https://sam.ensam.eu:443 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. Fri, 10 Apr 2026 12:24:10 GMT 2026-04-10T12:24:10Z http://hdl.handle.net/10985/26728 Disk-shaped compact tension test for fracture analysis on pharmaceutical tablets GIRARDOT, Jérémie; KOPP, Jean-Benoit; CROQUELOIS, Benjamin; TCHORELOFF, Pierre; MOREL, Stéphane; MAZEL, Vincent Pharmaceutical tablets must meet a number of requirements and among them, the mechanical strength plays an important role. The diametral compression test is generally used to evaluate it but can generate unstable failures. Thanks to load–unload cycles applied to the tablets subjected to a DCT test, it was shown that the concept of equivalent linear elastic fracture mechanics usually, can be successfully applied to the Mode I fracture behavior. Within this framework, the equivalent elastic crack growth resistance, commonly called resistance curve (R-curve), of the studied material was obtained and revealed the development of a Fracture Process Zone (FPZ) which is symptomatic of a quasi-brittle behavior. Moreover, the cyclic loading applied during the fracture test revealed the existence of a second dissipative mechanism leading to residual crack opening which seems to be mainly caused by friction phenomenon in the FPZ. Sun, 01 Jan 2023 00:00:00 GMT http://hdl.handle.net/10985/26728 2023-01-01T00:00:00Z GIRARDOT, Jérémie KOPP, Jean-Benoit CROQUELOIS, Benjamin TCHORELOFF, Pierre MOREL, Stéphane MAZEL, Vincent Pharmaceutical tablets must meet a number of requirements and among them, the mechanical strength plays an important role. The diametral compression test is generally used to evaluate it but can generate unstable failures. Thanks to load–unload cycles applied to the tablets subjected to a DCT test, it was shown that the concept of equivalent linear elastic fracture mechanics usually, can be successfully applied to the Mode I fracture behavior. Within this framework, the equivalent elastic crack growth resistance, commonly called resistance curve (R-curve), of the studied material was obtained and revealed the development of a Fracture Process Zone (FPZ) which is symptomatic of a quasi-brittle behavior. Moreover, the cyclic loading applied during the fracture test revealed the existence of a second dissipative mechanism leading to residual crack opening which seems to be mainly caused by friction phenomenon in the FPZ. http://hdl.handle.net/10985/21460 A damaging beam-lattice model for quasi-brittle fracture SAGE, Margaux; GIRARDOT, Jeremie; KOPP, Jean-Benoit; MOREL, Stéphane This work aims to propose a new damaging beam-lattice model using the Discrete Element Method paradigm dedicated to the simulation of quasi-brittle fracture under complex loadings. Enrichment of the elastic Euler–Bernoulli beam link, inspired by the cohesive zone models, is proposed to provide a damageable behavior in mixed mode and contribution of frictional behavior is not considered in this first version of the damage model. The tensile contribution on the beam link is taken into account from the first order elongation of the beam while all other contributions, i.e. bending, shear, and torsion are considered from the second-order elongation of the beam. These orders of elongation refer to beam theory, where the first elongation is induced by a force normal to the cross-section and the second is the elongation of the curvilinear length of the beam resulting from shear, bending and torsion loads. As these two kinematics do not correspond to the conventional modes I, II, and III, a deep checking step of the model is undertaken. First, mixed-mode testing on a single beam is performed to monitor the energy components dissipated in each mode and to ensure that energy dissipated in mixed mode exhibits a monotonic evolution between boundary values related to pure modes. Based on this first verification, a tensile test and a compression one are simulated on a cylinder specimen to evaluate the model capabilities to qualitatively describe the well-known characteristics of quasi-brittle fracture such as failure facies, unilateral effect, and the ratio between the compression and tensile strength. Finally, the model is used to simulate a complex crack propagation test coming from the recent international Carpiuc benchmark. Sat, 01 Jan 2022 00:00:00 GMT http://hdl.handle.net/10985/21460 2022-01-01T00:00:00Z SAGE, Margaux GIRARDOT, Jeremie KOPP, Jean-Benoit MOREL, Stéphane This work aims to propose a new damaging beam-lattice model using the Discrete Element Method paradigm dedicated to the simulation of quasi-brittle fracture under complex loadings. Enrichment of the elastic Euler–Bernoulli beam link, inspired by the cohesive zone models, is proposed to provide a damageable behavior in mixed mode and contribution of frictional behavior is not considered in this first version of the damage model. The tensile contribution on the beam link is taken into account from the first order elongation of the beam while all other contributions, i.e. bending, shear, and torsion are considered from the second-order elongation of the beam. These orders of elongation refer to beam theory, where the first elongation is induced by a force normal to the cross-section and the second is the elongation of the curvilinear length of the beam resulting from shear, bending and torsion loads. As these two kinematics do not correspond to the conventional modes I, II, and III, a deep checking step of the model is undertaken. First, mixed-mode testing on a single beam is performed to monitor the energy components dissipated in each mode and to ensure that energy dissipated in mixed mode exhibits a monotonic evolution between boundary values related to pure modes. Based on this first verification, a tensile test and a compression one are simulated on a cylinder specimen to evaluate the model capabilities to qualitatively describe the well-known characteristics of quasi-brittle fracture such as failure facies, unilateral effect, and the ratio between the compression and tensile strength. Finally, the model is used to simulate a complex crack propagation test coming from the recent international Carpiuc benchmark. http://hdl.handle.net/10985/25620 Full-scale hybrid fire test in real-time with multiple degree of freedom RENARD, Silvio; MINDEGUIA, Jean-Christophe; ROBERT, Fabienne; MOREL, Stéphane; FRANSSEN, Jean-Marc To experimentally assess the fire resistance of civil structures, testing whole structures is very costly but the standard tests on individual structural elements can sometimes be too simplistic, regarding their boundary conditions. Hybrid fire testing offers a promising solution to these limitations, but performing such tests is technically challenging and few full-scale tests have been conducted. Current approaches rely on high-performance sensors and actuator systems, as well as assumptions about the stiffness of the tested element. This paper presents the detailed methodology and results of a full-scale, real-time test with 3 degrees of freedom on a concrete beam. The use of an adaptive controller allowed for maintaining stability and achieving reasonable precision despite the use of relatively low-precision sensors, regular hydraulic actuators, and no assumptions about the tested element's stiffness. The comparison with the same element tested using a standard fire resistance test demonstrates the usefulness of this technique in achieving a more accurate representation of the performance of the tested element in realistic conditions. Tue, 01 Oct 2024 00:00:00 GMT http://hdl.handle.net/10985/25620 2024-10-01T00:00:00Z RENARD, Silvio MINDEGUIA, Jean-Christophe ROBERT, Fabienne MOREL, Stéphane FRANSSEN, Jean-Marc To experimentally assess the fire resistance of civil structures, testing whole structures is very costly but the standard tests on individual structural elements can sometimes be too simplistic, regarding their boundary conditions. Hybrid fire testing offers a promising solution to these limitations, but performing such tests is technically challenging and few full-scale tests have been conducted. Current approaches rely on high-performance sensors and actuator systems, as well as assumptions about the stiffness of the tested element. This paper presents the detailed methodology and results of a full-scale, real-time test with 3 degrees of freedom on a concrete beam. The use of an adaptive controller allowed for maintaining stability and achieving reasonable precision despite the use of relatively low-precision sensors, regular hydraulic actuators, and no assumptions about the tested element's stiffness. The comparison with the same element tested using a standard fire resistance test demonstrates the usefulness of this technique in achieving a more accurate representation of the performance of the tested element in realistic conditions. http://hdl.handle.net/10985/25021 Comparing failure tests on pharmaceutical tablets: Interpretation using experimental results and a numerical approach with cohesive zone models MAZEL, Vincent; GIRARDOT , Jeremie; KOPP, Jean-Benoit; MOREL, Stéphane; TCHORELOFF, Pierre The mechanical strength is an important quality attribute of pharmaceutical tablets. It can be determined using different failure tests like the Brazilian test or the three-point bending test. Nevertheless, literature shows that different failure tests often give conflicting values of tensile strengths (TS), which are generally calculated using the maximum stress criterion as a failure criterion. This work started from the hypothesis that these discrepancies are in fact due to the application of this criterion which is not suited to study pharmaceutical tablets, first due to heterogeneity of the stress distributions during the tests and second due to the quasi-brittle nature of pharmaceutical tablets. As an alternative, a numerical fracture criterion which is known to be well-suited for quasi-brittle solids (cohesive zone model, CZM) was used and calibrated using experiments. Using this approach, the breaking forces obtained numerically were shown to be in fair agreement with the experimental ones. Above all, the numerical results made it possible to catch the trends when comparing the different failure tests one to another. Especially, the model made it possible to retrieve the factor 2 between the TS obtained by three-point bending and by diametral compression found in the literature. Sat, 01 Jul 2023 00:00:00 GMT http://hdl.handle.net/10985/25021 2023-07-01T00:00:00Z MAZEL, Vincent GIRARDOT , Jeremie KOPP, Jean-Benoit MOREL, Stéphane TCHORELOFF, Pierre The mechanical strength is an important quality attribute of pharmaceutical tablets. It can be determined using different failure tests like the Brazilian test or the three-point bending test. Nevertheless, literature shows that different failure tests often give conflicting values of tensile strengths (TS), which are generally calculated using the maximum stress criterion as a failure criterion. This work started from the hypothesis that these discrepancies are in fact due to the application of this criterion which is not suited to study pharmaceutical tablets, first due to heterogeneity of the stress distributions during the tests and second due to the quasi-brittle nature of pharmaceutical tablets. As an alternative, a numerical fracture criterion which is known to be well-suited for quasi-brittle solids (cohesive zone model, CZM) was used and calibrated using experiments. Using this approach, the breaking forces obtained numerically were shown to be in fair agreement with the experimental ones. Above all, the numerical results made it possible to catch the trends when comparing the different failure tests one to another. Especially, the model made it possible to retrieve the factor 2 between the TS obtained by three-point bending and by diametral compression found in the literature.