Prediction of tablet characteristics based on sparse modeling for residual stresses simulated by the finite element method incorporating Drucker-Prager cap model

Abstract

Effects of residual stresses on the mechanical characteristics of tablets such as tensile strength (TS) and disintegration time (DT) were investigated. The residual stresses were simulated using the finite element method (FEM), in which the powder compaction was represented by a Drucker-Prager cap (DPC) model under unconstrained condition. As model tablet formulations, we employed powder mixtures comprising various quantities of lactose (LAC), corn starch (CS), and microcrystalline cellulose (MCC). Key parameters of DPC model were well predicted as a function of quantity ratio of LAC, CS, and MCC. A clear difference was observed in the residual stress distributions between the flat and convex tablets. Strong stresses remained in the convex tablets, while they were rather weak in the flat tablets. For a sparse modeling, an elastic-net (ENET) regression was employed to identify specific stress sites in the tablets. Consequently, the ENET regression revealed specific significant sites in the tablet affecting the TS and DT values. Both quantity and direction of the remaining stresses acting at specific sites close to the die wall were crucial in the convex tablets to predict the TS and DT values; however, no such tendency was seen in the flat tablet.