The disorder of the coronary circulation system, which supplies blood for the working heart, may cause ischemic heart disease such as myocardial infarction, angina pectoris. On the other hand, the interaction between intramyocardial pressure and coronary blood flow is recognized to be an important factor that influences the hemodynamics of coronary circulation. In this work, a multiphasic model for coronary circulation system is proposed based on mixture theory by treating the myocardial matrix and the blood in hierarchical coronary system as solid phase and multi-fluid phase respectively. The governing equations and constitutive relations have been derived by applying conservation laws and entropy inequality in the framework of mixture theory. The microscopic properties, such as the viscosity of blood or the compliance of the micro vessel are represented by their macroscopic counterparts. The abilities of representing the characteristic behavior of coronary system have been confirmed by numerical examples.

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Numerical modeling for the mechanical properties of human muscles, tendons and intervertebral discs are studied. These parts consist of fibrous tissues and mechanical properties under external load and constriction of muscles are highly anisotropic. In this paper, these parts are modeled as uniform elastic materials with elastic anisotropies and special attention is paid on the intervertebral discs where fibrous tissues make up a structure like an ellipsoidal basket. Numerical models developed are applied to our musculoskeletal model of a male adult and some simulations are made on the anteflexion and lateral fold of its trunk. Results show that deformation of intervertebral discs with the anisotropic character is more stiff against shear deformation and yet spinal column bend smoothly.

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A computational scheme of first-principles aided triple-scale analysis based on a process crystallography was proposed to design biocompatible piezoelectric thin films fabricated on substrate. To predict the crystal morphology of thin film such as preferred orientations and their ratio, the structural stability of all conformations of crystal cluster on substrate was evaluated by employing pseudo-potential method in density functional theory. Then, the predicted crystal morphology was introduced into micro structure and macro homogenized properties of piezoelectric thin film were estimated through dual-scale finite element analysis based on crystallographic homogenization theory. From the application to the existing biocompatible piezoelectric BaTiO₃thin films fabricated on SrTiO₃ (110), SrTiO₃ (001) and MgO (100), computational results of the preferred orientations of microstructure and the homogenized dielectric constants of macrostructure had good correlation with experimental ones. Additionally, the proposed computation was applied to a new biocompatible piezoelectric MgSiO₃thin film, which has been found by first-principles calculations in our previous studies. As a result, the computation indicated that Cr (110) substrate is most suitable for stable crystal growth of MgSiO₃orientated to [101] direction and it outputs the high piezoelectric stress constants e₃₃=5.39 C/m² ande₃₁=-3.64 C/m².

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Micro-via drilling technology using a laser has become the dominant method of drilling smaller blind via-holes in copper clad multi-layer printed wiring boards (PWBs). Cu-direct laser drilling has attracted attention as a new method. However, the defect of overhang occurs when copper and resin, having different processing thresholds, are drilled at the same time. The absorptance is an important factor for Cu-direct laser drilling. Therefore, we propose a new method using thermography to measure the absorptance of a PWB's surface for a CO₂laser. Moreover, we investigate how surface treatment of the outer copper foil influences the quality of a laser-drilled hole. Two kinds of surface treatment, roughening and application of black-oxide, were attempted as ways to improve the absorptance of a surface for the laser. As a result, it was found that not only the surface absorptance but also the method of surface treatment affects the quality of a drilled hole.

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It is well known that a stress concentration of a crack tip can be relaxed by holing there. The hole is called the stop drilling hole. Some researchers also have proposed other relaxation methods of the stress concentration of the crack. The relaxation effects of the stress concentration can improve by combining with some methods. The stress concentration of the crack with the stop drilling hole can be relaxed by adding two holes near the crack tip as the holes face with each other symmetrically. Then, it has been reported that the additional holes are effective in a retardation of the fatigue crack initiation. However, the optimum sizes and locations of the additional holes, and the extent of the relaxation effect of the stress concentration are not clarified quantitatively. In this paper, the finite element simulations were carried out on the cracks with the stop drilling holes and the additional holes changing the sizes and locations of the holes. The optimum sizes and locations of the stop drilling holes and the additional holes were examined.

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The mechanical behavior of Rubber is expressed by the entropy elasticity. This behavior is simulated by Finite Element Analysis based on the assumption of the isotropy. But if a material takes transversely isotropic behavior with respect to the reference configuration, then the strain energy function can depend on five principal invariants. Ordinary three invariants of principal strain represent the isotropic behavior, additional two invariants represent the reinforced anisotropic behavior. To simulate the transversely hyper elastic material, it is necessary to define the strain energy function that is constructed by five invariants and its material constants. In our first report, we propose the polynomial strain energy function and determinate its material constants for the fibre reinforced material. In order to capture the precise solution, in this report, we employ the equivalence of uniaxial test and biaxial test. The combination of two individual experiments makes more accurate result.

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So far, as a yield criterion on a deviatoric plane, Mises criterion has been widely used in soil as well as in metal in the prediction of plastic deformation behaviour. However, the criterion similar to Mohr-Coulomb fits well in soil rather than Mises criterion. Then, in our simulation of deformation behaviour, we took up the criterion obtained from the stress state at fracture and referred to the experimental results given by Lade & Duncan to estimate the deformation behaviour. In their experiment, compression tests were performed within the range from one dimensional compression to equi-two dimensional compression. On the criterion, J₂ is represented as a function of J₃ where J₂ and J₃ are the second and the third invariants of deviatoric stress respectively. In this paper, first, the method for including the criterion into analysis is introduced. Second, the strain developments in these compression processes are simulated and compared with the experimental values. The results in simulation are not always agree with experimental ones. However, stable limits in these compressions are situated nearly on a straight line (a critical line) in the yield plane composing of hydrostatic pressure and equivalent deviatoric stress. Third, we examine what criterion gives good correlations between simulation and experiment. The dependence of J₂ on J₃ in the criterion is similar on the whole to that obtained from the fracture state, but in detail, the difference is admitted between them.

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Phase field crystal (PFC) method is anticipated as a new multi scale numerical method, because it can reproduce physical phenomena resulted from atomic structures on the diffusive time scale. Although the PFC method has been applied to some phenomena, such as dendrite formation, alloy solidification and thin film growth, there are few studies about detailed deformation behaviors, such as generation and annihilation of dislocation and the interaction between dislocation and grain boundary using the PFC method. In this study, to investigate the possibility of the PFC method as a deformation simulation tool, we evaluated the deformation behaviors of single-crystal and nanopolycrystalline structure using the PFC method. First, it was clarified that a linear elastic behavior can be represented under sufficiently low strain rate by performing tensile deformation simulation of single-crystal. Second, we developed a method controlling crystal orientation during solidification to form a desired polycrystalline structure. Moreover, the intergranular plastic deformation such as grain rotation, grain boundary migration and grain coalescence was observed in a tensile deformation simulation of nanopolycrystalline structure formed during solidification. Thus, we concluded that the PFC model could reproduce appropriate elastic and plastic deformation behavior.

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Contact pressure measurement of GPa order is examined using Nickel-phosphorus alloy foil with conical projections. The foil arranged projections high density and heated at 400°C is possible to measure pressure about 1.5 GPa. It is clarified that the real contact pressure occurred at real contact area of projections is responsible to the plastic deformation of projections. The relationship among contact pressure, plastic deformation of projections, and projection density is formulated experimentally. The contact pressure distribution between flat end of a circular cylinder and an elastic plane is measured by this method. The pressure gradually increases with approaching cylinder edge. Moreover, the pressure of center portion becomes small and the edge pressure becomes large as the modulus of rigidity of cylinder becomes high. This tendency of pressure distribution is analogous to the numerical calculation result

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The promise of airbags for crew protection when automobiles collide has been realized. In previous airbag development, the prevailing purpose has been to protect the lives of the automobile's crew. It is necessary to understand in detail, as basic data, the impact of the airbag upon the crew, the crew's physique, and the specific accident situation, in order to minimize injuries due to airbag inflation for various accident situations and crews. There are two kinds of impact contact phenomena between the airbag and the crew. One occurs when the airbag is inflated then contacts the crew. The other occurs when the crew collides with the already inflated airbag. We focused our attention in the latter case in this research, designing an experiment apparatus based on a model of the airbag and the crew. The impact force is measured when the airbag contacts the crew under various conditions. The shock-absorbing characteristics of the airbag depend on the fabric's mechanical properties and contact conditions.

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Force transducers are extensively utilized in engineering fields in the form of load cells, 6-axis force sensors for force sensing in robotic manipulation, and wheel force transducers measuring 6-axis force components used in automotive applications. This paper describes a newly developed topology optimization method for the design of the force transducer structure in cases where strain gauges are used as sensor devices. First, design specifications to obtain sufficient output voltage in a Wheatstone bridge composed of strain gauges and structural stiffness requirements are clarified, and the objective functions that satisfy the required specifications are formulated. A multi-objective optimization problem is also formulated for use in finding an optimal structure that incorporates all the design specifications for multi-axis forces. An optimization algorithm is constructed based on a node-based topology optimization method, namely, the CAMD (Continuous Approximation of Material Distribution) method, and SLP (Sequential Linear Programming). Finally, several examples are presented to confirm the usefulness of our proposed methodology for the design of multi-axis force transducer structures.

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FRM is widely used as the structural member. However, a fatigue which occupies much of the fracture accidents of the structures cannot be avoided and the growth mechanism of the fatigue damage is very complicated. Our aim is to establish the evaluation method for the damage and the fracture mechanism of the fatigue. In the previous paper, the method that evaluates the fracture types was presented. As the results, the following things became clear : (1) the feature spaces of the fracture types are represented by the correlation dimensions and the largest lyapunov exponents of the AE signals; (2) it became clear that the recognition of each fracture type is evaluated by the mahalanobis distance for each feature space. In this paper, the method that evaluates the fatigue damage by the neural network is presented. The network has been configured by learning the pattern information which are expressed by the relationship between the input (i.e. the generation degree of each fracture type and AE parameters) and output data (i.e. the fatigue damage). And the validity of the network is confirmed.

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The reliability of a solder joint in a semiconductor structure greatly depends on its solder shape. However, predicting the solder shape of miniaturized and lead-free joints is difficult because of its large deformation, topology change, and the difference in solder wettability. Therefore, we developed a new method for shape prediction based on the moving-particle semi-implicit (MPS) method. The MPS method is suitable for calculating incompressible flow and can easily express large deformation and topology changes. However, the original MPS method cannot sufficiently express the effect of solder wettability. Therefore, we enhanced the surface tension formulation of the MPS method, making it possible to express this effect. We applied this method to predicting the solder shapes of various semiconductor packages and found that the method is effective in predicting the solder shapes of miniaturized joints. Moreover, we evaluated the fracture life of a solder joint with the predicted solder shape by coupling the shape prediction method with our crack propagation analysis method. Crack initiation points and propagation paths are automatically calculated using this crack propagation analysis, and the fracture life is evaluated quantitatively by finite element analysis. We applied these combined methods to evaluating the fracture life of solder joints that had different shapes due to different wettability conditions. As a result, we found the differences in crack initiation points and evaluated crack propagation paths and fracture lives in different wettability conditions.

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