• Journal of Mechanical Science and Technology
• /
• 제19권spc1호
• /
• pp.461-472
• /
• 2005

A formulation for flexible multibody systems (MBS) is investigated, where rigid MBS substructures are coupled with flexible bodies described by a nonlinear finite element (FE) approach. Several aspects that turned out to be crucial for the presented approach are discussed. The system describing equations are given in differential algebraic form (DAE), where many sophisticated solvers exist. In this paper the performance of several solvers is investigated regarding their suitability for the application to the usually highly stiff DAE. The substructures are connected with each other by nonlinear algebraic constraint equations. Further, partial derivatives of the constraints are required, which often leads to extensive algebraic trans-formations. Handcoding of analytically determined derivatives is compared to an approach utilizing algorithmic differentiation.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2007년도 춘계 학술대회논문집
• /
• pp.91-94
• /
• 2007

A GUI based pre/post processor program, which is based on the MFC and OpenGL library in the Windows O/S, hee been developed for NUFLEX Using this program, users are able to generate and modify structured or unstructured grid geometries, set all the parameters for the solver, and observe the results of the simulation in graphic view by vector or scalar plots. The mesh geometry data can be imported from or exported to other programs by supporting functions for reading from and writing to CGNS data format files.

• Journal of Advanced Marine Engineering and Technology
• /
• 제24권5호
• /
• pp.33-41
• /
• 2000

Three dimensional flow fields around passenger car body was computed by PAM-FLOW, well-known and validated computer program for thermal and fluid analysis. Regarding the computational method, a Navier-Stokes solver based on finite element method with various turbulent models and adaptive grid technique (H-refinement)was adopted. The results were physically reasonable and compared with experimental data, giving good agreement. It was found that three dimensional flow simulation with H-refinement technique had potential for prediction of low fie이 around vehicle and the ability to predict vortex in the wake, which is vital for CFD to be used for automobile aerodynamic calculation.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2002년도 춘계학술대회 논문집
• /
• pp.145-148
• /
• 2002

A three dimensional FEM system for supporting the design procedure of metal forming processes has been developed by integrating the FEA programs md the CAD interface modules. The system is developed to reduce the time, the extorts and the cost for establishing the successful metal forming processes for the given products. To promote practical application by engineers in medium-size enterprises who do not know much about theories of the FEA and others, various databases and intelligent interfacing modules have been developed in PC environment.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 1997년도 추계학술대회논문집
• /
• pp.17-23
• /
• 1997

In the two-dimensional Finite Element Method for forming simulation, mesh generation and remeshing process are very significant. In this paper, using the modified splitting mesh generation algorithm, we can overcome the limitation of existing techniques and acquire mesh, which has optimal mesh density. A modified splitting algorithm for automatically generating quadrilateral mesh within a complex domain is described. Unnecessary meshing process for density representation is removed. Especially, during the mesh generation with high gradient density like as shear band representation, the modified mesh density scheme, which will generate quadrilateral mesh with the minimized error, which takes effect on FEM solver, is introduced.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2014년도 추계학술대회 논문집
• /
• pp.569-569
• /
• 2014

The interior vehicle noise due to the exterior aerodynamic field is an important topic in the acoustic design of a car. The air flow detached from the A-pillar and impacting the side windows are of particular interest as they are located close to the driver / passenger and provides a lower insulation index than the trimmed car body parts. This paper presents a numerical analysis method for a simplified vehicle model. The internal air cavity including trim component are included in the simulation. The car body includes the windshield and two side windows. The body is made of aluminum and trimmed with porous layers. The methodology proposed in this paper relies on two steps: the first step involves the computation of the exterior flow and turbulence induced non-linear acoustic field using CFD Code. The second step consists in the computation of the vibro-acoustic transmission through the window using the finite element vibro-acoustic solver Actran.

• 한국자동차공학회논문집
• /
• 제10권2호
• /
• pp.132-140
• /
• 2002

A momentum backpropagation neural network is prepared to carry out real-time dynamics simulations of a passenger car. A full-car model of fifteen degrees of freedom was constructed for vehicle dynamics analysis. Human body dynamics analysis was performed for a male driver(50 percentile Korean adult) restrained by a three point seatbelt system. The trained data using the neural network were obtained using a dynamic solver, ADAMS . The neural network were formed based on the dynamics of the simulator. The optimized hidden layer was obtained by selecting the optimal number of hidden layers. The driving scenario including bump passing and lane changing has been used for the estimation of the proposed neural network. A comparison between the trained data and neural network outputs is found to be satisfactory to show the applicability of the suggested approach.

• International Journal of Aeronautical and Space Sciences
• /
• 제2권2호
• /
• pp.28-38
• /
• 2001

A numerical method for the assessment and correction of tunnel wall interference effects on forced-oscillation testing is presented. The method is based on the wall pressure signature method using computed wall pressure distributions. The wall pressure field is computed using unsteady three-dimensional full Navier-Stokes solver for a 70-degree pitching delta wing in a wind tunnel. Approximately-factorized alternate direction implicit (AF-ADI) scheme is advanced in time by solving block tri-diagonal matrices. The algebraic Baldwin-Lomax turbulence, model is included to simulate the turbulent flow effect. Also, dual time sub-iteration with, local, time stepping is implemented to improve the convergence. The computed wall pressure field is then imposed as boundary conditions for Euler re-simulation to obtain the interference flow field. The static computation shows good agreement with experiments. The dynamic computation demonstrates reasonable physical phenomena with a good convergence history. The effects of the tunnel wall in upwash and blockage are analyzed using the computed interference flow field for several reduced frequencies and amplitudes. The corrected results by pressure signature method agree well with the results of free air conditions.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
• /
• pp.439-442
• /
• 2005

In this paper, we propose a cell structure to improve transmittance and aperture ratio with FFS(Fringe Field Switching) mode. As an exemplary cell, we selected conventional FFS cell with dual domain. Optical transmittance and aperture ratio were calculated with 3DFEM numerical solver, TechWiz LCD. The simulation results revealed that transmission increases by more than 10% while aperture ratio increases by more than 4% when compared to conventional FFS mode.

• 한국해양공학회지
• /
• 제21권3호
• /
• pp.16-25
• /
• 2007

A comparative study on the turbulent flaw simulation and the potential flaw analysis has been performed. A law Mach number preconditioned Navier-Stokes solver, using the multi-block grid method and a panel method based on the velocity potential, have been developed and validated by comparison to the experimental data. The present numerical analysis methods are applied to the ground effect problem around the NACA 4412 airfoil. It has been confirmed that the potential flaw analysis on the ground effect, using the image method, is consistent, to some degree, with the viscous calculations for high Reynolds number flows.