• Title/Summary/Keyword: User Subroutine

Search Result 141, Processing Time 0.029 seconds

Study on the Void Growth and Coalescence in F.C.C. Single Crystals (F.C.C. 단결정재에서 기공의 성장과 합체에 관한 연구)

  • Ha, Sang-Yul;Kim, Ki-Tae
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.32 no.4
    • /
    • pp.319-326
    • /
    • 2008
  • In this study, we investigate the deformation behavior of F.C.C. single crystals containing micro- or submicron-sized voids by using three dimensional finite element methods. The locally homogeneous constitutive model for the rate-dependent crystal plasticity is integrated based on the backward Euler method and implemented into a finite element program (ABAQUS) by means of user-defined subroutine (UMAT). The unit cell analysis has been investigated to study the effect of stress triaxiality and crystallographic orientations on the growth and coalescence of voids in F.C.C. single crystals.

Simulation of Combustion Phenomena at Multiple Injection in HSDI Diesel Engine Using Modified Two Dimensional Flamelet Combustion Model (개량된 2 차원 화염편 연소 모델을 이용한 고속 직분식 엔진에서의 다단 분사시 연소 현상 해석)

  • Lim, Jae-Man;Min, Kyoung-Doug
    • Proceedings of the KSME Conference
    • /
    • 2007.05b
    • /
    • pp.3300-3305
    • /
    • 2007
  • Ignition delay of second injection of HSDI diesel engine was usually much shorter than that of first injection. It is due to the interaction between radicals generated during the combustion process, and mixed gas of second injection. In this paper, To analyze combustion phenomena of multiple injection mode in HSDI diesel engine effectively, two-dimensional flamelet combustion model was modified. To reduce calculation time, two-dimensional flamelet equations were only applied near stoichiometric region. If this region was ignited, species and temperature of other region were changed to the steady-state solutions of one dimensional flamelet equations. By this method calculation time for solving flamelet equations was reduced to 20 percents, thought the results were almost same. Modified flamelet combustion model was coupled to commercial CFD code interactively using user subroutine.

  • PDF

Finite Element Analysis of Superplastic Forming Considering Grain Growth-II. Superplastic Behavior of AZ31 Alloy (결정립 성장을 고려한 초소성 성형공정의 유한요소해석-II. AZ31 합금의초소성 거동)

  • Kim, Y.G.;Kim, S.H.;Kwon, Y.N.;Kim, Y.H.
    • Transactions of Materials Processing
    • /
    • v.21 no.7
    • /
    • pp.403-411
    • /
    • 2012
  • The aim of this study was to predict the results of superplastic forming on magnesium alloy, by considering the grain growth using numerical simulations. Superplastic behavior of AZ31 alloy was investigated through a set of uniaxial tensile tests that cover the forming temperatures ranges from 375 to $450^{\circ}C$. All the material parameters in the model, which consists of a constitutive equation and a grain growth equation, were determined. The model was used in the finite element analysis for uniaxial tensile tests and superplastic blow forming, through a user-subroutine available within ABAQUS. From this study, the effect of grain growth during forming was evaluated. The results show that it is essential to include the effect of grain growth in predicting the behavior during superplastic forming of this magnesium alloy.

Nonlinear Analysis of RC Slabs based on the Strain Decomposition Technique (변형률 분할기법을 이용한 철근콘크리트 슬래브의 비선형 유한요소해석)

  • Chung Won-Seok;Woo Young-Jin
    • Proceedings of the Computational Structural Engineering Institute Conference
    • /
    • 2005.04a
    • /
    • pp.433-439
    • /
    • 2005
  • This paper describes a reinforced concrete crack model, which utilizes a strain decomposition technique. The strain decomposition technique enables the explicit inclusion of physical behavior across the cracked concrete surface such as aggregate interlock and dowel action rather than intuitively defining the shear retention factor. The proposed concrete crack model is integrated into the commercial finite element software ABAQUS shell elements through a user-supplied material subroutine. The FE results have been compared to experimental results reported by other researchers. The proposed bridge FE model is capable of predicting the initial cracking load level, the ultimate load capacity, and the crack pattern with good accuracy.

  • PDF

Large Deformation and Inelastic Analysis of API X80 Steel (API X80 강의 대변형 비선형 해석)

  • Lee, Seung-Jung;Yoon, Young-Cheol;Zi, Goang-Seup;Cho, Woo-Yeon;Yu, Seong-Mun
    • Proceedings of the Computational Structural Engineering Institute Conference
    • /
    • 2009.04a
    • /
    • pp.375-378
    • /
    • 2009
  • 본 논문에서는 API X80 강의 대변형 비선형 거동을 모사하기 위해 비선형 유한요소해석을 수행하였다. 고강도 강재의 거동을 모사하기 위해 GTN(Gurson-Tvergaad-Needleman) 모델을 사용하였으며, 비선형 해석을 위해 범용 유한요소해석 프로그램인 ABAQUS와 User Subroutine의 사용자 재료모델(UMAT)을 연계하여 사용하였다. 해석결과와 인장실험의 결과와의 비교를 통해 GTN 모델에서 사용되는 재료모델 상수를 도출하였고, 도출된 값들은 개발된 사용자 재료모델과 함께 API X80 강의 각종 실험을 모사하고 대변형 상황의 강재 파이프의 거동을 분석하는데 유용하게 사용될 수 있다.

  • PDF

Coupled Analysis of Hydrogen Transport Within ABAQUS (ABAQUS 를 이용한 수소확산 해석)

  • Oh, Chang-Sik;Kim, Yun-Jae
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.33 no.6
    • /
    • pp.600-606
    • /
    • 2009
  • In this paper, the coupled model with hydrogen transport and elasto-plasticity behavior is introduced. This model is implemented to the general-purpose FE code, ABAQUS, via the user-defined subroutine UMAT and UMATHT. In UMAT, the spatial gradients of hydrostatic stress and hydrogen induced deformation are calculated, and then are passed into UMATHT. Heat transfer equation within UMATHT is substituted by hydrogen transport equation including the effects of stress states and strain hardening. To validate this model, the finite element analyses coupled with hydrogen transport and mechanical loading are performed for the boundary layer specimens with low and high strength steel properties. The FE results are compared with the previous studies by Taha and Sofronis (2001).

NUMERICAL STUDY OF STREAM REFORMER AND PRECONVERTER FOR MCFC (MCFC용 개질기 및 프리컨버터의 수치연구)

  • Byun, Do-Hyun;Sohn, Chang-Hyun
    • Journal of computational fluids engineering
    • /
    • v.16 no.1
    • /
    • pp.42-47
    • /
    • 2011
  • In this paper, various operating parameters of stream reforming process from methane in stream reformer and preconverter for MCFC is studied by numerical method. Commercial code is used to simulated the porous catalyst with user subroutine to model three dominant chemical reactions which are Stream Reforming(SR), Water-Gas Shift(WGS), and Direct Stram Reforming(DSR). The hydrogen production is tested with different wall temperature and different reactor shapes. The calculated results of the concentration of hydrogen in stream reformer are very well consistent with experimental results. This numerical study gives the design reactor wall temperature condition and size of reactor to satisfy the required fuel conversion.

Static and Dynamic Analysis of Wrinkled Membranes (주름이 있는 막재료의 정적 및 동적 해석)

  • Woo, Kyeong-Sik
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.33 no.11
    • /
    • pp.15-23
    • /
    • 2005
  • In this paper, the static and dynamic behavior of partly wrinkled membrane was studied. Membrane finite elements were used in the analysis and the wrinkling in the element was accounted for by a penalty-parameter material modeling which was implemented as a user subroutine to ABAQUS. The wrinkle algorithm was applied to a corner-loaded square membrane to investigate the effect of wrinkling on the static and dynamic behavior.

Three dimensional finite elements modeling of FGM plate bending using UMAT

  • Messaoudi, Khalid;Boukhalfa, Abdelkrim;Beldjelili, Youcef
    • Structural Engineering and Mechanics
    • /
    • v.66 no.4
    • /
    • pp.487-494
    • /
    • 2018
  • The purpose of the present paper is to study the bending and free vibration of Functionally Graded Material (FGM) plate using user-defined material subroutine on the finite element software ABAQUS. The FGM plate is simply supported and subjected to sinusoidal and uniform load. The Poisson's ratio is kept constant. The results obtained compared to those available in the literature show the convergence, the exactitude and the efficiency of the method used with various power index of the materials.

A study on the Heat Transfer Performance according to Ground Heat Exchanger Types (지중열교환기의 종류에 따른 열전달 성능에 관한 연구)

  • Hwang, SuckHo;Song, Doosam
    • KIEAE Journal
    • /
    • v.10 no.4
    • /
    • pp.75-80
    • /
    • 2010
  • Generally, ground-source heat pump (GSHP) systems have a higher performance than conventional air-source systems. However, the major fault of GSHP systems is their expensive boring costs. Therefore, it is important issue that to reduce initial cost and ensure stability of system through accurate prediction of the heat extraction and injection rates of the ground heat exchanger. Conventional analysis methods employed by line source theory are used to predict heat transfer rate between ground heat exchanger and soil. Shape of ground heat exchanger was simplified by equivalent diameter model, but these methods do not accurately reflect the heat transfer characteristics according to the heat exchanger geometry. In this study, a numerical model that combines a user subroutine module that calculates circulation water conditions in the ground heat exchanger and FEFLOW program which can simulate heat/moisture transfer in the soil, is developed. Heat transfer performance was evaluated for 3 different types ground heat exchanger(U-tube, Double U-tube, Coaxial).