Reevaluation of the diametral compression test for tablets using the flattened disc geometry

Nov. 1, 2016, midnight - by V. Mazel , S. Guerard , B. Croquelois , J.B. Kopp , J. Girardot , H. Diarra , V. Busignies , P. Tchoreloff

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The assessment of mechanical strength is a crucial quality attribute for tablets in the pharmaceutical field. Traditionally, the diametral compression test has been employed for this purpose. However, concerns have been raised about potential test invalidation due to the small contact area between the tablet and the platens, suggesting that failure might occur in tension away from the center. This study explores the use of a flattened disc geometry as an alternative to overcome these contact issues. The diametral compression on both flattened and standard geometries was initially investigated through finite element method (FEM) simulation. The results indicated that, for the flattened geometry, both maximum tensile strain and stress were concentrated at the center of the tablet, in contrast to the standard geometry. Experimental observations using digital image correlation (DIC) supported the numerical findings. Comparison of the experimental tensile strength obtained with both geometries revealed consistently higher tensile strength values for the flattened geometry. Furthermore, high-speed video capture of the test revealed that, for the standard geometry, crack initiation consistently occurred away from the center of the tablet.

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