Thèse soutenue

Étude numérique des méthodes de Relaxation Dynamique et contribution à la modélisation de gilets de sauvetage gonflables

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Auteur / Autrice : Javier Rodriguez Garcia
Direction : Gérard RioJean-Marc Cadou
Type : Thèse de doctorat
Discipline(s) : Sciences pour l'ingénieur
Date : Soutenance en 2011
Etablissement(s) : Lorient
Ecole(s) doctorale(s) : École doctorale Santé, information-communication et mathématiques, matière (Brest, Finistère)
Partenaire(s) de recherche : autre partenaire : Université européenne de Bretagne (2007-2016)

Résumé

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Dynamic relaxation (DR) is a numerical method introduced in 1965 by A. S. Day in the book "The Engineer". From 1983, with the works presented by P. Underwood, it became more and more used. Since then, many applications were found, and several authors presented different improvements on the method in order to optimize the calculations. Nowadays, its use is widely spread in fields as structural dynamics (particularly in form-finding), geomechanics or biomechanics. When using DR in numerical simulations, researchers followed two different paths in the choice of a damping strategy for the oscillations: some used DR combined with a viscous damping and others used DR combined with kinetic damping. However, it is difficult to find comparisons between both methods to help deciding whether one is better than the other for a particular application. Focused in the field of form-finding of thin structures, the main objective of this thesis is to make a contribution to the development of DR methods and a review of the existing DR methods in order to compare them. Therefore, a scientific paper is presented in this thesis comparing different DR methods with both kinetic and viscous damping in the case of form-finding of inflatable structures. Also, another paper is detailed where an extension for the DR method with kinetic damping is proposed. Then, as an application for the studied DR methods, a contribution to the modelling of inflatable lifejackets will be presented. The aim of this part of the work is to present some contributions to the creation of a numerical tool permitting to test the functioning of an inflatable lifejacket by means of Finite Elements calculations. This work covers the creation of a parameterized mannequin, a rough characterization of the involved technic textile, improvements in the numerical simulation of the inflation of the lifejacket using the DR method, and also a fist approach to the water dynamics and contact mechanics that will be involved in the final simulation.