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RISS 인기검색어
- 검색키워드
- 저자 : 하재선(Jason Har) (검색결과 5 건)
- 무료
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하재선(Jason Har) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.11
This paper presents a newly implemented parallel finite element procedure for contact-impact problems.<br/> Three sub-algorithms are includes in the proposed parallel contact-impact procedure, such as a parallel<br/> Belytschko-Lin-Tsay (BLT) shell element generation, a parallel explicit time integration scheme, and a<br/> parallel contact search algorithm based on the master slave slide-line algorithm. The underlying focus of the<br/> algorithms is on its effectiveness and efficiency for inclusion in future finite element systems on parallel<br/> computers. Throughout this research, a prototype code, named GT-PARADYN, is developed on the IBM SP2,<br/> a distributed-memory computer. Some numerical examples are provided to demonstrate the timing results of<br/> the procedure, discussing the accuracy and efficiency of the code.
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Comparison of Objective Stress Rates for Explicit Transient Shell Dynamics Analysis
Jason Har(하재선) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4
This paper presents applications of the objective stress rates to stress update algorithms for transient shell dynamic analysis within the context of explicit time integration. The hypo elasto-plastic materials are assumed in establishing constitutive equations. The derivation of the objective stress rates are investigated by use of the Lie derivative. Comparison results are given between the Kirchhoff and Cauchy stress formulation. The Jacobian determination algorithm proposed in this paper is presented in association with the Belytschko-Lin-Tsay shell theory. Several numerical examples are demonstrated including contact and non-contact examples, by which proposed algorithms are compared with respect to the accuracy and effectiveness.
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Unified Stress Update Algorithm for Explicit Transient Shell Dynamics Analysis
Jason Har(하재선) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.10
This paper discusses applications of the objective stress rates of the Kirchhoff or Cauchy stress to a unified stress update algorithm for transient shell dynamic analysis within the context of explicit time integration. The Eulerian ratetype constitutive equations of hypoelastic-plastic materials are established for the stress update algorithm. The equations are based on the additive decomposition of the rate of deformation tensor under the assumption that the elastic part of the rate of deformation tensor is characterized to be hypoelastic with grade zero, i.e., the fourth-rank constant isotropic tensor. Several objective stress rates are derived through the Lie derivative of the Kirchhoff or Cauchy stress tensor. Those stress rates cover, for instance, the Jaumann, Green-Naghdi, Truesdell, Oldroyd, and Cotter-Rivlin stress rates, based on the Cauchy or Kirchhoff stress. Furthermore, the unified stress update algorithm is embodied and fulfilled in association with the so-called radial return method and the phenomenological plasticity theory with combined isotropic/kinematic hardenings. Among the objective stress rates applied, the stress update procedure based on the Green-Naghdi stress rate for transient shell dynamics is especially crucial in this paper, because this algorithm developed in this work is not available even in the representative commercial codes, such as LS-DYNA and ABAQUS/EXPLICIT. In the implementation of the unified stress update algorithm, the Belytschko-Lin-Tsay shell theory is exploited to validate its accuracy and effectiveness. The ultimate objectivity of this work is to provide a guideline for the best choice of an appropriate objective stress rate for finite phenomenological elastoplasticity models. Several numerical examples are demonstrated including non-contact transient shell dynamics examples and contact-impact examples by which the accuracy and effectiveness of the unified stress update algorithm, developed in this work, are addressed.
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쉘 구조물의 비선형 과도 동적 해석에 응용된 병렬처리 알고리즘
하재선(Jason Har) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.5
An efficient parallel finite element procedure for nonlinear transient shell dynamic problems is presented within the framework of explicit finite element analysis. The procedure presented here in this paper includes a parallel Belytschko-Lin-Tsay shell element generation algorithm and a parallel explicit time integration scheme. An element-wise domain decomposition strategy and a communication minimization strategy are featured to achieve almost perfect load balancing among processors and to show scalability of the parallel performance. Throughout this work, a prototype code, named GT-PARADYN, is developed on the IBM SP2, to implement the procedure presented, under message-passing paradigm. Some examples are provided to demonstrate the timing results of the algorithms, discussing the accuracy and efficiency of the code.
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