Generally, in optimization problems of the real world, it is rare to require the strict solution in all domains. Therefore, two or more realistic solutions are desired in many cases. Furthermore, in the real world, the optimal solution under not static environments, but dynamic environments that continue changing intricately is required. In recent years, many researches have been made, which are applied to the combinatorial optimization problems and multi-objective optimization problems using Genetic Algorithm (GA). However, GA frequently loses the diversity of solutions, due to the characteristics of searching process. In this paper, an attempt is made to develop an improved GA method for construction management. Several numerical examples are presented to demonstrate the efficiency and applicability of the proposed method.

抄録全体を表示

Recently, the number of bus passengers is decreasing due to the distribution of own cars. This causes the reduction of scheduled bus service, which further decreases the number of passengers. Under such situations, demand bus service gains attention as a possible alternative, and actually, the demand bus system has been employed in several local cities. The demand bus system means the bus service that can change the schedule of bus service such as timetable and route according to the demand of users. In order to make the demand bus system effective, ITS technology can be used to satisfy the requirements of passengers and achieve the appropriate scheduling from the standpoint of bus management. In this paper, an attempt is made to develop a decision support system that can provide a reasonable and practical scheduling plan to optimize the timetable and route. It is noted that the system is intended to minimize the necessary cost and the traveling and waiting time of users. Numerical examples are presented to demonstrate the applicability of the system proposed here.

抄録全体を表示

One of the important in-core fuel management tasks in boiling water reactor (BWR) is to determine optimum positions of fuel assemblies and optimum patterns of control rods. Authors developed a two-stage automatic optimization algorithm using genetic algorithm (GA) for core design in BWR. In the first stage of this two-stage algorithm, loading pattern is optimized. In the second stage, control rod patterns of each burn-up points are optimized. In this paper, authors developed a new combinatorial optimization algorithm using multi-agents and applied this algorithm to the first stage of two-stage automatic optimization.

抄録全体を表示

Multi-objective optimization that can support agile and flexible decision-making has been highly required to deal with complex and global decision environment. We have proposed, in this paper, a general framework for solving multi-objective optimization problem relying on a prior articulation in tradeoff analysis among conflicting objectives. To overcome stiffness and shortcomings of the conventional methods, it has been developed by the virtue of simple subjective judgment and neural networks for identifying value function and its incorporation into an appropriate optimization method. Since the value function is decided by simple and relative responses that will be done separately from the searching process, DM's tradeoff analysis is not only very easy but also of small load compared with the conventional interactive methods. Another advantage is that we can carry cut MOP without particular knowledge about MOP and choose the most suitable optimization method. Such properties are very suitable to implement the algorithm on the Internet and to open it for the public users. A variety of illustrative applications are provided to verify effectiveness of the proposed method.

抄録全体を表示

As there are many elements to be treated at the same time in an optimum posture determination of an adaptive truss structure composed of some truss modules with variable-length members, it is difficult to solve it due to the existence of many local optimum solutions especially when not only the direction of the load but also the position of the load are constrained. So in this study, we consider the problem that determines an optimum posture of an adaptive truss structure taking account of buckling of truss members by using Immune Algorithm (IA) by which we can examine some local optimum solutions and have a high possibility for obtaining the global optimum solution.

抄録全体を表示

This paper presents an optimization method of production efficiency on the placement time in the chip mounter system. We have approached this production efficiency by control software. Placement time changes greatly by the performance of the chip mounter and the configuration of the system. The problem is how to distribute parts and parts feeders to each chip mounter. We have proposed a distributing method by GA. We describe three items. The first is suggestion of a design index value. The second is correspondence to multi-purpose optimization. And the third is handling of a constrain. Several numerical experiments about some systems composed of plural chip mounter with different performance were done. It was confirmed that our proposed method had effectiveness more than conventional method through the results of numerical experiments. Furthermore, practical examples to the produced utility system are shown.

抄録全体を表示

These days, requirements of functions tend to spread and the designers need to treat problems as multi-objective optimization. However, decision making through multi-objective optimization is not that simple and we need to give preference of the designer to give a solutions, which has been done through local information called trade off ratio. Usually, trade-off ratio and the results does not have linear relationships, thus it is quite hard to give desired trade-off ratio in a few steps. In the case there are a few objective functions, we can visualize so called Pareto solutions. Then, the designer can grasp the whole relationships of objective functions and it is useful information, something like a map in the whole relationships of objective functions and it is useful information, something like a map in exploring. For that purpose, multi-objective genetic algorithms are quite powerful tools, and there are tons of studies for it. We have been proposing a method to use Data Envelopment Analysis as estimating Pareto Optimality. In this study, we use Genetic Range Genetic Algorithms, and give a new range around obtained Pareto solution and between them. In order to show the effectiveness of the proposed method, we showed some simple example with and without ill setting.

抄録全体を表示

When we develop a new flexible transfer line (FTL) that links the preceding production line with subsequent production line, it is the important design process to decide which part is input into the bay of the FTL. This paper describes the off-line production simulator called RETOP that can assist the production engineers when they develop FTL. RETOP includes if-then rules, a discrete simulator and a genetic algorithm (GA) system. The GA system automatically decides the if-then rules after many generations. We compared simulation results acquired by RETOP with one by a conventional method. Though some application examples, it is ascertained that RETOP is useful.

抄録全体を表示

Automobiles have a major role to play in reducing CO_2 emissions as one of the efforts to protect the global environment. Automotive power train engineers have worked on various engineering developments such as the direct injection engine and the variable valve timing for fuel economy improvement or CO_2 reduction. However, in order to meet the increasing demand for CO_2 reduction, it is becoming more important to pursue total efficiency of the whole power train system, not particular technologies in the system. Because hybrid systems have the motor (the battery) as an additional power source to the engine, enabling better energy management of the vehicle compared with conventional technologies, they are capable of optimizing the power train system and that makes hybrid systems important technologies. We are determined to advance the application of this important technology and promote its and penetration into the market as front-running future technology to reduce CO_2.

抄録全体を表示

As CAE (Computer Aided Engineering) applications become increasingly precise, the knowledge required to operate these application are highly specialized. These tools have not been utilized in initial design process of mechanical products, in which designers cannot construct detailed analysis models. This paper proposed design optimization system a cross-sectional shape that can support the initial design process of bar structure. The cross-sectional design problem is formulated as a eight-objective optimization problem which can be solved using genetic algorithms. A method to generate a shape of cross-section satisfying characteristics that required by a designer is also proposed. These methods, which can reduce the number of trial and error process and failure in product design, are expected to contribute shortening product development lead-time.

抄録全体を表示

This paper describes a parameter optimization method of Statistical Energy Analysis (SEA) using Real Coded Genetic Algorithm (GA). SEA method was developed in '60s for vibration analysis of aerospace structures. It is noticed as vibration and noise analysis method which changes to FEM recently because it has advantages over FEM especially in the analysis of high frequency noise and vibration problems. Though its theory is very explicit, it can't be said that it has been established as the accurate prediction method since construction of SEA models and SEA parameter calculation method are indefinite at actual problems. Therefore, in this research, new SEA parameter estimation method using genetic algorithm (GA) is proposed.

抄録全体を表示

Algorithms where offsprings (new search points) are generated according to the estimated probability model of the good parents are called the Probabilistic Model-Building Genetic Algorithms (PMBGAs). In this paper, a new model of PMBGA, Distributed PMBGA (DPMBGA), is proposed. In the DPMBGA, the correlation between the design variables is considered by PCA when the offsprings are generated. The distribution of the offsprings is estimated as the normal distribution. The island model is also applied in the DPMBGA for maintaining the population diversity. Through the standard test functions, the effectiveness of the DPMBGA is examined. The result shows the good search ability of the DPMBGA with PCA for the test functions that have correlation between the design variables. On the other hand, the DPMBGA without PCA is good at optimizing the problems where there is no correlation between the design variables. The DPMBGA where PCA is executed in the half of the islands and not executed in the other island can find the good solutions in the problems whether or not the problems have the correlation between the design variables. The results of the DPMBGA are also compared with those of the UNDX with MGG. The results explain that the DPMBGA shows the better performance than the UNDX.

抄録全体を表示

The new optimization procedure of the tire block surface is proposed, in which FEM is combined with the optimality criteria. The objective function is the pressure uniformity on the block and the constraints are the contact area. We verified the effectiveness of this new procedure by the block samples. The block with the optimized surface has the uniform pressure distribution and the friction coefficient is increased ten percent compared with the block with the flat surface. Furthermore this procedure was applied to the tire block surface and was verified to be effective to improve handling, riding comfort and irregular wear.

抄録全体を表示

By using the basis of the origami engineering, we can easily crash a can or PET bottle with small force. Furthermore, using this structure to light collision or pedestrian by absorbing crushing energy, it is desirable to make deformation quantity large under small load. Then, in this research, to minimized average crushing force of an origami structure, the form of a structure and the angle of a polygonal line are optimized. The technique of optimization is a based on Holographic Neural Network (HNN), that is called one of Response Surface Method.

抄録全体を表示

The purpose of this study, optimization of a light weight structure was carried out for the vertical-type motor stator frame. In this study, in order to increase the accuracy of FEM model, conformity with the natural frequency doing research was performed by the basis vector method. Then, after carrying out the sensitivity analysis of a natural frequency and thickness change of each part material, , optimization analysis aiming at weight minimization was carried out. Consequently, as compared with the configuration, about 18% of weight reduction was attained conventionally.

抄録全体を表示

This paper presents numerical results of boundary shape and topology optimization problem for a three-dimensional arm design of linear elastic continuum with respect to minimization problem of volume under a mean compliance constraint. For boundary shape optimization, a program using a spring-loaded traction method was used. The spring-loaded traction method was proposed as an improvement of the traction method in convergence and a procedure for determining the velocity of the domain variation by solving a displacement of a pseudo-elastic body defined in the domain with distributed spring on boundary by the loading of a pseudo-external force in proportion to the negative value of the shape gradient. For topology optimization, a commercial program combining the topology optimization method based on the homogenization method and the basis vector method was employed. From the results of analyses for a three-dimensional arm design problem by the two kinds of optimization programs, it was demonstrated that there was the case that the only topology optimization obtained limited result.

抄録全体を表示

A new and direct topology optimization method of generation for rib layout pattern so called as growth technique is proposed in this paper. The method suggests that the ribs extend from the ground structure just like branches of tree grow from seed or trunk, so it should obey a certain growing and branching rule like tree. The initial growth points, so called seeds, are specified in advance, and baby ribs around seeds on the ground structure have the ability to grow along the grid nodes of finite elements by taking into account their design sensitivities. The potential ability of branching will be assigned to the ribs, dimensions of which are greater than the specified threshold value. During the growing process of rib, the volume growth rate is controlled so as to be possible to create new branches and to eliminate degenerated ribs. The stop condition of the growth process is that the rib volume reaches the given upper limit value. The validity and effectiveness of the suggested method is confirmed by the numerical results of some typical rib layout design examples, including both minimal compliance and vibration-proof design problems.

抄録全体を表示

In this paper, the authors present a new evolutionary optimization method for three-dimensional structural statics. The method consists of two optimization processes in series. The former process is to deal with the topology optimization. The latter process is to deal with the configuration optimization. The method finds an approximate optimum topology and configuration of the structures to be improved from any initial design of them. We show application of the method to a crank arm and a connecting rod as a fundamental verification.

抄録全体を表示

In this paper, the author has concentrated to the branching network structures such as the tree branches, root networks and arterial branch systems. The optimality of natural branching network systems is discussed and dominant parameters to control the branching networks are extracted. Then, the acquired branching and growth rules are used to simulate the construction of the numerical model of branching system. Some numerical examples of branching tree growth simulation in the two-and three-dimensional space will be shown, and the optimality of the simulated networks will be discussed.

抄録全体を表示

This paper presents and effective method for designing structures using a cellular automaton and a neuron model, representing a simple conceptual basis for the self-organization of structural systems. The proposed methods are sufficiently simple to solve topology optimization problems as pure 0-1 problems, and yet sufficiently complex to express a wide variety of complicated topologies. Local rules for the birth and death of cells are all that is required for this method, dependent on the type of design constraints, such as weight, stiffness and frequency. The effectiveness of the proposed method is demonstrated through numerical topology optimization problem examples. The method proposed in this paper offers a new approach to structural optimization, overcoming most of the problems associated with traditional techniques.

抄録全体を表示

Topology optimization method shows rapidly new development with discretization methods of the partial differential equation such as FEM and BEM. There are homogenization, cellular automata, evolutionary methods in this research field. The target of topology optimization is to have no restriction on the final form of the structure. The proposed self-organization method under the category of evolutionary methods is based on the simple concept that by removing under-stressed materials and simultaneously adding newly surrounding materials to over-stressed materials using the local rule. We show a numerical simulation method of topology optimization by FEM. The effectiveness of the developed simulation program is demonstrated by several examples and discussed fundamental important parameters etc.

抄録全体を表示

A truss topology optimization problem under stress constraints is formulated as a mixed integer programming problem with variables indicating existence of nodes and members. The local constrains on nodal stability and intersection of members are considered, and a moderately large lower bound is given for the cross-sectional area of an existing member. A branch-and-bound method is presented for obtaining good lower-and upper-bound solutions. A method is also presented for obtaining an approximate solution by successively solving relaxed nonlinear programming problems based on a variable fixing technique.

抄録全体を表示

In order to quickly obtain qualitative designs, a new concept of CAE, First Order Analysis (FOA) is proposed. The basic ideas include (1) graphic interfaces, (2) use of sophisticated formulations based on the theory of mechanics of material, (3) the topology optimization method. The key idea of topology optimization is based on the ground structure approach and the minimization of the mean compliance in order to maximize the global structural stiffness. To realize the above idea, we make the topology optimization tool "TOPO DANUKI" using beam element. In this tool, ground structure is easily constructed as if to pile building blocks. The min-max approach is employed to deal with multi-objective problems. The design variables are updated using the sensitivities by CONLIN (Convex Linearization). Some examples are presented to demonstrate the effectiveness and usefulness of "TOPO DANUKI"

抄録全体を表示

Computer Aided Engineering (CAE) has been successfully utilized in mechanical industries such as the automotive industry. It is, however, difficult for most automotive design engineers to directly use CAE due to the sophisticated nature of the operations involved. In order to mitigate this problem, a new type of CAE, First Order Analysis (FOA) has been proposed. This paper presents the outcome of research concerning the development of a structural topology optimization methodology within FOA. This optimization method is constructed based on discrete and function-oriented elements such as beam and panel elements, and sequential convex programming. In addition, examples are provided to show the utility of the methodology presented here for mechanical design engineers.

抄録全体を表示

In this paper, the APIs for general optimization system in the Grid is proposed. The system is supposed to be constructed with the Grid RPC. The proposed APIs consists of three modules. One of them is the API for searching for the data from the optimizer and analyzer. The others are the APIs for the optimizer and analyzer. In this paper, the optimization system is implemented with the proposed APIs and the NetSolve that is one of the Grid RPC systems. To discuss the effectiveness the proposed APIs and the implemented system, the structural optimization problem of truss structure is solved by the implemented system. Through the optimization, it is found that the proposed APIs are very useful to construct the optimization system in the Grid. At the same time, since there is an overhead time of NetSove, the calculation time of analyzing the problem should be longer to shorten the total execution time.

抄録全体を表示

A simple and computationally inexpensive approach is presented for obtaining the maximum load factor of an elastic structure considering reduction of load-carrying capacity due to inevitable initial imperfections. The structure has a stable bifurcation point if no initial imperfection exists. An anti-optimization problem is formulated for minimizing the maximum loads reduced by the most sensitive imperfection within the convex bounds on the imperfections of nodal locations and nodal loads. It is shown in the examples that a minor imperfection that is usually dismissed is very important in evaluating the maximum load of a flexible structure.

抄録全体を表示

A mathematical programming problem is proposed for form-finding of cable domes considering geometrical no linearity. The optimality conditions of the problem are derived to guarantee that the optimal solution coincides with the self-equilibrium configuration of the cable dome with specified member axial forces. The number of independent axial forces is investigated under the geometrical constraints as well as equilibrium conditions. An algorithm for design of cable domes is presented by using the primal-dual interior-point method. The self-equilibrium configurations are computed for cable domes to demonstrate efficiency of the proposed algorithm.

抄録全体を表示

This paper presents an optimization algorithm for the design of initial tension of cable structures in which various self-equilibrated stress states are possible. The optimization algorithm is based on the autonomous decentralized finite element method, and initial cable tension is determined by minimizing the strain energy under the design load. The local rule for changing initial cable tension is derived from the Kuhn-Tucker condition of the optimization problem. The algorithm is simple and does not need large-scale matrix analysis. A simple cable structure and a Geiger type cable dome are shown as numerical examples, the effectiveness of the present method is confirmed through these examples.

抄録全体を表示

This paper is concerned with a new procedure to determine an optimal shape of sound-insulating wall for auto-highways. A two dimensional cross-section of the wall is optimized by using the boundary element method (BEM) together with cellular automata (CA). In application of CA, a feasible area of the wall is divided into a number of uniform cells, and all the state variables defined on each cell are changed by a transition rule, e.g. minimizing a cost function, under a local rule for neighbor cells so that a final state of cells can be determined. In this paper, a new transition rule is proposed to find the final state of cells which may reduce noise. The reduction of noise is monitored by the mean absolute value of sound pressures measured at several points. It is assumed that a point noise source is placed at the center point of the road. Numerical computation is carried out for a typical model of the sound-insulating wall. Through discussion on the results obtained, it is revealed that the proposed procedure for estimationg an optimal shape of the sound-insulating wall is rather robast for a wider range of sound frequencies.

抄録全体を表示

The models of the ground structure method are employed to simulate the creation of structural design of the optimum layout problem. The lattice truss is modeled as assembleges of a number of unit cells which repeat to undergo finite element analysis to feed-back results of stress to the stiffness of each member. Through the feed-back stiffness control, the lattice truss model is represented to form the topological materials and the structural shape with the use of the local stress condition without mathematical optimum tools. It is successful to analyse the shape-layout problem as numerical samples on the lattice truss model.

抄録全体を表示

Evolutionary Structural Optimization (ESO) method is one of the most powerful and promising techniques for pursuing the optimal structural form. Although it is easy to carry out the calculation of ESO, there have been remained some weak points in its evolutionary process by which inefficiency of calculation is caused or unreasonable solutions are generated. A new method through the usage of the contour lines of the characteristic parameters. which is named Extended ESO method, in order to remove such defects of usual ESO as well as to enable the structures to not only be scraped but also grow up toward the final optimal structures. In this paper, extension for 3-dimensional structures of the Extended ESO method is proposed and the effectiveness of the proposed scheme is shown through some numerical examples.

抄録全体を表示

It is useful to propose a new algorithm to analyze the complicated optimization problems by imitating the function of living things. In this study, it is object to propose new optimization method using the microcosm which is model of natural ecosystem. The microcosm is constituted by considering a bone forming ecosystem that the interaction of each cell is clear and able to be regarded as ecosystem. The optimazation problems are analyzed by the microcosm using GA. The problems is to search the plane structure of the minimum value subjected to a load. Moreover, the validity of design solution is checked for the several design conditions.

抄録全体を表示

The conventional optimization methods were based on a deterministic approach, since their purpose is to find out an accurate solution. However, these methods have initial condition dependence and risk of falling into local solution. In this paper, we propose a new optimization method based on a concept of path integral method using in quantum mechanics. The method obtains a solution as an expectation using stochastic process. The advantages of this method are not to be affected by initial conditions and not to need techniques based on experience. For calculation example, a simple bench mark test, a classic brachistochrone problem, and an optimal gliding problem for a hang glider were selected.

抄録全体を表示

This paper points out that optimization methods should have robustness and adaptability to problems with different structure and adjustability of parameters provides adaptability. Particle swarm optimization, whose concept began as a simulation of a simplified social milieu, is known as one of the most powerful optimization methods for solving nonconvex continuous optimization problems. Then, in order to improve adjustability, several new parameters are introduced to particle swarm optimization on the basis of the Proximate Optimality Principle (POP). In this paper, we propose Adaptive Particle Swarm Optimization. And the effectiveness and feasibility of the proposed approach are demonstrated on simulations using typical nonconvex optimization problems.

抄録全体を表示

Stochastic methods have been proposed to derive global optimal solutions of nonlinear programming problems with any objective functions and constraints, and constraints have been treated indirectly by the penalty method. In this paper, a method of treating constraints directly is proposed to improve local optimal solutions of nonlinear programming problems, and is named modal trimming method. This method combines a gradient method for searching local optimal solutions, with an extended Newton-Raphson method based on the Moore-Penrose generalized inverse of a Jacobian matrix for searching initial feasible solutions used for the gradient method. To prevent traps into fathomed local optimal solutions, a strategy of transforming objective functions is adopted. Some features of the modal trimming method are investigated qualitatively, and the method is applied to small-scale optimization problems with strongly nonlinear objective functions and constraints to investigate its validity and effectiveness.

抄録全体を表示

Most of the actual optimization problems are large-scale, nonlinear and multi-peaked (nonconvex). Furthermore, with the widespread use of high-speed and large capacity computers as the background, it is felt necessary in resent years to derive a global solution for nonlinear and multi-peaked optimization problems. It is one of the most important topics in optimization. This paper proposes a new dynamic tunneling algorithm with multi trajectories (Multi-Trajectory Dynamic Tunneling Algorithm) that is composed of two systems, an optimization system and a tunneling system. These systems are used sequentially to approach a global optimal solution of an objective function. The numerical stability of the conventional dynamic tunneling algorithm is theoretically investigated and interaction between each trajectory of the tunneling system is introduced in order to improve search efficiency. The proposed algorithm is applied to 2-variable and 10-variable typical multi-peaked nonlinear optimization problems.

抄録全体を表示

This paper proposes a cumulative function approximation scheme based on Voronoi diagram and an adaptive global optimization method based on its superposability. In the function approximation scheme, the function is approximated as superposition of local quadratic polynomials for the subspaces around respective sample points based on geometric structure that is represented by Voronoi diagram, a technique of computational geometry. This scheme has an ability of cumulative function approximation under its superposability. Based on such a capability, a global optimization method is configured by adaptively arranging new sample points based on tentative optimal solution and the distribution of sample points. Their effectiveness and validity are ascertained through some numerical examples.

抄録全体を表示

Most of the actual problems with discrete mechanism can be formulated as a combinatorial optimization problem such as system scheduling problems. While many combinatorial optimization problems are supposed to be NP-Hard from the view point of complexity in a calculation theory. This means that it is extremely hard to obtain a strictly optimal solution within feasible computation time. Meta-heuristics is a new paradigm that aims to obtain an approximate solution within feasible computation time. In the meta-heuristics, Tabu search is one of the most effective algorithms for combinatorial optimization problems. While the intensification of Tabu Search is powerful, the diversification Tabu Search is not powerful. This paper proposes an algorithm-Tabu Search with multi-criteria for coordinating the intensification and diversification that takes a Proximate Optimality Principle (POP) into consideration-has several important features for solving combinatorial optimization problems. The Tabu Search with multi-criteria has two purpose, the value of objective functions and the evaluation of operations, these enable to achieve well-balanced search. The proposed algorithm is applied to Traveling Salesman Problems, that is typical combinatorial optimization problem, to verify the performance of search.

抄録全体を表示

Collaborative design works via computer networks became increasingly important to the architectural design and building industry. This paper introduces two types of design environments; one includes hardware and software, supporting the design collaboration in face-to-face meetings, instead of in Cyberspace, and the other is an WEB environment for collaborative design between distributed members.

抄録全体を表示

In this study, the design method of the surface shape where the tactile sense was taken into consideration was developed. In this method, tactile response is evaluated by considering a friction coefficient and a surface temperature. The optimization problem is solved using the Convex Linearization method (CONLIN). However, many optimum solutions exist and are dependent on an initial design. Therefore the design in consideration of 1/f fluctuation was performed by giving 1/f fluctuation to an initial state. Several examples show the change of surface shape to the various conditions.

抄録全体を表示

In this study, a non-conventional statistical mathematics based on method to mesh enhancement is introduced. The method explained here, is flexible in application i.e. it can be applied to planar and spatial meshes, as well as by choosing any quality parameter to evaluate the mesh architecture and enhance accordingly. In this statistical mathematics based approach, mesh generation is considered as a statistical problem rather than its geometric features and Monte Carlo technique is adopted for this random process. Geometry of mesh architecture involved only in so called 'template' to insert the new points. In the present paper, method is explained in a planar triangular mesh architecture and aspect ratio is chosen as the parameter to evaluate the mesh quality.

抄録全体を表示

A useful design tool dealing with 3-D topology optimization is being developed. We aim to develop such a tool as gives engineers inspiration of concept design in the engineering field. This design tool uses an adaptive optimization with multi-level voxel mesh to get both better efficiency of calculation and better optimal topology. This paper shows that one of the new targets of topology optimization; not only to use topology optimization in the phase of concept design in engineering but also to help engineers to design more directly, the efficiency of multi-level voxel method, the performance of the adaptive optimization and some 3-D numerical examples.

抄録全体を表示

We develop a method of topology optimization for structures at finite strains based on the mathematical homogenization theory. In this method, we define the design variables at each node of the finite element model, whereas the conventional approach defines one set of design variables in an element. Addition to this, the material distribution in an element is assumed, and approximated by the shape functions in a element and discretized values at nodes. The corresponding formulation approach is consistent with the mechanical problem modeled by the homogenization method. Several representative numerical examples are presented to show the validity and applicability of the proposed approach. In particular, we try to clarify the mechanism which generates the optimal structure prevented from revealing structural instabilities such as buckling.

抄録全体を表示

In this paper, we propose a topology optimization method of a structural members for crash-safety by using density approach. This method is based on the generalized layout optimization method and design variable is a virtual isotropic material whose properties are functions of the element density. Because of the finite element configuration, the optimal configuration tend to have checkerboard patterns and the gray scale density in this approach. For this reason, we applied the gravity control function for design of structural members for crash-worthiness as a filtering method. Moreover we also applied the parallel computing to reduce the calculation time. Several numerical examples are shown to verify the present method.

抄録全体を表示

This paper presents a new method to determine optimum topology of plate strucutres using conformal mapping which is used in fluid mechanics, electromagnetic, and elasticity. Fisrt we prove two invariants of bending moments satisfy Laplace equation. Then it is showed that corresponding relationship between fluid mechanics, electromagnetic and elasticity can be also valid in the theory of plate bending under a certain condition. Then a simple design method to optimum topology of plate strucutures is proposed. Several numerical examples are treated and it is confirmed the effectiveness and validity of proposed method.

抄録全体を表示

In this paper, the authors present a new evolutionary optimization method for three-dimensional structural statics. The method consists of two optimization processes in series. The former process in to deal with the topology optimization. The latter process in to deal with the configuration optimization. The method finds an approximate optimum topology and configuration of the structures from any initial design of them : That is, an optimum structure design can be obtained from a simple and small initial structure. Therefore, less computational cost and time will be required to obtain results by the method than those by conventional ones.

抄録全体を表示

Useless elements are eliminated from a design domain or a ground structure and its topology is changed in the process of most topology optimization methods such as the homogenization method and the genetic algorithms. In this paper, a method of inferring the change of topology of the structure before the elimination of an element is proposed. Using this method, topological constraint conditions can be set. For example, when the necessary condition of the optimum structure is chosen as a topological constraint, the probability of obtaining the optimum one can be increased. Designer's requests for topology also can be the constraint conditions. As numerical examples, topology of a three-dimensional structure consisting of triangular elements was optimized by simply removing an element with the least strain energy under various topological constraints. And as another example, topology optimization of a plate using the artificial model (similar to the homogenization method) was treated under a constraint on the number of holes. The validity of the proposed method was verified by these two examples.

抄録全体を表示