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

本课题的研究目的首先是建立描述粉末颗粒力学行为的颗粒细观力学基础理论。其次，在此基础上，开发研究粉末压制行为的模拟方法，以期实现近终形生产。第三，建立了分析永磁体等磁性器件磁特性的理论和仿真方法。磁体通常是由各向异性的磁粉在磁场中压制而成，压制过程中磁化轴的旋转或取向决定了磁体的特性；在生产中，还没有采取科学的方法，因此优化这些产品的磁特性是非常重要的。试图发展一种控制和优化磁体性能的理论和方法。得到的结果如下：1)在颗粒态…模拟中此外，我们在圆形或球形模型的基础上开发了易于处理的非圆形或非球形模型。2)虽然在模拟中考虑了颗粒间的摩擦，但不足以抵抗相对运动。我们开发了一种描述真实阻力的新的摩擦模型，因此，我们不仅能够定性地评估粉末压制过程，而且能够定量地评估粉末压制过程。3)在连续介质方法中，对粉末压制的弹性性能进行了实验研究，并用相对密度表示了杨氏模数。结合塑性理论建立了粉末压制的弹塑性有限元模型。通过应用这一点，我们将能够模拟压实过程，以产生复杂的形状。4)我们发展了一个描述局部旋转的新的磁Cosserat理论。开发了一种有限元模拟方法，能够分析在外加磁场中压实过程中易磁化轴的旋转或取向。结果表明，磁场强度和磁场作用方式对取向起决定性作用。该理论包括一些材料参数；这些参数在本项目中尚未确定。这应该是为了以后的工作而做的。较少

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