宮 健三 Kenzo MIYA This study proposes an investment for the evaluation of tube wastage by eddy current testing. EC T signals of differential and absolute type bobbin probes are presented by numerical simulation method. The relationships between percentage of wastage and ECT signals (amplitude and phase) ar e shown. Noise from ECT is considered and the percentage of wastage is estimated from safe side....
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Evaluation of Tube Wastage by Eddy Current Testing

This paper discusses the feasibility of shroud inspections using Eddy Current Testing (ECT). For the purpose, the three steps of simulations were carried out. At first, the propagation of postulated cracks in the H4 weld line of the shroud was estimated. Subsequently, the eddy current signals were numerically simulated based on the reduced vector potential method. At last, the inverse analyses were performed using simulated ECT signals, and crack shapes were reconstructed. The high accuracy of crack reconst...
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Simulation of Shroud Inspection based on Eddy Current Testing

The authors have proposed a novel eddy current testing(ECT) probe for thick-walled plates. A basic concept of the probe is that a couple of differential pick-up coils is arranged between two exciting coils carrying currents opposite to each other. This arrangement allows strong eddy currents opposite to scan surfaces and the weak decay of eddy currents in the thickness direction. In this study, the present probe was applied to ECT of welding area. For the purpose, experiments were carried out u...
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Weld Inspection Using Eddy Current Testing Probe for Thick-walled Plates

This report describes the applicability study result of the diagnostic te chnology by the electromagnetism to an internal rotation object. In order to perform further detailed study, measurement of the basic data of a pu mp and the preliminary experiment in an air drive turbine were conducted....
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Applicability study of the diagnostic technology by the electromagnetism to the rotating machines

The epochal electromagnetic nondestructive detection method was proposed. In that method a permanent magnet is zed to generate static magnetic field and a several hundred turn coil is used to detect the eddy currents induced inside ball bea rings. In the present study the signal procedure method of a autocorrelation method is also proposed in tion to that detection method and these methods are applied to observe and evaluate ball bearings wounded by grinder. erimental validatio ns are carried out using a c...
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Lectromagnetic Nondestructive Detection for Wounded Bearings and Proposalof the Signal Procedure Method for Estimating the Wound Width

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...
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Electromagnetic Nondestructive Detection for Ball Bearings Contaminated Extraneous Substances

This study proposes an electromagnetic method for the evaluation of the condition of the turbine in a nuclear power plant. Experimental re sults of a small turbine driven by an electric motor are shown in this paper. The results show that it is possible to detect the movement a nd condition of the impeller by applying the electromagnetic evaluation method. Moreover, an excitation experiment shows that the higher o rder vibration of the impeller can be detected and the distinction of the condition of with a...
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Material Evaluation of Cast Iron based on Eddy Current

In order to investigate a method for efficiently monitoring multiple machines in a building with an acoustic sensor, an experiment was performed to acquire acoustic data of three rotating machines running simultaneously in a state in which all three machines are normal or one of three is abnormal, with two microphones placed at different positions. The abnormality can be detected from the acoustic signal level, and it can also be specified that the bearing abnormality has occurred by frequency analysis. A m...
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Study of efficient condition monitoring method by acoustic diagnosis