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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society for Nondestructive Testing
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Journal DOI :
The Korean Society for Nondestructive Testing
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Volume & Issues
Volume 29, Issue 6 - Dec 2009
Volume 29, Issue 5 - Oct 2009
Volume 29, Issue 4 - Aug 2009
Volume 29, Issue 3 - Jun 2009
Volume 29, Issue 2 - Apr 2009
Volume 29, Issue 1 - Feb 2009
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Analysis of Stress Distribution around a Central Crack Tip in a Tensile Plate Using Phase-Shifting Photoelasticity and a Power Series Stress Function
Baek, Tae-Hyun ;
Journal of the Korean Society for Nondestructive Testing, volume 29, issue 1, 2009, Pages 1~9
This paper presents stress distribution around a central crack tip in a tensile plate using phase-shifting photoelasticity and a power series stress function. Isochromatic data along the straight lines far from the crack tip were obtained by phase shifting photoelasticity and were used as input data of the hybrid experimental analysis. By using the complex-type power series stress equations, the photoelastic stress distribution fields in the vicinity of the crack and the mode I stress intensity factor were obtained. With the help of image processing software, accuracy and reliability was enhanced by twice multiplying and sharpening the measured isochromatics. Actual and reconstructed fringes were compared qualitatively. For quantitative comparison, percentage errors and standard deviations of the percentage errors were calculated for all measured input data by varying the number of terms in the stress function. The experimental results agreed with those predicted by finite element analysis and empirical equation within 2 percent error.
Analysis of Heat Generation Mechanism in Ultrasound Infrared Thermography
Choi, Man-Yong ; Lee, Seung-Seok ; Park, Jeong-Hak ; Kim, Won-Tae ; Kang, Ki-Soo ;
Journal of the Korean Society for Nondestructive Testing, volume 29, issue 1, 2009, Pages 10~14
Heat generation mechanism of ultrasound infrared thermography is still not well understood, yet and there are two reliable assumptions of heat generation, friction and thermo-mechanical effect. This paper investigates the principal cause of heat generation at fatigue crack with experimental and numerical approach. Our results show most of heat generation is contributed by friction between crack interface and thermo-mechanical effect is a negligible quantity.
A Small Crack Length Evaluation Technique by Electronic Scanning
Cho, Yong-Sang ; Kim, Jae-Hoon ;
Journal of the Korean Society for Nondestructive Testing, volume 29, issue 1, 2009, Pages 15~20
The results of crack evaluation by conventional UT(Ultrasonic Test)is highly depend on the inspector's experience or knowledge of ultrasound. Phased array UT system and its application methods for small crack length evaluation will be a good alternative method which overcome present UT weakness. This study was aimed at checking the accuracy of crack length evaluation method by electronic scanning and discuss about characteristics of electronic scanning for crack length evaluation. Especially ultrasonic phased array with electronic scan technique was used in carrying out both sizing and detect ability of crack as its length changes. The response of ultrasonic phased array was analyzed to obtain the special method of determining crack length without moving the transducer and detect-ability of crack minimal length and depth from the material. A method of crack length determining by electronic scanning for the small crack is very real method which has it's accuracy and verify the effectiveness of method compared to a conventional crack length determination.
Change in Magnetic Flux in the Air Due to Load
Lee, Jeong-Hee ;
Journal of the Korean Society for Nondestructive Testing, volume 29, issue 1, 2009, Pages 21~26
In order to determine the effective way of measuring the Mode I stress intensity factor(
) by means of the alternating current potential drop(ACPD) technique for a material containing a two-dimensional surface crack, the change in magnetic flux in the air due to load was studied theoretically and experimentally. The magnetic flux in the air between crack surfaces is uniform and is not changed by increasing the load in the specimen and experimental results are the same as those obtained from theoretical analysis. Therefore, the change in potential drop due to load in the measuring system which was designed to induce a large amount of electro-motive force was caused by the change in internal inductance of material and the change in the mutual inductance concerned with internal inductance of material.
A Study on the Classification of Steam Generator Tube Defects Using an Improved Feature Extraction
Jo, Nam-Hoon ; Lee, Hyang-Beom ;
Journal of the Korean Society for Nondestructive Testing, volume 29, issue 1, 2009, Pages 27~35
In this paper, we study the classification of steam generator tube defects using an improved feature extraction. We consider 4 axisymmetric defect patterns of tube: I-In type, I-Out type, V-In type, and V-Out type. Through numerical analysis program based on finite element modeling, 400 ECT signals are generated by varying width and depth of each defect type. From those generated ECT signals, we propose new feature vectors that include an angle between the two points where the Maximum impedance and half the Maximum impedance, and angles between Maximum impedance point and 10%, 20%, 30%, 40% of Maximum impedance points. Also, multi-layer perceptron with one hidden layer is used to classify the defect patterns. Through the computer simulation study, it is shown that the proposed method achieves an improved defect classification performance in terms of Maximum Error and mean square Error.
Development of Graphical Solution for Computer-Assisted Fault Diagnosis: Preliminary Study
Yoon, Han-Bean ; Yun, Seung-Man ; Han, Jong-Chul ; Cho, Min-Kook ; Lim, Chang-Hwy ; Heo, Sung-Kyn ; Shon, Cheol-Soon ; Kim, Seong-Sik ; Lee, Seok-Hee ; Lee, Suk ; Kim, Ho-Koung ;
Journal of the Korean Society for Nondestructive Testing, volume 29, issue 1, 2009, Pages 36~42
We have developed software for converting the volumetric voxel data obtained from X-ray computed tomography(CT) into computer-aided design(CAD) data. The developed software can used for non-destructive testing and evaluation, reverse engineering, and rapid prototyping, etc. The main algorithms employed in the software are image reconstruction, volume rendering, segmentation, and mesh data generation. The feasibility of the developed software is demonstrated with the CT data of human maxilla and mandible bones.
Fatigue Crack Growth Behavior for Welded Joint of X80 Pipeline Steel
Kim, Young-Pyo ; Kim, Cheol-Man ; Kim, Woo-Sik ; Shin, Kwang-Seon ;
Journal of the Korean Society for Nondestructive Testing, volume 29, issue 1, 2009, Pages 43~48
The fatigue crack growth behavior of high strength X80 pipeline steel was investigated with compact tension specimens that crack growth directions were aligned either parallel or normal to the rolling direction of the pipeline. Also, the fatigue crack growth rates for welded joint of X80 pipeline steel were investigated with compact tension specimens that crack growth directions were aligned either parallel or normal to the welding line. The experimental results indicated the fatigue crack growth behavior was markedly different in three zones, weld metal, heat affected zone and base metal of welded joints. There was a trend toward increment in the fatigue life of weld metal and heat affected zone as compared with the X80 pipeline steel.