Shuji Ohsaki, Kazune Kushida, Yu Matsuda, Hideya Nakamura, Satoru Watano. 

Department of Chemical Engineering, Osaka Prefecture University 
1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan 

Purpose. 

Numerical simulations using finite element (FEM) method of tableting process is important to quantitatively understand the structural change inside the tablet and the mechanism of tableting failure. In the pharmaceutical field, the Drucker-Prager Cap (DPC) model is the most used to demonstrate the mechanical behavior of the powder. The DPC model, however, cannot consider the compaction speed, although the compaction speed has a large impact of the tablet strength and the frequency of tableting failure. In the present study, we proposed the combined model with DPC and Perzyna model, which incorporates a viscoplastic behavior with velocity dependence.  

Methods. 

We selected the cellulose as a model powder. The parameters for DPC-Perzyna model were calculated from experiments of compaction tests, unconfined compression tests, and tension tests. FEM simulation of powder compaction process was conducted by ANSYS Mechanical 18.0 (ANSYS Inc.). 

Results. 

Figure compared the experimental data of compression tests for different compaction speeds with FEM simulation results calculated with DPC and Perzyna model. From experimental data, we found that the relative density at the same axis stress decreased with an increase in the compaction speed. The calculation results agree fairly with both experimental data of different compaction speed. Furthermore, we investigated the effect of compaction speed on the internal structure of powder. 

Conclusions. 

Present study proposed the DPC-Perzyna model to calculate the tableting process in consideration of compaction speed. The effect of compaction speed on the structural change inside the tablet was investigated. 

Biosketch: Dr. Shuji Ohsaki

Dr. Shuji Ohsaki was received Ph. D. in chemical engineering from Kyoto university, Kyoto Japan, in 2017. He is now assistant professor of Osaka prefecture university, Osaka Japan. His research interest includes the numerical simulation of powder compression process