• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.22 no.3
• /
• pp.259-265
• /
• 2009

This paper studies the Element Connectivity Parameterization Method(ECP method) for topology optimization considering dynamic compliance. The previous element density based topology optimization method interpolates Young's modulus with respect to design variables defined in each element for topology optimization. Despite its various applications, these element density based methods suffer from numerical instabilities for nonlinear structure and multiphysics systems. To resolve these instabilities, recently a new numerical method called the Element Connectivity Parameterization(ECP) Method was proposed. Unlike the existing design methods, the ECP method optimizes the connectivities among plane or solid elements and it shows some advantages in topology optimization for both nonlinear structure and multiphysics systems. In this study, the method was expanded for topology optimization for the dynamic compliance by developing a way to model the mass matrix in the framework of the ECP method.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.05a
• /
• pp.321-321
• /
• 2004

본 연구에서는 웨이퍼 단면 연삭기 구조물의 경량화 고강성화 최적설계를 위하여 가변벌점함수 유전 알고리즘을 이용한 다단계 최적설계 방법을 적용하였다. 구조강성 최대화와 중량 최소화라는 상반된 성질의 목적함수를 최적화하기 위하여 강성의 역수 개념인 컴플라이언스(compliance)를 도입하여 목적함수론 최소화시키는 문제로 만들었으며, 가증방법(weighted method)을 이용하여 다목적 함수를 단일 목적함수로 변환시켰다. 부재 단면형상 최적화 단계와 정적설계 최적화 단계, 및 동적 설계 최적화 단계를 순차적으로 수행하는 다단계 최적설계를 방법을 연삭기 구조물의 최적설계에 적용하였다.(중략)

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.902-907
• /
• 2004

In this paper, a multi-step optimization using a G.A. (Genetic Algorithm) with variable penalty function is introduced to the structural design optimization of a 5-head route machine. Our design procedure consist of two design optimization stage. The first stage of the design optimization is static design optimization. The following stage is dynamic design optimization stage. In the static optimization stage, the static compliance and weight of the structure are minimized simultaneously under some dimensional constraints and deflection limits. On the other hand, the dynamic compliance and the weight of the machine structure are minimized simultaneously in the dynamic design optimization stage. As the results, dynamic compliance of the 5-head router machine was decreased by about 37％ and the weight of the structure was decreased by 4.48％ respectively compared with the simplified structure model.

• Korean Journal of Materials Research
• /
• v.8 no.6
• /
• pp.565-570
• /
• 1998

SiCp/6061AI 복합재료의 파괴인성을 평가하기 위하여 정적파괴인성에 대해서는 복수시험편법을, 동적파괴인성시험에 대해서는 stop block법을 실시하였다. 주균열은 예비균열의 선단에서 시험편두께방향 전역에 걸쳐서 일시에 발생하는 것이 아니고, 균열발생의 초기단계에서 국부적으로 형성된 균열이 시험편두께방향으로의 균열의 확장을 완료한 후 주균열로 이행해 간다. 정적 및 동적시험에서 컴플라이언스변화율법에 의해 검출된 균열발생점은 균열확장의 완료점과 거의 일치하고 있기 때문에 본 재료의 파괴인성 결정에 유효하다. 본 재료에서 동적파괴인성치는 정적파괴인성치보다 크게 나타났다. 이것은 동적충격시 입자파괴에 의한 에너지의 흡수.분산효과와 균열진전경로의 큰 편향에 기인한다고 생각된다.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2000.11a
• /
• pp.1006-1009
• /
• 2000

In this study, a multi-step optimization technique combined with a simple genetic algorithm is introduced in order to minimize the static compliance, the dynamic compliance, and the weight of a high speed machining center simultaneously. Dimensional thicknesses of the eight structural members on the static force loop are adopted as design variables. The first optimization step is a static design optimization, in which the static compliance and the weight are minimized under some dimensional and safety constraints. The second step is a dynamic design optimization, where the dynamic compliance and the weight are minimized under the same constraints. After optimization, the weight of the moving body only was reduced to 57.75% and the weight of the whole machining center was reduced to 46.2% of the initial design respectively. Both static and dynamic compliances of the optimum design are also in the feasible range even though they were slightly increased than before.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 1998.03a
• /
• pp.135-142
• /
• 1998

The performances of cutting process is mostly affected by the characteristics of closed loop system constructed with machine tool structure, work piece and tools. The chucking system is very important component in this system to hold work piece correctly in various static and dynamic load condition. Therefore, chucking force and accuracy must be considered carefully, from these reason, this paper describes the stability of chucking system which preserve high stiffness and accuracy of machine tool system.

• Proceedings of the Korean Fiber Society Conference
• /
• 2001.10a
• /
• pp.175-178
• /
• 2001

일반적으로 점탄성 거동을 나타내는 고분자 액체의 전단유동특성(shear flow properties)을 평가하기 위하여 정상전단(steady shear), 동적전단(dynamic shear), 응력완화(stress relaxation) 그리고 크리프(creep) 및 크리프 회복(creep recovery) 실험 등이 활용되고 있다[1], 이때 영전단점도(zero shear viscosity)와 정상상태 회복 컴플라이언스(steady-state recoverable compliance)는 정상상태(steady state)에서 얻어지는 물리량으로, 각 실험방법으로부터 직접적 또는 간접적으로 측정이 가능하다. (중략)

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.3 s.168
• /
• pp.146-153
• /
• 2005

In this paper, a multi-step optimization using genetic algorithm with variable penalty function is introduced to the structural design optimization of a grinding machine. The design problem, in this study, is to find out the optimum configuration and dimensions of structural members which minimize the static compliance, the dynamic compliance, and the weight of the machine structure simultaneously under several design constraints such as dimensional constraints, maximum deflection limit, safety criterion, and maximum vibration amplitude limit. The first step is shape optimization, in which the best structural configuration is found by getting rid of structural members that have no contributions to the design objectives from the given initial design configuration. The second and third steps are sizing optimization. The second design step gives a set of good design solutions having higher fitness for lightweight and minimum static compliance. Finally the best solution, which has minimum dynamic compliance and weight, is extracted from the good solution set. The proposed design optimization method was successfully applied to the structural design optimization of a grinding machine. After optimization, both static and dynamic compliances are reduced more than 58.4% compared with the initial design, which was designed empirically by experienced engineers. Moreover the weight of the optimized structure are also slightly reduced than before.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2001.04a
• /
• pp.74-78
• /
• 2001

In this study, a multi-step optimization technique combined with a simple genetic algorithm is introduce to the structural design optimization of a high speed machining center. In this case, the design problem is to find out the best design variables which minimize the static compliance, the dynamic compliance, and the weight of the machine structure and meet some design constraints simultaneously. Dimensional thicknesses of the thirteen structural members along the static force loop of the machine structure are adopted as design variables. The first optimization step is a static design optimization, in which the static compliance and the weight are minimized under some dimensional and safety constraints. The second step is a dynamic design optimization, where the dynamic compliance and the weight are minimized under the same constraints. After optimization, the weight of the moving body was reduced to 9.1% of the initial design respectively. Both static and dynamic compliances of the optimum design are also in the feasible range even thought they were slightly increased than before.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1997.10a
• /
• pp.23-27
• /
• 1997

This paper introduces the structural design optimization of a high speed machining center using multi-step optimization combined with G.A.(Genetic Algorithm) and Weighted Method. In this case, the design problem is to find out the best design variables which minimize the static compliance, the dynamic compliance, and the weight of the machine structure simultaneously. Dimensional thicknesses of the thirteen structural members of the machine structure are adopted as design variables. The first step is the cross-section configuration optimization, in which the area moment of inertia of the cross-section for each structural member is maximized while its area is kept constant The second step is a static design optimization, In which the static compliance and the weight of the machine structure are minimized under some dimensional and safety constraints. The third step IS a dynamic design optimization, where the dynamic compliance and the structure weight are minimized under the same constraints. After optunization, static and dynamic compliances were reduced to 62.3% and 95.7% Eorn the initial design, while the weight of the moving bodies are also in the feaslble range.