• Title/Summary/Keyword: ultrasonic tests

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Patterns of Resistographs for Evaluating Deteriorated Structural Wood Members

  • LEE, Jun Jae;KIM, Kwang Chul;BAE, Mun Sung
    • Journal of the Korean Wood Science and Technology
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    • v.31 no.6
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    • pp.45-54
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    • 2003
  • The density and strength of wood is affected by degradations and defects, such as voids and knots. Old wooden structures such as traditional cultural properties have been deteriorated by these types of defects. They were evaluated by a visual observation that is difficult to evaluate the inner deterioration in structures. In this study, three nondestructive testing techniques were investigated to detect the wooden structural members. Ultrasonic stress wave tests, drilling resistance tests and visual inspections were used to examine the structural wood members. Patterns of Resistograph using by drilling resistance tests could indicate the features of internal wood such as voids, knots, decay, fungi, and so on. The technique just like as ultrasonic stress wave tests, however, difficult to detect exactly area where small amounts of internal deterioration in logs are. In spite of results of ultrasonic stress wave test, the internal deterioration of wooden structural members could be evaluated by the relationship between ultrasonic stress wave tests and drilling resistance tests.

Studies on the Correlation between Mechanical Properties and Ultrasonic Parameters of Aging 1Cr-1Mo-0.25V Steel

  • Seok Chang-Sung;Kim Jeong-Pyo
    • Journal of Mechanical Science and Technology
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    • v.19 no.2
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    • pp.487-495
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    • 2005
  • Mechanical properties of in-service facilities are required to evaluate the integrity of power plants and chemical plants. Non-destructive technique can be used to evaluate the mechanical properties. To investigate the mechanical properties using ultrasonic technique, the four classes of thermally aged specimens were prepared using an artificially accelerated aging method. Ultrasonic tests, tensile tests, fracture toughness tests, and hardness tests were performed for the specimens. Then the mechanical properties were compared with ultrasonic parameters such as attenuation and non-linear parameter. From the investigation, we confirm that the ultrasonic parameter can be used to evaluate the mechanical properties.

Effect of High Frequency Oscillation on Compression Tests of Aluminum Cylindrical Specimens (알루미늄 실린더 압축실험에서의 고주파 진동의 영향)

  • Kim, S.W.;Lee, Y.S.
    • Transactions of Materials Processing
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    • v.25 no.6
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    • pp.373-378
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    • 2016
  • Recent researches have reported that the superposition of ultrasonic vibrations in metal forming provides beneficial effects such as the reduction of forming load, flow stress and interfacial friction which improves the surface quality of end products. This paper presents experimental investigations on the effects of ultrasonic vibrations in upsetting tests of aluminum. The ultrasonic exciting system consists of piezoelectric transducer and resonator was designed and constructed to superimpose high frequency oscillation on the forming tools. Ultrasonic vibration-assisted upsetting tests were performed for three vibration modes five amplitudes, and the results were compared with those of conventional upsetting tests. The results showed that the superimposition of ultrasonic vibration reduces the upsetting load, and the load reduction is only dependent on the amplitude of the applied vibration regardless of deformation histories and vibration modes.

초음파동전기세척 복합기법에 의한 오염부지 복원기술

  • 정하익;김상근;송봉준;강동우;이경국
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 2004.04a
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    • pp.183-185
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    • 2004
  • In this study, the combined electrokinetic and ultrasonic remediation technique, ultrasonically enhanced electrokinetic technique, was studied for the removal of heavy metal and organic substance in contaminated soils. The electrokinetic technique has been applied to remove mainly the heavy metal and the ultrasonic technique has been to remove mainly organic substance in contaminated soil. The laboratory soil flushing tests combined electrokinetic and ultrasonic technique were conducted using specially designed and fabricated devices to determine the effect of these both techniques. A series of laboratory experiments involving the simple, electrokinetic, ultrasonic, and electrokinetic & ultrasonic flushing test were carried out. A soil admixed with sand and kaolin was used as a test specimen, and Pb and ethylene glycol were used as contaminants of heavy metal and organic substance. An increase in out flow, permeability and contaminant removal rate was observed in electrokinetic and ultrasonic flushing tests. Some practical implications of these results are discussed in terms of technical feasibility of in situ implementation of electrokinetic ultrasonic remediation technique.

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A Study on the Evaluation of Material Degradation of 1Cr-1Mo-0.25V Steel using Ultrasonic Techniques (초음파법을 이용한 1Cr-1Mo-0.25V강의 열화도 평가에 관한 연구)

  • Kim, Jeong-Pyo;Seok, Chang-Sung
    • Proceedings of the KSME Conference
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    • 2001.06a
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    • pp.78-83
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    • 2001
  • It's required mechanical properties of in-service facilities to maintain safety operation in power plants as well as chemical plants. In this study the four classes of the thermally aged 1Cr-1Mo-0.25V specimens were prepared using an artificially accelerated aging method at $630^{\circ}C$. Ultrasonic tests, tensile tests, $K_{IC}$ tests and hardness tests were performed in order to evaluate the degree of degradation of the material. The mechanical properties were decreased as degraded, but the attenuation coefficient and the harmonic generation level of a ultrasonic signal were increased. Expecially the nonlinear parameter of the signal is sensitive and will be a good parameter to evaluate the material degradation.

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Medical Application of the Nondestructive Ultrasonic Tests: Diagnosis of Micro Bone Fractures using Ultrasonic C Scan Images (비파괴 초음파 검사법의 의학적 활용: 초음파 C 스캔 영상을 이용한 미세 골절의 진단)

  • Choi, Min-Joo
    • Journal of the Korean Society for Nondestructive Testing
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    • v.22 no.4
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    • pp.377-385
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    • 2002
  • Ultrasonic tests employing non-ionizing radiation are preferred in nondestructive examinations since they are safe and simple in use. The same principles of the techniques have been taken as valuable tools in medical area for the diagnoses of diseases, in other words, defects of the human body. The paper overviews the principles of the medical diagnosis based on nondestructive ultrasonic tests, and then evaluates experimentally the clinical potential of C scan images not popular in medicine, for detecting the micro fractures of the cortical bone. In the experiment the micro bone fractures were created on the femurs of porks by loading three point bending forces (2-4kN) with the speed of 1 mm/min. As the extent of the fracture was altered, not only X ray images but also ultrasonic C scan images using a focused ultrasonic probe resonated at 25 MHz were obtained. The results showed that ultrasonic C scan images were capable of detecting the micro bone fractures which were not possible to identify by conventional X ray images.

Feasibility study of wide-band low-profile ultrasonic sensor with flexible piezoelectric paint

  • Li, Xin;Zhang, Yunfeng
    • Smart Structures and Systems
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    • v.4 no.5
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    • pp.565-582
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    • 2008
  • This paper presents a feasibility study of flexible piezoelectric paint for use in wide-band low-profile surface-mount or embeddable ultrasonic sensor for in situ structural health monitoring. Piezoelectric paint is a piezoelectric composite with 0-3 connectivity. Because of its ease of application, piezoelectric paint can be readily fabricated into sensing element with complex pattern. This study examines the characteristics of piezoelectric paint in acoustic emission signal and ultrasonic guided wave sensing. A series of ultrasonic tests including pitch catch and pencil break tests were performed to validate the ultrasonic wave sensing capability of piezoelectric paint. The results of finite element simulation of ultrasonic wave propagation, and acoustic emission generated by a pencil lead break on an aluminum plate are also presented in this paper along with corresponding experimental data. Based on the preliminary experimental results, the piezoelectric paint appears to offer a promising sensing material for use in real-time monitoring of crack initiation and propagation in both metallic and composite structures.

토양의 종류에 따른 초음파토양세척의 투수특성 분석

  • 정하익;송봉준;이용수;유준;강동우
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 2004.09a
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    • pp.258-261
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    • 2004
  • In this study, the combined electrokinetic and ultrasonic remediation technique onto simple soil flushing was studied for the enhancement of water and liquid flows and the removal of contaminants in contaminated soils. The ultrasonic technique has been used to increase liquid flow and remove pollutants in contaminated soil. The laboratory soil flushing tests combined electrokinetic and ultrasonic technique were conducted using specially designed and fabricated devices to determine the effect of these both techniques. A series of laboratory permeability experiments involving the simple, electrokinetic, ultrasonic, and electrokinetic & ultrasonic flushing test were carried out. A soil admixed with sand and kaolin was used as a test specimen, and Pb and ethylene glycol were used as contaminants. An increase in out flow, permeability and contaminant removal rate was observed in electrokinetic and ultrasonic flushing tests.

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Determination of the elastic properties in CFRP composites: comparison of different approaches based on tensile tests and ultrasonic characterization

  • Munoz, Victor;Perrin, Marianne;Pastor, Marie-Laetitia;Welemane, Helene;Cantarel, Arthur;Karama, Moussa
    • Advances in aircraft and spacecraft science
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    • v.2 no.3
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    • pp.249-261
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    • 2015
  • The mechanical characterization of composite materials is nowadays a major interest due to their increasing use in the aeronautic industry. The design of most of these materials is based on their stiffness, which is mainly obtained by means of tensile tests with strain gauge measurement. For thin laminated composites, this classical method requires adequate samples with specific orientation and does not provide all the independent elastic constants. Regarding ultrasonic characterization, especially immersion technique, only one specimen is needed and the entire determination of the stiffness tensor is possible. This paper presents a study of different methods to determine the mechanical properties of transversely isotropic carbon fibre composite materials (gauge and correlation strain measurement during tensile tests, ultrasonic immersion technique). Results are compared to ISO standards and manufacturer data to evaluate the accuracy of these techniques.

A Study on the Evaluation of Material Degradation of 1Cr-lMo-0.25V Steel using Ultrasonic Techniques (초음파법을 이용한 1Cr-lMo-0.25V강의 열화도 평가에 관한 연구)

  • Kim, Jeong-Pyo;Seok, Chang-Seong
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.12
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    • pp.2116-2124
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    • 2001
  • It's required mechanical properties of in-service facilities to maintain safety operation in power plants as well as chemical plants. In this studdy the four classes of the thermally aged 1Cr-lMo-0.25V specimens were prepared using an artificially accelerated aging method at 630$\^{C}$. Ultrasonic tests, tensile tests, K$\_$IC/ tests and hardness tests were performed in order to evaluate the degree of degradation of the material. The mechanical properties were decreased as degraded, but the attenuation coefficient and the harmonic generation level of a ultrasonic signal were increased. Expecially the nonlinear parameter derived from the harmonic generation level is sensitive and will be a good parameter to evaluate the material degradation.