withstands. In order to reduce and control the engineering risk of the pressure equipment, appropriate nondestructive testing method and testing chance must be adopted at the stages of design, manufacture and installation to control the product quality and assess its safety status at the operation stage of pressure equipment. In this paper the importance of nondestructive testing method and chance selection for pressure equipment is discussed based on engineering cases. This paper shows that nondestructive testing technique is an important means for product quality control of pressure equipment and is also important guarantee for its safe operation. Under the condition that appropriate nondestructive testing method and testing chance are selected, the engineering risk of pressure equipment can be minimized.

This paper presents an experimental examination of the effect of high temperatures on concrete prepared with different fibers types. For this study the concrete were prepared with four types of fibers (Steel, polypropylene, carbon and the combination of several types of fibers) and water/cement ratio fixed (w/c of 0.35). Specimens were heated under five different temperatures: 20 °C (ambient temperature), of 200 ºC, 300, 400 ºC and 600 ºC respectively. The following settings: compressive strength, ultrasonic pulse velocity, rebound hammer, concrete mass loss, and water porosity were examined in this Research experimental. Also A scanning electron microscopy study was used to comprehend the change in texture. The cracks were also examined using a microscope and other methods. This article is a contribution to the general understanding of the impact of fibers in high temperature concrete and highlights the significant impact of different types of fibers on the physical and mechanical properties of concrete who they were explore using destructive and nondestructive methods.

Non-destructive test methods for structure analy-sis of ultra-high performance concrete were applied after 40 cycles of salt-scaling. Salt-scaling test method was per-formed using 3 % NaCl solution. The main aim of the ex-periment was to find new way to observe structure changes in ultra-high performance concrete products, which could help for scientists better understand deterioration mechanism of concrete after cyclic salt-scaling. Salt-scaling of UHPC were investigated by ultrasonic pulse velocity, dynamic modulus of elasticity and compressive strength methods. Surface defects were visually identified by fluorescence test method. There are a few publications about salt-scaling resistance of UHPC and fewer articles about nondestructive test methods how to evaluate structure of concrete after certain cycles of salt-scaling, however such research in Europe is not done at all. DOI: http://dx.doi.org/10.5755/j01.mech.20.2.6948

PURPOSES: This study is to evaluate the dynamic modulus changes of permeable asphalt mixtures by using non-destructive impact testing method and to compare the dynamic moduli of permeable asphalt mixtures through repeated freezing and thawing conditions. METHODS: For the study, non-destructive impact testing method is used in order to obtain dynamic modulus of asphalt specimen and to confirm the change of dynamic modulus before and after freezing and thawing conditions. RESULTS : This study has shown that the dynamic moduli of asphalt concrete specimens consisting of 10%, 15% and 20% porosity are reduced by 11.851%, 1.9564%, 24.593% after freezing and thawing cycles. CONCLUSIONS : Non-destructive impact testing method is very useful and has repeatability. Specimen with 15% porosity has high durability than others.

<div class="section abstract"> <div class="htmlview paragraph">Nondestructive tests are those tests which detect factors related to the serviceability or quality of a part or material without limiting its usefulness. Material defects such as surface cracks, laps, pits, internal inclusions, bursts, shrink, seam, hot tears, and composition analysis can be detected. Sometimes their dimensions and exact location can be determined. Such tests can usually be made rapidly. Processing results such as hardness, case depth, wall thickness, ductility, decarburization, cracks, apparent tensile strength, grain size, and lack of weld penetration or fusion may be detectable and measurable. Service results such as corrosion and fatigue cracking may be detected and measured by nondestructive test methods. In many cases, imperfections can be automatically detected so that parts or materials can be classified.</div> <div class="htmlview paragraph">The SAE Handbook describes the following nondestructive test methods:</div> <ol class="list nostyle"> <li class="list-item"> <div class="htmlview paragraph">SAE J359—Infrared</div></li> <li class="list-item"> <div class="htmlview paragraph">SAE J420—Magnetic Particle</div></li> <li class="list-item"> <div class="htmlview paragraph">SAE J425—Eddy Current</div></li> <li class="list-item"> <div class="htmlview paragraph">SAE J426—Liquid Penetrant</div></li> <li class="list-item"> <div class="htmlview paragraph">SAE J427—Penetrating Radiation</div></li> <li class="list-item"> <div class="htmlview paragraph">SAE J428—Ultrasonic</div></li> <li class="list-item"> <div class="htmlview paragraph">SAE J1242—Acoustic Emission</div></li> <li class="list-item"> <div class="htmlview paragraph">SAE J1267—Leakage Testing</div></li></ol> <div class="htmlview paragraph"><span class="xref">Table 1</span> summarizes the principal features of most of these tests. In addition to the tests described, other nondestructive tests exist which are less well established, but whose use is expanding. Among these are microwave tests, holography, and sonic tests. Microwaves are used to locate defects in nonmetallic substances and to determine some physical characteristics of those materials. Optical holography uses coherent light from a laser beam to detect strains and defects in materials by means of three-dimensional imaging and interferometry techniques. Acoustical holography uses ultrasonic waves to image discontinuities in the interior of solids. Recent refinements in sonic testing permit more objective determination of the physical properties of cast iron. Complete information concerning each nondestructive test can be obtained from books listed in the bibliographies of the aforementioned reports.</div> <div class="htmlview paragraph">Increasing consumer demand for product quality at reasonable cost has resulted in development of nondestructive tests which can be applied to materials and manufactured parts. Although a variety of complementary nondestructive methods is available, development time is generally required for application to specific materials or products. The effect of part contour, surface condition, heat treatment, composition variation, and other variables may limit the ability of certain tests to detect imperfections with desired accuracy.</div> <div class="htmlview paragraph">Nondestructive tests properly applied to basic material can add greater assurance of performance to design strengths, thereby affecting material and manufacturing economy. In addition, parts can be tested after each basic operation which is critical to service performance of the finished part. In-process nondestructive tests can also serve as basic components of feedback process control systems since all tests are based upon measurements which do not damage the material or part being inspected.</div></div>

Chapter 1 - Introduction

In this study, a new nondestructive testing (NDT) method that employs induction heating (IH) and infrared thermography camera is investigated for its applicability in the measurement of extent of corrosion of steel in concrete. Corrosion products have a very low heat conductivity. The more there are corrosion products on the steel bar in an reinforced concrete (RC) specimen subjected to IH, the higher the temperature rise of the steel bar, while the temperature rise of concrete surface is slower. The larger the rebar diameter, the higher the temperature rise on the concrete surface, which makes detection of corrosion easier.