One of the precious applications of Genetic Algorithms (Gas) is its application to multi-objective optimization (MO). In MO, we need a number of scalar optimization to obtain whole sets of Pareto solution for adequate information for decision-making. Thus, it becomes very time consuming and difficult to precede MO. In the proposed method, we use generalized data envelopment analysis (GDEA) for estimation of Pareto optimality. In GDEA, we can obtain Pareto sets even if it has some non-convex feature. Important key to obtain whole Pareto sets, we would like to concentrate searching range between interval of Pareto sets. In this paper, we will propose a new type of adaptive range genetic algorithms for that purpose. We will investigate the efficiency of the method, through numerical examples.

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This paper studies on the optimal stacking sequence for vibration of FRP laminated circular cylindrical shells. For this purpose, the frequency equation for a simply-supported shell is derived based on Flugge-type classical lamination theory, and then two types of optimization problems for the shell are formulated by employing continuous design variables and by discrete design variables, respectively. In optimization, two types of genetic algorithms are also employed to solve these optimization problems. Optimal design solutions are obtained for the laminated shells with different stacking sequence from numerical calculations, and the maximization for fundamental frequency of the shell is also studied by comparing with numerical results obtained.

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This paper presents a numerical analysis method for boundary shape optimization problems of steady state sound field to minimize sound pressure distribution in response to sound source in bass register on prescribed sub-domain. Squared sound pressure on prescribed sub-domain was chosen as an objective functional. The shape gradient function of the problem was derived using the Lagrange multiplier method and the formula of material derivative. Reshaping was accomplished by the traction method. The presented method was applied to a interior noise reduction problem of a car.

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In the topology optimization analysis based on the homogenization design method or the density approach, the checkerboards, that is the formation of regions of alternating solid and void elements ordered in a checkerboard-like fashion, often appear in the optimum solutions. Therefore, the filtering method is necessary for these approaches. In this paper, we present an effective filtering method for the topology optimization analysis using the optimality criteria method as optimizer. In this method, the value of the gravity control function is controlled as a constrained condition. The gravity control function is defined from the relations of the density of an element with that of its neighbor elements. An example of MBB beam is shown to demonstrated the effectiveness of the present method.

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圧力容器に従来から使用されているガスケットに代わりシリコーン系シール剤を用いた場合の応力分布及びそれによる密封性能の評価、有限要素法を用いた三次元弾性解析及び、実機を用い密封性能評価試験をおこなった。まず、軸対称三次元有限要素解析により、シール剤界面での応力分布を示唆し、これを用いて密封性能を評価した。更に、実際の締結体に内圧を作用させる実験を行い密封性能を検討する。結果、今回使用した薄板圧力容器に関し、従来から使用されているジョイントシートガスケットを用いた場合に比ベシリコーン系シール剤を使用した場合、解析結果及び実験結果双方において、優れた密封性能を示した。

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The cryogenic interlaminar shear behavior of G-10CR glass-cloth/epoxy laminates has been discussed through theoretical and experimental characterizations. The interlaminar shear tests were carried out with double-notch and short-beam shear specimens at room temperature, 77 K and 4 K to evaluate the interlaminar shear strength of G-10CR. The effects of temperature and specimen geometry on the apparent interlaminar shear strength are shown graphically. Photomicrographs (scanning electron micrographs, optical micrographs) of actual failure modes were utilized to verify the failure mechanisms. A three dimensional finite element analysis was also performed to investigate the effect of specimen geometry on the shear stress distribution in the expected fracture plane. Effective elastic moduli were determined under the assumption of uniform strain inside the representative volume element. The numerical findings are then correlated with the experimental results.

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Recently, the fracture toughness of rubber modified epoxy adhesives has been actively investigated using adhesively-bonded DCB and CT specimens. There are few studies investigating crack propagation resistance, though stable crack propagation has been observed in many rubber modified adhesives. However, in most studies the energy release rate was calculated based on the maximum load and initial crack length. In this study, J-integration tests were conducted to evaluate crack propagation resistance using CT specimen bonded by a rubber modified epoxy adhesive, where J_<1c>was evaluated based on the R-curve.

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This paper deals with the thermal stress problem of an elastic solid with a rigid circular cylindrical inclusion under a uniform temperature change. It is assumed that the end faces of the inclusion are semispherical form and there are partially debonded interfaces at the end faces of the inclusion. A method of solution is presented for the thermal stress problem by applying the fundamental solutions for axisymmetric body force problems of elasticity. Stress distributions around the inclusion are shown by numerical calculations.

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This paper deals with the stress concentration problem of an infinite elastic plate with a slender rigid inclusion under tension. It is assumed that there are partially debonded interfaces between the surfaces of the inclusion and the matrix. A method of solution is presented for the problem by using the Kelvin's solution in the two dimensional theory of elasticity. The problem is formulated by an integral equation with unknown body forces. Stress distributions around the inclusion are shown by numerical calcurations.

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The unsteady flow phenomena due to the breakdown of the tip leakage vortex in an axial compressor rotor have been investigated by Reynolds-averaged Navier-Stokes flow simulation with an algebraic turbulence model of Baldwin and Lomax. The simulations show the unsteady vortex behavior caused by the spiral-type breakdown of the tip leakage vortex. As the flow rate is decreased from the near-stall conditions, the movement of the tip leakage vortex due to its breakdown becomes so larger that the leakage vortex interacts with the suction surface as well as the pressure one. The interaction gives rise to the three-dimensional separation of the suction surface boundary layer.

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Nucleation, coalescence, and growth processes of metal nano-clusters are investigated by molecular dynamics simulation. We assume a condition realized in the Ionized Cluster Beam Deposition, which is regarded as the effective technique for film formation in nano-electronics industry. We set the initial position and the initial velocity as random. Atomic interaction is determined by Lennard-Jones potential with parameters for copper. Temperature, number of atoms, and cell size are treated as varying calculation parameter. In the case of constant temperature, we can observe coalescence processes of clusters. A lognormal distribution of cluster size, which is similar to the result obtained by Smoluchowski equation in our previous study, is presented by using an adequate cluster-counting technique.

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