• 제목/요약/키워드: Penetration behavior

검색결과 490건 처리시간 0.029초

피로균열의 지연거동에 따른 수명예측 및 비파괴평가 (Life Prediction by Retardation Behavior of Fatigue Crack and its Nondestructive Evaluation)

  • 남기우;김선진
    • 한국해양공학회지
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    • 제13권3호통권33호
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    • pp.36-48
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    • 1999
  • Fatigue life and crack retardation behavior after penetration were experimentally examined using surface pre-cracked specimens of aluminium alloy 5083. The Wheeler model retardation parameter was used successfully to predict crack growth behavior after penetration. By using a crack propagation rule, the change in crack shape after penetration can be evaluated quantitatively. Advanced, waveform-based acoustic emission (AE) techniques have been successfully used to evaluate signal characteristics obtained form fatigue crack propagation and penetratin behavior in 6061 aluminum plate with surface crack under fatigue stress. Surface defects in the structural members are apt to be origins of fatigue crack growth, which may cause serious failure of the whole structure. The nondestructive analysis on the crack growth and penetration from these defects may, therefore, be one of the most important subjects on the reliability of the leak before break (LBB) design. The goal of the present study is to determine if different sources of the AE could be identified by characteristics of the waveforms produced from the crack growth and penetration. AE signals detected in four stages were found to have different signal per stage. With analysis of waveform and power spectrum in 6061 aluminum alloys with a surface crack, it is found to be capabilities on real-time monitoring for the crack propagation and penetration behavior of various damages and defects in structural members.

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표면균열재의 피로균열 관통거동에 따른 어코스틱에미션 (Acoustic emission during fatigue crack penetration behavior of surface cracked plate)

  • 남기우;김선진;오세규;이건찬;오정환;이주석
    • 한국해양공학회지
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    • 제11권3호
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    • pp.29-38
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    • 1997
  • Crack penetration behavior by fatigue crack propagation and measurements of AE before-and-after crack penetration were examined using SS41 steel plate. Experimental crack shape of SU type was in good agreement with calculated shape rather than S type. Crack propagation behavior on the front surface appears not to change markedly after penetration. However, crack growth on the back surface appears to accelerate as reported by author. As a crack propagates, AE occurred heavily just before penetration. Then, it decreases and crack is penetrating. A transition from plane strain to plane stress was observed by fractographic study. At this time, separation of fracture surface was shown which affects AE occurrence.

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평활시험편에 있어서 균혈형상비 변화에 따른 표면균열의 피로수명과 균열관통거동 (The Fatigue Life and Penetration Behavior by Variety of Aspect Ration on Smooth Specimen)

  • 남기우;엄윤성
    • 수산해양기술연구
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    • 제28권2호
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    • pp.197-207
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    • 1992
  • Fatigue life and penetration behavior were examined analytically by variety of initial front face crack length and initial crack depth. The fatigue crack shape before penetration is almost semielliptical, and the aspect ratio by calculation using the Newman-Raju's formula is smaller than the value obtained by the experiment. It is found that the crack growth behavior on the back surface after penetration is unique and can be divided into three stage a, b and c. By using the K value proposed by the authors, particular crack growth behavior and the change in crack shape can be evaluated quantitatively. It is found that fatigue life and penetration behavior were more dependent on initial front face crack length than initial crack depth.

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긴 표면균열재의 관통후 응력확대계수 평가 (Evaluation of Stress Intensity Factor after Penetration of Plate with Long Surface Crack)

  • 남기우;이종락
    • 한국가스학회지
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    • 제4권1호
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    • pp.33-39
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    • 2000
  • 긴 표면균열을 갖는 알루미늄합금(A5083)의 평판을 사용하여, 균열관통후의 응력확대계수를 검토하였다. 짧은 표면균열의 관통후에 제안된 식에 의하여 긴 표면균열 관통시의 평가는 균열종횡비가 적을수록 오차가 크게 되므로, 진전거동을 정확하게 평가하기 위해서는 수정이 필요하였다. 따라서 긴 표면균열 관통시의 종횡비를 고려하여, 응력확대계수의 평가식을 수정함으로써 관통후 고정도의 해석이 가능하였다.

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긴 균열을 갖는 알루미늄판재의 관통전후 피로거동 (Fatigue Behavior of Before-and-After Penetration of Aluminium Plate with Long Surface Crack)

  • 남기우;이종락;안석환
    • 한국가스학회지
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    • 제3권1호
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    • pp.1-7
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    • 1999
  • 알루미늄합금(5083-0)의 표면균열시험편의 관통전후의 피로거동을 조사하였다. 관통전의 피로균열형상은 거의 반타원형이며, 측정된 형상비는 Newman-Raju식의 K를 이용하여 계산한 값보다 더 크다. 관통후의 뒷면에서의 피로균열성장거동은 거의 유사하였으며 3영역으로 나누어졌다. 표면균열길이가 긴 경우, 피로균열전파법칙을 사용함으로서 표면균열재의 판두께 관통후의 피로균열 전파특성을 정량적으로 평가될 수 있음을 알 수 있었다.

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The Perforation Behavior of the Anodized AI Light Armor under High Velocity Impact

  • Sohn, Se-Won;Lee, Doo-Sung;Kim, Hee-Jae;Hong, Sung-Hee
    • International Journal of Precision Engineering and Manufacturing
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    • 제4권4호
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    • pp.45-50
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    • 2003
  • In order to investigate the effect of surface treatment (Anodizing) and rolling on AI 5083-H131 alloy, under hyper velocity impact, a ballistic testing was conducted. Ballistic resistance of these materials was measured by a protection ballistic limit ($V_{50}$)' a statistical velocity with 50% probability of penetration. Perforation behavior and ballistic tolerance, described by penetration modes, were respectfully observed, by $V_{50}$ test and Projectile Through Plates (PTP) test at velocities greater than $V_{50}$. PTP tests were conducted with 0$^{\circ}$ obliquity at room temperature using 5.56mm ball projectiles. $V_{50}$ tests with 0$^{\circ}$ obliquity were also done with projectiles that were able to achieve near or complete penetration during PTP tests. Resistance to penetration, and penetration modes of Al 5052-H34 alloy were compared to those of Al 5083-H 131 alloy.

분위기 조건이 바이오디젤과 에탄올 혼합연료의 분무 거동 및 미립화 특성에 미치는 영향 (Effect of Ambient Conditions on the Spray Behavior and Atomization Characteristics of Biodiesel-ethanol Blended Fuels)

  • 박수한;김형준;서현규;전문수;이창식
    • 한국분무공학회지
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    • 제13권4호
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    • pp.180-186
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    • 2008
  • The aim of this work is to investigate the effect of ambient conditions on the spray behavior of biodiesel-ethanol blended fuels. In order to analyze the spray behavior, spray tip penetration and spray cone angle were obtained from the visualization system and the effects of ethanol blending are compared macroscopic characteristics with the numerical results. It was reveled that the ethanol contents in biodiesel-ethanol blended fuels affect the spray tip penetration a little and increased the spray cone angle. Increased ambient pressure induced the decrease of the spray tip penetration, and the increased ambient temperature lead to the increase of the spray tip penetration. In addition, the increased ambient temperature promoted the vaporization and atomization of spray with the effect of increasing ethanol fuel.

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Investigation of Spudcan Penetration Resistance in Layered Soil Deposits

  • Jan, Muhammad Asad;Nizamani, Zubair Ahmed;Park, Duhee
    • 한국지반환경공학회 논문집
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    • 제22권1호
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    • pp.13-20
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    • 2021
  • A suite of 3D large deformation finite element (FE) analyses was performed to investigate the load transfer mechanism and penetration resistance of spudcan foundations in heterogeneous soil profile consisting of sand and clay. The Elasto-Plastic models following Mohr-Coulomb and Tresca failure criteria were adopted for sand and clay, respectively. The accuracy of the numerical model was validated against centrifuge test measurements. The dense sand behavior with dilation is modeled using the non-associated flow rule. An investigation study consisting of key parameters, which includes variation in soil stratigraphy (sand-clay, sand-clay-sand), strength parameters of sand and clay (��' and su) and normalized height ratio of the sand layer (Hs/D) was conducted to assess the penetration behavior of spudcan. Based on calculated outputs, it was demonstrated that these parameters have a significant influence on the penetration resistance of spudcan. The calculated penetration resistance profiles are compared with the published (sand overlying clay) analytical model. It is confirmed that for the case of two-layer soil, the available theoretical model provides an accurate estimate of peak penetration resistance (qpeak). In the case of three-layer soil, the presence of a third stiff layer affects the penetration resistance profile due to the squeezing of the soil.

용융 알루미늄에 의한 점토결합 카올린 샤모트의 침식에 관한 연구 (A Study on Corrosion Behavior of the Clay-Bonded Kaolin Chamotte by Molten Aluminum)

  • 박정현;이승주
    • 한국세라믹학회지
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    • 제17권4호
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    • pp.188-196
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    • 1980
  • To investigate the corrosion behavior of the clay-bonded kaolin chamotte by molten aluminum, the mixture of 20 wt% fire clay and 80 wt% kaolin chamotte was prepared and fired in the temperature range 900~120$0^{\circ}C$. The specimens fired at each temperature were reacted with molten aluminum at 90$0^{\circ}C$. The results obtained in this experiment are as followed. 1) It was confirmed through X-ray diffraction analysis that the clay-bonded kaolin chamotte exposed to molten aluminum suffered penetration by the reaction of aluminum with silica forming alumina and metallic silicon. 2) Penetration was independent whether the silica existed as free or one component of mullite. 3) Penetration of the specimen fired at 90$0^{\circ}C$ was negligible while the others fired above 100$0^{\circ}C$ showed remarkable penetration. 4) Penetration rate at 90$0^{\circ}C$ was parabolically increased with the holding time as in the case of metal oxidation.

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