• Title/Summary/Keyword: Dynamic Optimization

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Topological optimized design considering dynamic problem with non-stochastic structural uncertainty

  • Lee, Dong-Kyu;Starossek, Uwe;Shin, Soo-Mi
    • Structural Engineering and Mechanics
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    • v.36 no.1
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    • pp.79-94
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    • 2010
  • This study shows how uncertainties of data like material properties quantitatively have an influence on structural topology optimization results for dynamic problems, here such as both optimal topology and shape. In general, the data uncertainties may result in uncertainties of structural behaviors like deflection or stress in structural analyses. Therefore optimization solutions naturally depend on the uncertainties in structural behaviors, since structural behaviors estimated by the structural analysis method like FEM need to execute optimization procedures. In order to quantitatively estimate the effect of data uncertainties on topology optimization solutions of dynamic problems, a so-called interval analysis is utilized in this study, and it is a well-known non-stochastic approach for uncertainty estimate. Topology optimization is realized by using a typical SIMP method, and for dynamic problems the optimization seeks to maximize the first-order eigenfrequency subject to a given material limit like a volume. Numerical applications topologically optimizing dynamic wall structures with varied supports are studied to verify the non-stochastic interval analysis is also suitable to estimate topology optimization results with dynamic problems.

Structural Design Optimization of a Micro Milling Machine for Minimum Weight and Vibrations (마이크로 밀링 머신의 저진동.경량화를 위한 구조 최적설계)

  • Jang, Sung-Hyun;Kwon, Bong-Chul;Choi, Young-Hyu;Park, Jong-Kweon
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.18 no.1
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    • pp.103-109
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    • 2009
  • This paper presents structural design optimization of a micro milling machine for minimum weight and compliance using a genetic algorithm with dynamic penalty function. The optimization procedure consists of two design stages, which are the static and dynamic design optimization stages. The design problem, in this study, is to find out thickness of structural members which minimize the weight, the static compliance and the dynamic compliance of the micro milling machine under several constraints such as dimensional constraints, maximum compliance limit, and safety factor criterion. Optimization results showed a great reduction in the static and dynamic compliances at the spindle nose of the micro milling machine in spite of a little decrease in the machine weight.

Study on Optimum Modification Method of Dynamic Charcteristics of Ship Structures by Multi-level Optimization (다단계최적화방법에 의한 선박구조물의 동특성의 최적변경법에 관한연구)

  • 박석주
    • Journal of Advanced Marine Engineering and Technology
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    • v.23 no.4
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    • pp.574-582
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    • 1999
  • This paper discusses the multi-level optimization method in dynamic optimization problems through stiffened plate of ship structures. In structural optimization the computational cost increases rapidly as the number of design variables increases. And we need a great amount of cal-culation and time on problems of modified dynamic characteristics of large and complicated struc-tures. In this paper the multi-level optimization is proposed which decreases computational time and cost. the dynamic optimum designs of stiffened plate that control the natural frequency and minimize weight subjected to constraints condition are derived. The way to apply the multi-level optimization methods in this study follow: In the first step the dynamic characteristics is controlled for the two-dimensional model of stiffened plate by sensitivity analysis and quasi-least squares methods. In the second step the cross-section of the stiffener is decided so that the weight is minimized under needed constraints by the steepest descent or ascent method. In the third the three-dimensional model is made based on the results of the first step and the second step confirmation and finer tuning of the objective function are carried out. It is shown that the results are effective in the optimum modification for dynamic characteristics of the stiffened plate.

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Structural Design Optimization of a High Speed Machining Center by Using a Simple Genetic Algorithm (유전 알고리즘을 이용한 고속 금형센터의 구조설계 최적화)

  • 최영휴;박선균;배병태;이재윤;김태형;박보선
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2000.11a
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    • pp.1006-1009
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    • 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.

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Structural Dynamic Optimization Using a Genetic Algorithm(GA) (유전자 알고리즘(GA)을 이용한 구조물의 동적해석 및 최적화)

  • 이영우;성활경
    • Journal of the Korean Society for Precision Engineering
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    • v.17 no.5
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    • pp.93-99
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    • 2000
  • In many dynamic structural optimization problems, the goal is to reduce the total weight of the structure without causing the resonance. Up to now, gradient informations(i.e., design sensitivity) have been used to achieve the goal. For some class of dynamic problems, especially coalescent eigenvalue Problems with multiobjective optimization, the design sensitivity analysis is too much complicated mathematically and numerically. Therefore, this article proposes a new technique fur structural dynamic modification using a mode modification method with Genetic Algorithm(GA). In GA formulation, fitness is defined based on penalty function approach. Design variables are iteratively improved by using genetic algorithm. Two numerical examples are shown, (ⅰ) a cantilevered plate, and (ⅱ) H-shaped structure. The results demonstrate that the proposed method is highly efficient.

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Structural dynamic optimization with probability constraints of frequency and mode

  • Chen, Jian-Jun;Che, Jian-Wen;Sun, Huai-An;Ma, Hong-Bo;Cui, Ming-Tao
    • Structural Engineering and Mechanics
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    • v.13 no.5
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    • pp.479-490
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    • 2002
  • The structural dynamic optimization problem based on probability is studied. Considering the randomness of structural physical parameters and the given constraint values, we develop a dynamic optimization mathematical model of engineering structures with the probability constraints of frequency, forbidden frequency domain and the vibration mode. The sensitivity of structural dynamic characteristics based on probability is derived. Two examples illustrate that the optimization model and the method applied are rational and efficient.

Dynamic sensitivity analysis and optimum design of aerospace structures

  • Gu, Yuanxian;Kang, Zhan;Guan, Zhenqun;Jia, Zhiwen
    • Structural Engineering and Mechanics
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    • v.6 no.1
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    • pp.31-40
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    • 1998
  • The research and applications of numerical methods of design optimization on structural dynamic behaviors are presented in this paper. The emphasis is focused on the dynamic design optimization of aerospace structures, particularly those composed of composite laminate and sandwich plates. The methods of design modeling, sensitivity analysis on structural dynamic responses, and the optimization solution approaches are presented. The numerical examples of sensitivity analysis and dynamic structural design optimization are given to demonstrate the effectiveness of the numerical methods.

A Novel Dynamic Optimization Technique for Finding Optimal Trust Weights in Cloud

  • Prasad, Aluri V.H. Sai;Rajkumar, Ganapavarapu V.S.
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.16 no.6
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    • pp.2060-2073
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    • 2022
  • Cloud Computing permits users to access vast amounts of services of computing power in a virtualized environment. Providing secure services is essential. There are several problems to real-world optimization that are dynamic which means they tend to change over time. For these types of issues, the goal is not always to identify one optimum but to keep continuously adapting to the solution according to the change in the environment. The problem of scheduling in Cloud where new tasks keep coming over time is unique in terms of dynamic optimization problems. Until now, there has been a large majority of research made on the application of various Evolutionary Algorithms (EAs) to address the issues of dynamic optimization, with the focus on the maintenance of population diversity to ensure the flexibility for adapting to the changes in the environment. Generally, trust refers to the confidence or assurance in a set of entities that assure the security of data. In this work, a dynamic optimization technique is proposed to find an optimal trust weights in cloud during scheduling.

Multiphase Dynamic Optimization of Machine Structures Using Genetic Algorithm (유전자 알고리즘을 이용한 공작기계구조물의 다단계 동적 최적화)

  • 이영우;성활경
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2000.05a
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    • pp.1027-1031
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    • 2000
  • In this paper, multiphase dynamic optimization of machine structure is presented. The final goal is to obtain ( i ) light weight, and ( ii ) rigidity statically and dynamically. The entire optimization process is carried out in two steps. In the first step, multiple optimization problem with two objective functions is treated using Pareto genetic algorithm. Two objective functions are weight of the structure, and static compliance. In the second step, maximum receptance is minimized using genetic algorithm. The method is applied to a simplified milling machine.

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A Dynamic Programming Approach to PCB Assembly Optimization for Surface Mounters

  • Park, Tae-Hyoung;Kim, Nam
    • International Journal of Control, Automation, and Systems
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    • v.5 no.2
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    • pp.192-199
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    • 2007
  • This paper proposes a new printed circuit board (PCB) assembly planning method for multi-head surface mounters. We present an integer programming formulation for the optimization problem, and propose a heuristic method to solve the large NP-complete problem within a reasonable time. A dynamic programming technique is then applied to the feeder arrangement optimization and placement sequence optimization to reduce the overall assembly time. Comparative simulation results are finally presented to verify the usefulness of the proposed method.