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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 30, Issue 6 - Dec 2010
Volume 30, Issue 5 - Oct 2010
Volume 30, Issue 4 - Aug 2010
Volume 30, Issue 3 - Jun 2010
Volume 30, Issue 2 - Apr 2010
Volume 30, Issue 1 - Feb 2010
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Locating Mechanical Damages Using Magnetic Flux Leakage Inspection in Gas Pipeline System
Kim, Jae-Joon ;
Journal of the Korean Society for Nondestructive Testing, volume 30, issue 6, 2010, Pages 521~526
Gas transmission pipelines are often inspected and monitored using the magnetic flux leakage method. An inspection vehicle known as a "pig" is launched into the pipeline and conveyed along the pipe by the pressure of natural gas. The pig contains a magnetizer, an array of sensors and a microprocessor-based data acquisition system for logging data. This paper describes magnetic flux leakage (MFL) signal processing used for detecting mechanical damages during an in-line inspection. The overall approach employs noise removal and clustering technique. The proposed method is computationally efficient and can easily be implemented. Results are presented and verified by field tests from an application of the signal processing.
Nondestructive Evaluation of Railway Bridge by System Identification Using Field Vibration Measurement
Ho, Duc-Duy ; Hong, Dong-Soo ; Kim, Jeong-Tae ;
Journal of the Korean Society for Nondestructive Testing, volume 30, issue 6, 2010, Pages 527~538
This paper presents a nondestructive evaluation approach for system identification (SID) of real railway bridges using field vibration test results. First, a multi-phase SID scheme designed on the basis of eigenvalue sensitivity concept is presented. Next, the proposed multi-phase approach is evaluated from field vibration tests on a real railway bridge (Wondongcheon bridge) located in Yangsan, Korea. On the steel girder bridge, a few natural frequencies and mode shapes are experimentally measured under the ambient vibration condition. The corresponding modal parameters are numerically calculated from a three-dimensional finite element (FE) model established for the target bridge. Eigenvalue sensitivities are analyzed for potential model-updating parameters of the FE model. Then, structural subsystems are identified phase-by-phase using the proposed model-updating procedure. Based on model-updating results, a baseline model and a nondestructive evaluation of test bridge are identified.
Attenuation of Fundamental Longitudinal Guided Wave Mode in Steel Pipes Embedded in Soil
Lee, Ju-Won ; Shin, Sung-Woo ; Na, Won-Bae ;
Journal of the Korean Society for Nondestructive Testing, volume 30, issue 6, 2010, Pages 539~547
In this study, characteristics of the fundamental longitudinal guided wave mode, L(0,1), which is a usual mode employed in the inspection of the above-ground pipe, of the buried pipe were numerically investigated considering property changes in the surrounding soil. Results showed that soil conditions are significantly affecting the attenuation of L(0,1) mode in the pipe embedded in soil. Especially, if the soil is partially saturated, the attenuation of L(0,1) mode is larger and is very similar regardless of the degree of water saturation in the surrounding soil. However, when the soil is fully saturated, the attenuation of L(0,1) mode is less and show different trend with its partially saturated counterparts.
Evaluation of Elastic Properties of Anisotropic Cylindrical Tubes Using an Ultrasonic Resonance Scattering Spectroscopy
Kim, Jin-Yeon ; Li, Zheng ;
Journal of the Korean Society for Nondestructive Testing, volume 30, issue 6, 2010, Pages 548~557
An ultrasonic resonance scattering spectroscopy technique is developed and applied for reconstructing elastic constants of a transversely isotropic cylindrical component. Immersion ultrasonic measurements are performed on tube samples made from a boron/aluminum composite material to obtain resonance frequencies and dispersion curves of different guided wave modes propagating in the tube. Theoretical analysis on the acoustic resonance scattering from a transversely isotropic cylindrical tube is also performed, from which complete backscattering and resonance scattering spectra and theoretical dispersion curves are calculated. A sensitive change of the dispersion curves to the elastic properties of the composite tube is observed for both normal and oblique incidences; this is exploited for a systematic evaluation of damage and elastic constants of the composite tube samples. The elastic constants of two boron/aluminum composite tube samples manufactured under different conditions are reconstructed through an optimization procedure in which the residual between the experimental and theoretical phase velocities (dispersion curves) is minimized.
Fault Diagnosis of Ball Bearings within Rotational Machines Using the Infrared Thermography Method
Kim, Dong-Yeon ; Yun, Han-Bit ; Yang, Sung-Mo ; Kim, Won-Tae ; Hong, Dong-Pyo ;
Journal of the Korean Society for Nondestructive Testing, volume 30, issue 6, 2010, Pages 558~563
In this paper, the novel approach for the fault diagnosis of the bearing equipped with rotational mechanical facilities was studied. As research works, by applying the ball bearing used extensively in many industrial fields, experiments were conducted in order to propose the new prognostic method about the condition monitoring for the rotational bodies based on the condition analysis of infrared thermography. Also, by using the vibration spectrum analysis, the real time monitoring was performed. As results, it was confirmed that infrared thermography method could be adapted into monitor and diagnose the fault for bearing by evaluating quantitatively and qualitatively the temperature characteristics according to the condition of the ball bearing.
Finite Element Analysis of Harmonics Generation by Nonlinear Inclusion
Yang, Seung-Yong ; Kim, No-Hyu ;
Journal of the Korean Society for Nondestructive Testing, volume 30, issue 6, 2010, Pages 564~568
When ultrasound propagates to a crack, transmitted and reflected waves are generated. These waves have useful information for the detection of the crack lying in a structure. When a crack is under residual stress, crack surfaces will contact each other and a closed crack is formed. For closed cracks, the fundamental component of the reflected and transmitted waves will be weak, and as such it is not easy to detect them. In this case, higher harmonic components will be useful. In this paper, nonlinear characteristic of a closed crack is modeled by a continuum material having a tensile-compressive unsymmetry, and the amplitude of the second harmonic wave was obtained by spectrum analysis. Variation of the second harmonic component depending on the nonlinearity of the inclusion was investigated. Two-dimensional plane strain model is considered, and finite element software ABAQUS/Explicit is used.
Time Reversal Focusing and Imaging of Point-Like Defects in Specimens with Nonplanar Surface Geometry
Jeong, Hyun-Jo ; Lee, Hyun-Kee ; Bae, Sung-Min ; Lee, Jung-Sik ;
Journal of the Korean Society for Nondestructive Testing, volume 30, issue 6, 2010, Pages 569~577
Nonplanar surface geometries of components are frequently encountered in real ultrasonic inspection situations. Use of rigid array transducers can lead to beam defocusing and reduction of defect image quality due to the mismatch between the planar array and the changing surface. When a flexible array is used to fit the complex surface profile, the locations of array elements should be known to compute the delay time necessary for adaptive heam focusing. An alternative method is to employ the time reversal focusing technique that does not require a prior knowledge about the properties and structures of the specimen and the transducer. In this paper, a time reversal method is applied to simulate beam focusing of flexible arrays and imaging of point-like defects contained in specimens with nonplanar surface geometry. Quantitative comparisons are made for the performance of a number of array techniques in terms of the ability to focus and image three point-like reflectors positioned at regular intervals. The sinusoidal profile array studied here exhibits almost the same image quality as the flat, reference case.
Effect of Hysteresis on Interface Waves in Contact Surfaces
Kim, Noh-Yu ; Yang, Seung-Yong ;
Journal of the Korean Society for Nondestructive Testing, volume 30, issue 6, 2010, Pages 578~586
This paper describes a theoretical model and acoustic analysis of hysteresis of contacting surfaces subject to compression pressure. Contacting surfaces known to be nonlinear and hysteretic is considered as a simple spring that has a complex stiffness connecting discontinuous displacements between two solid contact boundaries. Mathematical formulation for 1-D interfacial wave propagation between two contacting solids is developed using the complex spring model to derive the dispersion relation between the interface wave speed and the complex interfacial stiffness. Existence of the interface wave propagating along the hysteretic interface is studied in theory and discussed by investigating the solution to the dispersion equation. Unlike the linear interface without hysteresis, there can exist only one distinct mode of interface waves for the hysteretic interface, which is anti-symmetric motion. The anti-symmetric mode of interface wave propagates with the velocity faster than the Rayleigh surface wave but less than the shear wave depending on the interfacial stiffness. If the contacting surfaces are compressed so much that the linear interfacial stiffness is very high, the hysteretic stiffness does not affect the interface wave velocity. However, it has an effect on the speed of interface wave for a loosely contact surfaces with a relatively low linear stiffness. It is also found that the phase velocity of anti-symmetric wave mode converges to the shear wave velocity in despite of the linear stiffness value if the hysteretic stiffness approaches 0.5.