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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 26, Issue 6 - Dec 2006
Volume 26, Issue 5 - Oct 2006
Volume 26, Issue 4 - Aug 2006
Volume 26, Issue 3 - Jun 2006
Volume 26, Issue 2 - Apr 2006
Volume 26, Issue 1 - Feb 2006
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Estimation of the Axial Stress in High-Tension Bolt by Acoustoelastic Method
Chun, Hae-Hwa ; Lee, Tae-Hoon ; Jhang, Kyung-Young ; Kim, Noh-Yu ;
Journal of the Korean Society for Nondestructive Testing, volume 26, issue 5, 2006, Pages 285~290
The evaluation of clamping condition has been regarded as the main issue in the safety-maintenance of the clamped high-tension bolts. For this, this paper proposes a method to estimate the axial stress by measuring the TOF (Time-Of-Flight) of ultrasonic wave, which is based on the acoustoelasticity or the dependency of sound speed on the stress. In this method, however, the variation of sound speed within the range of stress induced under the field condition is very small, and thus the accuracy of the TOF measurement is important. We adopted the phase detection method using tone-burst ultrasonic wave to measure the precise TOF. In order to verify the usefulness of the proposed method experiments are carried out and the results were compared with the stress measured by the strain gage. The results show good agreement with each other, and from these we can conclude that the proposed method is highly useful fnr the evaluation of clamping condition in the clamped high-tension bolts.
Characterization of Residual Stress in Shot Peened Al 7075 Alloy Using Surface Acoustic Wave
Kim, Chung-Seok ; Kim, Yong-Kwon ; Park, Ik-Keun ; Kwun, Sook-In ;
Journal of the Korean Society for Nondestructive Testing, volume 26, issue 5, 2006, Pages 291~296
The residual stress in shot-peened Al 7075 alloy was evaluated using surface acoustic wave (SAW). Shot peening was conducted to produce a variation in the residual stress with the depth below the surface under a shot velocity of 30 m/s. The SAW velocity was measured from the V(z) curve using a scanning acoustic microscopy (SAM). The Vickers hardness profile from the surface showed a significant work hardening near the surface layer with a thickness of about 0.25 mm. As the residual stress became more compressive, the SAW velocity increased, whereas as the residual stress became more tensile, the SAW velocity decreased. The variation in the SAW velocity through the shot peened surface layer was in good agreement with the distribution of the residual stress measured by X-ray diffraction technique.
Detection of Thermal Ratcheting Deformation for Cylindrical Shells by Ultrasonic Guided Wave
Joo, Young-Sang ; Lee, Hyeong-Yeon ; Kim, Jong-Bum ; Park, Chang-Gyu ; Lee, Jae-Han ;
Journal of the Korean Society for Nondestructive Testing, volume 26, issue 5, 2006, Pages 297~305
The thermal ratcheting deformation at the reactor baffle and upper internal structure of the liquid metal reactor (LMR) can occur due to movement of the hot sodium free surface. In in-service inspection of reactor internals of LMR, a new inspection technique should be developed for the detection of the thermal ratcheting damage. In this study, an inspection technique using ultrasonic guided wave is proposed for the detection of the thermal ratcheting damage of cylindrical vessels. A 316L stainless steel cylindrical shell specimen has been prepared. The thermal ratchet structural tests were cyclically performed by heat-up up to
with steep temperature gradients along the axial direction after cool-down by cooling water. Ultrasonic guided wave propagation has been characterized by analysis of dispersion curve of the stainless steel plate. The zero-order antisymmetric
guided wave has been selected as the optimal mode for detection of the ratcheting deformation. It is confirmed that the thermal ratcheting deformation can be detected by the measurement of transit time difference of circumferentially propagated
Instrumented Indentation Technique: New Nondestructive Measurement Technique for Flow Stress-Strain and Residual Stress of Metallic Materials
Lee, Kyung-Woo ; Choi, Min-Jae ; Kim, Ju-Young ; Kim, Kwang-Ho ; Kwon, Dong-Il ;
Journal of the Korean Society for Nondestructive Testing, volume 26, issue 5, 2006, Pages 306~314
Instrumented indentation technique is a new way to evaluate nondestructive such mechanical properties as flow properties, residual stress and fracture toughness by analyzing indentation load-depth curves. This study evaluated quantitatively the flow properties of steels and residual stress of weldments. First, flow properties can be evaluated by defining a representative stress and strain from analysis of deformation behavior beneath the rigid spherical indenter and the parameters obtained from instrumented indentation tests. For estimating residual stress, the deviatoric-stress part of the residual stress affects the indentation load-depth curve, so that by analyzing the difference between the residual-stress-induced indentation curve and residual-stress-free curve, the quantitative residual stress of the target region can be evaluated. The algorithm for flow property evaluation was verified by comparison with uniaxial tensile test and the residual stress evaluation model was compared to mechanical cutting and ED-XRD results.
Stress Analysis and Fatigue limit Evaluation of Plate with Notch by Lock-In Thermography
Kim, Won-Tae ; Kang, Ki-Soo ; Choi, Man-Yong ; Park, Jeong-Hak ; Huh, Yong-Hak ;
Journal of the Korean Society for Nondestructive Testing, volume 26, issue 5, 2006, Pages 315~320
This paper describes stress analysis and fatigue limit evaluation of plate with V-notch and hole-notch by lock-in infrared thermography. Temperature variation of a specimen under cyclic loading is negatively proportional to the sum of principle stress change and the surface temperature measured by infrared camera is calculated to the stress of notch specimens, based on thermoelastic equation. And also, fatigue limitation can be evaluated by the change of intrinsic energy dissipation. Fatigue limitation of two notch specimens is evaluated as 164 MPa and 185 MPa, respectively and the stress measured by Lock-in infrared Thermography show good agreement within 10% error.
Deformation Measurement of Well Thinning Elbow by Using Shearography
Jung, Hyun-Chul ; Kim, Koung-Suk ; Chang, Ho-Sub ; Jung, Sung-Wook ; Kang, Ki-Soo ;
Journal of the Korean Society for Nondestructive Testing, volume 26, issue 5, 2006, Pages 321~328
In this study, the deformation oi wall thinning elbow is measured and the position of the internal thinning defect is found out by shearography. Shearography is an optical method which has applied to nondestructive testing (NDT) and the strain/stress and deformation analysis. This technique has the merit of the directly measuring the first derivative of displacement with sensitivity which can be adjusted by handling the tilt mirror in the interferometer. In this paper, we tested carbon steel pipe locally wall thinned and loaded internal pressure and the shearography was applied to measure the out-of-plane deformation of wall thinning elbow and to investigate the internal thinning defect of it. From the results, it was confirmed that this technique is proper to the practical application on the pipe line system with internal defect.
Stress Measurement around a Circular Role in a Cantilever Beam under Bending Moment Using Strain Gage and Reflective Photoelasticity
Baek, Tae-Hyun ; Park, Tae-Geun ; Yang, Min-Bok ;
Journal of the Korean Society for Nondestructive Testing, volume 26, issue 5, 2006, Pages 329~335
It is necessary to study on the stress concentration experimentally, which is the main reason to avoid mechanical dilapidation and failure, when designing a mechanical structure. Stress concentration factor of a specimen of cantilever beam with a circular hole in the center was measured using both strain gage and photoelastic methods in this paper. In strain-gage measurement, three strain gages along the line near a hole of the specimen were installed and maximum strain was extrapolated from three measurements. In photoelastic measurement, two methods were employed. First, the Babinet-Soleil compensation method was used to measure the maximum strain. Secondly, photoelastic 4-step phase shilling method was applied to observe the strain distribution around the hole. Measurements obtained by different experiments were comparable within the range of experimental error.
Study on Ultrasonic Birefringence by Uniaxial Stress in Axisymmetric Solids
Kim, Noh-Yu ; Chang, Young-Chul ;
Journal of the Korean Society for Nondestructive Testing, volume 26, issue 5, 2006, Pages 336~342
Uniaxial stress in ail axisymmetric body is the simplest example of ultrasonic stress measurement. However, the birefringence theory cannot be applied for axisymmetric solids because the axisymmetric stress field in the body does not make shy velocity difference in SH waves propagating in the axisymmetric direction. Conventional ultrasonic technique using the time-of-flight method also needs ultrasonic lengths of the unstressed and stressed body, which is very impractical. In this paper, the birefringence effect in axisymmetric solids under uniaxial stress is formulated to evaluate the axial stress inside the solid without measuring tile ultrasonic length. Theoretical derivation for the birefringence characteristics in the axisymmetric solids is made using the longitudinal and shear waves instead of two horizontally polarized shear waves. Tension test is conducted for carbon-steel specimen to measure the birefringence coefficient and investigate the validity of the theory. It is observed from experimental results that the velocity difference in two differently polarized acoustic waves is proportional to the uniaxial stress in the axisymmetric solid with a good agreement with the theoretical value.
A Study on the Nondestructive Test Method for Adhesively Bonded Joint in Motor Case Assembly
Hwang, Tae-Kyung ; Lee, Sang-Ho ; Kim, Dong-Ryun ; Moon, Soon-Il ;
Journal of the Korean Society for Nondestructive Testing, volume 26, issue 5, 2006, Pages 343~352
In the present paper, the nondestructive test method was suggest to establish the bonding status of a motor case assembly composed of a steel motor case, adiabatic rubber layer and an ablative composite tube with strain data, AE(acoustic emission) signals and UT(ultrasonic test) data. And, finite element analysis was conducted to verify quantitatively the bonding status of motor case assembly under inner pressure loading. The bonding status could be judged whether the bonding status is perfect or contact condition by the data correlation study with AE signals and strain data measured from air pressure test. And, to classify the bonding status of motor case and rubber layer among bonding layers, UT method was also applied. From this study, the bonding status could be classified and detected into fourth types for all bonding layers as follows: (1) initial un-bonding, (2) perfect do-bonding during an air pressure test, (3) partially de-bonding during an air pressure test, and (4) perfect bonding.