Les ondes de choc de cisaillement dans les solides quasi-incompressibles sont un type d'onde peu exploré car accessible à la mesure seulement depuis une douzaine d'années. Elles se distinguent des ondes de choc de compression par leur non-linéarité cubique au lieu de quadratique. Les faibles vitesses des ondes de cisaillement, de l'ordre du mètre par seconde, permettent notamment d'atteindre des régimes assez fortement non linéaires sur de faibles distances, et de contrebalancer l'absorption relativement importante dans ces milieux. A notre connaissance, ces ondes ont été étudiées presque exclusivement en ondes planes. Or, la focalisation est un phénomène fondamental dans la physique des ondes et ses applications. C'est cette focalisation que l'on s'est attaché à étudier spécifiquement ici, tant du point de vue théorique et numérique, qu'expérimental. L'objectif était de mettre en évidence la focalisation des ondes de choc de cisaillement. Ce travail est en particulier motivé par son application potentielle en biomécanique. On a ici fait l'hypothèse que les ondes de choc de cisaillement pourraient jouer un rôle dans la formation de certaines lésions cérébrales suite à un traumatisme crânien, la géométrie du crâne induisant leur focalisation. Ces considérations nous ont conduits à dimensionner les phénomènes étudiés en conséquence, en termes de fréquence, d'amplitude et de géométrie. La focalisation a ainsi été montrée dans le cas d'un gel simulant un tissu biologique. Les comparaisons avec le modèle théorique et numérique se sont avérées favorables. Pour approfondir l'analyse de l'hypothèse, il resterait à prouver que ces ondes de choc peuvent induire des lésions. / Shear shock waves in quasi-incompressible soft solids have been observed experimentally only twelve years ago. They differ from compression shock waves because their nonlinearity is cubic instead of quadratic. Velocities of shear waves are small, of the order of the meter per second, and thus induce a strong nonlinear behavior over small distances. This allows to counter-balance the quite strong absorption in such media. To our knowledge, these shear shock waves have been studied only for plane waves. However, focusing is a fundamental phenomenon in the wave physics and its applications. This is why our objective is to investigate the focusing of shear waves theoretically, numerically, and experimentally. This work was in particular motivated by a potential application in biomechanics. We have hypothesized that shear shock waves could play a role in the formation of some traumatic brain injuries, the geometry of the skull producing the focusing effect. These hypotheses have governed our studies for the choice of the different parameters such as the frequency, the amplitude and the geometry. The focusing has been demonstrated in a biological tissue-mimicking gel. Comparisons with the theoretical and numerical model have shown a good agreement. Further studies should concern the possible formation of lesions by shear shock waves.

Este trabalho teve como objetivo desenvolver uma sequência didática para professores de ensino médio que ensinam física ondulatória, mais precisamente o ensino de ondas eletromagnéticas a partir da pesquisa realizada pelos alunos, tornando-os agentes ativos no processo de ensinoaprendizagem e dando-lhes liberdade na escolha do material a ser pesquisado. Essa sequência didática foi aplicada em cinco turmas de uma escola particular da cidade de Porto Alegre – RS, totalizando 150 alunos participantes, e está alinhada à teoria de Pedro Demo, que serviu de referencial teórico. Foram realizados dez encontros, divididos em aulas expositivas dialogadas, para trabalhar os conceitos iniciais de física ondulatória, uma aula no Laboratório de Física e aulas em sala de aula para realizar as pesquisas com o uso do celular e realizar as discussões em grupos. As pesquisas sobre história da ciência e as aplicações de ondas eletromagnéticas também aconteceram fora da sala de aula a partir do uso das redes sociais. Os alunos fizeram resumos das suas pesquisas e produziram vídeos sobre a descoberta das ondas eletromagnéticas, explicando como a tecnologia tem evoluído e quais são suas aplicações no dia a dia. O autor considera que o ensino de física no ensino médio não é atrativo para os alunos por três motivos: falta de conhecimento matemático, falta de motivação e não entendimento da importância do conteúdo, pois o aluno não vê aplicabilidade do estudo com o seu dia a dia. O trabalho de pesquisa e criação de vídeos ajuda a enfrentar dois desses três problemas. Todos os vídeos estão disponíveis no youtube e diversas formas artísticas foram exploradas pelos alunos – textos com desenhos e narração, compilação de imagens e vídeos legendados, alunos que se transformam em atores -. Os alunos gostam de estudos episódios da história da ciência e de ter liberdade para escolher o que pesquisar. / This work aimed to prepare a didactic sequence for high school teachers who teach wave physics, more precisely the teaching of electromagnetic waves from the research carried out by the students, making them active agents in the process of teaching and learning and giving them freedom in the choice of material to be searched. This didactic sequence was applied in five classes of a private school in the city of Porto Alegre, RS, totaling 150 students, and is aligned with the theory of Pedro Demo, which served as a theoretical reference. Ten meetings were held, divided into expository dialogues, to work on the initial concepts of wave physics, a class in the Physics Laboratory, and classes in the classroom to carry out research using the cell phone and carry out group discussions. Research on the history of science and the applications of electromagnetic waves also happened outside the classroom from the use of social networks. The students summarized their research and produced videos on the discovery of electromagnetic waves, explaining how technology has evolved and what its applications are in everyday life. The author considers that the teaching of physics in high school is not attractive to students for three reasons: lack of mathematical knowledge, lack of motivation and lack of understanding of the importance of content, since the student does not see applicability of the study with his or her day to day. Researching and creating videos helps you tackle two of these three issues. All videos are available on youtube and various artistic forms have been explored by the students - texts with drawings and narration, compilation of images and videos subtitled, students that become actors. Students enjoyed studying the history of science and being free to choose what to research.

Les signaux enregistrés à la surface du globe sont composés de trois types d'ondes : des ondes directes, des ondes réfléchies plus ou moins facilement interprétables, et des ondes multiplement diffusées beaucoup plus complexes à interpréter. Certaines propriétés physiques de ces ondes multiplement diffusées permettent de les assimiler au bruit sismique ambiant. Nous appliquons des techniques de corrélation de bruit sismique développées ces dernières années à la coda sismique, afin de tirer des informations sur le caractère multiplement diffusant du milieu. En particulier, nous montrons que le théorème reliant fonction de Green et champ ambiant peut être utilisé dans la coda. La dynamique temporelle de la reconstruction de la fonction de Green est alors un indicateur de la répartition de l'énergie dans le milieu. En reconstruisant la fonction de Green à l'aide de corrélations pour plusieurs fenêtres de temps dans la coda, nous montrons qu'il est possible de relier la symétrie des parties causales et acausales de la fonction de Green au libre parcours moyen du milieu. Nous développons ensuite des simulations numériques de propagation d'onde acoustique en 2D. Nous observons que l'évolution de la reconstruction des fonctions de Green observée dans ce milieu et celle prédite par la théorie est proche. La même approche est ensuite appliquée à des données sismologiques de terrain, sans permettre de retrouver la même dynamique. Nous développons alors une méthode de type MCMC permettant de reconstruire les fonctions de Green du milieu de manière optimale. / Most of the waves recorded by seismometers are hard to interpret because of the complexity of the propagation medium, especially the late part of the seismic coda. These multiply scattered coda waves are close in nature to the ambient noise. We are applying recent noise correlation techniques to coda waves in order to retrieve information about the scattering medium. We show how the relationship between ambient noise and Green's function can be used in the case of the seismic coda. The quality of the Greens function retrieved by cross correlation of time windows in the coda is a proxy indicating the energy partition in the propagation medium. In particular, we establish a link between the symmetry of the causal and acausal parts of the reconstructed Green's function and the mean free path. We validate this theoretical approach with acoustical 2D numerical simulations. The same approach seems inefficient on a seismological dataset, due to the high S/N ratio and the non optimal repartition of receivers. Hence, we develop an MCMC based algorithm in order to optimally reconstruct the green's function in the seismic coda.

Este trabalho teve como objetivo desenvolver uma sequência didática para professores de ensino médio que ensinam física ondulatória, mais precisamente o ensino de ondas eletromagnéticas a partir da pesquisa realizada pelos alunos, tornando-os agentes ativos no processo de ensinoaprendizagem e dando-lhes liberdade na escolha do material a ser pesquisado. Essa sequência didática foi aplicada em cinco turmas de uma escola particular da cidade de Porto Alegre – RS, totalizando 150 alunos participantes, e está alinhada à teoria de Pedro Demo, que serviu de referencial teórico. Foram realizados dez encontros, divididos em aulas expositivas dialogadas, para trabalhar os conceitos iniciais de física ondulatória, uma aula no Laboratório de Física e aulas em sala de aula para realizar as pesquisas com o uso do celular e realizar as discussões em grupos. As pesquisas sobre história da ciência e as aplicações de ondas eletromagnéticas também aconteceram fora da sala de aula a partir do uso das redes sociais. Os alunos fizeram resumos das suas pesquisas e produziram vídeos sobre a descoberta das ondas eletromagnéticas, explicando como a tecnologia tem evoluído e quais são suas aplicações no dia a dia. O autor considera que o ensino de física no ensino médio não é atrativo para os alunos por três motivos: falta de conhecimento matemático, falta de motivação e não entendimento da importância do conteúdo, pois o aluno não vê aplicabilidade do estudo com o seu dia a dia. O trabalho de pesquisa e criação de vídeos ajuda a enfrentar dois desses três problemas. Todos os vídeos estão disponíveis no youtube e diversas formas artísticas foram exploradas pelos alunos – textos com desenhos e narração, compilação de imagens e vídeos legendados, alunos que se transformam em atores -. Os alunos gostam de estudos episódios da história da ciência e de ter liberdade para escolher o que pesquisar. / This work aimed to prepare a didactic sequence for high school teachers who teach wave physics, more precisely the teaching of electromagnetic waves from the research carried out by the students, making them active agents in the process of teaching and learning and giving them freedom in the choice of material to be searched. This didactic sequence was applied in five classes of a private school in the city of Porto Alegre, RS, totaling 150 students, and is aligned with the theory of Pedro Demo, which served as a theoretical reference. Ten meetings were held, divided into expository dialogues, to work on the initial concepts of wave physics, a class in the Physics Laboratory, and classes in the classroom to carry out research using the cell phone and carry out group discussions. Research on the history of science and the applications of electromagnetic waves also happened outside the classroom from the use of social networks. The students summarized their research and produced videos on the discovery of electromagnetic waves, explaining how technology has evolved and what its applications are in everyday life. The author considers that the teaching of physics in high school is not attractive to students for three reasons: lack of mathematical knowledge, lack of motivation and lack of understanding of the importance of content, since the student does not see applicability of the study with his or her day to day. Researching and creating videos helps you tackle two of these three issues. All videos are available on youtube and various artistic forms have been explored by the students - texts with drawings and narration, compilation of images and videos subtitled, students that become actors. Students enjoyed studying the history of science and being free to choose what to research.

Este trabalho teve como objetivo desenvolver uma sequência didática para professores de ensino médio que ensinam física ondulatória, mais precisamente o ensino de ondas eletromagnéticas a partir da pesquisa realizada pelos alunos, tornando-os agentes ativos no processo de ensinoaprendizagem e dando-lhes liberdade na escolha do material a ser pesquisado. Essa sequência didática foi aplicada em cinco turmas de uma escola particular da cidade de Porto Alegre – RS, totalizando 150 alunos participantes, e está alinhada à teoria de Pedro Demo, que serviu de referencial teórico. Foram realizados dez encontros, divididos em aulas expositivas dialogadas, para trabalhar os conceitos iniciais de física ondulatória, uma aula no Laboratório de Física e aulas em sala de aula para realizar as pesquisas com o uso do celular e realizar as discussões em grupos. As pesquisas sobre história da ciência e as aplicações de ondas eletromagnéticas também aconteceram fora da sala de aula a partir do uso das redes sociais. Os alunos fizeram resumos das suas pesquisas e produziram vídeos sobre a descoberta das ondas eletromagnéticas, explicando como a tecnologia tem evoluído e quais são suas aplicações no dia a dia. O autor considera que o ensino de física no ensino médio não é atrativo para os alunos por três motivos: falta de conhecimento matemático, falta de motivação e não entendimento da importância do conteúdo, pois o aluno não vê aplicabilidade do estudo com o seu dia a dia. O trabalho de pesquisa e criação de vídeos ajuda a enfrentar dois desses três problemas. Todos os vídeos estão disponíveis no youtube e diversas formas artísticas foram exploradas pelos alunos – textos com desenhos e narração, compilação de imagens e vídeos legendados, alunos que se transformam em atores -. Os alunos gostam de estudos episódios da história da ciência e de ter liberdade para escolher o que pesquisar. / This work aimed to prepare a didactic sequence for high school teachers who teach wave physics, more precisely the teaching of electromagnetic waves from the research carried out by the students, making them active agents in the process of teaching and learning and giving them freedom in the choice of material to be searched. This didactic sequence was applied in five classes of a private school in the city of Porto Alegre, RS, totaling 150 students, and is aligned with the theory of Pedro Demo, which served as a theoretical reference. Ten meetings were held, divided into expository dialogues, to work on the initial concepts of wave physics, a class in the Physics Laboratory, and classes in the classroom to carry out research using the cell phone and carry out group discussions. Research on the history of science and the applications of electromagnetic waves also happened outside the classroom from the use of social networks. The students summarized their research and produced videos on the discovery of electromagnetic waves, explaining how technology has evolved and what its applications are in everyday life. The author considers that the teaching of physics in high school is not attractive to students for three reasons: lack of mathematical knowledge, lack of motivation and lack of understanding of the importance of content, since the student does not see applicability of the study with his or her day to day. Researching and creating videos helps you tackle two of these three issues. All videos are available on youtube and various artistic forms have been explored by the students - texts with drawings and narration, compilation of images and videos subtitled, students that become actors. Students enjoyed studying the history of science and being free to choose what to research.

In Operations Enduring Freedom and Iraqi Freedom, explosions accounted for 81% of all injuries; this is a higher casualty percentage than in any previous wars. Blast wave overpressure has recently been associated with varying levels of traumatic brain injury in soldiers exposed to blast loading. Presently, the injury mechanism behind primary blast brain injury is not well understood due to the complex interactions between the blast wave and the human body. Despite these limitations in the understanding of head injury thresholds, head kinematics are often used to predict the overall potential for head injury. The purpose of this study was to investigate head kinematics, and predict injury from a range of simulated blast loads at varying standoff distances and differing heights of bursts. The validated Generator of body data multi-body human surrogate model allows for numerical kinematic data simulation in explicit finite element method fluid structure interaction blast modeling. Two finite element methods were investigated to simulate blast interaction with humans, an enhanced blast uncoupled method, and an Arbitrary Lagrangian Eularian fully coupled method. The enhanced blast method defines an air blast function through the application of a blast pressure wave, including ground reflections, based on the explosives relative location to a target; the pressures curves are based on the Convention Weapons databases. LBE model is efficient for parametric numerical studies of blast interaction where the target response is the only necessary result. The ALE model, unlike classical Lagrangian methods, has a fixed finite element mesh that allows material to flow through it; this enables simulation of large deformation problems such as blast in an air medium and its subsequent interaction with structures. The ALE model should be used when research into a specific blast scenario is of interest, since this method is more computationally expensive. The ALE method can evaluate a blast scenario in more detail including: explosive detonation, blast wave development and propagation, near-field fireball effects, blast wave reflection, as well as 3D blast wave interaction, reflection and refraction with a target. Both approaches were validated against experimental blast tests performed by Defense Research and Development Valcartier and ConWep databases for peak pressure, arrival time, impulse, and curve shape. The models were in good agreement with one another and follow the experimental data trend showing an exponential reduction in peak acceleration with increasing standoff distance until the Mach stem effect reached head height. The Mach stem phenomenon is a shock front formed by the merging of the incident and reflected shock waves; it increases the applied peak pressure and duration of a blast wave thus expanding the potential head injury zone surrounding a raised explosive. The enhanced blast model was in good agreement with experimental data in the near-field, and mid-field; however, overestimated the peak acceleration, and head injury criteria values in the far-field due to an over predicted pressure impulse force. The ALE model also over predicted the response based on the head injury criteria at an increased standoff distance due to smearing of the blast wave over several finite elements leading to an increased duration loading. According to the Abbreviated Injury Scale, the models predicted a maximal level 6 injury for all explosive sizes in the near-field, with a rapid acceleration of the head over approximately 1 ms. There is a drastic exponential reduction in the insult force and potential injury received with increasing standoff distance outside of the near-field region of an explosive charge.