[in Japanese]

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A three-dimensional numerical method for crack analysis with discrete dislocations was developed. A through crack was modelled with discrete dislocations, and the relaxed dislocation arrangement was obtained using dislocation dynamics method. In order to improve the accuracy of the numerical method, the Burgers vector of dislocations are controlled in accordance with the estimated crack opening. Consequently, the numerical accuracy, stability and computational time could be drastically improved.

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In this study, the effects of random laminate misalignment on the microscopic mechanical behavior of ultrafine plate-fin structures are statistically investigated using the Monte Carlo simulation. For the mechanical analysis, the homogenization theory based on unit cell analysis is used. Moreover, the substructure method is introduced into the theory to deal with random laminate misalignment. The present method is applied to the analysis of microscopic stress and strain distribution and their concentration in ultrafine plate-fin structures made of Ni-based alloy with random laminate misalignment. Then, the analysis results are statistically examined using histograms, and compared with the results without misalignments. It is shown that the effects of random laminate misalignment on the mechanical behavior of the plate-fin structures become remarkably strong depending on the loading condition.

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An iterative domain decomposition method is proposed for numerical analysis of 3-Dimensional (3D) linear magnetostatic problems taking the magnetic vector potential as an unknown function. The iterative domain decomposition method is combined with the Preconditioned Conjugate Gradient (PCG) procedure and the Hierarchical Domain Decomposition Method (HDDM). Our previously employed preconditioner was the Neumann-Neumann preconditioner. Numerical results showed that the method was only effective for smaller problems. In this paper, we consider its improvement with a variant of balancing domain decomposition preconditioner (BDD-DIAG). Specially, we consider the dealing without explicit construction of Schur complement matrix towards multi-part processing.

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This paper proposes stailized formulation of F-bar aided edge-based smoothed finite element method with tetrahedral elements (F-barES-FEM-T4) for explicit dynamics, which is named SymF-barES-FEM-T4. SymF-barES-FEM-T4 can take over some advantages of F-barES-FEM-T4, namely, no increace in degrees of freedom and no restriction for material constituitive models since the modification for stabilization is restricted to the formulation of internal force vector. A demonstration analysis reveals that SymF-barES-FEM-T4 shows acceptable pressure distribution but less suppression for pressure checkerboarding compared to F-barES-FEM-T4 although this formulation can suppress energy divergence which is occured in explicit dynamics of F-barES-FEM-T4.

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[in Japanese]

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Halide chemical vapor deposition is used in developing thick silicon carbide film which is used to fabricate semiconductor devices. Chemical vapor deposition process involved with many complex phenomena and better understanding of kinetics, flow and heat is needed to improve the process further. In this study, a simple hot horizontal reactor model is used to investigate physics involved in the chemical vapor deposition and its effect on silicon carbide film growth.

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[in Japanese]

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We developed a coupling method of the blood flow, interstitium flow and flow resistance of the blood vessel for three-dimensional analysis of a tumor capillary network based on the boundary data immersion method. The method was applied to an one-dimensional validation problem, and the pressure jump at the interface and pressure drop in the interstitium are reproduced. The optical width of the interface and the grid convergence of the proposed method were confirmed.

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In this research, we conduct topology optimization for the design of periodic structure based on the highfrequency homogenization method for the Helmholtz equation, by which we can examine macroscopic behaviors of waves propagating in the periodic structure even if the wavelength is comparable to the size of the unit cell. A levelset based topology optimization method is incorporated to the high-frequency homogenization method so that we can obtain optimized designs in a unit cell for desired macroscopic wave behaviors, especially for acoustic hyperbolic metamaterials which exhibits hyperbolic dispersion relationship. Numerical example is provided to validate our proposed method, and it was found that obtained optimized design shows hyperbolic dispersion relationship.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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Flying insects are capable of achieving remarkable maneuverability with their flapping wings. The wing-driving mechanism in their thorax, called the musculoskeletal system, is flexible unlike conventional drones that normally control their body attitudes with rigid elements. In this study, we investigate the effects of the flexibility in the musculoskeletal system on the kinematics and aerodynamic performance of flapping wings. A dynamic musculoskeletal model (DMSM) consisted of springs, dampers and a mass is developed with a simplified thorax structure of the insect. The DMSM is loosely coupled with a computationally cheap quasi-steady model (CIQSM) and a high-fidelity computational fluid dynamic (CFD) model. The structural properties of DMSM are adjusted through optimization that utilizes the CIQSM and can minimize the power consumption to drive the wing, while generating enough amount of vertical force to support its own weight. The kinematics and the aerodynamic performances with the DMSM are further evaluated by the integrated model coupling the DMSM with the CFD simulator. While the discrepancy between the CIQSM and CFD becomes bigger when the DMSM is more flexible because the error is amplified by the flexible structure, our results reveal that the flexible DMSM can reduce the power consumption to drive the flapping wing noticeably in comparison with the rigid wing-driving mechanism. The results point out the importance of interaction between the flexible wing-driving mechanism and flapping wing aerodynamics for the design of the micro air vehicles as well as the insects.

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