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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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Active-Sensing Lamb Wave Propagations for Damage Identification in Honeycomb Aluminum Panels
Flynn, Eric B. ; Swartz, R.Andrew ; Backman, Daniel E. ; Park, Gyu-Hae ; Farrar, Charles R. ;
Journal of the Korean Society for Nondestructive Testing, volume 29, issue 4, 2009, Pages 269~282
This paper presents a novel approach for Lamb wave based structural health monitoring(SHM) in honeycomb aluminum panels. In this study, a suite of three signal processing algorithms are employed to improve the damage detection capability. The signal processing algorithms used include wavelet attenuation, correlation coefficients of power density spectra, and triangulation of reflected waves. Piezoelectric transducers are utilized as both sensors and actuators for Lamb wave propagation. These SHM algorithms are built into a MatLab interface that integrates and automates the hardware and software operations and displays the results for each algorithm to the analyst for side by side comparison. The effectiveness of each of these signal processing algorithms for SHM in honeycomb aluminum panels under a variety of damage conditions is then demonstrated.
Development of Ultrasonic Wave Propagation Imaging System
Chia, Chen-Ciang ; Lee, Jung-Ryul ; Kim, Jong-Heon ;
Journal of the Korean Society for Nondestructive Testing, volume 29, issue 4, 2009, Pages 283~292
Laser-based ultrasonic sensing requires the probe with fixed fecal length, but this requirement is not essential in laser-based ultrasonic generation. Based on this fact, we designed a pulsed laser-based ultrasonic wave propagation imaging (UWPI) system with a tilting mirror system for rapid scanning of target, and an in-line band-pass filtering capable of ultrasoaic mode selection. 1D-temporal averaging, 2D-spatial averaging, and 3D-data structure building algorithms were developed far clearer results allowing fur higher damage detectability. The imaging results on a flat stainless steel plate were presented in movie and snapshot formats which showed the propagation of ultrasound visible as a concentric wavefield emerging from the location of an ultrasonic sensor. A hole in the plate with a diameter of 1 mm was indicated by the scattering wavefields. The results showed that this robust UWPI system is independent of focal length and reference data requirements.
Elastic Imaging of Material Surface by Ultrasonic Atomic Force Microscopy
Kim, C.S. ; Park, Tae-Sung ; Park, It-Keun ; Lee, Seung-Seok ; Lee, C.J. ;
Journal of the Korean Society for Nondestructive Testing, volume 29, issue 4, 2009, Pages 293~298
The ultrasonic atomic force microscope(UAFM) has been developed in order to enhance the characterization technology for nano-scale surface combining ultrasonic property to atomic force microscope. This UAFM technique enables elasticity imaging due to the physical properties on the heterogeneous surface in addition to the novel topography of surface height in the nano-surface layer. In this study, the prototype UAFM system was constructed and applied to several materials, silicon deposited wafer, spherodized cold heading steel, and carbon fiber reinforced plastic specimen. Clear elastic contrast was successfully obtained using this developed prototype UAFM.
Development of Load Cell Using Fiber Brags Grating Sensors and Differential Method for Structural Health Monitoring
Kim, Dae-Hyun ;
Journal of the Korean Society for Nondestructive Testing, volume 29, issue 4, 2009, Pages 299~307
Emerging fiber optic sensor technologies have shown great potential to overcome the difficulties associated with conventional sensors. Fiber optic sensors are immune to EM noise and electric shock and thus can be used in explosion-prone areas. Several kinds of fiber optic sensors have been developed over the last two decades to take advantage of these merits. There have also been many field applications of fiber optic sensors for structural health monitoring as NDT/HDE. However, very few sensors, particularly a load cell have been successfully commercialized. This Paper Presents a load cell using fiber Bra99 gra1ing (FBG) sensors. The shape of the load cell is a link type, and three FBG sensors are used for measuring strains at three different points. Especially, these strains are processed with a differential method in order to exclude common mode noise such as temperature. Moreover, the sensitivity, the linearity and the resolution of the load cell were successfully verified from the experiment of tension test.
Study on the Characteristics of Wavelet Decomposed Details of Low-Velocity Impact Induced AE Signals in Composite Laminaes
Bang, Hyung-Joon ; Kim, Chun-Gon ;
Journal of the Korean Society for Nondestructive Testing, volume 29, issue 4, 2009, Pages 308~315
Because the attenuation of AE signal in composite materials is relatively higher than that of metallic materials, it is required to develop a damage assessment technique less affected by the attenuation property of composite materials in order to use AE sensing as a damage detection method. In the signal processing procedure, it is profitable to use the leading wave that arrives first because the leading wave is less influenced by the boundary conditions. Using wavelet transform, we investigated the frequency characteristics of impact induced AE signals focused on the leading wave in advance and chose the key factors to discriminate the damaged condition quantitatively. In this research, we established a damage assessment technique using the sharing percentage of the wavelet detail components of AE signal, and conducted a low-velocity impact test on composite laminates to confirm the feasibility of the proposed signal processing method.
Static Behavior of Hollow Cantilever Beam Using Multiplexed FBG Sensors
Lee, Tae-Hee ; Kang, Dong-Hoon ; Chung, Won-Seok ; Mok, Young-Jin ;
Journal of the Korean Society for Nondestructive Testing, volume 29, issue 4, 2009, Pages 316~322
This paper presents a preliminary study to monitor the lateral behavior of pile foundation using multiplexed fiber Bragg grating(FBG) sensors. In the Preliminary study, an 1.7 meter long cantilever beam with the shape of square hollow box was fabricated and tested under the static loading. Four FBG sensors were multiplexed in a single optical fiber and installed into the top and bottom of the cantilever beam. The strains are directly measured from FBG sensors followed by curvature calculations based on the plane section assumption. Vertical deflections are then estimated using the regression analyses based on the geometric relationships. It has been found that excellent correlation with conventional sensing system was observed. The success of the test encourages the use of the FBG sensing system as a monitoring system for pile foundations. However, further consideration should be given in the case of the sensor malfunction for the practical purpose.
Self-Diagnosis of Damage in Carbon Fiber Reinforced Composites Using Electrical Residual Resistance Measurement
Kang, Ji-Ho ;
Journal of the Korean Society for Nondestructive Testing, volume 29, issue 4, 2009, Pages 323~330
The objective of this research was to develop a practical integrated approach using extracted features from electrical resistance measurements and coupled electromechanical models of damage, for in-situ damage detection and sensing in carbon fiber reinforced plastic(CFRP) composites. To achieve this objective, we introduced specific known damage (in terms of type, size, and location) into CFRP laminates and established quantitative relationships with the electrical resistance measurements. For processing of numerous measurement data, an autonomous data acquisition system was devised. We also established a specimen preparation procedure and a method for electrode setup. Coupon and panel CFRP laminate specimens with several known damage were tested. Coupon specimens with various sizes of artificial delaminations obtained by inserting Teflon film were manufactured and the resistance was measured. The measurement results showed that increase of delamination size led to increase of resistance implying that it is possible to sense the existence and size of delamination. A quasi-isotropic panel was manufactured and electrical resistance was measured. Then three different sizes of holes were drilled at a chosen location. The panel was prepared using the established procedures with six electrode connections on each side making a total of twenty-four electrodes. Vertical, horizontal, and diagonal pairs of electrodes were chosen and the resistance was measured. The measurement results showed the possibility of the established measurement system for an in-situ damage detection method for CFRP composite structures.
Nondestructive Inspection of Launch Vehicle Structural Components
Kong, Cheol-Won ; Youn, Jong-Hoon ; Park, Jae-Sung ; Eun, Se-Won ; Jang, Young-Soon ; Yi, Yeong-Moo ;
Journal of the Korean Society for Nondestructive Testing, volume 29, issue 4, 2009, Pages 331~337
Space launch vehicles require highly reliable, lightweight structures. It is thus important to monitor the structural health of these components with nondestructive inspections. In this paper, we studied an example of a nondestructive inspection that was partially applied to the manufacture and inspection of a launch vehicle. Ultrasonic tests, X-rays, tapping, and acoustic emissions comprised the inspection method. A payload fairing, high pressure tank, fastener part, and bonding part were used as hardware to be inspected. We proposed a quantitative standard for debonding inspection of the payload fairing and acoustic emission data for the proof test of the high pressure tank. We analyzed the fracture mode of the sandwich fastener part according to frequency changes. We also proposed a standard specimen for ultrasonic inspection of bonds of different materials. The present analyses and results provide data for evaluation of the launch operation sequence to ensure launch vehicles afford high reliability.
Guided Wave Tomographic Imaging Using Boundary Element Method
Piao, Yunri ; Cho, Youn-Ho ; Jin, Lianji ; Ahn, Bong-Young ; Kim, Noh-Yu ; Cho, Seung-Hyun ;
Journal of the Korean Society for Nondestructive Testing, volume 29, issue 4, 2009, Pages 338~343
Tomography is the imaging method of cross sectional area using multi beam signals and is mainly applied to the medical diagnosis to acquire the image of the inside human body. This method is pretty meaningful in nondestructive evaluation field since the imaging of the inspection region can enhance the comprehension of the inspector. Recently, much attention has been paid to the guided wave for the diagnosis of platelike structures. So, in this work, a study on the imaging of the damage location in a plate was carried out on the basis of computer aided analysis of guided waves and tomographic imaging. To this end, boundary element method was employed to analyze the effect of the damage in plate on the propagation of the guided waves and the analytic results were applied to the tomographic imaging method to identify the damage location. Consequently, it was shown that the number of sensors heavily affect the inspection performance of the damage location.
Acoustic Nonlinearity of Surface Wave and Experimental Verification of Characteristics
Lee, Jae-Ik ; Kwon, Goo-Do ; Lee, Tae-Hun ; Jhang, Kyung-Young ;
Journal of the Korean Society for Nondestructive Testing, volume 29, issue 4, 2009, Pages 344~350
The goal of this study is to introduce the theoretical background of acoustic nonlinearity in surface wave and to verify its characteristics by experiments. It has been known by theory that the nonlinear parameter of surface wave is proportional to the ratio of
harmonic amplitude and the power of primary component in the propagated surface wave, as like as in bulk waves. In this paper, in order to verify this characteristics we constructed a measurement system using contact angle beam transducers and measured the nonlinear parameter of surface wave in an Aluminum 6061 alloy block specimen while changing the distance of wave propagation and the input amplitude. We also considered the effect of frequency-dependent attenuation to the measurement of nonlinear parameter. Results showed good agreement with the theoretical expectation that the nonlinear parameter should be independent on the input amplitude and linearly dependent on the input amplitude and the
harmonic amplitude is linearly dependant on the propagation distance.
Development of an MCNP-Based Cone-Beam CT Simulator
Lim, Chang-Hwy ; Cho, Min-Kook ; Han, Jong-Chul ; Youn, Han-Bean ; Yun, Seung-Man ; Cheong, Min-Ho ; Kim, Ho-Kyung ;
Journal of the Korean Society for Nondestructive Testing, volume 29, issue 4, 2009, Pages 351~359
We have developed a computer simulator fur cone-beam computed tomography (CBCT) based on the commercial Monte Carlo code, MCNP. All the functions to generate input files, run MCNP, convert output files to image data, reconstruct tomographs were realized in graphical user-interface form. The performance of the simulator was demonstrated by comparing with the experimental data. Although some discrepancies were observed due to the ignorance of the detailed physics in the simulation, such as scattered X-rays and noise in image sensors, the overall tendency was well agreed between the measured and simulated data. The developed simulator will be very useful for understanding the operation and the better design of CT systems.
Acoustic Emission Signal Analysis for Damage Assessment of the Reinforced Concrete Slab Structures
Kim, Jeong-Hee ; Han, Byeong-Hee ; Seo, Dae-Cheol ; Yoon, Dong-Jin ;
Journal of the Korean Society for Nondestructive Testing, volume 29, issue 4, 2009, Pages 360~367
The acoustic emission(AE) behavior of reinforced concrete slab under flexural loading was investigated to assess the integrity. This study was aimed at identifying the characteristics of AE response associated with damage development. By applying cyclic loading in various load steps, it was able to differentiate each AE source such as distributed micro crack initiation, friction, flexural crack and localized diagonal tension crack. The secondary peak and the change of AE hit rate gave valuable criteria fur assessment. From the analysis of the felicity ratio, furthermore, it was shown that this values can be used for evaluating the degree of concrete damage. Based on the experimental results, this approach for practical AE application may provide a promising method for estimating the level of damage and distress in concrete structures.
Ultrasonic Phantom Based on Plastic Material for Elastography
Ahn, Dong-Ki ; Joung, Mok-Keun ;
Journal of the Korean Society for Nondestructive Testing, volume 29, issue 4, 2009, Pages 368~373
A human tissue mimicking phantom is constructed to assess the performance of a medical ultrasound elasticity imaging system. In a human body, the tumor or cancer is stiffer than its surrounding normal tissue. A technique fur imaging the elasticity of such a tissue is referred to as elastography. Homogeneous elasticity phantoms with differing Young's moduli are constructed using a plastic hardener and softener to simulate the mechanical characteristics of a diseased human tissue. The Young's modulus of the fabricated homogeneous phantom materials were measured from 11.1 to 79.6 kPa depending on the mixing ratio of the amount of the hardener to that of the softener. An ultrasound lesion mimicking phantom was made of these materials, and ultrasound elasticity imaging was performed on it. It is confirmed in this paper that the fabricated plastic-based elasticity phantom is useful in representing the elastic characteristics of a human tissue.
Quantitative EC Signal Analysis on the Axial Notch Cracks of the SG Tubes
Min, Kyong-Mahn ; Park, Jung-Am ; Shin, Ki-Seok ; Kim, In-Chul ;
Journal of the Korean Society for Nondestructive Testing, volume 29, issue 4, 2009, Pages 374~382
Steam generator(SG) tube, as a barrier isolating primary to the secondary coolant system of nuclear power plants(NPP), must maintain the structural integrity far the public safety and its efficient power generation capacity. And SG tubes bearing defects must be timely detected and taken repair measures if needed. For the accomplishment of these objectives, SG tubes have been periodically examined by eddy current testing(ECT) on the basis of administrative notices and intensified SG management program(SGMP). Stress corrosion cracking(SCC) on the SG tubes is not easily detected and even missed since it has lower signal amplitude and other disturbing factors against its detection. However once SCC is developed, that can cause detrimental affects to the SG tubes due to its rapid propagation rate. Accordingly SCC is categorized as prime damage mechanism challenging the soundness of the SG tubes. In this study, reproduced EDM notch specimens are examined for the detectability and quantitative characterization of the axial ODSCC by +PT MRPC probe, containing pancake, +PT and shielded pancake coils apart in a single plane around the circumference. The results of this study are assumed to be applicable fur providing key information of engineering evaluation of SCC and improvement of confidence level of ECT on SG tubes.