Non-destructive Electromagnetic Testing Research Articles

Barkhausen Noise as A Magnetic Nondestructive Testing Technique

Magnetic Barkhausen Noise (MBN) is a magnetic-based non-destructive electromagnetic testing method. Due to the electromagnetic working principle of MBN, it can be used for ferromagnetic materials, which consist of small magnetic fields discredited by domain walls and oriented in various directions. In an external magnetic field application, the fields turn to the magnetic direction, and the domain walls move and cause magnetic flux jumps. The jumps are named Barkhausen Noise (BN). The domain wall movements are sometimes pushed down by microstructure, composition, and defects. As the magnetic domain walls break away from the pinning sites produce MBN signal. MBN can be used for different material properties such as microstructure, composition, residual stress, and hardness. The paper's purpose is to analyze MBN as an improved NDT, clarify the relationship between material properties and MBN profile, and introduce MBN's applications and test equipment of MBN.

Evaluation of the Embrittlement in Reactor Pressure-Vessel Steels Using a Hybrid Nondestructive Electromagnetic Testing and Evaluation Approach.

The nondestructive determination of the neutron-irradiation-induced embrittlement of nuclear reactor pressure-vessel steel is a very important and recent problem. Within the scope of the so-called NOMAD project funded by the Euratom research and training program, novel nondestructive electromagnetic testing and evaluation (NDE) methods were applied to the inspection of irradiated reactor pressure-vessel steel. In this review, the most important results of this project are summarized. Different methods were used and compared with each other. The measurement results were compared with the destructively determined ductile-to-brittle transition temperature (DBTT) values. Three magnetic methods, 3MA (micromagnetic, multiparameter, microstructure and stress analysis), MAT (magnetic adaptive testing), and Barkhausen noise technique (MBN), were found to be the most promising techniques. The results of these methods were in good agreement with each other. A good correlation was found between the magnetic parameters and the DBTT values. The basic idea of the NOMAD project is to use a multi-method/multi-parameter approach and to focus on the synergies that allow us to recognize the side effects, therefore suppressing them at the same time. Different types of machine-learning (ML) algorithms were tested in a competitive manner, and their performances were evaluated. The important outcome of the ML technique is that not only one but several different ML techniques could reach the required precision and reliability, i.e., keeping the DBTT prediction error lower than a ±25 °C threshold, which was previously not possible for any of the NDE methods as single entities. A calibration/training procedure was carried out on the merged outcome of the testing methods with excellent results to predict the transition temperature, yield strength, and mechanical hardness for all investigated materials. Our results, achieved within the NOMAD project, can be useful for the future potential introduction of this (and, in general, any) nondestructive evolution method.

Reliable non-destructive detection and characterization of material degradation caused by high-temperature corrosion

Components made from nickel-based superalloys are widely used in gas turbines for aircraft and power plants. In addition to high corrosion resistance, they feature very good creep and fatigue strength at temperatures near 1000 °C. Yet, corrosive attack can significantly reduce the mechanical properties, and thus the expected remaining service life of these components. Therefore, in the case of safety-critical parts, detailed information on the component’s actual condition is crucial. In the present study, a non-destructive electromagnetic testing technique was developed that is capable of reliably detecting early degradation caused by high-temperature corrosion on components made of nickel-based alloys. The testing technique combines the use of temperature-resistant sensors and a variation of the component temperature in a wide range. This allows the determination of the magnetic properties of the component as a function of temperature. It was shown that the measurement signals obtained correlates with the degree of chromium depletion. Thus, a reliable and non-destructive detection of degradation caused by high-temperature corrosion was possible. A special feature of the presented testing technique is that degradation can be detected at an earlier stage compared to conventional methods. In addition, the technique enables the characterization of the microstructure condition directly in the component. The applicability of the testing technique was demonstrated for components with concave surface geometries, like turbine blades.

Influence of the defect characteristic in aluminum alloy 7075 in non-destructive electromagnetic testing

The paper presents the results obtained from aluminum alloy 7075 T6 using eddy current testing method (ECT). This method is based on eddy current 3x3 sensor array, commanded through PC by a data acquisition system, allowing several different delay and amplitude technique at transmission and reception. The response of each sensor is stored, ensuring details for reconstructions and imaging procedures. Based on software CIVA simulation and experiment, defect characterization is obtained using the information received by each sensor of the array and establishing the position of the flaw upon the reacting sensor from array. The signal is post processed using super resolution algorithm to enhance signal to noise ratio, thus both surface and under surface flaws shall be identified, (thin or volumetric) or having different tilting reported to the surface and correlation between theoretical and experimental results.

Surface Eddy Current Probes: Excitation Systems of the Optimal Electromagnetic Field (Review)

Development of technical tools with improved metrological and operational characteristics is the actual problem of the eddy current testing. Ensuring the optimal distribution of the electromagnetic excitation field in the testing zone carries out confident detection of the defects and determination of their geometrical parameters by means of eddy current testing. The purpose of the work was to conduct an analysis of scientific and technical information in the field of eddy current testing to study of the use of electromagnetic excitation fields with a priori specified properties, as well as to generalize and systematize the accumulated experience and approaches to conduct theoretical research in this direction.A review of publications in the field of non-destructive electromagnetic testing devoted to the improvement of the excitation systems of eddy current flaw probes was carried out. The authors considered approaches in which a uniform distribution of the electromagnetic field on the control object surface was achieved by linear and non-linear optimal synthesis of excitation systems, provided the immobility of the probe relative to the testing object. Analysis of eddy current probe designs with a homogeneous excitation field created by circular, rectangular tangential and normal coils, as well as by creating a rotational excitation field was carried out. The authors studied designs of the excitation coils of probes with fields of complex configuration characterized by the original fractal geometry which can increase the probability of identifying defects that were not amenable to detection by classical probes.Studies that suggested the formation of optimal configuration fields in a given area using magnetic cores, field concentrators made of conductive materials and specially shaped screens were analyzed. The authors studied approaches to the implementation of the optimal synthesis of excitation systems of probes with uniform sensitivity in the testing zone using surrogate optimization for cases of moving testing objects taking into account the speed effect.The experience, as well as the results of theoretical studies devoted to the problem of designing eddy current probes with uniform sensitivity in the testing zone due to the uniform density distribution of the induced currents flowing in the object were generalized and systematized. As a result, the classification of probes on a number of features that characterize the excitation systems was proposed.

Conductivity of Powders Graphene, Graphite, Oxides, Sulfides, Etc. of Electrode Materials Are Critical Parameters for Efficiency Li Batteries. Non-Destructive Electromagnetic Testing. Electrochemical Properties

Correlation between conductivity the components of electrodes mass of Li batteries and electrochemical properties of these electrodes and Li batteries based on these electrodes have been investigation. The various types of the graphene and the graphite have been used as conductive additives for cathodes (positive electrodes). Various types of sulfide, manganese dioxide, lithium manganese spinel, and sulfides have been used as active materials of electrodes of Li batteries. The conductivity of powder materials have been investigated using the innovating non-contact non-destructive electromagnetic method. Impedance, galvanic cycling and current-voltage characteristics of the electrodes have been investigated.

Thermo-magneto-elastoplastic coupling model of metal magnetic memory testing method for ferromagnetic materials

Metal magnetic memory (MMM) testing (also known as micro-magnetic testing) is a new non-destructive electromagnetic testing method that can diagnose ferromagnetic materials at an early stage by measuring the MMM signal directly on the material surface. Previous experiments have shown that many factors affect MMM signals, in particular, the temperature, the elastoplastic state, and the complex environmental magnetic field. However, the fact that there have been only a few studies of either how these factors affect the signals or the physical coupling mechanisms among them seriously limits the industrial applications of MMM testing. In this paper, a nonlinear constitutive relation for a ferromagnetic material considering the influences of temperature and elastoplastic state is established under a weak magnetic field and is used to establish a nonlinear thermo-magneto-elastoplastic coupling model of MMM testing. Comparing with experimental data verifies that the proposed theoretical model can accurately describe the thermo-magneto-elastoplastic coupling influence on MMM signals. The proposed theoretical model can predict the MMM signals in a complex environment and so is expected to provide a theoretical basis for improving the degree of quantification in MMM testing.

ORIENTED FOR CAD UNIVERSAL MATHEMATICAL MODEL OF THE EDDY CURRENT PROBE. PART 1. THE RESULTING FIELD OF THE DRIVE WINDING

The work relates to the field of CAD methods and means of nondestructive electromagnetic testing of conductive flat products. The problem of constructing mathematical model of the drive winding eddy current probe linearly extended form is polygon in cross section. This allows you to create a universal mathematical model, which includes a model of a simpler shape in cross-section, as a special case.

Electromagnetic nondestructive testing at high lift-off using a magnetic image conduit

To protect sensors from the extreme environments, such as, heat, moisture, pollution and radiation, cracks must be inspected for; this can be done by measuring the distribution of magnetic fields at high lift-off through nondestructive electro-magnetic testing. However, as the intensity of an electro-magnetic field is inversely proportional to the square of the lift-off, it becomes increasingly difficult to effective inspect a crack as the lift-off increases. In this paper, a magnetic image conduit to minimize the intensity loss of an electro-magnetic field at high lift-off is proposed, and the effectiveness of a conduit for magnetic imaging is verified by means of both theoretical and experimental approaches.

RC建築工事におけるかぶり厚さ確保の信頼性向上を目指した施工管理方法の検討

This study aimed at developing quality controlling technology for securing concrete cover thickness in construction process. Toward this goal, field investigation for cover thickness measuring was conducted and obtained data were subjected to statistical analysis. Field study results showed smaller failure probability against required cover thickness is smaller than in literature. This appears partially due to high accuracy cover thickness measuring scheme adopting nondestructive electromagnetic testing apparatus, where data correction with steel arraignments on site. Furthermore, cover thickness data comparison before and after concrete placing process revealed that cover thickness tend to be larger after concrete placing process than before the process. This phenomenon can lead to proposing effective quality controlling action such that cover thickness is enlarged than required cover thickness before concrete placing to secure required cover thickness with high reliability.

Advanced geometric formulations for the design of a long defects detection system

The aim of the paper is to highlight some of the innovative methodologies, techniques and systems for nondestructive electromagnetic testing, which have been developed in the framework of the applications of methods of a diagnostics electromagnetic project partially funded by the Italian Ministry of University and Research. In particular, we will present the feasibility design of a suitable exciting-receiving coils configuration able to detect long defects by means of eddy-currents. To solve the forward eddy-currents problem, advanced analysis tools have been developed and validated.

Non-Contact Non-Destructive Electromagnetic Testing of Reserve Batteries

not Available.

Nondestructive electromagnetic testing of hardened layers on surfaces of steel components

In order to improve the measurement accuracy of hardened layer thickness, we suggest to use combination harmonics in a signal from an attached electromagnetic transducer. The paper describes an instrument for testing a hardened layer and generating a multidimensional digitized signal characterizing this layer. Results of tests of an experimental version of the device by measuring the thickness and hardness of case-hardened layers are given.