Two examples of extention of crack growth model with phase field approach are derived. A crack growth model for visco-elastic material is introduced from exctended free energy which add effect of Maxwell fluid. Another model with effect of H-embrittlement is introduced by adding some equations. Ability of phase field model which can describe crack growth phenomena of various material is shown.

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[in Japanese]

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In solidification of metal and alloy, an equiaxed structure is formed through the growth, motion and collision of multiple dendrites. In this study, we construct a model expressing the formation process of equiaxed structure by coupling multi-phase-field equation, lattice Boltzmann equation and equation of motion. Furthermore, we challenge to simulate the formation process of equiaxed structure.

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We present a fluid–structure interaction analysis of blood flow in the thoracic aorta as it relates to aortic aneurysms. There are so many parameters characterizing the blood flow such as geometric, kinematic and physiologic parameters. In this study, we draw attention to geometrical characteristics of the blood vessels such as curvature and torsion distributions. A machine learning technique is applied to predict wall shear stress and oscillatory shear index distributions by using curvature and torsion distributions.

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In the case that there are no braces in the column-type truss structures, such kind of structure is equivalent to an unstable mechanism. However, if it is in hanging configuration, it is stable due to the effect of gravitational force; simultaneously, this kind of structure can isolate an apparatus installed at its tip end from the influence of the vibration of the support ceiling, where the hanging truss structure is placed. The relationship between the stress and strain of the shape memory alloy (SMA) material in relatively high temperature condition has a hysteretic loop, which can be adopted for the purpose of vibration attenuation. In this study, dynamic behavior of the hanging truss having SMA wires is discussed, and the optimized placements of the SMA wires are calculated from the viewpoints of vibration isolation and attenuation under the constrained condition of the fixed number of the SMA wires.

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The exact formulation of the multiplicative hyperelastic-based plastic constitutive equation is given for the conventional elastoplastic constitutive equation with the yield surface enclosing the purely-elastic domain in this article. The novel rigorous flow rules for the plastic strain rate and the rate of kinematic hardening variable and their related plastic spins are incorporated in this formulation. Hereinafter, the multiplicative hyperelastic-based plastic fomulation proposed here must become widespread rapidly disusing the hypoelastic-based plasticity .

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[in Japanese]

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The effect of the stress field near the free-surface region of CFRP laminate on crack formation is investigated by multiscale analysis based on the mesh superposition method. Our multiscale approach consists of two finite-element analyses on different scale: local analysis considering microscopic structure of laminate, and global analysis assumed to be a homogeneous and anisotropic elasto-plastic body. Global analysis is performed to evaluate macroscopic deformation behavior of laminate. Local analysis is then conducted to predict crack formation in CFRP laminate, utilizing the displacement history obtained from the global analysis. Global analysis and local analysis are solved iteratively to obtain convergence results that reflect the interaction between macroscopic deformation and heterogeneity of CFRP. Our multiscale approach is applied to unidirectional CFRP laminates to evaluate the effect of the free surface on crack formation.

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Our previous study, dynamic stress intensity factors are evaluated for dynamic stationary crack problem.In present study, M_θ-integral is employed to eveluate dynamics stress intensity factors for dynamic crack propagation problem. In ordinary state-based peridynamics, the dynamic propagation problem and is introduced damping function fracture model and effectiveness is examined.

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Peridynamics (PD) was reformulated as a new continuum mechanics technique by Silling . So far many brittle fracture problems have been performed and the effectiveness is examined, it also has a potential for ductile fracture problem. This paper presents a formulation and discretization for elastic-plastic deformation for ductile fracture. Plastic strain increments are assumed by force state increments in each bond in ordinary state based PD unlike considering stress increments in classical continuum mechanics theory. The validity of plastic deformation is examined by simple problem as a rectangular plate applied cyclic tensile/compressive loads.

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Buckling strength analyses for cracked plates and cylindrical shells are carried out by efficient Reproducing Kernel Particle Method (RKPM). The accuracy and efficiency of the RKPM is examined by series of Finite Element Analyses (FEAs) as well as available reference solutions. Derivation of stiffness matrices is performed by Stabilized Conforming Nodal Integration (SCNI) and Sub-domain Stabilized Nodal Integration (SSCI) methods. Singular Kernel (SK) approach is employed so as to impose essential boundary conditions (BCs). Effect of crack size and crack orientation is investigated through numerical examples.

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In this paper, a posteriori error estimation technique for strong-form meshfree/particle methods, using the meshfree compact schemes, is presented. The proposed methodology is quite simple and provides accurate approximation of pointwise local error, and evaluated error distribution could be utilized for the relocation procedures of particle distributions for meshfrees adaptive analyses.

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In recent years, FEM has been wideley used in a variety of field. One of them is application of welding problem. Welding problem is modeled by heat conduction problem with a moving heat source and thermo-elastic-plastic problem. It is necessary to interconnect nodal flux data at the boundary interface for the numerical implementation of moving heat problem for the Domain Decompositin Method (DDM) when calculating equivalent nodal flux. Moreover, material properties change with drastic temperature change during welding process. And then, In this research, assuming that heat source is point heat source, proposed method is implemented in ADVENTURE Thermal, which is a parallel finite element analysis software using domain decomposition method.

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The improvement of the atomization of liquid jets is required in several engineering applications. Although the breakup process of liquid jets has been studied so far, the mechanism of second breakup contributing to the performance of atomization has not been well explained. Hence, in the present paper the temporal numerical simulation, which is a predictably effective method to analyze the breakup process in detail, is proposed. As remarkable features, the Cahn-Hilliard equation is employed to trace the interface between the gas-liquid two-phase flow. In order to enhance the breakdown of liquid jet, we investigate the effects of different inflow conditions on the development of liquid jet, and demonstrate the usefulness of the proposed inflow condition

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The present study proposes multi-scale topology optimization applying the multi-phase field method for metallic crystalline structure to maximize the macroscopic heat conductivity. This method utilizes the framework of multi-phase field method for updating microstructure in topology optimization. Allen-Cahn time evolution equation with the equality constraint for material volume is proposed. The two-scale boundary value problem for heat conductivity equation is solved by the so-called decoupling multi-scale analysis with a homogenization approach. The proposed method is verified by the series of numerical examples.

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In this paper, we purpose a method of nearby problems (MNP) for finite element analysis of nearly incompressible hyperelasticity. Nearby solutions are constructed by the projection of displacement field to a B-Spline function in the H¹ Sobolev space. Nearly incompressible properties of the nearby solutions are attained by adding a penalty term associated with volumetric constraint.

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