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 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
Selecting the target year
Leak Evaluation for Power Plant Valve Using Multi-Measuring Method
Lee, Sang-Guk ; Park, Jong-Hyuck ; Kim, Young-Bum ;
Journal of the Korean Society for Nondestructive Testing, volume 28, issue 6, 2008, Pages 469~476
Condition based maintenance(CBM) for the preventive diagnosis of important equipments related to safety or accident in power plant is essential by using the suitable methods based on actual power plant conditions. To improve the reliability and accuracy of the measured value at the minute leak situation, and also to monitor continuously internal leak condition of power plant valve, the development of a diagnosis and monitoring technique using multi-measuring method should be performed urgently. This study was conducted to estimate the feasibility of multi-measuring method using three different methods such as acoustic emission(AE) method, thermal image measurement and temperature difference
measurement that are applicable to internal leak diagnosis for the power plant valve. From the experimental results, it was suggested that the multi-measuring method could be an effective way to precisely diagnose and evaluate internal leak situation of valve.
Influence of Dislocation Substructure on Ultrasonic Velocity under Tensile Deformation
Kim, C.S. ; Lissenden, Cliff J. ; Kang, Kae-Myhung ; Park, Ik-Keun ;
Journal of the Korean Society for Nondestructive Testing, volume 28, issue 6, 2008, Pages 477~482
The influence of dislocation substructure of metallic materials on ultrasonic velocity has been experimentally investigated. The test materials of pure Cu, brass (Cu-35Zn), 2.25Cr-1Mo steel, and AISI 316 with different stacking fault energy (SFE) are plastically deformed in order to generate dislocation substructures. The longitudinal wave velocit
decreases as a function of tensile strain in each material. The
of Cu-35Zn and AISI 316 decreases monotonously with tensile strain, but
of Cu and 2.25Cr-1Mo steel shows plateau phenomena due to the stable dislocation substructure. The variation of ultrasonic velocity with the extent of dislocation damping and dislocation substructures is discussed.
Numerical Evaluation of Phase Velocity and Attenuation of Ultrasonic Waves in Fiber-Reinforced Composites Using the Mass-Spring-Dashpot Lattice Model
Baek, Eun-Sol ; Yim, Hyun-June ;
Journal of the Korean Society for Nondestructive Testing, volume 28, issue 6, 2008, Pages 483~495
The paper presents a numerical study to evaluate the phase velocities and attenuations of the average longitudinal and shear ultrasonic waves resulting from multiple scattering in fiber-reinforced composites. A computational procedure developed in this work is first used to produce a random, yet largely even distribution of fibers. Both the viscoelastic epoxy matrix and lossless randomly distributed graphite fibers are modeled using the mass-spring-dashpot lattice model, with no damping for the latter. By numerically simulating ultrasonic through-transmission tests using this direct model of composites, phase velocities and attenuations of the longitudinal and shear waves through the composite are found as functions of frequency or fiber concentration. The numerical results are observed to generally agree with the corresponding results in the literature. Discrepancies found in some detail aspects, particularly in the attenuation results, are also addressed.
Design and Fabrication of the Spiral Coils for Guided Wave Magnetostrictive Transducers
Choi, Myoung-Seon ; Heo, Won-Nyoung ; Jun, Jong-Kil ;
Journal of the Korean Society for Nondestructive Testing, volume 28, issue 6, 2008, Pages 496~503
We propose rectangular type spiral coils with folded comers for the applications to low frequency guided wave magnetostrictive transducers and describe a method for making the proposed coils from insulated electrical wire such as enameled copper wire. Expressions for the electrical properties of the coils are also presented and compared with experimental measurements. An overlapped-2-channel folded-comer spiral-coil array is fabricated and applied to a magnetostrictive strip transducer generating and detecting fundamental torsional mode guided waves. From the results we conclude that the design and fabrication method make it possible to use the magnetostrictive transducers optimized for various guided wave applications and also will greatly help engineers gain easy access to the optimized transducers.
Ultrasonic Evaluation of Interfacial Stiffness for Nonlinear Contact Surfaces
Kim, Noh-Yu ; Kim, Hyun-Dong ; Cho, Youn-Ho ;
Journal of the Korean Society for Nondestructive Testing, volume 28, issue 6, 2008, Pages 504~511
This paper proposes an ultrasonic measurement method for measurement of linear interfacial stiffness of contacting surface between two steel plates subjected to nominal compression pressures. Interfacial stiffness was evaluated by using shear waves reflected at contact interface of two identical solid plates. Three consecutive reflection waves from solid-solid surface are captured by pulse-echo method to evaluate the state of contact interface. A non-dimensional parameter defined as the ratio of their peak-to-peak amplitudes are formulated and used to calculate the quantitative stiffness of interface. Mathematical model for 1-D wave propagation across interfaces is developed to formulate the reflection and transmission waves across the interface and to determine the interfacial stiffness. Two identical plates are fabricated and assembled to form contacting surface and to measure interfacial stiffness at different states of contact pressure by means of bolt fastening. It is found from experiment that the amplitude of interfacial stiffness is dependent on the pressure and successfully determined by employing pulse-echo ultrasonic method without measuring through-transmission waves.
Pipe Wall Thinning Evaluation through the Arrival Time Delay of A0 Lamb Wave Using Magnetostrictive Patch Transducers
Cho, Seung-Hyun ; Kwon, Hyu-Sang ; Ahn, Bong-Young ; Lee, Seung-Seok ;
Journal of the Korean Society for Nondestructive Testing, volume 28, issue 6, 2008, Pages 512~518
Guided wave technology is advantageous for fast inspection of pipe wall thinning since the guided wave propagates long distance. In this investigation, the method to evaluate gradual wall thinning in a pipe based on the arrival time delay with magnetostrictive patch transducers is presented. Low frequency A0 Lamb waves were generated and measured by the present transducer and it was applied to arrival time delay measurement experiments on a test pipe having gradual wall thinnings artificially manufactured. From experiments, consistent results that wall thinning increases the arrival time delay of A0 waves were obtained. Consequently, the feasibility of the magnetostrictive patch transducers to evaluate wall thinning was verified.
Poisson's Ratio Scanning Using Immersion Ultrasonic Testing
Oh, Seo-Young ; Kim, Young-H. ; Shin, Yo-Sub ; Cho, Hyun-Joon ;
Journal of the Korean Society for Nondestructive Testing, volume 28, issue 6, 2008, Pages 519~523
Poisson's ratio is one of elastic constants of elastic solids. However, it has not attracted attention due to its narrow range and difficult measurement. Transverse wave velocity as well as longitudinal wave velocity should be measured for nondestructive measurement of Poisson's ratio. Hard couplant for transverse wave prevents transducer from scanning over specimen. In the present work, a novel measurement of Poisson's ratio distribution was proposed. Immersion method was employed for the scanning over the specimen. Echo signals of normal beam longitudinal wave were collected. Transverse wave modes generated by mode conversion were identified. From transit time of longitudinal and transverse waves, Poisson's ratio can be determined without information of specimen thickness. This technique was demonstrated for aluminum and steel specimens.
Analysis of Spin Valve Tunneling Magnetoresistance Sensor for Eddy Current Nondestructive Testing
Kim, Dong-Young ; Yoon, Seok-Soo ; Lee, Sang-Hun ;
Journal of the Korean Society for Nondestructive Testing, volume 28, issue 6, 2008, Pages 524~530
The spin valve tunneling magnetoresistance (SV-TMR) sensor performance is analyzed using Stoner-Wohlfarth model for the detection of eddy current signals in nondestructive testing applications. The SV-TMR response in terms of the applied AC magnetic field dominantly generates the second harmonic amplitude in hard axis direction. The second harmonic eddy current signal detection using SV-TMR sensor shows higher performance than that of the coil sensor at lower frequencies. The SV-TMR sensor with high sensitivity gives a good solution to improve the low frequency performance in comparison with the inductive coil sensors. Therefore, the low frequency eddy current techniques based on SV-TMR sensors are specially useful in the detection of hidden defects, and it can be applied to detect the deeply embedded flaws or discontinuities in the conductive materials.
On the Beam Focusing Behavior of Time Reversed Ultrasonic Arrays Using a Multi-Gaussian Beam Model
Jeong, Hyun-Jo ; Lee, Jeong-Sik ; Jeong, Yon-Ho ; Bae, Sung-Min ;
Journal of the Korean Society for Nondestructive Testing, volume 28, issue 6, 2008, Pages 531~537
One of the fundamental features of time reversal acoustic (TRA) techniques is the ability to focus the propagating ultrasonic beam to a specific point within the test material. Therefore, it is important to understand the focusing properties of a TR device in many applications including nondestructive testing. In this paper, we employ an analytical scheme for the analysis of TR beam focusing in a homogeneous medium. More specifically, a nonparaxial multi-Gaussian beam (NMGB) model is used to simulate the focusing behavior of array transducers composed of multiple rectangular elements. The NMGB model is found to generate accurate beam fields beyond the nonparaxial region. Two different simulation cases are considered here for the focal points specified on and off from the central axis of the array transducer. The simulation results show that the focal spot size increases with increasing focal length and focal angle. Furthermore, the maximum velocity amplitude does not always coincide with the specified focal point. Simulation results for the off-axis focusing cases do demonstrate the accurate steering capability of the TR focusing.