Papers by Keyword: Eddy Current Testing

Abstract: The present experimental study proposes an alternative for diagnostic methods and quality control in cylinder head defectology. The composition of the material is characterized by spectrometry, obtaining an approximation of aluminum 2117. For the detection of defectologies, non-destructive tests (NDT) are carried out, applicable to cylinder heads such as: visual inspection (VT) under conditions of standard EN 13018, penetrating inks (PT) visible according to ASTM E 165-02 and others not yet included in the vehicle fleet.; infrared thermography (IRT) with equipment specifications under ISO 18434 - 1, ultrasound (UT) based on standard EN 583 for the use of the equipment and Eddy currents (ECT) conforming standard ISO 15548, the analysis is carried out on the flat surface of the cylinder head, combustion chamber, valve seats and intake - exhaust ports, the different defects found are: cracks, fissures, discontinuities and pitting, showing longitudinal dimensions from 0,8 [mm]. To determine the reliability of results, an analogy is made of the tests mentioned in the same defect, the method with the greatest scope is Eddy currents as it has more inspection coverage with respect to the remaining tests; the simulation of computer-aided engineering CAE of the defect is performed, applying an AC magnetic analysis to identify the flux density, current density and visualize how the Eddy currents act in the cylinder head. After this research, artificial intelligence will be used as a complementary diagnosis, to predict defectologies not perceived by the human eye and to obtain a better analysis of defectologies in cylinder heads.

Abstract: This paper describes the physics of the interaction of the eddy current probe and the delamination in multidirectional carbon fiber reinforced polymer (CFDR). Currently, there is an opinion that eddy current signals obtained due to delamination in multidirectional CFRP are caused by the redistribution of the vertical eddy current arising from the excitation of eddy currents in the sample by a rectangular coil whose surface is orthogonal to the surface of the sample. The analysis performed by us shows that the possibility of creation and deformation of the vertical eddy current is very questionable, and that the observed eddy current signals associated with the delamination are most likely caused by carbon fiber plies misalignment towards the sample surface. In this paper was compare eddy-current signals from the delamination in CFRP in samples where the existence of vertical eddy current is possible in theory and in samples where this is not possible. The obtained signals had similar measurements, and this indirectly indicates the doubtfulness of the hypothesis of the delamination detection in CFRP samples due to vertical eddy current.

Abstract: The equipment of oil refineries and other hazardous production facilities operate under high pressures and temperatures. Such operation conditions require continuous control and equipment remaining operation life period assessment. The existing methods of diagnostics are based on probabilistic remaining life assessment and use data regarding wall thickness variation during the operation process. The present article presents the method of accumulated damage assessment and its approximation to the limiting state, based on electromagnetic processes studying by means of eddy current control method. The main purpose of studies was determination of optimal value of input signal frequency, which could the most informative for determination of regularity of electric signal parameters change depending on the level of accumulated damages. Steel grade 09Г2С samples were used as the subject of studies. The samples were exposed to static tension under constant rate and during the process of samples deformation we measured the value of electric signal under three frequencies: 100 Hz, 10 kHz, and 1 MHz Based on the obtained results we prepared output signal voltage-relative elongation dependencies, which showed that accumulation of plastic deformations in metal leads to reduction of signal amplitude. Particularly interesting was dependence under 1 MHz frequency, under which electromagnetic processes occur in subsurface and surface layers. This dependence was of some regular nature, which was described by means of the sinusoidal function. Graph of the obtained function qualitatively describes the experimental dependence. On the basis of obtained results we can make a conclusion that optimal input signal frequency is within megahertz range, under which difference between the sinusoidal function graph and the empirical curve is minimum.

Abstract: The present study, which is based on the finite element method, investigates the alloy element content assessment of these Fe-Si alloy steel sheets from the view point of eddy current testing. The relative permeability and conductivity were preset parameters. Eddy current signals were gathered by a differential type cylindrical probe and subsequent nondestructive tests were carried out with the preparation of four Fe-Si alloy steel sheets with different silicon contents. The result of the numerical simulation demonstrated that the signal increased with the increase of the silicon content in the Si-Fe alloy steel sheets. And the measured result confirmed the rationality of the application of eddy current testing in the average silicon content assessment.

Abstract: Eddy current testing and metal magnetic memory testing, cooperated with special testing devices, were applied to detect the superficial defects of old cylinder barrel. It was indicated that there were three types of the signals, which were non-defect signals, discontinuous peak signals and continuous peak signals. Non-defect signals indicated that there was no defect in cylinder barrel, and the discontinuous peak signals denoted that there was circumferential cracking, and the continuous peak signals showed that there was longitudinal cracking in the surface of cylinder barrel. The amplitude of eddy current testing signals characterizes the depth of cracking, and the gradient of magnetic signals descript the degree of stress concentration. The method mentioned above detects the cracking and stress concentration in the superficial coat of old cylinder barrel, which effectively guarantee the quality of automobile cylinder.

Abstract: Inverse eddy current problem using Artificial Neural Networks (ANN) approach for the localization and the classification shape of defects is considered. The task of reconstructing the cracks and damage in the plate profile of an inspected specimen in order to estimate its material properties can be described in this research work. This is accomplished by inverting eddy current probe impedance measurements that are recorded as a function of probe position, excitation frequency or both. In eddy current nondestructive evaluation, this is widely recognized as a complex theoretical problem whose solution is likely to have a significant impact on the characterization of cracks in materials .

Abstract: In this paper, we present a method for computing the Stress Intensity Factor (SIF) and J-Integral, by measuring and testing related Eddy currents. In the process, we provide a magnetic vector based formulations for the theoretical set up. Furthermore, we provide relevant applications having theory consistent results.

Abstract: This paper presents a flaw inspection method based on eddy current effect, by comparison of environment analysis and inspection methods for the high-speed train bogie surface flaw. It designed a testing physical prototype and a reasonable control system which was based on eddy current inspection bogie surface flaw, what’s more, it made use of restraining lift-off effect in testing two times, and the result of experiment indicated that method which tested bogie surface flaw was feasible and effective by digital monitor. The method will offer a guarantee for moving of the high-speed train safely and comfortably, and establish a little base to inspect interior flaw and research farther.

Abstract: Eddy current sensor with online non-contact measurement, no coupling medium and high sensitivity etc, is widely used in engineering. In this paper, based on the eddy current testing principle, the eddy current sensor is modeled in ANSYS software to complete the optimization design. The article research on the method of flaw recognition after extracting the detection signal features and analysis the impact of the flaw size on the detection signal, so as to provide a theoretical method of qualitative detection in the practical application.

Abstract: Based on the Maxwell equations in time-harmonic conditions, analytical model for cylindrical coil above multi-layered conductive structures of infinite large is built, the general solution for integral expression of coil’s impedance is derived. As the complex computation and inconvenient adjustment for calculating precision of integral form, the truncated region eigenfunction expansion is adopted to derive the series expansion expression of coil’s impedance. Calculating precision is ensured by selecting the truncating radius and the number of summation terms properly. Use Mathematica and CIVA separately compute the impedance variation of coil above the single conductive layer of different thickness. The results are highly identical and verify the validity of series expansion expression. The expression can provide help for optimizing the parameters of eddy current sensor.