This talk introduces the UMP (Unified Multi-Phase) modeling method, recently developed for the streamlined analysis and systematic design of complex vibro-acoustic systems. The main difference between the conventional method and the UMP method is that the latter uses the same governing equations for all acoustic components while the former , different equations for different acoustic components. The UMP approach also treats all interface conditions b y a unified formulation unlike the conventional approach. Consequently, physically different components an d various interface conditions are treated b y a unified multi-phase model along with unified interface conditions. The key in this approach is the use of Biot' s equations of poroelastic media and the adjustment of poroelastic material coefficients for the representation o f any acoustic component. The unified approach becomes extremely useful w hen an iterative design process requiring interface evolutions at ever y iteration step is implemented as in the topology optimization of complex vibro-acoustic systems.

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Glaucoma is a common ocular disease in which mechanics plays a central role. Due to the difficulty of making experimental measurements, computational modeling is ideally suited to help understand the link between mechanics and the disease process. We describe the results of simulations on idealized and patient-specific models that highlight the importance of scleral properties on the biomechanics of the eye.

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Dislocation nucleation is a stress mediated, thermally activated transition process. Although it is an atomistic phenomenon, an accurate elucidation of its mechanism is not accessible to Molecular Dynamics because of its limited time-scale. In this study, Reaction Pathway Sampling methods were utilized to find out the minimum energy path and the activation energy for homogeneous nucleation in diamond-cubic Si. This was followed by a derivation of relationship between the activation energy and the resolved shear stress. The results obtained were also compared with results for homogeneous dislocation nucleation in face centered cubic Cu.

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[in Japanese]

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A phase transition of perfect crystal of α-quartz-type GeO_2 was found to be 6.0 GPa at 300 K. It was also shown a large volume shrinkage of approximately 12 % due to phase transition. Phase transition pressure of α-quartz-type GeO_2 crystal contained vacancies was decreased with increased of density of vacancies. In case of phase transition of GeO_2 crystal contained dislocation, phase transition was estimated to be 3.7 GPa.

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Dendrite pattern in solidified alloys characterizes the solute segregation pattern and often result in the formation of second phases in the interdendritic region, which deteriorate the properties of materials. Hence, the evaluation of the complex dendrite pattern is quite important for controlling the solidified structure of an alloy. The complex dendrite pattern exhibits self-similar structure with spatial periodicity, i.e. the fractal structure. In the present study, a phase-field simulation was carried out for the formation of the dendrite pattern in Fe base multi-component alloys. The fractal dimension of the simulated dendrite patterns was calculated based on the box counting method. The complexities of dendrite patterns were evaluated by using fractal dimension, and the effect of the process variables such as solute element, cooling rate and composition on the dendrite pattern formation was examined.

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Stress distribution in a cellular microstructure is simulated using a phase field model. As a typical binary alloy system, Ni-Cu alloy is focused, for which various cellular structure have been reported by researchers. The volumetric contraction due to the solidification is considered as a source of deformation, and only the elastic behavior is taken into account. As a whole, tensile stress is generated in the bulk solid, due to the contraction under a constrained boundary condition. Complicated stress distribution is, on the contrary, generated in the interfacial area, especially when the interface shape is no longer flat. When droplets and grooves appear in the cell structure, the stress becomes more complex, and large stress concentrations around these area are observed.

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We devise improved Jacobi method based on IDR (Induced Dimension Reduction) Theorem proposed by Sonneveld and van Gijzen in 2008. Moreover, we devise the IDR-based Jacobi method extended with relaxation parameter and that with adaptively tuning, Through some numerical experiments, we verify effectiveness and robustness of the IDR-based Jacobi methods.

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