This study reports the results of nondestructive testing and evaluation of artificial thermal fati gue cracks using direct current potential drop method. ?ix artificial thermal fatigue cracks, intro duced into type 304L austenitic stainless steel plates with a thickness of 25mm, are prepared; and potential drops across the cracks are measured using a direct current source of approximately 80A. The specimens are then served to destructive tests to reveal the true profiles of the cracks. Fini te element simu...
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Nondestructive Testing and Evaluation of Artificial Thermal Fatigue Cracksusing Direct Current Potential Drop Method

This study evaluates the distribution of electrical contact across the surface of thermal fatigue cracks by four- terminal direct current potential drop method. This study prepared seven artificial thermal fatigue cracks, artificially introduced into Inconel or type 316L stainless steel plates with a thickness of 25 mm. Columnar specimens embedded into a resin were fabricated from the plate s to measure the electrical resistance across the cracks directly. The results indicated th at thermal fatigue crac...
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Evaluation of the electrical contacts of thermal fatigue cracks across their surfaces 東北大院・工学研究科

The PIRT process was developed as a part of the systematic and documented means of demonstrating the validation of best estimate simulation codes in USNRC licensing of nuclear power plants. In this paper the PIRT process was applied for finding influential factors giving an impact on the accuracy of ultrasonic testing and eddy current testing and related problems required to improve the accuracy and also reports the results that the problems were ranked from the viewpoint of importance, knowledge and c...
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Accuracy of Non-destructive Examination Techniques to Detect Fatigue Crack

This study develops a low frequency magnetic flux leakage testing method for monitoring a wall thinning appearing on the inner surface of a magnetic pipe. We conducted the numerical simulations to evaluate how the presence of wall thinning perturbates electromagnetic fields induced by an encircling coil. The result of the simulations shows measuring the axial component of magnetic flux density enables to detect and evaluate wall thinning. ...
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Development of low frequency magnetic flux leakage testing method aimed at monitoring a wall thinning appearing in a magnetic pipe

This paper reports research activities in the authors’ group to develop a novel non-destructive testing method using a microwave to quickly inspect the inner surface of a pipe. The method propagates a microwave inside a pipe to detect anomalies appearing the inner surface on the basis of the reflection of the microwave due to the anomalies. Because the method does not require probe scanning unlike conventional non-destructive testing methods such as eddy current testing, it can inspect a long pipe quit...
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Development of a non-destructive testing method for a long-range inspection of the inner surface of a long pipe

This study proposes a technique that would enhance the sizing ability of remote field eddy c urrent testing. Numerical simulations are conducted in an axisymmetric configuration modelin g remote field inspection of ferromagnetic steam generator tube. The simulations confirm an abrupt change of measured signal, and the change depends on the depth of a defect measured....
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Remote field eddy current testing with controlled current distributions

The epochal electromagnetic nondestructive detection method was proposed. In this method a permanent magnet is utilized to generate a static magnetic field and a coil with several hundred turns is used to detect the eddy currents induce d inside the ball bearings. In the present study the method is applied to observed and evaluate ball bearings contaminated extraneous substances. Experimental validations are carried out using a common ball bearing. A wound and the malf unction of bearings are well detected...
英字タイトル:
Electromagnetic Nondestructive Detection for Ball Bearings Contaminated Extraneous Substances