27 research outputs found
Experimental and Numerical Strategy for the Determination of Mechanical Properties Related to Human Cortical Bone Fracture
ICTAEM 2020, Proceedings of the Third International Conference on Theoretical, Applied and Experimental Mechanics , Athenes, GRECE, 14-/06/2020 - 17/06/2020The paper presents an experimental test of macrocrack propagation in bones associated with a numerical strategy to determine from this test some mechanical properties by inverse identification. A 3 point bending test is performed on a notched segment of long human bone, and the load vs notch opening displacement is measured. The compliance method is applied in the context of a realistic FE simulation of the test. A first application of this methodology is described and shows its feasibility and capabilities. The ultimate objective of this research project is to develop a probabilistic modelling of the macrocracking processes in human long bone tissues based on an experimental database of mechanical parameters fed up by this methodology
Propagation de fissure sur tronçon d'os long rainuré
International audienceUn essai de propagation dâune macrofissure dans un tronçon dâos cortical humain est dĂ©veloppĂ© dans lâobjectif de comprendre les mĂ©canismes de rupture du tissu Ă cette Ă©chelle et dâidentifier des propriĂ©tĂ©s de rupture, prĂ©requis indispensables Ă une modĂ©lisation ultĂ©rieure. Une premiĂšre campagne dâessais a Ă©tĂ© rĂ©alisĂ©e sur des segments de diaphyses fĂ©morales entaillĂ©s soumis Ă une flexion trois points [1, 2]. Toutefois, lâorientation de la macrofissure est influencĂ©e par lâanisotropie du matĂ©riau. Afin dâorienter les processus de rupture dans la direction transversale uniquement, une modification de la procĂ©dure dâessai est proposĂ©e. InspirĂ©e de travaux bibliographiques [3, 4], les tronçons entaillĂ©s sont prĂ©alablement rainurĂ©s : une gorge hĂ©misphĂ©rique est usinĂ©e sur la surface externe de lâos afin de guider la fissure dans la direction transversale au niveau de lâentaille. Les prĂ©cautions prises pour la rĂ©alisation de lâessai de flexion trois points garantissent une maĂźtrise de la procĂ©dure de test malgrĂ© la variabilitĂ© gĂ©omĂ©trique des spĂ©cimens : positionnement et conditions dâappuis des Ă©chantillons, alignement des supports du capteur dâouverture dâentaille, positionnement et hauteur de lâentaille, profondeur uniforme de la gorge. Le vĂ©rin est pilotĂ© indirectement par lâouverture dâentaille, via un capteur de dĂ©placement inductif. Une sĂ©rie de cycles de dĂ©chargements/rechargements est mise en Ćuvre afin de suivre les Ă©volutions des quantitĂ©s rĂ©siduelles, de lâendommagement prĂ©-pic et de la propagation de macrofissure en post-pic. Les rĂ©sultats obtenus sont exprimĂ©s en termes de courbes dâeffort en fonction de lâouverture dâentaille. Lâexploitation des cycles de charges-dĂ©charges ainsi que des ouvertures rĂ©siduelles permettent de mettre en Ă©vidence le rĂŽle primordial de la fissuration dans les mĂ©canismes de rupture. Les rĂ©sultats montrent que lâouverture rĂ©siduelle est directement liĂ©e au niveau dâaffaiblissement structurel, consĂ©quence des processus de fissuration, et quâaucun mĂ©canisme de plasticitĂ© nâest visible Ă cette Ă©chelle. Lâanalyse de ces cycles permet Ă©galement dâĂ©mettre une hypothĂšse sur le rĂŽle de contraintes internes rĂ©siduelles sur les dĂ©formations permanentes. Les rĂ©sultats montrent Ă©galement que la rainure permet de guider parfaitement la macrofissure dans la direction transversale et la comparaison avec les rĂ©sultats sur tronçons non-rainurĂ©s montrent bien lâimpact de cette modification gĂ©omĂ©trique du spĂ©cimen. En perspective future, cet essai sera utilisĂ© pour lâidentification par analyse inverse de propriĂ©tĂ©s mĂ©caniques dans la direction transversale
Effet de la flexion mandibulaire sur la symphyse : modélisation par la méthode des éléments finis de 3 morphotypes de mandibules
International audienc
Influence de la flexion mandibulaire : modélisation par la méthode des éléments finis par 3 morphotypes de mandibules édentées
International audienc
Aspects mĂ©thodologiques de lâestimation de l'Ăąge chez l'adulte en fonction du systĂšme haversien
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Leaflet stress quantification of porcine vs bovine surgical bioprostheses: an in vitro study
International audienc
Macrocrack propagation in a notched shaft segment of human long bone: Experimental results and mechanical aspects
Experimenting with crack propagation in human cortical tissue is a necessary prerequisite for developing a cracking model. A three-point bending test on a shaft section of a notched human long bone is presented. A procedure for carrying out the experimental test, including unloading/reloading cycles, is implemented. The results obtained are analyzed regarding the physical mechanisms which occur in the different phases of the test, and during the cycles. The prominent role of cracking is highlighted. In addition a hypothesis is proposed concerning the potential effect of initial internal residual stresses, due to bone remodelling, on the significant residual notch openings after unloading and on the cycles' shape
Development and validation of an optimized finite element model of the human orbit
The authors' main purpose was to develop a detailed finite element model (FEM) of the human orbit and to validate it by analyzing its behavior under the stress of blunt traumas. Materials and methods: A pre-existing 3D FEM of a human head was modified and used in this study. Modifications took into account preliminary research carried out on PubMed database. Data from a CT scan of the head were computed with Mimics [10TDDIF]'s properties and the simulations of blunt orbital traumas were conducted on Hyperworks1 software. Results: The resulting 3D FEM was composed of 640 000 elements and was used to perform blunt trauma simulations on an intact orbit. A total of 27 tests were simulated. Fifteen tests were realized with a metallic cylinder impactor; 12 tests simulated a hit by a closed fist. In all the tests conducted (27/27), the orbital floor was fractured. Fracture patterns were similar to those found in real clinical situations according to the buckling and hydraulic theories of orbital floor fractures. Discussion: The similitude between the fracture patterns produced on the model and those observed in vivo allows for a validation of the model. This model constitutes, at the authors knowledge, the most sophisticated one ever developed
Salivary side effects after radioiodine treatment for differentiated papillary thyroid carcinoma: Longâterm study
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Finite element analysis of the human orbit. Behavior of titanium mesh for orbital floor reconstruction in case of trauma recurrence
IntroductionThe authorsâ main purpose was to simulate the behavior of a titanium mesh implant (TMI) used to reconstruct the orbital floor under the stress of a blunt trauma.Materials and methodsThe orbital floor of a previously validated finite element model (FEM) of the human orbit was numerically fractured and reconstructed by a simplified TMI. Data from a CT scan of the head were computed with MICMICS (Materialise, Louvain, Belgium) software to re-create the skull's geometry. The meshing production, the model's properties management and the simulations of blunt traumas of the orbit were conducted on HYPERWORKSÂź software (Altair Engineering, Detroit, MI, USA). Some of the elements of the orbital floor were selected and removed to model the fracture; these elements were duplicated, their characteristics being changed by those of titanium to create a TMI covering this fracture. A 3D FEM composed of 640,000 elements was used to perform 21 blunt trauma simulations on the reconstructed orbit.ResultsIn 90.4% (19/21) of the tests conducted, the TMI, whether free from any bony attachment or screwed to the orbital rim, has tended to move in the orbit and/or to deform.DiscussionIn the event of traumatic recurrence, which is not rare, TMIs may deform in a âblow-inâ motion and threaten intra-orbital structures