• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.6
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• pp.635-644
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• 2003

To ensure the reliability of ultrasonic nondestructive testing techniques for modern structural materials, the effects of anisotropy and inhomogeneity and the influence of non-planar component geometries on ultrasonic wave propagation have to be taken into account. In this article, fundamentals and applications of two analytical approaches to three-dimensional elastic beam field calculation are presented. Results for both isotropic materials including curved interfaces and for anisotropic media like composites are presented, covering field profiles for various types of transducers and the modeling of time-dependent rf-signals.

• Journal of the Korean Society for Nondestructive Testing
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• v.34 no.1
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• pp.77-84
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• 2014

• Journal of the Korean Society for Nondestructive Testing
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• v.22 no.6
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• pp.627-636
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• 2002

Identification and sizing of surface breaking vertical cracks using angle beam ultrasonic testing in practical situation quite often become very difficult tasks due to the presence of non-relevant signals caused by geometric reflectors. The present work introduces effective and systematic approaches to take care of such a difficulty by use oi angle beam ultrasonic testing models that can predict the expected signals from various targets very accurately. Specifically, the model-based TIFD (Technique for Identification of Flaw signals using Deconvolution) is Proposed for the identification of the crack tip signals from the non-relevant geometric reflection signals. In addition, the model-based Size-Amplitude Curve is introduced for the reliable sizing of surface breaking vertical cracks.

• Journal of the Korean Society for Nondestructive Testing
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• v.4 no.2
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• pp.15-19
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• 1985

Computerization of ultrasonic scanner is considered to achieve more quantitative and reliable ultrasonic testing. Testech LS-24 ultrasonic scanner is modified, and step motors in this modified ultrasonic scanner are driven by multiprogrammer controlled by computer. Two step motors can be controlled independently and simultaniously. The performance of computerized ultrasonic scanner is examined entloying modified C scan for a flat bottom hole ultrasonic reference block.

• Journal of the Korean Society for Nondestructive Testing
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• v.17 no.2
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• pp.108-113
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• 1997

Ultrasonic testing is one of the most widely used method of nondestructive testing for pre-service inspection(PSI) & in-service inspection(ISI) in structures of bridges, power plants, chemical plants & heavy industrial fields. It is very important to estimate safety, life, quality of structures. Also, a lot of research for quantities evaluation & analyses inspection data is proceeding. But traditional portable ultrasonic flaw detector had been following disadvantages. 1) Analog ultrasonic flaw detector decreased credibility of ultrasonic test, because it is impossible for saving data & digital signal processing. 2) Stand-alone digital ultrasonic flaw detector cannot effectively evaluate received signals because of lack of its storage memory. To overcome this shortcoming, we develop the computer based ultrasonic flaw detector for nondestructive testing. It can store the received signal and effectively evaluate the signal, and then enhance the reliability of the testing results.

• Journal of the Korea institute for structural maintenance and inspection
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• v.5 no.4
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• pp.155-160
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• 2001

KS-code(KS B 0896) for nondestructive ultrasonic testing classifies the quality level by relative flaw size only. But flaw position is more important than the flaw size. Test blocks having artificial holes near surface show lower yield load than the blocks having deeply located holes from the surface. So, level calibration table was proposed for classifying the quality level of welded steel structures.

• Journal of the Korean Society for Nondestructive Testing
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• v.10 no.1
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• pp.65-72
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• 1990

Comparison of acoustic emission, ultrasonic testing and crack gauge in 3-point bending testing have been studied. As the results, COD is indirectly assumed by strain gauge rate and grid pitch width when crack gauge grid is out. Acoustic emission is qualitatively able to measure crack growth by total count but ultrasonic testing has a difficulty in measuring it because of echo height fluctuation according to the change and pressure of UT. probe.

• Journal of the Korean Society for Nondestructive Testing
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• v.9 no.2
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• pp.25-36
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• 1989

This essay is a general review of the application of ultrasonic NDE techniques to the performance assessment and characterization of composite materials. A brief review of ultrasonic input-output characterization of a composite plate by shear waves is presented. A theoretical development of ultrasonic wave propagation in isotropic and anisotropic media excited, respectively, by a circular transducer and an oscillatory point source is summarized. Some experimental results are described in which ultrasonic velocity and attenuation measurements give insight into material degradation of fatigued composite laminates. Ultrasonic determination of the elastic constants of a composite plate and an experimental attempt at ultrasonic testing of an isotropic plate containing a crack are also included. A recent effort for the characterization of viscoelastic materials using the ultrasonic NDE technique is outlined. Finally, the reliability of ultrasonic NDE is briefly touched upon.

• Journal of the Korean Society for Nondestructive Testing
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• v.11 no.1
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• pp.44-51
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• 1991

This paper describes the practical difficulties experienced with ultrasonic testing during site fabrication of the offshore structures, and indicates some of the problems when UT indications are evaluated according to written procedure which is prepared to the requirements of the applicable code (standard) and/or specification.

• Journal of the Korean Society for Nondestructive Testing
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• v.20 no.2
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• pp.116-129
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• 2000

Due to the great complexity of the physical phenomena involved in most ultrasonic nondestructive testing, the numerical method is effective in many cases of their theoretical modeling. A brief overview is provided in this paper of the numerical methods used in modeling ultrasonic nondestructive testing, with an emphasis on the finite difference and the finite element methods. The procedures of execution, special considerations required, and some previous research results of the finite difference and the finite element methods are presented, with a rather extensive list of work reported in the literature. These numerical modeling techniques for ultrasonic nondestructive testing are expected to be more reliable and more convenient, as a result of the continuing technological development of computers.