Establishment of Particle-micromechanics -Road to Net-shaping-

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The objective of this research project it first to establish fundamental theory for particle micro-mechanics that describes mechanical behavior of powder particles. ; second, based on this, to develop simulation method for investigating powder compaction behavior with a view to performing near net shape production. ; third, to develop a theory and simulation method for analyzing magnetic characteristics of magnetic devices such as permanent magnet. Magnet is usually made from anisotropic magnetic powders by compacting them in magnetic field ; rotation or alignment of the easy axs of magnetization during compaction determines the characteristics of the magnet ; in the production, scientific approach has not been undertaken, thus optimization of magnetic characteristics of these products is of geat importance. An attempt is made to develop a theory and method for controlling and optimizing the function of the magnet. The results obtained are as follows :1)In simulation by particulate mod … More eling, we developed non-circular or non-spherical model, on top of circular or spherical model, that are easily treated.2)Although inter-particle friction was incorporated in this simulation, it was not sufficient as resistant against relative movement. We developed a new model for friction that describes real resistant, and therefore, we shall be able to evaluate powder compaction process not only qualitatively but also quantitatively.3)In the continuum approach, elastic properties of powder compacts were investigated experimentally, and we expressed the Young modulus in terms of relative density. Elasto-plastic finite element formulation was carried out combining plasticity theory for powder compaction. By applying this, we shall be able to simulate compaction processes for producing complicated shapes.4)We developed a new magnetic Cosserat theory that describes local rotation. A finite element simulation was developed that is capable of analyzing rotation or alignment of easy axs of magnetization during compaction in applied magnetic field. It was thus shown that the strength of magnetic field and application pattern of magnetic field gave a decisive role to the alignment. The theory includes a few material parameters ; these were not yet determined in this project. This should be done for future work. Less