Establishment of Simulation Methodology for Fabrication of High Performance Magnet

本研究项目的目的是建立高性能磁体制造的仿真方案；磁性能越高，电机本身越小。然而，目前还没有科学的方法来预测或确定高磁性的最佳工艺。具体目标如下：1)建立磁- cosserat连续统理论及基于该理论的NdFeB磁粉在磁场中压实过程中磁向模拟方案；2)建立描述NdFeB磁粉特性的模型，开展基于粒子模型的仿真；并与磁场压实实验结果进行了比较。3)调查研究磁场中磁向与压实条件的关系。得到的结果如下：1)基于已建立的磁-余弦理论中确定的参数，我们提出了一种模拟方案，该方案包含了描述磁化粒子所产生磁场的模型。然后我们模拟了钕铁硼粉末在磁场中的压实，发现在外加磁场下，由于磁化颗粒而产生的磁场影响不大，而当外加磁场消除时，这对粉末的行为有相当大的影响。在相对密度为0.4时，密实体上部密度较高，底部密度较低；这与实验结果一致。2)在给定初始密度变化的情况下，随着压实的进行，磁场对中效果随着压实的进行而变差，在施加磁场后对中效果最好；这与实验结果吻合较好。3)对磁粉在外加磁场作用下的压实行为进行了现场观察，发现磁粉颗粒的位移是连续的，且在靠近粉末底部的地方，外加磁场对粉末的位移更为明显。4)压实相对密度达到0.4后，有磁场压实的上部密度大于无磁场压实的上部密度。作为目标之一的三维仿真方案的开发尚未实现。今后的工作应该这样做，以便实际应用成为可能。少

The objective of this research project is to establish a simulation scheme for fabrication of high performance magnets ; the higher the magnetic performance, the smaller the motor itself. However, there has been no scientific methodology for predicting or determining the optimum process for high magnetic performance. The concrete objectives are as follows :1) Establish a magneto-Cosserat continuum theory and a scheme based on this theory for simulating magnetic alignment during compaction of NdFeB magnetic powder in magnetic filed2) Carry out simulation based on paniculate modeling by developing a model that describes characteristics of NdFeB powder; thus compare with results of experiment on compaction in magnetic field.3) Investigate and study the relationship between magnetic alignment and conditions of compaction in magnetic field. The obtained results are as follows :1) Based on the determined parameters in the developed magneto-Cosserat theoy, we developed a simulation scheme tha … More t incorporated a model for describing the magnetic field that is induced by the magnetized particles. We then simulated compaction of NdFeB powder in magnetic field and found that under the applied magnetic field the effect of the field due to the magnetized particles is not influential, while thisgives quite a large effect on powder behvior when the applied magnetic field is removed. It was also observed that up to a relative density of 0.4 the density was higher at the upper part of the compact and lower at the bottom part; this agreed with experimental results.2) For a case where an initial density variation was given in the simulation, the magnetic alignment, which was best just after application of a magnetic field, became worse as compaction proceeded; this is in good agreement with experimental result.3) In-situ observation of the behavior of magnetic powder during compaction in an applied magnetic field revealed that the displacement of the particles were continuous and that the applied magnetic field displaced the powder more significantly near the bottom part of the powder.4) After compaction up to a relative density of 0.4, the density at the upper part was higher in compaction in magnetic field than in without magnetic field.Development of 3-D simulation scheme, which was one of the objectives, was not realized. This should be done for future work, so that actual application will become possible. Less