• Title/Summary/Keyword: advanced thermal analysis

Search Result 782, Processing Time 0.039 seconds

High Temperature Flexural Strengths of the Ceramic-Metal Brazed Joints (세라믹-금속 브레이징 접합조인트의 고온 접합강도에 관한 연구)

  • Lee, Su-Jeong;Jeong, Myung-Yeong;Lee, Dai-Gil;Goo, Hyung-Hoi
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.20 no.2
    • /
    • pp.520-528
    • /
    • 1996
  • Four point bending tests of the brazed joint composed of sintered silicon nitride and 0.2% carbon steel with Cusil ABA filler which were fabricated at 86$0^{\circ}C$ were performed at temperatures, 25, 100, 200, 300, 400, 50$0^{\circ}C$ From the experiments, the maximum bending strength was measured at 30$0^{\circ}C$ From the 3D FE analysis of the residual stress of the brazed joint, it was revealed that the thermally induced residual stresses were minimized when the environmental temperature was 35$0^{\circ}C$ Considering the degradation of the filler material at high temperatures, it was calculated that the maximum bending strength of the brazed joint occured just below the temperature of the minimum thermal residual stress and the thermal residual stress was the dominative parameter of the brazed joint.

Synthesis of Nanocrystalline Ceria for IT-SOFC by Glycine Nitrate Combustion Process (연소합성을 이용한 저온형 고체산화물 연료전지용 나노구조 세리아계 전해질 제조)

  • Jo, Seung-Hwan;Kim, Jong-Ho;Kim, Do-Kyung
    • Journal of the Korean Ceramic Society
    • /
    • v.42 no.12 s.283
    • /
    • pp.821-826
    • /
    • 2005
  • Gadolinia-doped ceria nanopowder was prepared by glycine-nitrate combustion method with different glycine/nitrate mixing ratio. The characteristics of the synthesized powder were investigated by X-ray diffraction method, transmission electron microscopy, thermal gravity, differential thermal analysis and thermo-mechanical analysis. The smallest powder was obtained with glycine/nitrate ratio 1.00 and the lowest organic and water vapor contained powder was made with glycine/nitrate ratio 1.75. According to dilatometry, fast densification was occurred around $1000^{\circ}C$ and shows full density over $1300^{\circ}C$. Finally near-fully dense ceria electrolyte was fabricated with conventional sintering technique. Glycine-nitrate process yields fine nanopowders which enable low temperature sintering and fabrication of fully dense and nanostructured oxide electrolyte.

An Analysis of Critical Heat Flux on the External Surface of the Reactor Vessel Lower Head

  • Yang, Soo-Hyung;Baek, Won-Pil;Chang, Soon-Heung
    • Proceedings of the Korean Nuclear Society Conference
    • /
    • 1999.10a
    • /
    • pp.190-190
    • /
    • 1999
  • CHF (Critical heat flux) on the external surface of the reactor vessel lower head is major key in the evaluation on the feasibility of IVR-EVC (In-Vessel Retention through External Vessel Cooling) concept. To identify the CHF on the external surface, considerable works have been performed. Through the review on the previous works related to the CHF on the external surface, liquid subcooling, induced flow along the external surface, ICI (In-Core Instrument) nozzle and minimum gap are identified as major parameters. According to the present analysis, the effects of the ICI nozzle and minimum gap on CHF are pronounced at the upstream of test vessel: on the other hand, the induced flow considerably affects the CHF at downstream of test vessel. In addition, the subcooling effect is shown at all of test vessel, and decreases with the increase in the elevation of test vessel. In the real application of the IVR-EVC concept, vertical position is known as a limiting position, at which thermal margin is the minimum. So, it is very important to precisely predict the CHF at vertical position in a viewpoint of gaining more thermal margins. However, the effects of the liquid subcooling and induced flow do not seem to be adequately included in the CHF correlations suggested by previous works, especially at the downstream positions.

  • PDF

Development of a one-dimensional system code for the analysis of downward air-water two-phase flow in large vertical pipes

  • Donkoan Hwang;Soon Ho Kang;Nakjun Choi;HangJin Jo
    • Nuclear Engineering and Technology
    • /
    • v.56 no.1
    • /
    • pp.19-33
    • /
    • 2024
  • In nuclear thermal-hydraulic system codes, most correlations used for vertical pipes, under downward two-phase flow, have been developed considering small pipes or pool systems. This suggests that there could be uncertainties in applying the correlations to accident scenarios involving large vertical pipes owing to the difference in the characteristics of two-phase flows, or flow conditions, between large and small pipes. In this study, we modified the Multi-dimensional Analysis of Reactor Safety KINS Standard (MARS-KS) code using correlations, such as the drift-flux model and two-phase multiplier, developed in a plant-scale air-inflow experiment conducted for a pipe of diameter 600 mm under downward two-phase flow. The results were then analyzed and compared with those based on previous correlations developed for small pipes and pool conditions. The modified code indicated a good estimation performance in two plant-scale experiments with large pipes. For the siphon-breaking experiment, the maximum errors in water flow for modified and original codes were 2.2% and 30.3%, respectively. For the air-inflow accident experiment, the original code could not predict the trend of frictional pressure gradient in two-phase flow as / increased, while the modified MARS-KS code showed a good estimation performance of the gradient with maximum error of 3.5%.

Analysis for the Thermal Properties of the Electrical Wire according to Overload and Disconnection (과부하 및 물리적 손상(반단선)에 의한 전선의 열적특성 해석)

  • Kim, Sung-Chul;Kim, Doo-Hyun
    • Journal of the Korean Society of Safety
    • /
    • v.22 no.4
    • /
    • pp.26-31
    • /
    • 2007
  • According to the statistical analysis on the electrical fire of 2005 years, most of electrical fire is generated from short circuit(4,985 cases), overcurrent(755 cases) leakage current(391 cases), poor contact(378 cases), disconnection(36 cases) on the electrical wiring device. The researches for the fire hazard about normal electric wiring have already been progressing in the advanced country such as USA and Japan, but Comparative study of the disconnection has not been conducted. Therefore, in this paper, we have simulated the thermal analysis for electrical wire according to deteriorating time in a normal state and disconnection with electrical wire using the electrical-thermal finite element method(Flux 3D). This paper acquire basis data of electricity fire signal by disconnection and wish to help for electrical fire cause diagnosis business.

Design of exhaust manifold for pulse converters considering fatigue strength due to vibration

  • Cho, Kyung-Sang;Son, Kyung-Bin;Kim, Ue-Kan
    • Journal of Advanced Marine Engineering and Technology
    • /
    • v.37 no.7
    • /
    • pp.694-700
    • /
    • 2013
  • The design of the exhaust manifold for the pulse converters of a 4 strokes high power medium-speed diesel engine is presented in terms of fatigue analysis. The said system undergoes thermal expansion due to high temperature of exhaust gas and is exposed to intrinsic vibration of the internal combustion engine. Moreover, the exhaust pulse generates pressure pulsating along the runner inside manifold. Under such circumstances, the design and construction of exhaust manifold must be carried out in a way to prevent early failure due to fracture. To validate the design concept, a test rig was developed to simulate the combination of thermal and vibrational movements, simultaneously. Experimental results showed that a certain sense of reliability can be achieved by considering a field factor obtained from the results of engine bench tests.

Coupled Thermal-Structure Analysis of UV Laser Pulsing according to the Thickness of Copper Film on the Surface of Polyimide (UV 펄스 레이저 가공의 구리 박막 두께에 따른 열-구조 연성 해석)

  • Shin, Minjae;Shin, Bosung
    • Laser Solutions
    • /
    • v.16 no.2
    • /
    • pp.7-11
    • /
    • 2013
  • Recently advanced laser processing is widely introduced to improve the efficiency of micro part production and to reduce the rate of inferior goods. In this paper the trend of delamination of single layer with both thin copper and polyimide according to the variation of copper thickness was investigated using the coupled thermal-structural analysis of ANSYS. From these analyses results, some conclusions were obtained. Firstly, the maximum temperature was increasing with respect to decrease of copper thickness. Secondly the maximum strain which was in general estimation the main effect of the delamination was observed in case of the copper thickness of $5{\mu}m$. Finally the trend of the delamination was decreasing with increasing the thickness of copper layer.

  • PDF

The effects of repetitive firing processes on the optical, thermal, and phase formation changes of zirconia

  • Ozdogan, Alper;Ozdemir, Hatice
    • The Journal of Advanced Prosthodontics
    • /
    • v.12 no.1
    • /
    • pp.9-14
    • /
    • 2020
  • PURPOSE. The aim of this study was to investigate the effect of different numbers of heat treatments applied to superstructure porcelain on optical, thermal, and phase formation properties of zirconia. MATERIALS AND METHODS. Forty zirconia specimens were prepared in the form of rectangular prism. Specimens were divided into four groups (n = 10) according to the number of firing at heating values of porcelain. Color differences and translucency parameter were measured, and X-ray diffraction (XRD) analysis and differential scanning calorimetry (DSC) were performed. Data were analyzed with analysis of variance (ANOVA). RESULTS. There were no statistically significant differences in ∆E, TP, L, a, and b value changes of the zirconia specimens as a result of repetitive firing processes (P>.05). CONCLUSION. Although additional firing processes up to 4 increase peak density in thermal analysis, additional firing processes up to 4 times can be applied safely as they do not result in a change in color and phase character of zircon frameworks.

EVALUATION OF THE FINITE ELEMENT MODELING OF A SPOT WELDED REGION FOR CRASH ANALYSIS

  • Song, J.H.;Huh, H.;Kim, H.G.;Park, S.H.
    • International Journal of Automotive Technology
    • /
    • v.7 no.3
    • /
    • pp.329-336
    • /
    • 2006
  • The resistance spot-welded region in most current finite element crash models is characterized as a rigid beam at the location of the welded spot. The region is modeled to fail with a failure criterion which is a function of the axial and shear load at the rigid beam. The calculation of the load acting on the rigid beam is important to evaluate the failure of the spot-weld. In this paper, numerical simulation is carried out to evaluate the calculation of the load at the rigid beam. At first, the load on the spot-welded region is calculated with the precise finite element model considering the residual stress due to the thermal history during the spot welding procedure. And then, the load is compared with the one obtained from the model used in the crash analysis with respect to the element size, the element shape and the number of imposed constraints. Analysis results demonstrate that the load acting on the spot-welded element is correctly calculated by the change of the element shape around the welded region and the location of welded constrains. The results provide a guideline for an accurate finite element modeling of the spot-welded region in the crash analysis of vehicles.

Analysis of control rod driving mechanism nozzle rupture with loss of safety injection at the ATLAS experimental facility using MARS-KS and TRACE

  • Hyunjoon Jeong;Taewan Kim
    • Nuclear Engineering and Technology
    • /
    • v.56 no.6
    • /
    • pp.2002-2010
    • /
    • 2024
  • Korea Atomic Energy Research Institute (KAERI) has operated an integral effect test facility, the Advanced Thermal-Hydraulic Test Loop for Accident Simulation (ATLAS), with reference to the APR1400 (Advanced Power Reactor 1400) for tests for transient and design basis accidents simulation. A test for a loss of coolant accident (LOCA) at the top of the reactor pressure vessel (RPV) had been conducted at ATLAS to address the impact of the loss of safety injections (LSI) and to evaluate accident management (AM) actions during the postulated accident. The experimental data has been utilized to validate system analysis codes within a framework of the domestic standard problem program organized by KAERI in collaboration with Korea Institute of Nuclear Safety. In this study, the test has been analyzed by using thermal-hydraulic system analysis codes, MARS-KS 1.5 and TRACE 5.0 Patch 6, and a comparative analysis with experimental and calculation results has been performed. The main objective of this study is the investigation of the thermal-hydraulic phenomena during a small break LOCA at the RPV upper head with the LSI as well as the predictability of the system analysis codes after the AM actions during the test. The results from both codes reveal that overall physical behaviors during the accident are predicted by the codes, appropriately, including the excursion of the peak cladding temperature because of the LSI. It is also confirmed that the core integrity is maintained with the proposed AM action. Considering the break location, a sensitivity analysis for the nodalization of the upper head has been conducted. The sensitivity analysis indicates that the nodalization gave a significant impact on the analysis result. The result emphasizes the importance of the nodalization which should be performed with a consideration of the physical phenomena occurs during the transient.