• Title/Summary/Keyword: Void defect

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Non-Destructive Evaluation of Separation and Void Defect of a Pneumatic Tire by Speckle Shearing Interferometry

  • Kim, Koung-Suk;Kang, Ki-Soo;Jung, Hyun-Chul;Ko, Na-Kyong
    • Journal of Mechanical Science and Technology
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    • v.18 no.9
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    • pp.1493-1499
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    • 2004
  • This paper describes the speckle shearing interferometry, a non-destructive optical method, for quantitative estimation of void defect and monitoring separation defect inside of a pneumatic tire. Previous shearing interferometry has not supplied quantitative result of inside defect, due to effective factors. In the study, factors related to the details of an inside defect are classified and optimized with pipeline simulator. The size and the shape of defect can be estimated accurately to find a critical point and also is closely related with shearing direction. The technique is applied for quantitative estimation of defects inside of a pneumatic tire. The actual traveling tire is monitored to reveal the cause of separation and the starting points. And also unknown void defects on tread are inspected and the size and shape of defects are estimated which has good agreement with the result of visual inspection.

Considerations on correlation between partial discharge and breakdown using void-simulated defect (보이드 모의결함을 이용한 부분방전과 절연파괴와의 상관관계에 대한 고찰)

  • Lee, Tae-Seong;Jang, Su-Gil;Kim, Jeong-Tae
    • Proceedings of the KIEE Conference
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    • 2011.07a
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    • pp.21-22
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    • 2011
  • In this paper, considerations on correlation between partial discharge and breakdown using void-simulated defect, investigating the characteristics of void discharges. For the purpose, the relationship between PDIV(Partial Discharge Inception Voltage) and BDV(BreakDown Voltage) was analyzed. As a result, it is noticed that the higher PDIV, the higer BDV.

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Partial Discharge Characteristics of the XLPE/EPDM Interface in Power Cable Joint (전력케이블 접속재 XLPE/EPDM 계면의 부분방전 특성)

  • Cho, Kyung-Soon;Hong, Jin-Woong
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.20 no.9
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    • pp.780-786
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    • 2007
  • This paper describes the influence on partial discharge characteristics of defects at the model XLPE/EPDM interfaces of power cable joints. The defects of void and copper which could inadvertently be present at the joint interface. We measured ${\Phi}-n,\;{\Phi}-q$ patterns by a computer-aided partial discharge measuring system. Several parameters i, e, maximum discharge $q_{max}$ [pC], average discharge q [pC/cycle], and average angle of discharge ${\Theta}g$ [deg] were found to depend upon the defect type varying applied voltage. As the result of time evaluation, partial discharges are small different at copper defects, but is decreasing obviously about 20 minutes at void defect. It considered that difference of magnitude of total positive discharge of Q+ [pC] and total negative discharge of Q- [pC] is SPMD(swarming pulsive micro discharges).

Effect of Radial Parameters in Cogging Process on Void Closure for Large Forged Products (단강품 기공의 압착성 향상을 위한 레이디얼 단련변수의 영향)

  • Choi, H.J.;Choi, S.;Yoon, D.J.;Jung, J.H.;Baek, D.K.;Choi, S.K.;Park, H.J.;Lim, S.J.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2008.05a
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    • pp.67-70
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    • 2008
  • This paper deals with the effect of radial parameters in cogging process such as reduction in height (Rh) and rotational angle ($\theta$) of a billet on a void closure for large forged products. Usually closing and consolidation of internal void defects in a ingot is a vital matter when utilized as large forged products, using a press with limited capacity and the sizes of the ingots becoming larger. Consequently, it is important to develop cogging process for improvement of internal soundness without a void defect and cost reduction by solid forging alone with limited press capacity. For experiments of cogging process, hydraulic press with a capacity of 800 ton was used together with a small manipulator which was made for rotation and overlapping of a billet. Size of a void was categorized into two types; $\emptyset$ 6.0 mm and $\emptyset$ 9.0 mm to investigate the change of closing and consolidation of void defects existed in the large ingot during the cogging process. Also open void and closed void in the ingot were tackled to show the differentiation of closing process of internal voids with respect to void sizes. In this paper systematic configuration for closing process of void defects were expressed based on this experiment results in the cogging process.

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Detecting of the defects of pavement of a road by using infrared thermography (열화상 비파괴 검사법을 이용한 도로포장 결함 검출)

  • Sim, Jun-Gi;Kim, Ki-Hyun
    • Journal of the Korean Society for Advanced Composite Structures
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    • v.6 no.3
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    • pp.69-76
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    • 2015
  • The purpose of this paper is to find an limitation to detect the defect of damaged asphalt pavement structures for infrared thermography. We use heat source of a natural light to detect the defect efficiently. The heat source was applied to the asphalt specimens. Four asphalt specimens were used: one was the asphalt containing depth of 1cm internal timber, two was the asphalt containing depth of 2cm internal void, Three was the asphalt containing depth of 3cm internal timber and four was not the asphalt containing internal timber. It was found that the depth of 3cm internal timber could be detected by this method. In addition, we used the image processing to make the damage zone displayed clear in the image obtained from the thermographic operation.

Void Formation Induced by the Divergence of the Diffusive Ionic Fluxes in Metal Oxides Under Chemical Potential Gradients

  • Maruyama, Toshio;Ueda, Mitsutoshi
    • Journal of the Korean Ceramic Society
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    • v.47 no.1
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    • pp.8-18
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    • 2010
  • When metal oxides are exposed to chemical potential gradients, ions are driven to diffusive mass transport. During this transport process, the divergence of ionic fluxes offers the formation/annihilation of oxides. Therefore, the divergence of ionic flux may play an important role in the void formation in oxides. Kinetic equations were derived for describing chemical potential distribution, ionic fluxes and their divergence in oxides. The divergence was found to be the measure of void formation. Defect chemistry in scales is directly related to the sign of divergence and gives an indication of the void formation behavior. The quantitative estimation on the void formation was successfully applied to a growing magnetite scale in high temperature oxidation of iron at 823 K.

The Analysis of Discharge Distribution due to the Inner Void of Extra High Voltage Cable

  • Kim Tag-Yong;Hong Jin-Woong
    • KIEE International Transactions on Electrophysics and Applications
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    • v.5C no.4
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    • pp.155-160
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    • 2005
  • This paper addresses the discharge characteristics of cross-linked polyethylene according to void by the Weibull function. It analyzes discharge number and amount of discharge using Weibull distribution to identify the inter-relationship between partial discharge and defect. We detected a 10 second discharge. The applied voltage increased by 1 [kV] at discharge inception voltage. As a result, in a no-void specimen, the shape parameter was consistent according to the increase of voltage, whereas, in a void specimen, it increased according to the increase of voltage. As the result, the shape parameter expressed a fixed value at no-void specimen. However, in void specimen, according to increasing voltage shape parameter rapidly increases.

Reliability-based assessment of high-speed railway subgrade defect

  • Feng, Qingsong;Sun, Kui;Chen, Hua-peng
    • Structural Engineering and Mechanics
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    • v.77 no.2
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    • pp.231-243
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    • 2021
  • In this paper, a dynamic response mapping model of the wheel-rail system is established by using the support vector regression (SVR) method, and the hierarchical safety thresholds of the subgrade void are proposed based on the reliability theory. Firstly, the vehicle-track coupling dynamic model considering the subgrade void is constructed. Secondly, the subgrade void area, the subgrade compaction index K30 and the fastener stiffness are selected as random variables, and the mapping model between these three random parameters and the dynamic response of the wheel-rail system is built by using the orthogonal test and the SVR. The sensitivity analysis is carried out by the range analysis method. Finally, the hierarchical safety thresholds for the subgrade void are proposed. The results show that the subgrade void has the most significant influence on the carbody vertical acceleration, the rail vertical displacement, the vertical displacement and the slab tensile stress. From the range analysis, the subgrade void area has the largest effect on the dynamic response of the wheel-rail system, followed by the fastener stiffness and the subgrade compaction index K30. The recommended safety thresholds for the subgrade void of level I, II and III are 4.01㎡, 6.81㎡ and 9.79㎡, respectively.

Analysis on Partial Discharge Fault Signals of PRPD for High Voltage Motor Stator Winding (고압전동기 고정자 권선의 PRPD 부분방전 결함신호 해석)

  • Park Jae-Jun;Lee Sung-Young;Mun Dae-Chul
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.19 no.10
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    • pp.942-946
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    • 2006
  • We simulated insulation defects of stator winding wire on high voltage generator by 5 types. 4 types have one discharge source and other one has multi discharge source by simulation. For accurate decision, measurements used to PRPD pattern to occurred partial discharge source of various types. In this research, when PRPD pattern carried out or analyzed pattern recognition of discharge source, it used to powerful tools. In this result, PRPD Pattern defined to have single discharge source of 4 types by insulation defect. When insulation defect simulated, all the defected winding have not the same result. Errors for a little different can make mistakes from a subtle distinction. The difference between internal and void discharge have magnitude of pulse amplitude of inner discharge bigger than void discharge and have a shape of bisymmetry. But void discharge has a shape of bisymmetry against maximum value on polarity respectively. In cases of slot and surface discharge, we confirmed to show similar results those other researchers. In case of multi-discharge, as a result of we could classify not perfect match with occurred patterns in single discharge eachother. In the future, we will have to recognize and classify with results of multi-discharge.