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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 14, Issue 3 - Dec 1994
Volume 14, Issue 2 - Aug 1994
Volume 14, Issue 1 - May 1994
Volume 13, Issue 4 - Jan 1994
Selecting the target year
The Directivity Measurement of Angle Probe by Photoelastic Visualization Method
Nam, Y.H. ; Date, K. ;
Journal of the Korean Society for Nondestructive Testing, volume 14, issue 2, 1994, Pages 83~89
It is important for an ultrasonic testing to know the sound pressure field and the directivity of ultrasonic waves propagating in a solid. The directivity of ultrasonic wave is closely related to the sensitivity, the scanning pitch, the arrangement of angle probe, and the defect kind in ultrasonic testing. This paper describes on the directivity measurement of ultrasonic wave using ultrasonic wave visualization method. The directivity of the shear wave emitted from the angle probes were constant during propagation. The difference of directivity was existed between 2MHz and 4MHz angle probes. The centers of directivity were located backward from the incident poing and inside of the angle probe and were not changed during the wave propagation.
Nondestructive Evaluation of Advanced Ceramics by Means of Ultrasonic Velocity and a Micromechanics Model
Jeong, Hyun-Jo ;
Journal of the Korean Society for Nondestructive Testing, volume 14, issue 2, 1994, Pages 90~100
Ultrasonic velocities are widely used in the investigation of material properties. In this paper, a micromechanics model and the ultrasonic velocity were used to develop a nondestructive method to determine the density variation due to porosity in structural SiC. The micromechanics model developed can consider the pore shape and orientation. The model also takes into account the interaction between pores so that it can be applied to the material with high porosity content. A contact pulse overlap method was used to measure the ultrasonic velocities of porous SiC samples, and there was a linear correlation between the velocity and density (or porosity). Using the model and the measured velocity, the bulk density can be easily calculated. The calculated density was in good agreement with that obtained by Archimedes' method.
A Study on the Strain Analysis of Plane by Electronic Speckle Pattern Interferometry(ESPI)
Kim, Koung-Suk ; Choi, Hyoung-Chul ; Yang, Seung-Pil ; Kim, Hyoung-Soo ; Chung, Jae-Kang ; Kim, Dong-Hyun ;
Journal of the Korean Society for Nondestructive Testing, volume 14, issue 2, 1994, Pages 101~111
Electronic speckle pattern interferometry(ESPI) using a CW laser, a video system and an image processor were applied to the in-plane displacement measurements. Unlike traditional strain gauges or Moire method, ESPI method requires no special surface preparation or attachments and it can be measured in-plane displacement without any contact and real time. In this experiment, specimen was loaded in paralled with a loa cell. The specimen was plance to which strain gauges was attached. The study provides an example of how ESPI have been used to measure displacement and strain distribution in this specimen. The results measured by ESPI were compared with the data which were measured by strain gauge method in tensile testing.
Ultrasonic C-scan Technique for Nondestructive Evaluation of Spot Weld Quality
Park, Ik-Gun ;
Journal of the Korean Society for Nondestructive Testing, volume 14, issue 2, 1994, Pages 112~121
This paper discusses the feasibility of ultrasonic C-scan technique for nondestructive evaluation of spot weld quality. Ultrasonic evaluation for spot weld quality was performed by immersion method with the mechanical and the electronic scanning of point-focussed ultrasonic beam(25 MHz). For the sake of the approach to the quantitative measurement of nugget diameter and the discrimination of the corona bond from nugget, preliminary infinitesimal gap experiment by newton ring is tried in order to set up the optimum ultrasonic test condition. Ultrasonic image data obtained were confirmed and compared by optical microscope and SAM(Scanning Acoustic Microscope) observation of the spot-weld cross section. The results show that the nugget diameter can be measured with the accuracy of 1.0mm, and voids included in nugget can be detected to
extent with simplicity and accuracy. Finally, it was found that it is necessary to make a profound study of definite discrimination of corona bond from nugget and the approach of quantitative evaluation of nugget diameter by utilizing the various image processing techniques.
Acoustic Emission Monitoring of Incipient Failure in Journal Bearing Part II : Intervention of Foreign Particles in Lubrication
Yoon, Dong-Jin ; Kwon, Oh-Yang ; Jung, Min-Hwa ; Kim, Kyung-Woong ;
Journal of the Korean Society for Nondestructive Testing, volume 14, issue 2, 1994, Pages 122~131
Journal bearings in the rotating machineries are vulnerable to the contamination or the insufficient supply of lubricating oil, which is likely to be the cause of unexpected shutdown or malfunction of these systems. Various destructive and nondestructive testing methods had been used for the reduction of maintenance cost and the operational safety problems due to the accidents related to bearing damages. In this experimental approach, acoustic emission monitoring is employed to the detection of incipient failure caused by intervention of foreign particles most probable in the journal bearing systems. Experimental schedules for the intervention of foreign particles was composed to be more quantitative and systematic than last study in consideration of minimum oil film thickness and particle size. The experiment was conducted under such designed conditions as inserting alumina particles to the lubrication layer in the simulated journal bearing system. Several parameters such as AE rms level, waveform, AE energy distribution and other AE event parameters are used for analysis and characterization of damage source. The results showed that the history of damage was well correlated with the changes of AE rms level and the type of damage source signal can be verified using other informations such as waveform, distributions of AE parameters etc.