Papers by Keyword: Eddy Current

Abstract: The condenser in Steam Power Plant is critical equipment to convert steam from the steam output of the low-pressure turbine to become liquid. Thus, maintaining the reliability of the condenser will prevent progressive failure to other equipment. One of the methods to investigate their reliability is using eddy current test on the pure titanium grade 2 condenser tubes to measure their wall thinning level in comparison to their original thickness of 0.5 mm. Based on the measurement, any tubes having 0.05 mm in thickness (wall thinning level of 90%) and below are plugged to prevent potential leakage. In 2018, the condenser in unit 2 of Labuan steam power plant in Banten province, Indonesia was tested by eddy current on all tubes. Results indicate that condenser tube with wall tube thinning ≥ 90% were totaling 733 tubes (± 5% of the total tubes). The location and distribution of the highest probability of tubes leaking due to wall thinning problems were generated after statistical analysis. The data obtained in this unit can be used as a reference for maintenance strategy on other units working in the same condition. In order to understand the tube thinning mechanism, one tube at A-side inlet that has 97% of wall thinning level was cut and submitted to metallography and hardness testing. The results point out that no crack or corrosion product was found and the microstructure of the tubes did not alter as compared to their original tubes. This indicates that pure erosion mechanism takes place causing the thinning of the tubes.

Abstract: The dependences of the surface eddy current probe added voltage at the interaction of the probe magnetic field with an aluminum pipe from the following main interference factors are determined: the pipe wall thickness, the gap between the probe and the surface of the pipe, the electrical conductivity of the material, the curvature of the pipe wall, the presence of areas with a smooth thickness change of the wedge character and a local spherical thinning, axis misalignment with respect to the pipe surface, the lateral misalignment of the probe axis. The problem is solved with the help of the finite element method (FEM). These data are consistent with the experimental results.

Abstract: The paper develops analyses electromagnetic compatibility issues in electric vehicles. Particular techniques are developed involving special elements of tubular geometry based on the analytical solution of diffusion equation combined with standard finite elements, for analysis of electromagnetic shielding effectiveness in power cables due to power static converter operation. Particular simulations analyze the exposure levels due to variable frequency magnetic field on anatomically detailed human models in electric vehicle cabin environment. The results obtained have been compared to those found in the literature and to measured ones.

Abstract: Fast-steering Secondary Mirror (FSM) will be installed to the Giant Magellan Telescope (GMT) as a first generation secondary mirror. The FSM implements a tip-tilt mechanism which compensates image degradations caused by wind turbulence and structure jitter. A prototype segment of the FSM has been developed, which comprised of a dummy mirror, a mirror cell, axial and lateral supports, vacuum devices, etc. Several test-bed frames have been developed to hang the segment and to test tip-tilt functionalities. They have been designed, manufactured, assembled, and verified successfully step by step. Tip-tilt measurements were performed mainly by displacement measuring sensors which detect eddy currents precisely. The results proved that the prototype segment worked successfully, by complying the requirements of the FSM for the tip-tilt actuations.

Abstract: Article is focused on using eddy current to measure of internal residual stress after milling. In presented article is described methodical process of identification residual stress in internal layers of the surface after machining of steel C45. Eddy current provides fast identification of residual stress directly in engineering areas without necessity to transfer samples in specialized laboratories. Presented article also describe procedure of evaluating measured values of deviation and its transformation to values of residual stress by conversion coefficients.

Abstract: The objective of this paper is an analysis of statistical discreteness and measurement capability of an eddy-current measurement system for residual stress assessment in stainless steel Grade 304 (SS304). Cylindrical specimens with 50 mm in diameter and 12 mm thickness were prepared to generate residual stress by Resistance Spot Welding at which the welding currents were set at 12, 14, and 16 kA. The eddy-current measurement system was including a probe with frequency range of 0.1 to 3 MHz and an eddy current flaw detector. They were performed by contacting the probe on the specimen. The measurements were performed particularly in the vicinity of heat affected zone (HAZ). In order to determine the results of the residual stress measurement, the calibration curves between static tensile stress and eddy current impedance at various frequencies were accomplished. The Measurement System Analysis (MSA) was utilized to evaluate the changed eddy-current probe impedance from residual stress. The results showed that using eddy current technique at 1 MHz for residual stress measurement was the most efficient. It can be achieved the Gauge Repeatability & Reproducibility %GR&R at 16.61479 and Number of Distinct Categories (NDC) at 8. As applied on actual butt welded joint, it could yield the uncertainty of ± 58 MPa at 95 % (U_ISO).

Abstract: The article presents the results of the influence of geometrical features of defects in materials on the level of identification by the eddy current method. The study involved the inner ring of the tapered roller bearing. Four test defects, located at a constant distance from the inner surface, and a subsurface marker defect were performed in the treadmill of the tested ring. The test defects had a constant cross-sectional area in a perpendicular direction to the surface of the eddy current head. The geometrical features of each defect were the following: shape, the perimeter of the defect projected onto the surface of the ring, and the width and height of the defect projected on the face of the measuring head. The study involved an inner surface (subsurface defect detection) and external surface (the study of surface defects). It has been shown that the shape of the defect affects the level of detection using the eddy current method.

Abstract: The influence of most physical factors on the revelation ability of magneto-optic eddy current defectoscopy of linear defects in metallic objects is investigated. Uniaxial anisotropy multi-component Bi-substituted garnet film is used as the sensor element. The efficiency of visualization depends on frequency and amplitude of the inducer’s electric current and the biasing magnetic field. Optimal values of these parameters are obtained. It is shown that the alternative magnetic field exerts the most influence on the eddy current magneto-optic image.

Abstract: The porosity is unwanted phenomenon mostly that is tried to eliminate. The pores are initiation site of fatigue fractions usually, they worse strength and ductility of materials, quality of machined surfaces and their following surface treatment.

Abstract: The wear is very difficult to characterize because of its complexity and its measurement phenomenon. Our work is to prepare samples Fan blades, worn, to determine the nature of the wear and damage them. For these reasons, the characterization of these samples was conducted in different microscopic and macroscopic scales. We used non-destructive techniques such as eddy current and penetrant methods. The results obtained allowed us to see the deterioration of fins from one floor to another. These results are directly related to the effects of mechanical, thermal and pressure. It has been, in addition to detecting a different type of damage these fan blades that is the fatigue damage.