title: Reevaluation of the diametral compression test for tablets using the flattened disc geometry.
abstract: Mechanical strength is an important critical quality attribute for tablets. It is classically measured, in the pharmaceutical field, using the diametral compression test. Nevertheless, due to small contact area between the tablet and the platens, some authors suggested that during the test, the failure could occur in tension away from the center which would invalidate the test and the calculation of the tensile strength. In this study, the flattened disc geometry was used as an alternative to avoid contact problems. The diametral compression on both flattened and standard geometries was first studied using finite element method (FEM) simulation. It was found that, for the flattened geometry, both maximum tensile strain and stress were located at the center of the tablet, which was not the case for the standard geometry. Experimental observations using digital image correlation (DIC) confirmed the numerical results. The experimental tensile strength obtained using both geometries were compared and it was found that the standard geometry always gave lower tensile strength than the flattened geometry. Finally, high-speed video capture of the test made it possible to detect that for the standard geometry the crack initiation was always away from the center of the tablet.
authors.affiliation: Univ. Bordeaux, CNRS, Bordeaux INP, Arts et Métiers ParisTech, I2M, UMR 5295, F-33000 Bordeaux, France. Electronic address: vincent.mazel@u-bordeaux.fr.
authors.forename: V
authors.initials: V
authors.lastname: Mazel
authors.affiliation: Arts et Métiers ParisTech, Univ. Bordeaux, Bordeaux INP, I2M, UMR 5295, F-33000 Bordeaux, France.
authors.forename: S
authors.initials: S
authors.lastname: Guerard
authors.affiliation: Univ. Bordeaux, CNRS, Bordeaux INP, Arts et Métiers ParisTech, I2M, UMR 5295, F-33000 Bordeaux, France.
authors.forename: B
authors.initials: B
authors.lastname: Croquelois
authors.affiliation: Arts et Métiers ParisTech, Univ. Bordeaux, Bordeaux INP, I2M, UMR 5295, F-33000 Bordeaux, France.
authors.forename: J B
authors.initials: JB
authors.lastname: Kopp
authors.affiliation: Arts et Métiers ParisTech, Univ. Bordeaux, Bordeaux INP, I2M, UMR 5295, F-33000 Bordeaux, France.
authors.forename: J
authors.initials: J
authors.lastname: Girardot
authors.affiliation: CNRS, Univ. Bordeaux, Bordeaux INP, Arts et Métiers ParisTech, I2M, UMR 5295, F-33000 Bordeaux, France.
authors.forename: H
authors.initials: H
authors.lastname: Diarra
authors.affiliation: Univ. Bordeaux, CNRS, Bordeaux INP, Arts et Métiers ParisTech, I2M, UMR 5295, F-33000 Bordeaux, France.
authors.forename: V
authors.initials: V
authors.lastname: Busignies
authors.affiliation: Univ. Bordeaux, CNRS, Bordeaux INP, Arts et Métiers ParisTech, I2M, UMR 5295, F-33000 Bordeaux, France.
authors.forename: P
authors.initials: P
authors.lastname: Tchoreloff
mesh_terms: D002130:Calcium Phosphates / Q000737:chemistry; D020342:Finite Element Analysis; D007785:Lactose / Q000737:chemistry; D008353:Mannitol / Q000737:chemistry; D011208:Powders / Q000737:chemistry; D013229:Stearic Acids / Q000737:chemistry; D013314:Stress, Mechanical; D013607:Tablets / Q000737:chemistry*; D013678:Technology, Pharmaceutical / Q000379:methods*; D013718:Tensile Strength
chemical_list: D002130:Calcium Phosphates; D011208:Powders; D013229:Stearic Acids; D013607:Tablets; D008353:Mannitol; C031183:stearic acid; C020243:calcium phosphate; D007785:Lactose
keywords: Compression; Diametral compression; Numerical simulation; Tablet; Tensile strength