Abstract In the production process of pharmaceutical pellets with a narrow size distribution and a high sphericity, a combined extrusion-spheronization technique is frequently used. The rounding of the wet cylindrical extrudates in the spheronizer after the extrusion step is influenced by various interfering mechanisms, in particular plastic deformation, breakage, attrition and coalescence. Due to the complexity of these mechanisms which depend on the particle dynamics, there is no sufficient description of the particle rounding process in the spheronizer. In this study, the Discrete Element Method (DEM) which runs on the micro scale is coupled with a Particle Shape Evolution (PSE) model on the macro scale to describe how the particle shape changes due to collisions. For the DEM simulation a new contact model was used which was developed to capture the cyclic, dominant visco plastic deformation behaviour. Based on the DEM collision data, the changing particle shape was described in the PSE model by applying the proposed submodels for the different formation mechanisms. The resulting particle shapes obtained with this simulation framework are in a good agreement with experimental data.

中文翻译：

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形成机制在药丸滚圆过程的 DEM 模拟中的实现

摘要 在粒径分布窄、球形度高的药丸生产过程中，常采用挤出滚圆联合工艺。挤出步骤后，湿圆柱形挤出物在滚圆机中的倒圆受各种干扰机制的影响，特别是塑性变形、断裂、磨损和聚结。由于这些依赖于粒子动力学的机制的复杂性，没有充分描述滚圆机中的粒子圆整过程。在这项研究中，在微观尺度上运行的离散元方法 (DEM) 与宏观尺度上的粒子形状演化 (PSE) 模型相结合，以描述粒子形状如何因碰撞而变化。对于 DEM 模拟，使用了一种新的接触模型，该模型用于捕捉循环的、占主导地位的粘塑性变形行为。基于 DEM 碰撞数据，通过将建议的子模型应用于不同的形成机制，在 PSE 模型中描述了不断变化的粒子形状。使用该模拟框架获得的最终粒子形状与实验数据非常吻合。