• Title/Summary/Keyword: Material Allowable

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Characterization of a Misaligned Supercritical Shaft of Flexible Matrix Composite (축어긋남이 있는 유연복합재 고속구동축의 특성 분석)

  • 홍을표;신응수
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.14 no.1
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    • pp.32-39
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    • 2004
  • This research is to investigate the performance of a flexible matrix composite driveshaft with respect to shaft design parameters such as the number of layers, ply orientations, and material properties. A finite element formulation is utilized to estimate the allowable misalignment under given driving torque, the maximum temperature at steady states, and external damping for ensuring whirling stability under supercritical speed. Results indicate that the system performance can be greatly affected by the shaft laminate parameters, especially the ply orientations. Several sets of shaft parameters that will provide satisfactory overall system performance are derived.

Development of Analysis Scheme to Predict Regrinding in Shearing Process (전단가공 금형의 재연삭시기 예측을 위한 해석기법 개발)

  • Ko, Dae-Cheol;Kim, Byung-Min
    • Journal of the Korean Society for Precision Engineering
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    • v.16 no.1 s.94
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    • pp.182-190
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    • 1999
  • The objective of this study is to develop an analysis scheme in order to predict regrinding due to tool wear in shearing process. The analysis of material now and fracture in shearing process should precede the prediction of tool wear. Thus the developed FE-program to analyze shearing process is used. In order to predict tool wear, the wear model is reformulated as an incremental form and then the wear depth of tool is calculated at each deformation path. Because the regrinding of shearing tool is determined on the basis of allowable size of burr, the analysis of shearing process is iteratively performed using the worn profile of tool. To show the effectiveness of the scheme the simulation result is compared with experimental one.

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A Study on Durability Characteristics of Automobile Clutch Diaphragm Spring Steel According to Heat-Treatment Condition (자동차 클러치용 다이아프램 스프링 강(50CrV4)의 열처리 조건에 따른 내구특성에 관한 연구)

  • 남욱희;이춘열;채영석;권재도;배용탁;우승완
    • Journal of the Korean Society for Precision Engineering
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    • v.17 no.2
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    • pp.137-143
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    • 2000
  • An automobile clutch diaphragm spring is operating in a closed clutch housing under high temperature and subject to high stress concentration in driving condition, which frequently causes cracks and fracture. The material of spring is required to possess sufficient fatigue strength and tenacity, which depend largely on the condition of tempering heat treatment. In this paper, specimens are made under a number of different tempering temperatures md tested to find the optimal tempering heat treatment condition. The experiments include the verification of microscopic structure, hardness, tensile strength, fatigue crack growth rate, stress intensity factor range and residual stress. Also, decarbonization, which occurs in actual heat treatment process, is measured and allowable decarbonization depth is studied by durability test.

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Development of a Simplified Design Method for LBB Application to Nuclear Piping (원전 배관의 LBB 개념 적용을 위한 간략 설계기법 개발)

  • 허남수;이철형;김영진;석창성;표창률
    • Journal of the Korean Society of Safety
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    • v.14 no.2
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    • pp.32-41
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    • 1999
  • If the Leak-Before-Break (LBB) concept is applicable to the nuclear piping design, it is not necessary to consider the dynamic effect due to pipe rupture. Therefore, the construction cost can be significantly reduced by eliminating unnecessary pipe whip restraints and jet impingement devices. The objective of this paper is to develop the Piping Evaluation Diagram (PED) for efficient application of LBB concept to piping system at an initial piping design stage. For this purpose, the 3-D finite element analyses were performed to evaluate the crack stability. And the stress-strain curve based on the pipe material tests were used to calculate the detectable leakage crack length. Finally, the present PED which was composed as a function of NOP load and allowable SSE load, was developed for an application of LBB concept to the safety injection and shutdown cooling line in Korean Next Generation Reactor (KNGR).

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Comparative Study for Fire Protective Materials of Column According to Variance of Lengths (길이변화에 따른 기둥부재의 내화피복 비교연구)

  • Kwon, In-Kyu
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2014.05a
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    • pp.118-119
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    • 2014
  • A fire in a steel framed building can decrease a structural stability and cause deformation. And the fire continues the building can be demolished. Therefore, every country requires fire resistance performance of structural elements. In case of column, fire protective thickness derived from a specific fire test using an horizontal furnace is allowed to apply any kinds of sections and lengths of column. However, the lengths and sections of the column in steel framed buildings are various. In this paper, to know the differences of fire performance of steel column according to variance of lengths, a maximum allowable stress, steel surface temperature history, deflection are calculated and the thickness of fire protective material for longer column(4700 mm) need to enforce about 10% more than shorter column (3500 mm).

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Design Optimization of Thermo-Elastic Structure (열탄성 구조물의 최적설계)

  • 조희근;박영원
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2000.11a
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    • pp.381-384
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    • 2000
  • Multi-disciplinary optimization design concept can provide a solution to many engineering problems. In the field of structural analysis, much development of size or topology optimization has been achieved in the application of research. This paper demonstrates an optimum design of a multi-layer cylindrical tube which behaves thermoelastically. A multi-layer cylindrical tube that has several different material properties at each layer is optimized within allowable stress and temperature range when mechanical and thermal loads are applied simultaneously. To analyze these problems using an efficient and precise method, the optimization theories are adopted to perform thermoelastic finite element analysis.

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A Seismic Analysis for Driving Gear Reducer of ESW Traveling Sea Water Screen (ESW형 해수여과장치의 구동 기어감속기에 대한 내진해석)

  • Kim, Chang-Won;Lee, Young-Shin;Kim, Heung-Tae;Kim, Jee-Won
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.22 no.7
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    • pp.599-604
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    • 2012
  • In this study, the safety of the driving gear reducer of ESW(essential service water) traveling sea water screen was evaluated through seismic analysis. Mode analysis of gear reducer was performed for reliability of analysis. Seismic analysis was performed in operating basis earthquake(OBE) and safe shutdown earthquake(SSE), which were applied as design condition using floor response spectrum( FRS). The maximum strain of gear reducer under OBE and SSE were 20.4 ${\mu}$ and 33.6 ${\mu}$, respectively. The maximum stresses were 2.42 MPa under OBE condition and 4.36 MPa under SSE condition, which were smaller than the allowable strength of material.

Development of Austempered Ductile Iron With High Strength and High Toughness for Automotive Parts (고강도 ADI 의 자동차 부품개발에 관한 연구)

  • Kim, Won-Yong;Lee, Young-Sang;Kim, Gwang-Bae;Kang, In-Chan
    • Journal of Korea Foundry Society
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    • v.10 no.5
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    • pp.408-416
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    • 1990
  • The application of this new design approach called fracture mechanics allow one to determine the maximum allowable stress from the knowledge of the largest expected flow size and the plane strain fracture toughness of a material. In this study we examined the relation between retained austenite, mechanical property and fracture toughness accompanied by austempering heat treatment. Fracture toughness values and retained austenite volume were higher with the ADI(austempered ductile iron) which were austempered at $380^{\circ}C$ than austempered at $320^{\circ}C$. Additionally, fracture toughness values were increased for 1~2 hour austempering time but it was slowly decreased for 5 hour ADI maintaining the predominant fracture toughness($K_{IC}:83MPa{\sqrt{m}}$) is obtained following condition, namely, austempering temperature and time ($380^{\circ}C$ and 1 hour).

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Evaluation of the Preirradiation Baseline Material Characteristics for Yonggwang Nuclear Reactor Pressure Vessel (영광 원자력 발전소 원자로 소재의 가동전 재료 물성 특성)

  • Kim, K.C.;Kim, J.T.;Suk, J.I.;Kwon, H.K.;Sung, U.H.
    • Proceedings of the KSME Conference
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    • 2000.11a
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    • pp.153-158
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    • 2000
  • Nuclear reactor pressure vessel should be safety even in the case that hypothetical defects with allowable size are in vessel. Therefore, the materials should have excellent fracture resistance characteristics. The purpose of this study is to analyze the results of preirradiation baseline test of nuclear pressure vessel for Yonggwang Unit 5/6. In experiments, drop weight tests and impact tests are carried out to obtain nil-ductility transition reference temperature, $RT_{NDT}$ and static and dynamic fracture toughness tests are performed to compare with $K_{IR}$ curve in accordance with ASME Sec.III. The test results show that the materials had sufficiently fracture resistance characteristics for 40 years of design life.

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Fracture Mechanics Analysis of Reactor Pressure Vessel Under Pressurized Thermal Shock-The Effect of Elastic-Plastic Behavior and Stainless Steel Cladding- (원자로 용기의 가압열충격에 대한 파괴역학 해석 - 탄소성 거동과 클래드부의 영향 -)

  • Ju, Jae-Hwang;Gang, Gi-Ju;Jeong, Myeong-Jo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.1
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    • pp.39-47
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    • 2002
  • Performed here is an assessment study for deterministic fracture mechanics analysis of a pressurized thermal shock(PTS). The PTS event means an event or transient in pressurized water reactors(PWRs) causing severe overcooling(thermal shock) concurrent with or followed by significant pressure in the reactor vessel. The problems consisting of two transients and 10 cracks are solved and maximum stress intensity factors and maximum allowable nil-ductility reference temperatures are calculated. Their results are compared each other to address the general characteristics between transients, crack types and analysis methods. The effects of elastic-plastic material behavior and clad coating on the inner surface are explored.