• Title/Summary/Keyword: Coupled-field analysis

Search Result 531, Processing Time 0.027 seconds

A Study on the Estimation of Underground Parameters by Coupling of Finite and Boundary Elements (유한요소 - 경계요소 조합에 의한 지반매개변수 추정에 관한 연구)

  • 김문겸;장정범;오금호
    • Proceedings of the Computational Structural Engineering Institute Conference
    • /
    • 1995.04a
    • /
    • pp.28-34
    • /
    • 1995
  • Behavior of underground structural systems is usually complicated because of various unknown parameters. In order to construct those structural systems safely and economically, exact identification of the system parameters and accurate analysis of the system behaviors are essentially required. In this study, a forward analysis program, which is able to eliminate numerical errors due to far field boundary effect, is developed by coupling finite and boundary elements. In this coupled analysis, boundary elements are used in the semi-infinite domain where stress variation is small, and finite elements in the stress concentration region where material nonlinearity should be considered. Then, a back analysis program which can identify the system parameters is developed using the direct method to be combined with the forward analysis program. The elastic modulus and initial stress, which are most important in the description of the behavior of underground structures, are taken as the system parameters. A simple example is examined 0 show that the method can be used effectively.

  • PDF

Finite element analysis for laterally loaded piles in sloping ground

  • Sawant, Vishwas A.;Shukla, Sanjay Kumar
    • Coupled systems mechanics
    • /
    • v.1 no.1
    • /
    • pp.59-78
    • /
    • 2012
  • The available analytical methods of analysis for laterally loaded piles in level ground cannot be directly applied to such piles in sloping ground. With the commercially available software, the simulation of the appropriate field condition is a challenging task, and the results are subjective. Therefore, it becomes essential to understand the process of development of a user-framed numerical formulation, which may be used easily as per the specific site conditions without depending on other indirect methods of analysis as well as on the software. In the present study, a detailed three-dimensional finite element formulation is presented for the analysis of laterally loaded piles in sloping ground developing the 18 node triangular prism elements. An application of the numerical formulation has been illustrated for the pile located at the crest of the slope and for the pile located at some edge distance from the crest. The specific examples show that at any given depth, the displacement and bending moment increase with an increase in slope of the ground, whereas they decrease with increasing edge distance.

3D Transient Analysis of Linear Induction Motor Using the New Equivalent Magnetic Circuit Network Method

  • Jin Hur;Kang, Gyu-Hong;Hong, Jung-Pyo
    • KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
    • /
    • v.3B no.3
    • /
    • pp.122-127
    • /
    • 2003
  • This paper presents a new time-stepping 3-D analysis method coupled with an external circuit with motion equation for dynamic transient analysis of induction machines. In this method, the magneto-motive force (MMF) generated by induced current is modeled as a passive source in the magnetic equivalent network. So, by using only scalar potential at each node, the method is able to analyze induction machines with faster computation time and less memory requirement than conventional numerical methods. Also, this method is capable of modeling the movement of the mover without the need for re-meshing and analyzing the time harmonics for dynamic characteristics. From comparisons between the results of the analysis and the experiments, it is verified that the proposed method is capable of estimating the torque, harmonic field, etc. as a function of time with superior accuracy.

Analysis of Vibration and Electromagnetic Forces on a Generator End-winding for 500 MW Fossil Power Plant (500MW 급 대형 발전기 권선단부의 전자기력과 동특성 해석)

  • 김철홍;주영호
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2001.11b
    • /
    • pp.826-831
    • /
    • 2001
  • Electromagnetic forces generate vibrations in the end-winding of large generators. A finite element analysis using a commercial S/W is performed to calculate electromagnetic force of end-winding in two pole generator for 500 MW fossil power plant. Also, this paper presents analytical and experimental modal analysis results of generator end- winding. Using validated FE model, 3D electromagnetic model which computes the forces on the end-winding is coupled with a 3D mechanical model which calculates the dynamic displacement and stress under electromagnetic forces. These results will be used to evaluate reliability of end-winding and applied to update model.

  • PDF

Analysis of the Effect of Casting Residual Stress on Durability by a Combination of Different Numerical Methods (이종해석 연계 기법을 통한 주조 잔류응력이 내구성에 미치는 영향 분석)

  • Cheon, Jinho;Park, Yongho;Park, Ikmin
    • Korean Journal of Metals and Materials
    • /
    • v.49 no.6
    • /
    • pp.468-473
    • /
    • 2011
  • Determining the residual stress during casting processes is important for evaluating the mechanical properties and strength of materials and to optimize manufacturing conditions. In this study, we propose a field data interface procedure between FDM and FEM in a 3-dimensional space for analyzing the casting process and structural analysis. The casting process was analyzed using FDM and the data of the temperature distribution were converted into a format suitable for FEM analysis to calculate the thermal stress and safety factor by tightening force. The results of the coupled analysis between FDM and FEM showed that casting residual stress is an important factor in predicting life time and evaluating durability.

Effects of Mg on corrosion resistance of Al galvanically coupled to Fe (Fe와 galvanic couple된 알루미늄의 내식성에 미치는 마그네슘의 영향)

  • Hyun, Youngmin;Kim, Heesan
    • Corrosion Science and Technology
    • /
    • v.12 no.1
    • /
    • pp.40-49
    • /
    • 2013
  • Effects of magnesium and pH on corrosion of aluminum galvanically coupled to iron have studied by using potentio- dynamic and static tests for polarization curves, Mott-Schottky test for analysis of semiconductor property, and GD-AES and XPS for film analysis. Pitting potential was sensitive to magnesium as an alloying element but not to pH, while passive current was sensitive to pH but not to magnesium. It was explained with, instead of point defect model (PDM), surface charge model describing that the ingression of chloride depends on the state of surface charge and passive film at film/solution interface is affected by pH. In addition, galvanic current of aluminum electrically coupled to iron was not affected by magnesium in pH 8.4, 0.2M citrate solution but was increased by magnesium at the solution of pH 9.1. The galvanic current at pH 9.1 increased with time at the initial stage and after the exposure of about 200 minute, decreased and stabilized. The behavior of the galvanic current was related with the concentration of magnesium at the surface. It agreed with the depletion of magnesium at the oxide surface by using glow discharge atomic emission spectroscopy (GD-AES). In addition, pitting potential of pure aluminum was reduced in neutral pH solution where chloride ion maybe are competitively adsorbed on pure aluminum. It was confirmed by the exponential decrease of pitting potential with log of [$Cl^-$] around 0.025 M of [$Cl^-$] and linear decrease of the pitting potential. From the above results, unlike magnesium, alloying elements with higher electron negativity, lowering isoelectric point (ISE), are recommended to be added to improve pitting corrosion resistance of aluminum and its alloys in neutral solutions as well as their galvanic corrosion resistance in weakly basic solutions.

Analysis of HEMP Coupling Signal for a Coaxial Cable with Braided Shields (Braided Shield를 가진 동축 케이블의 HEMP 결합 신호 해석)

  • Lee, Jin-Ho;Cho, Jea-Hoon;Kim, Eung-Jo
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
    • /
    • v.22 no.8
    • /
    • pp.790-796
    • /
    • 2011
  • The system which is exposed in the impact range of High-altitude Electromagnetic Pulse(HEMP) may get serious damage because HEMP has a very large electric field value, a very fast rise-time, and so on. Electromagnetic analysis should be performed for signals coupled to the opening or cables of the system prior to derive the system design specifications in order to protect the system against HEMP adequately. In this paper, we analyzed the HEMP coupled signals for the coaxial cable which is generally used to transmit and receive video or RF signals and compared the coupled signal of the one wire with that of the inner conductor of a coaxial cable to confirm the decreased effect of HEMP by the shield. The coaxial cable is analyzed by the external and internal region of the shield separately. For the external region of the coaxial cable, general scattered equation was applied to calculate currents on the surface of the shield and for internal region of the coaxial cable, chain matrix algorithm is used. To verify this paper the analyzed results were compared the results of the existing paper and the two results have good agreements.

Current Status of the Numerical Models for the Analysis of Coupled Thermal-Hydrological-Mechanical Behavior of the Engineered Barrier System in a High-level Waste Repository (고준위폐기물처분장 공학적방벽시스템의 열-수리-역학적 복합거동 해석 모델 개발 현황)

  • Cho, Won-Jin;Kim, Jin Seop;Lee, Changsoo;Choi, Heui-Joo
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
    • /
    • v.10 no.4
    • /
    • pp.281-294
    • /
    • 2012
  • The current status of the computer codes for the analysis of coupled thermal-hydrological-mechanical behavior occurred in a high-level waste repository was investigated. Based on the reported results on the comparison between the predictions using the computer codes and the experimental data from the in-situ tests, the reliability of the existing computer codes was analyzed. The presented codes simulated considerably well the coupled thermal-hydrological-mechanical behavior in the near-field rock of the repository without buffer, but the predictions for the engineered barrier system of the repository located at saturated hard rock were not satisfactory. To apply the current thermal-hydrological-mechanical models to the assessment of the performance of engineered barrier system, a major improvement on the mathematical models which analyze the distribution of water content and total pressure in the buffer is required.

NUMERICAL METHOD FOR TWO-PHASE FLOW ANALYSIS USING SIMPLE-ALGORITHM ON AN UNSTRUCTURED MESH (비정렬격자 SIMPLE 알고리즘기반 이상유동 수치해석 기법)

  • Kim, Jong-Tae;Park, Ik-Kyu;Cho, Hyung-Kyu;Kim, Kyung Doo;Jeong, Jae-Jun
    • Journal of computational fluids engineering
    • /
    • v.13 no.4
    • /
    • pp.86-95
    • /
    • 2008
  • For analyses of multi-phase flows in a water-cooled nuclear power plant, a three-dimensional SIMPLE-algorithm based hydrodynamic solver CUPID-S has been developed. As governing equations, it adopts a two-fluid three-field model for the two-phase flows. The three fields represent a continuous liquid, a dispersed droplets, and a vapour field. The governing equations are discretized by a finite volume method on an unstructured grid to handle the geometrical complexity of the nuclear reactors. The phasic momentum equations are coupled and solved with a sparse block Gauss-Seidel matrix solver to increase a numerical stability. The pressure correction equation derived by summing the phasic volume fraction equations is applied on the unstructured mesh in the context of a cell-centered co-located scheme. This paper presents the numerical method and the preliminary results of the calculations.

Near electromagnetic field analysis of HTS microstrip patch antenna (고온초전도 마이크로스트립 패치 안테나의 근거리 전자장 해석)

  • 정동철;허원일;김민기;한태희;한병성
    • Electrical & Electronic Materials
    • /
    • v.9 no.8
    • /
    • pp.783-788
    • /
    • 1996
  • In this paper, the high-$T_c$ , superconductor (HTS) microstrip patch antenna which is directly coupled to a microstrip transmission line is designed and the numerical solution which evaluate near electromagnetic field of HTS antenna is presented. This solution uses the interpolation function with the vector edge triangular element. The advantage of this element is the elimination of spurious solutions attributed to the lack of enforcement of the divergence condition. The results of this method have a good agreement with $TM_10$ mode in HTS microstrip patch antenna and show that the computation of resonant length considering the fringing capacitance effect at radiating edge are proper.

  • PDF