Novel Noncontact Eddy Current Measurement of Electrical Conductivity

2018 ◽  
Vol 18 (22) ◽  
pp. 9352-9359 ◽  
Author(s):  
Cuiping Wang ◽  
Mengbao Fan ◽  
Binghua Cao ◽  
Bo Ye ◽  
Wei Li
2015 ◽  
Vol 659 ◽  
pp. 623-627 ◽  
Author(s):  
Cherdpong Jomdecha ◽  
Isaratat Phung-On

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 % (UISO).


2013 ◽  
Vol 740 ◽  
pp. 128-133 ◽  
Author(s):  
Wei Wen Liu ◽  
Kai Jiang ◽  
Hui Zhao ◽  
Cheng Long Wang

The spine, which is throughout the trunk, is of great importance to the skeleton structure of human beings. For spine is vulnerable, the rate of spine incident trauma injury is relatively high. In the contemporary technology, the internal fixation prosthetics with implanting pedicle screws is the most efficient way in clinical treatment. However spine internal fixation surgery has many disadvantages like complex in the operation, the high penetration rate and inability to be used in the field battle. As a result, according to the magnetic property difference of different vertebra tissues, an eddy current detection method which is used in localization and recognition of different vertebra tissues to realize the navigation of spine internal fixation surgery is proposed in this paper. A set of improved series-reverse-three coils eddy current sensor is used to test the NaCl solution which electrical conductivity matches that of biological tissue. And the result of several experiments indicates this method can detect the biological tissue with the electrical conductivity no less than 0.5 S/m, which lays a solid foundation to further study of recognition different vertebra tissues.


1996 ◽  
Vol 29 (2) ◽  
pp. 103-109 ◽  
Author(s):  
Benoit de Halleux ◽  
Bruno de Limburg Stirum ◽  
Andrei I'tchelintsev

Author(s):  
Hector Carreon

Due to elevated temperatures, excessive stresses and severed corrosion conditions, turbine engine components are subject to creep processes that limit the components life such as a turbine bucket. The failure mechanism of a turbine bucket is related primarily to creep and corrosion and secondarily to thermal fatigue. As a result, it is desirable to assess the current condition of such turbine component. This study uses the eddy current (EC) nondestructive evaluation technique in an effort to monitor the creep damage in a nickel base super-alloy, 7FA stage 2 turbine bucket after service. The experimental results show significative electrical conductivity variations in eddy current images on the creep damage zone of nickel base super-alloy samples cut from a turbine bucket. Thermoelectric power (TEP) measurements were also conducted in order to obtain a direct correlation between the presence of material changes due to creep damage and the electrical conductivity measurements.


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