Go to the main menu
Skip to content
Go to bottom
REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of the Korean Society for Nondestructive Testing
Journal Basic Information
Journal DOI :
The Korean Society for Nondestructive Testing
Editor in Chief :
Volume & Issues
Volume 24, Issue 6 - Dec 2004
Volume 24, Issue 5 - Oct 2004
Volume 24, Issue 4 - Aug 2004
Volume 24, Issue 3 - Jun 2004
Volume 24, Issue 2 - Apr 2004
Volume 24, Issue 1 - Feb 2004
Selecting the target year
Evaluation on Mechanical Properties of a Smart Composite Using the finite Element Method and the Acoustic Emission Technique
Park, Young-Chul ; Lee, Jin-Kyung ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 3, 2004, Pages 233~239
Smart material is used in various applications such as for glass frame, for medical instruments and for a part of sensors. Smart composite materials ran be applied to a part of aircraft and to the on-line monitoring system for industrial structures, using the shape memory effect. However, it is very difficult to simulate and analyze the shape memory effect in smart composites. In this paper, a two dimensional axisymmetric model was proposed to analyze the smart composite of one fiber and matrix using the finite element method(FEM). The finite element analysis was carried out in two renditions of the room temperature(293K) and a higher temperature (363K). The results we.e compared with the experimental results to confirm the validity of the analysis. In addition, the acoustic emission(AE) technique was used to study the microscopic damage behavior and the effect of pre-strains on TiNi/A16061 shape memory alloy composite.
Measurement of the Torsional Vibrations in Nonuniform Waveguides by Using an In-plane Laser Vibrometer
Jeong, Hyung-Gon ; Kim, Jin-Oh ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 3, 2004, Pages 240~245
Torsional characteristics of nonuniform circular waveguides were studied experimentally by using an in-plane laser vibrometer. The circumferential displacement along the axis of a rod was measured as a response of the torsional oscillation excited at one end of the rod. The experimental results obtained for a stepped circular rod and a conically-tapered rod were compared with theoretical predictions. The results of this paper show the possibility of using the in-plane laser vibrometer for the measurement of torsional vibrations.
Quantitative Evaluation of Delamination Inside of Composite Materials by ESPI
Kim, Koung-Suk ; Yang, Kwang-Young ; Kang, Ki-Soo ; Ji, Chang-June ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 3, 2004, Pages 246~252
Electronic speckle pattern interferometry (ESPI) for quantitative evaluation of delaminations inside of a composite material plate is described. Delaminations caused by the impact on composite materials are difficult to detect visual inspection and ultrasonic testing due to non-homeogenous structure. This paper proposes the quantitative evaluation technique of the defects made in the composite plates by impact load. Artificial defects are introduced inside of the composite plate for the development of a reliable ESPI inspection technique. Real defects produced by impact tester are inspected and compared with the results of visual inspection which shows a good agreement within 5% error.
Study of Economic Storage Method for Differential ECT Signals
Lee, Chang-Jun ; Lee, Jin-Ho ; Shin, Young-Kil ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 3, 2004, Pages 253~258
To get accurate information about the defect from the test signal, NDT engineers should have a good knowledge on forward problems. Such knowledge is usually obtained by a lot of testing experiences. Another why of obtaining such knowledge is to build a database containing lots of defect information and their corresponding signals. However, the archiving of raw test data would require a lot of storage space. In this paper, an economic way of storing signals is studied by using Fourier descriptors. Instead of saving raw signal data, Fourier descriptors are saved and the storage spare is reduced. Of course, the defect signal can be reconstructed from the stored descriptors. By using differential ECT signals produced by numerical modeling and experiment, the savings of 85% from the original signal and
from the filtered signal in the storage space were confirmed. The similarity of the reconstructed signal and the original signal was also demonstrated. This Fourier descriptor approach could contribute significantly in building differential signal databases.
Finite Element Simulation of Laser-Generated Ultrasound and Interaction with Surface Breaking Cracks
Jeong, Hyun-Jo ; Park, Moon-Cheol ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 3, 2004, Pages 259~267
A finite element method is used to simulate interaction of laser-based ultrasounds with surface breaking tracks in elastic media. The laser line source focused on the surface of semi-infinite medium is modeled as a shear dipole in 2-D plane strain finite elements. The shear dipole-finite clement model is found to give correct directivity patterns for generated longitudinal and shear waves. The interaction of surface waves with surface breaking cracks (2-D machined slot) is considered in two ways. Both the source and receiver are fixed with respect to the cracks in the first case, while the source is moving in another case. It is shown that the crack depth tested in the range of 0.3-5.0mm
can be measured using the corner reflected waves produced by the fixed laser source. The moving laser source is found to cause a large amplitude change of reflected waves near crack, and the crack whose depth is one order lower than the wavelength ran be detected from this change.
A Study on Detection of Elastic Wave Using Patch Type Piezo-Polymer Sensor
Kim, Ki-Bok ; Yoon, Dong-Jin ; Kueon, Jae-Hwa ; Lee, Young-Seop ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 3, 2004, Pages 268~274
Patch type piezo-polymer sensors for smart structures were experimented to detect elastic wave. The pencil lead braking test was performed to analyze the characteristics of patch-type piezo-polymer sensors such as polyvinyliden fluoride (PVDF) and polyvinylidene fluoride trifluorethylene (P(VDF-TrFE)) for several test specimens with various elastic wave velocities and acoustical impedances. The characteristics of the patch-type piezo-polymer sensor were compared with the commercial PZT acoustic emission (AE) sensor. The vacuum grease and epoxy resin were used as a couplant for the acoustic impedance matching between the sensor and specimen. The peak amplitude of elastic wave increased as the diameter of piezo-film and acoustical impedance of the specimen increased. The frequency detection range of the piezo-film sensors decreased with increasing diameter of the piezo-film sensor. The P(VDF-TrFE) sensor was more sensitive than the PVDF sensor.
Development of the Automated Ultrasonic Testing System for Inspection of the flaw in the Socket Weldment
Lee, Jeong-Ki ; Park, Moon-Ho ; Park, Ki-Sung ; Lee, Jae-Ho ; Lim, Sung-Jin ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 3, 2004, Pages 275~281
Socket weldment used to change the flow direction of fluid nay have flaws such as lack of fusion and cracks. Liquid penetrant testing or Radiography testing have been applied as NDT methods for flaw detection of the socket weldment. But it is difficult to detect the flaw inside of the socket weldment with these methods. In order to inspect the flaws inside the socket weldment, a ultrasonic testing method is established and a ultrasonic transducer and automated ultrasonic testing system are developed for the inspection. The automated ultrasonic testing system is based on the portable personal computer and operated by the program based Windows 98 or 2000. The system has a pulser/receiver, 100MHz high speed A/D board, and basic functions of ultrasonic flaw detector using the program. For the automated testing, motion controller board of ISA interface type is developed to control the 4-axis scanner and a real time iC-scan image of the automated testing is displayed on the monitor. A flaws with the size of less than 1mm in depth are evaluated smaller than its actual site in the testing, but the flaws larger than 1mm appear larger than its actual size on the contrary. This tendency is shown to be increasing as the flaw size increases. h reliable and objective testing results are obtained with the developed system, so that it is expected that it can contribute to safety management and detection of repair position of pipe lines of nuclear power plants and chemical plants.