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The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.Mon, 17 Feb 2020 19:54:40 GMT2020-02-17T19:54:40ZReevaluation of the diametral compression test for tablets using the flattened disc geometry
http://hdl.handle.net/10985/11248
Reevaluation of the diametral compression test for tablets using the flattened disc geometry
MAZEL, Vincent; GUERARD, Sandra; CROQUELOIS, Benjamin; KOPP, Jean-Benoit; GIRARDOT, Jérémie; DIARRA, Harona; BUSIGNIES, Virginie; TCHORELOFF, Pierre
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.
Fri, 01 Jan 2016 00:00:00 GMThttp://hdl.handle.net/10985/112482016-01-01T00:00:00ZMAZEL, VincentGUERARD, SandraCROQUELOIS, BenjaminKOPP, Jean-BenoitGIRARDOT, JérémieDIARRA, HaronaBUSIGNIES, VirginieTCHORELOFF, PierreMechanical 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.Breaking pharmaceutical tablets with a hole: Reevaluation of the stress concentration factor and influence of the hole size
http://hdl.handle.net/10985/17336
Breaking pharmaceutical tablets with a hole: Reevaluation of the stress concentration factor and influence of the hole size
CROQUELOIS, Benjamin; GIRARDOT, Jérémie; KOPP, Jean-Benoît; CAZAUTETS, C.; TCHORELOFF, Pierre; MAZEL, Vincent
Mechanical strength is an important property for pharmaceutical tablets. Its study using the theory of linear elastic fracture mechanics has been introduced in the pharmaceutical field through the Brittle Fracture Index (BFI). This index is based on the stress concentration factor (SCF) and contradictory results have been published in the pharmaceutical literature about the value of the SCF during the diametral compression of a disc with a hole. In this work, thanks to the use of numerical simulations (FEM) and analytical results, the value of the SCF was proved to be equal to 6. The result was also applicable for the case of the flattened disc geometry that was introduced in a previous work. The value of the SCF is found to be nearly independent of the hole size if the ratio between the hole and the tablet diameterswas lower than 0.1. Nevertheless, experimental results presented in this paper show that the load needed to break a compact varieswith the hole size. This influence is due to the change in the stress distribution around the hole when the hole size is changing. Criteria such as the average stress criterion, which takes into account the stress distribution, made it possible to explain the influence of the hole on the breaking load.
Sun, 01 Jan 2017 00:00:00 GMThttp://hdl.handle.net/10985/173362017-01-01T00:00:00ZCROQUELOIS, BenjaminGIRARDOT, JérémieKOPP, Jean-BenoîtCAZAUTETS, C.TCHORELOFF, PierreMAZEL, VincentMechanical strength is an important property for pharmaceutical tablets. Its study using the theory of linear elastic fracture mechanics has been introduced in the pharmaceutical field through the Brittle Fracture Index (BFI). This index is based on the stress concentration factor (SCF) and contradictory results have been published in the pharmaceutical literature about the value of the SCF during the diametral compression of a disc with a hole. In this work, thanks to the use of numerical simulations (FEM) and analytical results, the value of the SCF was proved to be equal to 6. The result was also applicable for the case of the flattened disc geometry that was introduced in a previous work. The value of the SCF is found to be nearly independent of the hole size if the ratio between the hole and the tablet diameterswas lower than 0.1. Nevertheless, experimental results presented in this paper show that the load needed to break a compact varieswith the hole size. This influence is due to the change in the stress distribution around the hole when the hole size is changing. Criteria such as the average stress criterion, which takes into account the stress distribution, made it possible to explain the influence of the hole on the breaking load.