Dissertations / Theses on the topic 'Modélisation du crâne'
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Niass, Abou. "Contribution à la modélisation mécanique du crâne et de la face humaine." Université Louis Pasteur (Strasbourg) (1971-2008), 2003. http://www.theses.fr/2003STR13200.
Rambaud, Fabienne. "Caractérisation, Analyse et Modélisation statistiques de fragments osseux crâniens pour la prédiction de paramètres mécaniques lésionnels." Phd thesis, Université de Valenciennes et du Hainaut-Cambresis, 2007. http://tel.archives-ouvertes.fr/tel-00290942.
Cette thèse est une contribution à l'amélioration de la connaissance du comportement mécanique des os crâniens, en particulier dans le contexte accidentologique.
Les mécanismes de fractures du crâne ont été étudiés par un grand nombre de chercheurs. De multiples techniques et approches ont été élaborées pour la modélisation du comportement mécanique des os crâniens ; ces modèles ne permettent cependant pas de pallier aux problèmes de dispersions inter et intra individuelles propres aux sujets humains.
Dans un premier temps, selon un protocole expérimental, 289 éprouvettes prélevées sur différentes zones osseuses de 17 calottes crâniennes humaines sont testées en essais de flexion trois points quasi-statiques. La force de rupture obtenue à partir des courbes effort/déplacement représente le paramètre mécanique à prédire dans nos modèles statistiques. A partir de mesures morphométriques obtenues par analyse d'images et tests expérimentaux, 15 paramètres morphométriques et densitométriques sont définis pour chaque éprouvette.
Ensuite, une analyse de données exploratoire multidimensionnelle est réalisée sur le tableau de données préalablement fuzzifiées. Cette analyse a permis de nous orienter sur les liaisons linéaires et non linéaires existant entre les paramètres. Des régressions multiples linéaires et curvilinéaires sont réalisées par ajustement des paramètres jugés pertinents. Les modèles sont choisis par la méthode de validation croisée, et par une étude complète de diagnostic des résidus.
L'élaboration de modèles statistiques a permis, selon un sexe et une classe d'âge, de prédire le comportement mécanique de fragments osseux crâniens soumis à des sollicitations de flexion quasi-statique de manière personnalisée.
Nicolle, Stéphane. "Identification et modélisation du comportement viscoélastique linéaire et non linéaire du tissu cérébral en situation d'impacts." Université Louis Pasteur (Strasbourg) (1971-2008), 2003. http://www.theses.fr/2003STR13157.
The aim of this work is to contribute to the development of the ULP human head Finite Element model. This study concerns the linear and nonlinear viscoelastic brain tissue behaviour of which the knowledge remains currently incomplete and contrasted. The small shear strains brain properties are determined on new frequency range (from 0. 1 to more than 6000 Hz) which includes frequencies associated with traffic road accidents and non penetrating ballistic impacts. The robustness of the protocol and the reliability of the experimental results are confirmed by the use of two different testing devices and by the analysis of several factors which could affect measurements objectivity. The study is also accompanied by an analysis of the anisotropy for a particular area of the brain (the corona radiate), and inter-species and regional differences. The large strain brain behaviour is characterized by shear relaxation tests between 0. 1% and 50% strain. The results show the increase of the strain level affect the modulus magnitude but not their relaxation times. The brain linear behaviour is modelled by a phenomenological five-mode Maxwell model. The brain rubberlike behaviour is modelled by an Ogden hyperelastic law. This law is extended to take account of the observed dissipative effects on all time range (visco-hyperelastic law). Finally, a comparison of these brain linear and nonlinear constitutive laws is realised from numerical simulations of a reference and a ballistic impact. The conclusion is that the pertinence of the different laws contribution requires other numerical model validation criteria
Fin, Loïc. "Etude et modélisation de la circulation du liquide cérébro-spinal (LCS)." Compiègne, 2002. http://www.theses.fr/2002COMP1406.
Autuori, Barbara. "Modélisation par éléments finis de la face humaine en vue de la simulation de sa réponse au choc." Phd thesis, INSA de Lyon, 2004. http://tel.archives-ouvertes.fr/tel-00008231.
En vue de prédire précisément les risques de blessures de la face et du contenu intracrânien, l'objectif de cette thèse est de développer un modèle en éléments finis de la structure osseuse de la face et du crâne pour la simulation de sa réponse au choc.
Une première partie du travail a consisté à construire le maillage d'une structure osseuse cranio-faciale à partir de coupes scanner de tête. Le choix d'un maillage en éléments de type plaque, de densité suffisante pour représenter fidèlement la géométrie complexe de cette structure osseuse et d'épaisseur variable, a été fait.
L'hypothèse d'un matériau osseux homogène et isotrope a été choisie pour l'ensemble de la structure cranio-faciale. Des essais de flexion statique sur des échantillons d'os crânien, associés à leur simulation numé-rique et une méthode d'identification, ont permis de définir les propriétés élasto-plastiques de ce matériau. Les résultats se situent correctement par rapport aux intervalles de valeurs de la littérature.
La réponse du modèle cranio-facial a été validée sous sollicita-tions statiques. Pour cela des essais spécifiques de compression de la face ont été réalisés sur pièce anatomique. Les courbes globales effort - déplacement expérimentale et numérique ont été comparées pour « calibrer » les propriétés du matériau. La réponse du modèle a ensuite été validée par comparaison du champ de déplacement mesuré expérimentalement par une méthode de corrélation d'images et obtenu par simulation.
Le modèle ainsi validé en statique a été évalué sous sollicitations dynamiques. Sa réponse au choc a été comparée aux résultats d'un impact sur la face réalisé spécifiquement. La réponse au choc globale du modèle est similaire à celle enregistrée expérimentalement.
Plusieurs perspectives d'exploitation de ce modèle sont envisa-geables dans le domaine du choc ou celui de la chirurgie. En particulier, il aidera à définir des critères de blessures de la tête en cas de choc sur la face.
Siegel, Alice. "Etude de l’interaction mécanique entre un dispositif médical implantable actif crânien et le crâne face à des sollicitations dynamiques." Thesis, Paris, ENSAM, 2019. http://www.theses.fr/2019ENAM0012.
Active cranial implants are more and more developed to cure neurological diseases. In this context it is necessary to evaluate the mechanical resistance of the skull-implant complex under impact conditions as to ensure the patient’s security. The aim of this study is to quantify the mechanical interactions between the skull and the implant as to develop a finite element model for predictive purpose and for use in cranial implant design methodologies for future implants. First, material tests were necessary to identify the material law parameters of titanium and silicone. They were then used in a finite element model of the implant under dynamic loading, validated against 2.5 J-impact tests. The implant dissipates part of the impact energy and the model enables to optimize the design of implants for it to keep functional and hermetic after the impact. In the third part, a finite element model of the skull-implant complex is developed under dynamic loading. Impact tests on ovine cadaver heads are performed for model validation by enhancing the damage parameters of the three-layered skull and give insight into the behavior of the implanted skull under impact.This model is a primary tool for analyzing the mechanical interaction between the skull and an active implant and enables for an optimized design for functional and hermetic implants, while keeping the skull safe
Deck, Caroline. "Modélisation par éléments finis des lésions crânio-encéphaliques : Application à l'optimisation du casque vis à vis de critères biomécaniques." Université Louis Pasteur (Strasbourg) (1971-2008), 2004. http://www.theses.fr/2004STR13191.
Traumatic head injuries remain a common cause of death and severe disabilities around the world. FE modelling of the head is a well accepted tool to study head impact biomechanics. The first goal of this work was to optimise a full face helmet finite element model based on the dynamic behaviour of its components against biomechanical criteria. After a validation with a headform FE model as used in the experimental normative tests, the helmet model was coupled with a previously developed finite element model of the human head in order to predict intra-cranial field parameters. Four impacts on a flat anvil has been simulated with the same boundary conditions as for the normative test (ECER022) with standard helmet mechanical properties. The estimated intra-cranial stresses suggested that some brain tolerance limits were reached in these impacts configurations. In order to define the influence of the helmet shell and foam properties on the human head, a parametric study of the model was undertaken and all results were analyse with a PCA method to propose an helmet optimisation against biomechanical criteria. The second goal of this work was to improve a number of geometrical aspects and material constitutive laws of this complex human segment. The skull representation is improved at the geometrical point of view in order to simulate skull depressive and linear fractures. At the other hand brain constitutive law improvement is based on original experimental tests focusing on non linear behaviour in order to investigate the brain material properties influence in the head model validation procedure against existing experimental brain deformation recording. Main result is a detailed skull geometry including skull reinforced beams and thickness variation validated against existing head impacts involving skull fracture as well as a linear and a non-linear brain constitutive law which permit an accurate validation against brain deformation under impact
Roth, Sébastien. "Modélisation numérique de la tête de l'enfant par la méthode des éléments finis : application à la biomécanique des chocs." Strasbourg 1, 2007. http://www.theses.fr/2007STR13233.
Angla, Célestine. "Fast transcranial acoustic simulations for personalized dosimetry in ultrasound brain therapy." Electronic Thesis or Diss., université Paris-Saclay, 2023. http://www.theses.fr/2023UPAST207.
Ultrasound brain therapy is a promising method, as it is non-invasive when ultrasonic waves are sent through the skull. However, the skull bone complex structure strongly attenuates and aberrates the ultrasound beam, altering the dimensions, position and intensity of the focal spot. These focal parameters must be perfectly controlled to ensure both treatment efficacy and safety. Due to the high inter/intra-individual variability of skull geometry and acoustic properties, personalized simulations are required to predict focal characteristics depending on the patient skull and the ultrasonic probe position. Most simulation methods currently in use, such as k-Wave, are very time- and memory-intensive, limiting them to pre-intervention planning tools. The aim of this thesis was to develop a fast and realistic semi-analytical method for ultrasound field computation through the skull. As a first step, we developed a smooth and homogeneous model of the skull, realistic and suited to fast field computation algorithms. To this end, we modeled the skull inner and outer surfaces using a method called "Multi-level Bspline Approximation", and we developed a skull acoustic property homogenization method, which was numerically validated. This smooth and homogeneous skull model was then used as input to the field computation algorithm developed. This algorithm, named SplineBeam, is based on an ultrasonic path computation method that minimizes the time-of-flight function, which is fast and accurate, and which, combined with the pencil method, enables a regular sampling of the ultrasound probe. SplineBeam was validated numerically, by comparison with the pencil method, embedded in the CIVA HealthCare simulation platform, developed at the CEA, and with other numerical solvers (including k-Wave) on a series of configurations, and experimentally, by comparison with hydrophone measured pressure fields through an ex vivo skull sample. SplineBeam simulated fields were found to be closer to the experimentally measured ones than those simulated with k-Wave. This validates both the skull model and the field computation method. Furthermore, SplineBeam can restrict its computation to the focal spot, which allows it to drastically reduce the number of computation points, making it faster than k-Wave by two orders of magnitude, for a large probe
Nadarasa, Jeyendran. "Modélisation par éléments-finis des traumatismes crâniens du nourrisson." Thesis, Strasbourg, 2018. http://www.theses.fr/2018STRAD003.
Impact biomechanics aim at studying injuries, establishing tolerance limit and propose efficient protective systems. The finite-element method permits to study precisely injury mechanisms by avoiding questions linked to experimentation and ethics. For the human adult head biomechanics, this methodology was taken earlier and several stable and validated models exist worldwide, among which one can find the Strasbourg University Finite Element Head Model (SUFEHM). This thesis aims at widening the human head biomechanics by studying infant head trauma. The research work has been conducted in two steps. In the first one, an infant eye numerical model was developed in order to study retinal hemorrhages. The second one consisted in improving the infant head model by integrating medical images data such as axonal fiber density and orientations into the infant brain and by validating the mechanical formulation of the infant skull in order to predict skull fractures
Olivares, Amaro Marisnel Carolina. "Analyse, modélisation et implémentation de stratégies d'assistance : déploiement d'orthèses cognitives pour les activités instrumentales de la vie quotidienne des traumatisés crâniens." Thesis, Ecole nationale supérieure Mines-Télécom Atlantique Bretagne Pays de la Loire, 2017. http://www.theses.fr/2017IMTA0006/document.
Severe traumatic Brain Injury (TBI) is considered a public health problem. ; Indeed, severe TBI causes significant cognitive, emotional and behavioral repercussions that impact the lives of these individuals, particularly their independence in Instrumental Activities of Daily Living (IADLs). Individuals who have experienced severe TBI frequently return to live in their homes despite the severe difficulties associated with their condition, though the need for assistance to perform IADLs frequently persists. The objective of this thesis is to design, represent, formalize and implement a context-aware and adaptive structure of cognitive assistance. This assistance is created according to the general needs of individuals with severe TBI for IADL performance. The proposed assistance will promote their independence to perform IADL in a home environment. The design of this cognitive assistance technology involves an interdisciplinary collaboration between occupational therapy and computer science, to evolve from the assistance provided by the clinicians to a formal computer science formulation and implementation. This design is based on a participative design approach that mainly involves TBI residents of a smart alternative housing unit.A prototype of a cognitive orthotic for meal preparation (COOK) was created and deployed within an alternative housing unit. Implementation of this cognitive orthotic lifted the prohibition on use of a stove for meal preparation that had previously been place on their residents. By allowing these residents to cook independently, COOK has contributed to helping them become more independent in cooking and more confident in their ability to do so
Premi, Sumedha. "Investigation of mechanical threshold to concussion." Thesis, Strasbourg, 2019. http://www.theses.fr/2019STRAD050.
Concussion, in spite of being a mild traumatic brain injury, involves serious long term consequences and can adversely affect the life of an individual, their family and the society. Concussion is a neurological disturbance caused by a direct or indirect impulsive mechanical loading of the head. These neurological disturbances result in functional impairments of the brain. As diffuse axonal injury (DAI) is found to be one of the most frequent pathological features of traumatic brain injury, knowledge of mechanical threshold to concussion in terms of axonal elongation can help in developing better brain injury prediction tools and in optimizing head protection systems. Computational models have proved to be efficient means for such studies. In comparison to experimentation, computational models are more accurate, economic and easier to use. Further, they do not involve any ethical concerns that are always present in case of experimentation on biological subjects. Still, experimental data is essential for the validation of a computational model. Unfeasibility of experimentation on human brain restricts the detailed investigation on concussion. However, small animals, such as rat, seem to be an interesting opportunity for such investigations. The literary observations that an adult rat brain can be considered neurologically equivalent to an adult human brain and that at tissue level inter species brains respond similarly further support the significance of investigations through rat brain model. Hence, as a part of this doctoral thesis work, an anisotropic viscous hyperelastic finite element rat brain model is developed, validated and utilized for the investigation of mechanical threshold to concussion in terms of axonal elongation. This doctoral work contributes to the research on the development of better brain injury prediction tools and the optimization of head protection systems
Milne, Gérald. "Evaluation biomécanique du casque de protection pour cycliste : proposition d'une nouvelle norme d'homologation." Thesis, Strasbourg, 2013. http://www.theses.fr/2013STRAD006/document.
Traumatic head injuries remain a common cause of death and severe disabilities worldwide. FE modeling of the head is a well accepted tool to study head impact biomechanics. The objective of this PhD thesis was to evaluate the head protection capability offered by a commercial bicycle helmet. Experimental characterization tests, standard and tangential impacts were performed to develop and validate the finite element helmet model. In order to estimate the injury risk sustained in case of realistic head impacts, the helmet model has been coupled to an anatomical head and intracranial parameters were computed. Calculated values were higher than published tolerance limits. An in-deep investigation of the current EN1078 European standard was then carried out and relevant modifications were proposed to assess and optimize bicycle helmets against biomechanical criteria
Canaple, Bertrand. "Contribution au développement d'un outil de simulation prédictif des lésions cranio-encéphaliques par reconstruction d'accidents de la circulation." Valenciennes, 2001. https://ged.uphf.fr/nuxeo/site/esupversions/2da57bb0-4297-47b6-afd3-65f19f98f2b1.
In traffic accidents, head injuries are considered to be frequent and serious. Because of the various kind of injuries (bone, vascular and neurology) and limitations of the biomechanical representation of the head, old and simple protection criteria (such as the HIC or the peak linear acceleration of the head ) are still used in standard tests. Contrary to the others body segments, it’s not possible to use a direct approach (consisting in impacting biological human body models) to determine the tolerance and the threshold. In order to better represent the physical phenomena, an original research methodology that is based on traffic accidents reconstruction is developed. The first batch of works deals with the definition of a new finite element model of the head. The features concern the cerebro-spinal fluid described by an hyperelastic material defined by a sliding without separation interface with the brain in order to represent its relative movement with respect to the skull. The confrontations with experimental tests made on cadaver’s head confirm the model prediction. An accident reconstruction methodology has been developed. It is based on kinematics reconstruction, experimental reconstruction of the vehicle’s collision, multibody simulation of the second collision and study of the internal head response with the head model. This reconstruction approach is then validated on a real automotive accident. Furthermore, the development of a generic model applied to motorcycle accidents is also analysed. From the results of the automotive accident reconstruction, the intercerebral contusion observed has been bridged to a particular time duration of a certain level of von Mises stresses
Feytout, Benjamin. "Commande crone appliquée à l'optimisation de la production d'une éolienne." Thesis, Bordeaux 1, 2013. http://www.theses.fr/2014BOR14946/document.
The research studies, in collaboration with VALEOL and IMS laboratory, propose several solutions to optimize the production and the efficiency of a wind turbine. The general theme of the work is based on control laws of the system or subsystems using the CRONE robust design. Each part highlights aspects of modeling, system identification and design before simulations or tests of scale and full size models. Chapter 1 provides an overview of the issues discussed in this manuscript, using states of the art and precisions on the industrial and economic context of 2013.Chapter 2 introduces the CRONE command for robust design. It is used to achieve the control of the rotation speed of a variable speed wind turbine, with an innovative architecture - mechanical variable speed solution and synchronous generator.Chapter 3 makes a comparison of three new optimization criteria for CRONE design. The aim is to reduce the methodology complexity and to facilitate handling by any user. The results are obtained through simulations on an academic example, then with a DFIG wind turbine model. Chapter 4 focuses on the reduction of structural loads transmitted by the wind on the turbine. It is about better control of the pitch angle by individual pitch control, depending on the rotor position or wind disturbances.Chapter 5 deals with the design of an anti-icing/de-icing system for blades. After the modeling and identification steps, the CRONE design is used to control the temperature of a heating coating disposed on the blades. An observer is finally designed to detect the presence of ice
Lamara, Abderrahim. "Approche CRONE multivariable : développement et application à la régulation de bancs d'essais moteur haute dynamique." Thesis, Bordeaux, 2015. http://www.theses.fr/2015BORD0069/document.
The work presented in this Thesis is part of the CRONE (robust control with fractional integration order) multivariable methodology development. It deals with the simplification of the robust multivariable control system implementation with application to the control of high dynamic engine test-benches, including those developed by the D2T company. The first chapter introduces different kind of test-benches and gives a general idea about how those systems work while explaining their problems. While the first part of chapter II presents a simple method for test-benches modeling which then allows their simulation, the second part is dedicated to their frequency-domain system identification. The defined identification procedure is applied to a test-bench equipped with a Diesel engine. The third chapter presents the CRONE multivariable methodology and different developments to simplify its use. Reflecting these developments, the developed CRONE multivariable toolbox is used to design a control system for a test-bench consists of two asynchronous motors. The fourth chapter is dedicated to validate the presented work by applying these developments to a high dynamic test-bench with a spark ignition engine. This chapter presents the various software tools developed to simplify the implementation to D2T products of the CRONE full MIMO methodology
Serrier, Pascal. "Analyse de l’influence des non-linéarités dans l’approche CRONE : application en isolation vibratoire." Thesis, Bordeaux 1, 2008. http://www.theses.fr/2008BOR13625/document.
The thesis deals with the synthesis and the realisation of a band limited fractional differentiator. The realisation is made thanks to a small number of resistive and capacitive cells (RC cells). The first part of this thesis is about some new methods to compute the physical parameters of the RC cells from the 4 high-level parameters of the band limited fractional differentiator. The specificities of a realisation using hydropneumatic technology are detailed. It is shown that, in vibration isolation, they lead to remarkable performances. The stability degree robustness and the rapidity robustness towards the variation of the sprung mass value are obtained in spite of non- linearities. Volterra serie expansion is used to study the non-linearities. The second part is about the application of the previous results to the automotive field. The design and the realisation of an hydractive CRONE suspension is proposed. An hydractive CRONE suspension is a suspension with several operating modes and which allows to obtain the stability degree robustness. The hydractive CRONE suspension is then test with a 14 degrees of freedom model of a car
Racewicz, Szymon. "Identification et modélisation d'ordre fractionnaire des machines synchrones fonctionnant comme générateur." Phd thesis, 2010. http://tel.archives-ouvertes.fr/tel-00552148.