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The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.Tue, 16 Jul 2024 06:11:13 GMT2024-07-16T06:11:13ZA damaging beam-lattice model for quasi-brittle fracture
http://hdl.handle.net/10985/21460
A damaging beam-lattice model for quasi-brittle fracture
SAGE, Margaux; KOPP, Jean-Benoit; MOREL, Stéphane; GIRARDOT, Jeremie
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 GMThttp://hdl.handle.net/10985/214602022-01-01T00:00:00ZSAGE, MargauxKOPP, Jean-BenoitMOREL, StéphaneGIRARDOT, JeremieThis 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.Comparing failure tests on pharmaceutical tablets: Interpretation using experimental results and a numerical approach with cohesive zone models
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 GMThttp://hdl.handle.net/10985/250212023-07-01T00:00:00ZMAZEL, VincentGIRARDOT , JeremieKOPP, Jean-BenoitMOREL, StéphaneTCHORELOFF, PierreThe 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.