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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 28, Issue 6 - Dec 2008
Volume 28, Issue 5 - Oct 2008
Volume 28, Issue 4 - Aug 2008
Volume 28, Issue 3 - Jun 2008
Volume 28, Issue 2 - Apr 2008
Volume 28, Issue 1 - Feb 2008
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Advances in Ultrasonic Testing of Austenitic Stainless Steel Welds
Moysan, J. ; Ploix, M.A. ; Corneloup, G. ; Guy, P. ; Guerjouma, R. El ; Chassignole, B. ;
Journal of the Korean Society for Nondestructive Testing, volume 28, issue 3, 2008, Pages 245~253
A precise description of the material is a key point to obtain reliable results when using wave propagation codes. In the case of multipass welds, the material is very difficult to describe due to its anisotropic and heterogeneous properties. Two main advances are presented in the following. The first advance is a model which describes the anisotropy resulting from the metal solidification and thus the model reproduces an anisotropy that is correlated with the grain orientation. The model is called MINA for modelling anisotropy from Notebook of Arc welding. With this kind of material model1ing a good description of the behaviour of the wave propagation is obtained, such as beam deviation or even beam division. But another advance is also necessary to have a good amplitude prediction: a good quantification of the attenuation, particularly due to grain scattering, is also required as far as attenuation exhibits a strong anisotropic behaviour too. Measurement of attenuation is difficult to achieve in anisotropic materials. An experimental approach has been based both on the decomposition of experimental beams into plane waves angular spectra and on the propagation modelling through the anisotropic material via transmission coefficients computed in generally triclinic case. Various examples of results are showed and also some prospects to continue refining numerical simulation of wave propagation.
Neural Netwotk Analysis of Acoustic Emission Signals for Drill Wear Monitoring
Prasopchaichana, Kritsada ; Kwon, Oh-Yang ;
Journal of the Korean Society for Nondestructive Testing, volume 28, issue 3, 2008, Pages 254~262
The objective of the proposed study is to produce a tool-condition monitoring (TCM) strategy that will lead to a more efficient and economical drilling tool usage. Drill-wear monitoring is an important attribute in the automatic cutting processes as it can help preventing damages of the tools and workpieces and optimizing the tool usage. This study presents the architectures of a multi-layer feed-forward neural network with back-propagation training algorithm for the monitoring of drill wear. The input features to the neural networks were extracted from the AE signals using the wavelet transform analysis. Training and testing were performed under a moderate range of cutting conditions in the dry drilling of steel plates. The results indicated that the extracted input features from AE signals to the supervised neural networks were effective for drill wear monitoring and the output of the neural networks could be utilized for the tool life management planning.
SAFT Based Imaging and Centroid Technique for Classification of UT Signals from the Steam Generator of a Nuclear Power Plant
Kim, Dae-Won ;
Journal of the Korean Society for Nondestructive Testing, volume 28, issue 3, 2008, Pages 263~272
Many technical methods are used for nondestructive testing field for solid materials. Among those, ultrasonic inspection methods are widely used and one of the popular methods involves the extraction of an appropriate set of features followed by the use of a neural network for the classification of the signals in the feature space. This paper describes an approach which uses LMS method to determine the coordinates of the ultrasonic probe followed by the use of SAFT with centroid technique to estimate the location of the ultrasonic reflector. The method is employed for classifying UT-NDE signals from the steam generator tubes in a nuclear power plant. The classification results are presented for the ultrasonic signals from cracks and deposits within steam generator tubes.
Analysis on Thermoelastic Stress in the Cantilever Beam by Lock-in Thermography
Kang, K.S. ; Choi, M.Y. ; Park, J.H. ; Kim, W.T. ;
Journal of the Korean Society for Nondestructive Testing, volume 28, issue 3, 2008, Pages 273~278
In this paper, effects of thermoelastic stress by using lock-in thermography was measured in the cantilever beam. In experiment, a circular holed plate was applied to analyze variation of transient stress under the condition of repeated cyclic loading. And the finite element modal analysis as computational work was performed. According to the surface temperature obtained from infrared thermography, the stress of the nearby hole was predicted based on thermoelastic equation. As results, each stress distributions between 2nd and 3rd vibration mode were qualitatively and quantitatively investigated, respectively. Also, dynamic stress concentration factors according to the change of vibration amplitude were estimated for the resonance frequency.
Correlation Analysis between Ultrasonic Parameters and Elastic Modulus of Apple
Kim, Ghi-Seok ; Kim, Ki-Bok ; Park, Jeong-Gil ; Lee, Sang-Dae ; Jung, Hyun-Mo ; Kim, Man-Soo ;
Journal of the Korean Society for Nondestructive Testing, volume 28, issue 3, 2008, Pages 279~284
The firmness of fruit is one of the most important quality factors and is highly correlated to the elastic modulus. In this study, the ultrasonic transmission method was applied to evaluate the elastic modulus of the apple. In order to transmit and receive the ultrasonic wave through the whole apple, the ultrasonic measurement setup consisted of ultrasonic pulser, two specially fabricated ultrasonic transducers for fruit and digital storage oscilloscope. Ultrasonic parameters such as ultrasonic wave velocity, apparent attenuation, and peak frequencies were analyzed. The elastic modulus of apple was measured by using compression test apparatus. The correlations between ultrasonic parameters and elastic modulus were analyzed. A multiple linear regression model describing the relationship between elastic modulus and ultrasonic parameters was proposed.
Experimental Characterization of Cyclic Deformation in Copper Using Ultrasonic Nonlinearity
Kim, C.S. ; Park, Ik-Keun ; Jhang, Kyung-Young ; Kim, Noh-Yu ;
Journal of the Korean Society for Nondestructive Testing, volume 28, issue 3, 2008, Pages 285~291
We have experimentally investigated the cyclic deformation in copper using ultrasonic nonlinearity. The observation and characterization of dislocation substructure have been conducted using transmission electron microscope and electron backscattered diffraction technique. The ultrasonic nonlinearity (
) was measured by the harmonic generation technique after various fatigue cycles. The microstructural effect on the nonlinearity was discussed regarding the extent of dislocation substructures evolved from low cycle fatigue. The ultrasonic nonlinearity of copper monotonically increased with the fatigue cycles due to the evolution of dislocation cell substructures.
Reflection and Transmission of Acoustic Waves Across Contact Interfaces
Kim, Noh-Yu ; Jhang, Kyung-Young ; Lee, Tae-Hoon ; Yang, Seung-Yong ; Chang, Young-Chul ;
Journal of the Korean Society for Nondestructive Testing, volume 28, issue 3, 2008, Pages 292~301
A linearized model for hysteretic acoustic nonlinearity of imperfectly joined interface is proposed and analyzed by using Coulomb damping to investigate the characteristics of the reflection and transmission coefficients for harmonic waves at the contact interface. Closed crack is modeled as non welded interface that has nonlinear discontinuity condition in displacement across its boundary. Based on the hysteretic contact stiffness of the contact interface, the reflected and transmitted waves are determined by deriving the tractions on both sides of the interface in terms of the discontinuous displacements across the interface. It is found that the amplitudes of the reflected and transmitted waves are dependent on the frequency and the hysteretic stiffness. As the frequency of the incident wave increases, the higher reflection and lower transmission are obtained. It also shows that the hysteresis of the interface increases the reflection coefficient, but reduces the transmission coefficient. A fatigue crack is also made in aluminum specimen to demonstrate these characteristics of the reflection and transmission of contact interfaces.
Deformation Analysis of Impact Damaged Composite Tube Using Thermal Shearography
Kim, Koung-Suk ; Chang, Ho-Seob ; Jang, Su-Ok ; Lee, Seung-Seok ; Jang, Wan-Sik ; Jung, Hyun-Chul ;
Journal of the Korean Society for Nondestructive Testing, volume 28, issue 3, 2008, Pages 302~308
Composite materials are widely used as structural materials for aerospace engineering because of its excellent mechanical properties such as light weight, high stiffness, and low thermal expansion. In driving, impact damage is one of the common but dangerous damages, caused by internal failure of the laminas interface which is not detected by in the surface. Many techniques to detect defects or delaminate between laminates have been reported. Shearography is a kind of laser speckle pattern interferometry with the advantages of non-destructive, non-contact, high resolution and displacement slope measurement. In this paper, the shearography is used to evaluate non-destructively impact damaged surface of the composite material and a measuring method using shearography for the thermal deformation of a impact damaged composite material is discussed. The basic principles of the technique are also described briefly.