• Title/Summary/Keyword: ultrasonic inspection

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A Study of the Couplant Effects on Contact Ultrasonic Testing

  • Kim, Young-H.;Song, Sung-Jin;Lee, Sung-Sik;Lee, Jeong-Ki;Hong, Soon-Shin;Eom, Heung-Seop
    • Journal of the Korean Society for Nondestructive Testing
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    • v.22 no.6
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    • pp.621-626
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    • 2002
  • The amplitude of a back-wall echo depends on the reflection coefficient of the interface between a transducer and a test material when using contact pulse-echo ultrasonic testing. A couplant is used to transmit ultrasonic energy across the interface, but has an influence on the amplitude of the pulse-echo signal. To investigate the couplant effect on pulse-echo ultrasonic testing, back-wall echoes are measured by using various couplants made of water and glycerine in a carbon and austenitic stainless steel specimens. The amplitude of the first back-wall echo and the apparent attenuation coefficient increases with the acoustic impedance of the couplant. The couplant having a higher value of the transmission coefficient is more effective for flaw detection. The reflection coefficient should be known in order to measure the attenuation coefficient of the test material.

Visualization of Elastic Waves Propagating on a Solid Surface with Fatigue Cracks by Laser Ultrasonic Technology

  • Imade, Masaaki;Miyauchi, Hidekazu;Okada, Saburo;Yamamoto, Shigeyuki;Takatsubo, Jyunji
    • 제어로봇시스템학회:학술대회논문집
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    • 2001.10a
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    • pp.109.4-109
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    • 2001
  • We have developed a laser ultrasonic system for visualization of elastic waves propagating on a solid surface, in order to visualize ultrasonic waves propagating on opaque media. This system can produce a series of successive images as an animation of wave propagation, because of scanning an optical heterodyne probe to measure surface transient displacements. Using this visualization technique, we observed the scattering and diffraction of ultrasonic waves around various shapes of artificial defects, and examined its application to nondestructive inspection. This imaging system provides various kinds of visualization images such as propagation image, amplitude image, arrival time image and velocity image. We have been confident that this technique is available for nondestructive inspection and materials ...

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A Study on an Automated Ultrasonic Testing System for the Inspection of Pipe Welding (배관 용접부 자동 초음파 검사 시스템 연구)

  • Kim, Han-Jong;Park, Jong-Hoon
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2008.10a
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    • pp.520-523
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    • 2008
  • As a result of the recent development of the electro-information industry, the hardware of an automated ultrasonic testing system is getting lighter and diversified image processing techniques are applied to its software so that the possible precise totaling and detecting of the flaws are studied. This study proposes an automated ultrasonic testing system of the pipe in order to organize the optimized system, and also describes the data flow and general composition of the software for the design of the system.

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Kinematics Analysis of a 5-Axis Ultrasonic Inspection Equipment (5축 초음파 검사장비의 기구학 해석)

  • Han, Myung-Chul;Sung, Chang-Min
    • Journal of the Korean Society for Precision Engineering
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    • v.32 no.1
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    • pp.89-96
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    • 2015
  • In this paper, it is studied that kinematic analysis of a 5-axis ultrasonic inspection equipment. The equipment is comprised of three straight axes and two rotary axes. With features of ultrasonic, the transmitter and receiver of the equipment are vertical to a test surface, operating at regular intervals. To perform this well, the motions of every link should be found on the based of kinematic analysis of the equipment. We chose starting point for testing and defined relations among all links through transformation of coordinates. For double curvature-shaped test object, we generated test paths. To follow these, we found motions of all links using inverse kinematics. By using Matlab/Simulink, simulator was developed, so that we could find out desired trajectories of main axes for a scan.

Research on the Non-Contact Detection of Internal Defects in a Rail using Ultrasonic Waves (비접촉 초음파 방식의 철도레일 내부결함 검출에 관한 연구)

  • Han, Soon Woo;Cho, Seung Hyun;Kim, Joon Woo;Heo, Tae Hoon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2012.10a
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    • pp.617-625
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    • 2012
  • Non-contact detection of internal defects in a rail using ultrasonic waves is discussed in this paper. Cracks in a rail may be a cause of a serious railway accident such as derailment if left undetected. Concurrent rail inspection method based on ultrasonic testing using piezoelectric transducers has several limitations as it should keep physical contact with the rail. This work suggests a non-contact detection of internal defects in a rail using ElectroMagnetic Acoustic Transducers (EMAT) which can produce and measure ultrasonic waves in a rail without any couplant. The EMATs for rail inspection are designed and fabricated and their working performance is verified through a series of experiments on various types of internal defects in test rails. The effect of lift-off between the transducers and the rail on the generated signals is also discussed.

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Guided-Wave Tomographic Imaging of Plate Defects by Laser-Based Ultrasonic Techniques

  • Park, Junpil;Lim, Juyoung;Cho, Younho
    • Journal of the Korean Society for Nondestructive Testing
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    • v.34 no.6
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    • pp.435-440
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    • 2014
  • Contact-guided-wave tests are impractical for investigating specimens with limited accessibility and rough surfaces or complex geometric features. A non-contact setup with a laser-ultrasonic transmitter and receiver is quite attractive for guided-wave inspection. In the present work, we developed a non-contact guided-wave tomography technique using the laser-ultrasonic technique in a plate. A method for Lamb-wave generation and detection in an aluminum plate with a pulsed laser-ultrasonic transmitter and Michelson-interferometer receiver was developed. The defect shape and area in the images obtained using laser scanning, showed good agreement with the actual defect. The proposed approach can be used as a non-contact online inspection and monitoring technique.

Measurement of Crack Depth Located under Steel Reinforcement in Reinforced Concrete Specimens using Ultrasonic Method (초음파를 이용한 콘크리트 시편의 피복두께 이하에 위치한 균열깊이 탐사)

  • Rhim, Hong-Chul;Kim, Yeon-Su;Woo, Sang-Kyun;Song, Young-Chul
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.6 no.4
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    • pp.181-188
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    • 2002
  • The objective of this study is to determine crack depth located under steel reinforcement in concrete specimens using ultrasonic method. Experimental studies were performed on concrete specimens containing vertical and inclined surface-opening cracks with known depths. The other studies were carried out on specimens with flexural crack. Experimental results have shown that the crack depth is effectually measured when the distance between the probes is less than the crack depth. The effect of steel on crack depth estimation is studied through a model by considering P-waves diffaction at the tip of crack and steel. In addition, experimental results show that the ultrasonic method is one of useful methods to evaluate the crack depth in reinforced concrete.

Application on the Prediction Model of the Compressive Strength of Concrete by Maturity Method (적산온도에 의한 콘크리트 압축강도 추정모델의 적용성 검토)

  • Khil, Bae-Su;Kwon, Young-Jin;Nam, Jae-Hyun;Kim, Moo-Han
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.3 no.2
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    • pp.177-183
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    • 1999
  • The major object of this study is to investigate experimentally the experimental equation by the non-destructive testing methods of ultrasonic pulse velocity, rebound number, combined method of ultrasonic pulse velocity and rebound number, maturity which are applicable to the evaluation of compressive strength of concrete at early ages. Also test result of mix are statistically analyzed to infer the correlation coefficient between the maturity and the compressive strength of concrete. The results show good application of Logistic curve for estimating strength development under various curing temperature. The relation between ultrasonic pulse velocity, rebound number, combined method of ultrasonic pulse velocity and rebound number and compressive strength of concrete have low correlation coefficient, but maturity method show good correlation coefficient.

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Field Application of Ultrasonic Inspection System for Stay Welds at Steam Generator of KSNP (한국표준형 원전 증기발생기 Stay 용접부 자동검사시스템 및 현장 검증)

  • Lim, Sa Hoe;Park, Chi Seung;Park, Chul Hoon;Joo, Keum Chong;Noh, Hee Chung;Yoon, Kwang Sik
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.6 no.1
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    • pp.37-42
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    • 2010
  • The stay cylinder weld at the steam generator of Korean Standard Nuclear Power Plants is safety class I component and is subjected to be inspected by the volumetric examination such as ultrasonic method. As accessibility of this area is limited due to the narrow space and high radiation, the existing manual inspection method involves various difficulties. Moreover operators may be exposed to internal contamination by contaminated dust during the surface buffing process to improve the inspection reliability of this area. Recently the new automatic inspection system for stay cylinder welds has been developed. The inspection system basically consists of a driving assembly, data acquisition device and signal processing units. The driving assembly is classified by 1) the scanner for inspecting and buffing the weld, 2) pillars for guiding the scanner and 3) the base frame for loading and supporting pillars. The scanner has 4 sensor modules to inspect in 4 refracted angles and 4 incident directions. These components can be inserted into the skirt of the stay cylinder through the manway hole and assembled easily by one-touch in the skirt. Data acquisition device and signal processing units developed in previous works are also newly upgraded for better processing of data analysis and evaluation. The system has been successfully demonstrated not only in the mock-up but also in the field. In this paper, newly developed inspection system for the stay cylinder weld of the steam generator is introduced and their field applications are discussed.

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Nondestructive Inspection of Launch Vehicle Structural Components (우주 발사체 구조 요소의 비파피검사)

  • 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
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    • v.29 no.4
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    • pp.331-337
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    • 2009
  • 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.