Calibration and interpretation of DEM parameters for simulations of cylindrical tablets with multi-sphere approach
March 1, 2018, midnight
Jan Henrik Finke
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Enhancing the quality of finishing and transport operations in pharmaceutical tablet manufacturing, such as coating and conveying processes, requires a nuanced understanding of the interplay between process parameters and product quality attributes. This study marks an initial step towards simulating these processes by calibrating the motion modeling of uniaxial-compressed cylindrical tablets using the multi-sphere approach (MS) within the Discrete Element Method (DEM). Achieving high accuracy in representing the cylindrical tablet shape, especially concerning edges, is crucial for a favorable agreement between simulated and experimentally observed packing fractions.
Model parameter sensitivity in calibration was assessed through tumbling drum tests, a common occurrence in the industry, and the pouring experiment, which extracted static and dynamic angles of repose. This analysis identified sliding and rolling friction as the most sensitive parameters, successfully calibrated through an iterative crossed analysis in tumbling drum and pouring tests. Additionally, a comprehensive determination and subsequent calibration strategy were provided for the Coefficient of Restitution and Young's modulus. The results of the final numerical modeling exhibit both qualitative and quantitative agreement with experimental test case experiments. A conclusive validation was conducted through the simulation of an attrition tester with a single baffle, underscoring one of the primary limitations of DEM: its operation-focused calibration nature.