基于离散元的不同粒径配比粉末压制相对密度与力链分析

利用PFC三维数值模拟软件，通过改变粉末颗粒粒径分布建立各组冷压模型，得到压制过程中相对密度变化规律与力链分布情况。在特定粉末粒径配比下，能够得到相对密度最高的压坯。结果表明:在大、中、小粒径颗粒质量比为60:15:25的粒径配比下，压坯相对密度最高，压坯相对密度并不会随着细粉比例不断增加而一直提高；在压制过程中，随着附加细粉占比上升，压制方向上能产生更大应变。侧压系数与泊松比受粉末粒径分布影响较小，且在压制后期，在压坯已获得较高相对密度的情况下，会因缺乏足够的驱动力与位移空间发生下降；混合粒径粉末试样的力链数量远大于单一粒径粉末试样，在强力链数目充足的前提下，结合大量的弱力链能获得更高的压坯相对密度。

Compacting relative density and force chain analysis of powders with different particle size ratios based on discrete element

Using the PFC three-dimensional numerical simulation software, the law of relative density change and force chain distribution during the pressing process were obtained by changing the particle size distribution of powders to establish the cold pressing models. Under the specific particle size ratio of powders, the compacts with the highest relative density could be obtained. In the results, the large, medium, and fine particles in the mass ratio of 60:15:25 show the highest compact relative density, and the compact relative density does not increase with the increase of the fine powder ratio. As the proportion of the additional fine powders rises during the pressing process, the greater strain can be generated in the pressing direction. The lateral pressure coefficient and Poisson's ratio are less affected by the particle size distribution of powders, which can decline due to the lack of sufficient driving force and displacement space in the case that the compacts have obtained the higher relative density in the later stage of the compaction. The number of force chains for the powders with the mixed particle size is much greater than that of the powders in the single particle size. In the case that the number of strong force chains is sufficient, the higher compact relative density can be obtained, combining a large number of weak force chains.