• Title/Summary/Keyword: Mass lumping

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The dynamic explicit analysis of auto-body panel stamping process and investigating parameter affects of dynamic analysis (차체판넬 스템핑공정의 동적 외연적해석과 동적해석에 미치는 영향인자 분석)

  • Jung, Dong-Won
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.22 no.2
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    • pp.380-390
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    • 1998
  • In the present work a finite element formulation using dynamic explicit time integration scheme is used for numerical analysis of auto-body panel stamping processes. The lumping scheme is employed for the diagonal mass matrix and linearizing dynamic formulation. A contact scheme is developed by combining the skew boundary condition and direct trial-and-error method. In this work, for economic analysis the faster punch velocity and the mass scaling method are introduced. To investigate the effects of punch velocity and mass scaling, the various values of punch velocity and the various mass scalings are used for numerical analysis. Computations are carried out for analysis of complicated auto-body panel stamping processes such as forming of an oil pan and a fuel tank.

A MASS LUMPING AND DISTRIBUTING FINITE ELEMENT ALGORITHM FOR MODELING FLOW IN VARIABLY SATURATED POROUS MEDIA

  • ISLAM, M.S.
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.20 no.3
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    • pp.243-259
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    • 2016
  • The Richards equation for water movement in unsaturated soil is highly nonlinear partial differential equations which are not solvable analytically unless unrealistic and oversimplifying assumptions are made regarding the attributes, dynamics, and properties of the physical systems. Therefore, conventionally, numerical solutions are the only feasible procedures to model flow in partially saturated porous media. The standard Finite element numerical technique is usually coupled with an Euler time discretizations scheme. Except for the fully explicit forward method, any other Euler time-marching algorithm generates nonlinear algebraic equations which should be solved using iterative procedures such as Newton and Picard iterations. In this study, lumped mass and distributed mass in the frame of Picard and Newton iterative techniques were evaluated to determine the most efficient method to solve the Richards equation with finite element model. The accuracy and computational efficiency of the scheme and of the Picard and Newton models are assessed for three test problems simulating one-dimensional flow processes in unsaturated porous media. Results demonstrated that, the conventional mass distributed finite element method suffers from numerical oscillations at the wetting front, especially for very dry initial conditions. Even though small mesh sizes are applied for all the test problems, it is shown that the traditional mass-distributed scheme can still generate an incorrect response due to the highly nonlinear properties of water flow in unsaturated soil and cause numerical oscillation. On the other hand, non oscillatory solutions are obtained and non-physics solutions for these problems are evaded by using the mass-lumped finite element method.

A Study on Wave Transformation Analysis using Higher-Order Finite Element (고차유한요소의 파랑변형해석에의 적용에 관한 소고)

  • Jung, Tae-Hwa;Lee, Jong-In;Kim, Young-Taek;Ryu, Yong-Uk
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.21 no.2
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    • pp.108-116
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    • 2009
  • The present study introduces a Legendre interpolation function which is capable of analyzing wave transformation effectively in a finite element method. A Lagrangian interpolation function has been mostly used for a finite element method with a higher-order interpolation function. Although this function has an advantage of giving an accurate result with less number of elements, simulation time increases. Calculation time can be reduced by mass lumping, whereas the accuracy of solution is lowered. In this study, we introduce a modified Lagrangian interpolation function, Legendre cardinal interpolation, which can reduce simulation time with keeping up favorable accuracy. Through various numerical simulations using a Boussinesq equations model, the superiority of the Legendre cardinal interpolation function to a Lagrangian interpolation function was shown.

Wiggle-free Finite Element Model for extended Boussinesq equations (확장형 Boussinesq FEM model의 수치진동오차 개선)

  • Woo, Seung-Buhm;Choi, Young-Kwang;Gonzalez-Ondina, Jose M.
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.22 no.1
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    • pp.47-57
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    • 2010
  • Subgrid scale stabilization method is applied to Woo and Liu(2004)'s extended Boussinesq FEM numerical model to eliminate the 2dx wiggles. In order to optimize the computational efficiency, Hessian operator is introduced and the matrix of velocity vector is combined to one matrix for solving matrix equations. The mass lumping technique is also applied to the matrix equations of auxiliary variables. The newly developed code is applied to simulate Vincent and Briggs(1989)' wave transformation experiments and the results show that the numerical solution is almost wiggle-free and it matches very well with experimental data. Due to improvement of computational efficiency and wiggle reduction, it is plausible to apply this model to a realistic problem such as harbor oscillation problems.

Analysis of Driving Characteristics by Putting Voltage of Charged Particle Type Display Device (대전입자형 디스플레이 소자의 충전전압에 따른 구동특성 분석)

  • Kim, Jin-Sun;Kim, Young-Cho
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.25 no.1
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    • pp.48-52
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    • 2012
  • The charged particle type display device is a kind of the reflectivity type display and shows an image by absorption and reflection of external light source. The charged particle is important factor for driving of the display and quantity of charge per mass of the charged particle determines the driving voltage, contrast ratio, response time, etc. But it is easy for the charged particles to be damaged in the putting process of the display and the damages cause lumping phenomenon of the charged particles. Because the lumping phenomenon makes high driving voltage, low quality of optical properties, short life time, etc, so the charged particles must be filled by stable putting methods. In this paper, we filled the charged particles into the panels by electric fields to improve the electrical and optical characteristics of the display. Also, we analyzed the driving characteristics of the charged particles according to the applied putting voltages.

A Dynamic-explicit Finite Element Analysis for Hydro-forming Process (Hydro-forming 공정을 위한 동적-외연적 유한요소해석)

  • Jung, D.W.;Hwang, J.S.
    • Journal of Power System Engineering
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    • v.8 no.3
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    • pp.23-29
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    • 2004
  • In this paper, a finite element formulation using dynamic-explicit time integration scheme is used for numerical analysis of Hydro-forming processes. The lumping scheme is employed for the diagonal mass matrix and dynamic explicit formulation. Hydro-forming process for auto-body panel forming is analyzed by using dynamic-explicit finite element method. Further, the simulated results of the Hydro-forming processes are shown and discussed. Its application is being increased especially in the automotive industrial area for the cost reduction, weight saving, and improvement of strength.

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A Study of Auto-body Panel Correction of Forming Analysis that Use Dynamic-extensive Finite Element Method (동적-외연적 유한요소법을 이용한 차체 판넬 성형해석에 관한 연구)

  • Jung Dong Won;Hwang Jae Sin
    • Journal of the Korean Society for Precision Engineering
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    • v.21 no.10
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    • pp.115-126
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    • 2004
  • In the present work a finite element formulation using dynamic-explicit time integration scheme is used for numerical analysis of auto-body panel stamping processes. The lumping scheme is employed for the diagonal mass matrix and dynamic explicit formulation. Analyzed auto-body panel stomping process correction of forming using software called Dynaform using dynamic extensive method. Further, the simulated results for the auto-body panel stamping processes are shown and discussed. Its application is being increased especially in the automotive industrial area for the cost reduction, weight saving, and improvement of strength.

A Study of Forming Analysis by using Dynamic-explicit Finite Element Method in Can-container Production Process of Multi-Stage Assembly (Multi-Stage 조립품인 캔-용기 생산 공정에서 동적-외연적 유한요소법을 이용한 성형해석에 관한 연구)

  • Jung, Dong-Won;Hwang, Jae-Sin
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.3 no.3
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    • pp.58-63
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    • 2004
  • In the present work a finite element formulation using dynamic-explicit time integration scheme is used for numerical analysis of multi-stage stamping processes. The lumping scheme is employed for the diagonal mass matrix and dynamic explicit formulation Multi-Stage stamping is analyzed by using dynamic-explicit finite element method. Further, the simulated results for the panel stamping processes are shown and discussed. Its application is being increased especially in the stamping industrial area for the cost reduction, weight saving, and improvement of strength.

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A Study of Forming Analysis by using Dynamic-Explicit Finite Element Method in Auto-Body Stamping (차체 판넬 스템핑 공정에서 동적-외연적 유한요소법을 이용한 성형해석에 관한 연구)

  • Jung, Dong-Won;Hwang, Jae-Sin
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.3 no.4
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    • pp.63-72
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    • 2004
  • In this paper, a finite element formulation using dynamic-explicit time integration scheme is used for numerical analysis of auto-body panel stamping processes. The lumping scheme is employed for the diagonal mass matrix and dynamic explicit formulation. Auto-body panel forming is analyzed by using dynamic-explicit finite element method. Further, the simulated results of the auto-body panel stamping processes are shown and discussed. Its application is being increased especially in the stamping industrial area for the cost reduction, weight saving, and improvement of strength.

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Multilphase Flow in Heterogeneous Groundwater Systems (이질적 지하수계에서 다상흐름)

  • 최우희;선우중호
    • Proceedings of the Korea Water Resources Association Conference
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    • 1992.07a
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    • pp.504-505
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    • 1992
  • 이질적 지하수계에서 물과 DNAPL(dense nenaqueous phase liquids)의 동시적 움직임을 연구하기 위한 수직단면 2차원 유한요소모형이 개발되었다. 물과 DNAPL의 흐름방정식은 비포화 영역 뿐만 아니라 연속적으로 모사하기 위하여 유체 압력항으로 형식화하였다. 이들 지배방정식의 비선형성을 다루기 위하여 mass lumping과 수정 Picard 기법이 이용되었고, 수치진동과 분산을 줄이기 위하여 전방가중이 사용되었다. 본 수치모형의 검증은 중력과 모세관 효과를 모두 고려한 McWhoter와 Sudana(1990)의 해석해와 비교함으로써 행하였다. 또한 수치모형의 타당성 검토의 연구는 진행되고 있다.

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