• Title, Summary, Keyword: Coupled analysis framework

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Coupled Analysis of Thermo-Fluid-Flexible Multi-body Dynamics of a Two-Dimensional Engine Nozzle

  • Eun, WonJong;Kim, JaeWon;Kwon, Oh-Joon;Chung, Chanhoon;Shin, Sang-Joon;Bauchau, Olivier A.
    • International Journal of Aeronautical and Space Sciences
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    • v.18 no.1
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    • pp.70-81
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    • 2017
  • Various components of an engine nozzle are modeled as flexible multi-body components that are operated under high temperature and pressure. In this paper, in order to predict complex behavior of an engine nozzle, thermo-fluid-flexible multi-body dynamics coupled analysis framework was developed. Temperature and pressure on the nozzle wall were obtained by the steady-state flow analysis for a two-dimensional nozzle. The pressure and temperature-dependent material properties were delivered to the flexible multi-body dynamics analysis. Then the deflection and strain distribution for a nozzle configuration was obtained. Heat conduction and thermal analyses were done using MSC.NASTRAN. The present framework was validated for a simple nozzle configuration by using a one-way coupled analysis. A two-way coupled analysis was also performed for the simple nozzle with an arbitrary joint clearance, and an asymmetric flow was observed. Finally, the total strain result for a realistic nozzle configuration was obtained using the one-way and two-way coupled analyses.

Strongly-coupled Finite Element Method Approach to Multi-scale Modelingof Polycrystalline Solids (유한요소법을 이용한 다결정 고체의 복합스케일 모델링)

  • Han Tong-Seok;Dawson Paul R.
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.531-534
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    • 2006
  • A multi-scale (macro-micro) finite element framework for analysis of polycrystalline solids is suggested. The proposed frame work is strongly-coupled in a sense that the two scale calculation is performed at the same time. The issue of averaging micro-scale material stress and stiffness is addressed and a strategy is proposed. The proposed framework is implemented and applied to two examples having different geometries and loading modes. It is concluded that the proposed multi-scale framework can be used for more detailed and accurate analysis compared with the single-scale finite element analysis.

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Modeling of coupled THMC processes in porous media

  • Kowalsky, Ursula;Bente, Sonja;Dinkler, Dieter
    • Coupled systems mechanics
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    • v.3 no.1
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    • pp.27-52
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    • 2014
  • For landfill monitoring and aftercare, long-term prognoses of emission and deformation behaviour are required. Landfills may be considered as heterogeneous porous soil-like structures, in which flow and transport processes of gases and liquids interact with local material degradation and mechanical deformation of the solid skeleton. Therefore, in the framework of continuous porous media mechanics a model is developed that permits the investigation of coupled mechanical, hydraulical and biochemical processes in municipal solid waste landfills.

Stress-Pore Pressure Coupled Finite Element Modeling of NATM Tunneling (NATM 터널의 응력-간극수압 연계 유한요소모델링)

  • Yoo, Chung-Sik;Kim, Sun-Bin
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.189-198
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    • 2006
  • This paper concerns the finite element (FE) modeling approach for NATM tunneling in water bearing ground within the framework of stress-pore pressure coupled analysis. Fundamental interaction mechanism of ground and groundwater lowering was first examined and a number of influencing factors on the results of coupled FE analysis were identified. A parametric study was then conducted on the influencing factors such as soil-water characteristics, location of hydraulic boundary conditions, the way of modeling drainage flow, among others. The results indicate that the soil-water characteristics plays the most important role in the tunneling-induced settlement characteristics. Based on the results, modeling guidelines were suggested for stress-pore prssure coupled finite element modeling of NATM tunneling.

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Implementation and Performance Analysis of SOA Model using Service Platform for .NET Framework (.NET Framework를 서비스 플랫폼으로 사용한 SOA모델 구현 및 성능분석)

  • Lee, Seong-Kyu;Jin, Chan-Uk;Kim, Tai-Suk
    • Journal of the Korea Society for Simulation
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    • v.16 no.4
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    • pp.33-41
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    • 2007
  • Service-Oriented Architecture(SOA) define the interaction method between two computing entities that one entity performs a unit task instead of another entity. This, unit task, is called "Service" and interaction of these services should have independency and loosely coupled task. The effect of SOA's main functions such as loosely coupled task and independent interoperability with influence the possibility of flexible message communication between different way and different users. In this article, we analyzed the performance about system stabilization between general web service and SOA based application that implemented through WCF based messaging framework using .NET Framework and integrated data presentation method. As the result of test, we confirmed that SOA environment using WCF have more advantages.

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High-frequency force balance technique for tall buildings: a critical review and some new insights

  • Chen, Xinzhong;Kwon, Dae-Kun;Kareem, Ahsan
    • Wind and Structures
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    • v.18 no.4
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    • pp.391-422
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    • 2014
  • The high frequency force balance (HFFB) technique provides convenient measurements of integrated forces on rigid building models in terms of base bending moments and torque and/or base shear forces. These base moments or forces are then used to approximately estimate the generalized forces of building fundamental modes with mode shape corrections. This paper presents an analysis framework for coupled dynamic response of tall buildings with HFFB technique. The empirical mode shape corrections for generalized forces with coupled mode shapes are validated using measurements of synchronous pressures on a square building surface from a wind tunnel. An alternative approach for estimating the mean and background response components directly using HFFB measurements without mode shape corrections is introduced with a discussion on higher mode contributions. The uncertainty in the mode shape corrections and its influence on predicted responses of buildings with both uncoupled and coupled modal shapes are examined. Furthermore, this paper presents a comparison of aerodynamic base moment spectra with available data sets for various tall building configurations. Finally, e-technology aspects in conjunction with HFFB technique such as web-based on-line analysis framework for buildings with uncoupled mode shapes used in NALD (NatHaz Aerodynamic Loads Database) is discussed, which facilitates the use of HFFB data for preliminary design stages of tall buildings subject to wind loads.

Validation study on numerical simulation of RC response to close-in blast with a fully coupled model

  • Gong, Shunfeng;Lu, Yong;Tu, Zhenguo;Jin, Weiliang
    • Structural Engineering and Mechanics
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    • v.32 no.2
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    • pp.283-300
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    • 2009
  • The characteristic response of a structure to blast load may be divided into two distinctive phases, namely the direct blast response during which the shock wave effect and localized damage take place, and the post-blast phase whereby progressive collapse may occur. A reliable post-blast analysis depends on a sound understanding of the direct blast effect. Because of the complex loading environment and the stress wave effects, the analysis on the direct effect often necessitates a high fidelity numerical model with coupled fluid (air) and solid subdomains. In such a modelling framework, an appropriate representation of the blast load and the high nonlinearity of the material response is a key to a reliable outcome. This paper presents a series of calibration study on these two important modelling considerations in a coupled Eulerian-Lagrangian framework using a hydrocode. The calibration of the simulated blast load is carried out for both free air and internal explosions. The simulation of the extreme dynamic response of concrete components is achieved using an advanced concrete damage model in conjunction with an element erosion scheme. Validation simulations are conducted for two representative scenarios; one involves a concrete slab under internal blast, and the other with a RC column under air blast, with a particular focus on the simulation sensitivity to the mesh size and the erosion criterion.

Simplified formulations for flutter instability analysis of bridge deck

  • Vu, Tan-Van;Kim, Young-Min;Han, Tong-Seok;Lee, Hak-Eun
    • Wind and Structures
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    • v.14 no.4
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    • pp.359-381
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    • 2011
  • This paper deals with the flutter instability problem of flexible bridge decks in the framework of bimodal-coupled aeroelastic bridge system analysis. Based on the analysis of coefficients of the polynomials deduced from the singularity conditions of an integral wind-structure impedance matrix, a set of simplified formulations for calculating the critical wind velocity and coupled frequency are presented. Several case studies are discussed and comparisons with available approximated approaches are made and presented, along with a conventional complex eigenvalue analysis and numerical results. From the results, it is found that the formulas that are presented in this study are applicable to a variety of bridge cross sections that are not only prone to coupled-mode but also to single-mode-dominated flutter.

Stress-Pore Pressure Coupled Finite Element Modeling of NATM Tunneling (NATM 터널의 응력-간극수압 연계 유한요소모델링)

  • Yoo, Chung-Sik;Kim, Sun-Bin
    • Journal of the Korean Geotechnical Society
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    • v.22 no.10
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    • pp.5-20
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    • 2006
  • This paper concerns the finite element (FE) modeling approach for NATM tunneling in water bearing ground within the framework of stress-pore pressure coupled analysis. Fundamental interaction mechanism of ground and groundwater lowering was first examined and a number of influencing factors on the results of coupled FE analysis were identified. A parametric study was then conducted on the influencing factors such as soil-water characteristics, location of hydraulic boundary conditions, the way of modeling drainage flow, among others. The results indicate that the soil-water characteristics play the most important role in the tunneling-induced settlement characteristics. Based on the results, modeling guidelines were suggested for stress-pore pressure coupled finite element modeling of NATM tunneling.

Wind-induced lateral-torsional coupled responses of tall buildings

  • Wu, J.R.;Li, Q.S.;Tuan, Alex Y.
    • Wind and Structures
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    • v.11 no.2
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    • pp.153-178
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    • 2008
  • Based on the empirical formulas for power spectra of generalized modal forces and local fluctuating wind forces in across-wind and torsional directions, the wind-induced lateral-torsional coupled response analysis of a representative rectangular tall building was conducted by setting various parameters such as eccentricities in centers of mass and/or rigidity and considering different torsional to lateral stiffness ratios. The eccentricity effects on the lateral-torsional coupled responses of the tall building were studied comprehensively by structural dynamic analysis. Extensive computational results indicated that the torsional responses at the geometric center of the building may be significantly affected by the eccentricities in the centers of mass and/or rigidity. Covariance responses were found to be in the same order of magnitude as the along-wind or across-wind responses in many eccentricity cases, suggesting that the lateral-torsional coupled effects on the overall wind-induced responses can not be neglected for such situations. The calculated results also demonstrated that the torsional motion contributed significantly to the total responses of rectangular tall buildings with mass and/or rigidity eccentricities. It was shown through this study that the framework presented in this paper provides a useful tool to evaluate the wind-induced lateral-torsional coupled responses of rectangular buildings, which will enable structural engineers in the preliminary design stages to assess the serviceability of tall buildings, potential structural vibration problems and the need for a detailed wind tunnel test.