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Deformační a napjatostní analýza nárazníkové částí automobilu při rázovém zatěžování / Strain and stress analysis of the car buffer zone under impact loadingNedělka, Pavel January 2011 (has links)
The master thesis deals with a stress-strain analysis of the front crash structure of a race car by using the finite element method. The structure is loaded by an impact loading. This type of analysis belongs to the transient analysis so the explicit formulation of the finite element method is used. The LS-DYNA software was used for calculations. The goal of this thesis is to express the influence of the crash structure to the change of the car's kinetic energy as well as the amount of absorbed energy in case of frontal impact.
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Parametrická studie absorpčního prvku přední části vozidla z hlediska bezpečnosti posádky vozidla při čelní kolizi / Parametric study of the absorption element of the frontal vehicle part from the passangers safety point of view during the frontal car collisionStráník, Radim January 2016 (has links)
The main subject of this master thesis is the computational modeling of stress-strain analysis of the loaded front part of Toyota Yaris from the year 2010 using an explicit finite element method (FEM). The aim of this thesis is the assessment of resistance of the front part of the car (longeron) at the impact stress. This thesis describes the selection, editing, and creation of the computational model of longeron and simulation of the barrier collision. The objective of the thesis is to use a real vehicle, suggest modified longerons to be implemented in it, test various shape and material versions of the longeron and make their comparison.
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Approche expérimentale de la collision entre les plis vocaux en phonation et du phonotraumatisme : études in vivo et sur larynx humains excisés / Experimental approach of the collision between the vocal folds during phonation and phonotrauma : in vivo and human excised larynx studiesLagier, Aude 13 December 2016 (has links)
La collision entre les plis vocaux lors de la phonation, phénomène physiologique essentiel pour la synchronisation de la vibration des plis, est également une composante du phonotraumatisme. Le rôle du phonotraumatisme dans la physiopathologie des dysphonies est communément admis mais sa nature reste mal définie et sa quantification difficile. Ce travail propose d’aborder cette question au moyen d’approches in vivo sur des sujets sains et ex vivo sur des larynx humains excisés. L’objet de ce travail est l’étude du comportement laryngé lorsque le larynx est soumis à des conditions de pression sous-glottique extrêmement élevées. In vivo, l’étude de la voix criée reposait sur la mesure constante de la pression sous-glottique. Ex vivo, cette dernière était manipulée en dehors de toute modification des autres paramètres de contrôle. Le volet ex vivo a nécessité un développement méthodologique (modernisation et adaptation au larynx humain) du banc expérimental utilisé pour des larynx animaux. Les résultats ont montré l’existence chez les locuteurs sains d’un « plafonnement » dans l’intensité vocale et le signal électroglottographique pour les très hauts niveaux de pression sous-glottique. Les études sur larynx humains excisés mesuraient la force de collision entre les plis vocaux sous l’effet de la pression sous-glottique et ont mis en évidence l’existence, ici aussi, d’un « plafonnement » de cette force lorsque la pression sous-glottique est très élevée. Les observations rapportées par ce travail ont un intérêt clinique important même si les phénomènes physiques sous-jacents restent à préciser. / The collision between the vocal folds during phonation is a physiological phenomenon with a powerful role in the synchronization of their vibration. This collision is also a component of the phonotrauma. The role of phonotrauma in the pathophysiology of dysphonia is commonly accepted but its nature still unclear and its quantification remains difficult. This work proposes, an in vivo study in healthy subjects, and an ex vivo one on excised human larynges. The purpose of this work was to study of the laryngeal behavior when the larynx is subjected to extremely high subglottic pressure. In vivo, it is studying the shouted voice with constant measure of subglottal pressure. Ex vivo, the subglottic pressure is directly manipulated. The ex vivo study required a methodological development to modernize the experimental bench used for animal larynges studies and to adapt it to the human larynx. The results showed, in healthy speakers the existence of a "plateau" in the vocal intensity and in the electroglottographic signal for very high levels of subglottic pressure. The excised larynx studies measured the collision force between the vocal folds and its changes depending on other acoustic and electroglottographic parameters. They highlighted the existence, here too, of a "plateau" in the level of the collision force when the subglottic pressure was very high. The observations presented in this work are, to our knowledge, unprecedented. They have important clinical interest for understanding the concept of phonotrauma. Their interpretation in physical terms remains very incomplete.
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