{"id":170,"date":"2022-05-12T16:10:22","date_gmt":"2022-05-12T14:10:22","guid":{"rendered":"https:\/\/www.monia-grabow.de\/?page_id=170"},"modified":"2022-05-13T15:00:51","modified_gmt":"2022-05-13T13:00:51","slug":"recherche","status":"publish","type":"page","link":"https:\/\/www.monia-grabow.de\/index.php\/fr\/recherche\/","title":{"rendered":"Recherche"},"content":{"rendered":"

Doctorante \u00e0 l\u2019Universit\u00e9 Bretagne Sud et \u00e0 l\u2019Institut de Recherche Dupuy de L\u00f4me <\/strong>\u00e0 Lorient, France<\/strong><\/h3>\n

Titre de la th\u00e8se : Contribution \u00e0 l\u2019\u00e9tude des r\u00e9sistances en compression et au d\u00e9laminage de composites stratifi\u00e9s \u00e0 fibres continues dans le contexte du nautisme de comp\u00e9tition.<\/strong><\/p>\n

Mot cl\u00e9s : CFRP, r\u00e9sistance en compression, r\u00e9sistance hors plan, d\u00e9salignement de fibre, placement de fibres automatis\u00e9, drapage manuel, secteur nautique, crit\u00e8res de r\u00e9sistance<\/strong><\/p>\n

R\u00e9sum\u00e9 :<\/strong><\/p>\n

Les hydrofoils, des ailes sous-marines en mat\u00e9riau composite stratifi\u00e9 (fibre de carbone, matrice \u00e9poxy), sont dimensionn\u00e9s en r\u00e9sistance en compression et en r\u00e9sistance hors-plan. Les contraintes de compression agissent principalement dans la zone de cale basse de l\u2019hydrofoil. Dans le cas de l\u2019inversion de portance, les contraintes hors plan peuvent engendrer une rupture du coude par d\u00e9laminage. La d\u00e9termination des deux r\u00e9sistances est encore aujourd\u2019hui un d\u00e9fi. Ces derni\u00e8res d\u00e9cennies, des mod\u00e8les micro-m\u00e9caniques ont \u00e9t\u00e9 d\u00e9velopp\u00e9s pour d\u00e9crire le comportement fibre-matrice des stratifi\u00e9s composites sollicit\u00e9s en compression. L\u2019un des param\u00e8tres dominants est l\u2019angle de d\u00e9salignement de fibres, car il est responsable des instabilit\u00e9s locales de la matrice. Jusqu\u2019\u00e0 pr\u00e9sent, la r\u00e9sistance hors plan a \u00e9t\u00e9 principalement \u00e9tudi\u00e9e dans les secteurs a\u00e9rospatial et a\u00e9ronautique, ce sujet n\u2019\u00e9tant toujours pas enti\u00e8rement ma\u00eetris\u00e9.
\nLes travaux de cette th\u00e8se sont divis\u00e9s en deux parties. La premi\u00e8re est consacr\u00e9e \u00e0 la confrontation de deux m\u00e9thodes exp\u00e9rimentales pour d\u00e9terminer les r\u00e9sistances en compression de sept mat\u00e9riaux (fibre de carbone\/matrice \u00e9poxy) diff\u00e9rents. Ces derniers sont fr\u00e9quemment utilis\u00e9s dans le secteur nautique. L\u2019accent \u00e9tait mis sur la d\u00e9termination de l\u2019angle de d\u00e9salignement de fibres en utilisant la m\u00e9thode de Yurgartis. Les r\u00e9sistances en compression ont \u00e9t\u00e9 confront\u00e9es en prenant en compte la distribution spatiale de fibres. La deuxi\u00e8me partie traite la confrontation des r\u00e9sistances hors plan des corni\u00e8res unidirectionnelles en fibre de carbone\/matrice \u00e9poxy, fabriqu\u00e9es \u00e0 la main et par la technologie de placement automatis\u00e9 de fibres (AFP). Des essais de flexion quatre points ont \u00e9t\u00e9 mis en mesure et la r\u00e9sistance hors plan a \u00e9t\u00e9 d\u00e9termin\u00e9e en utilisant les solutions de Lekhnitskii et de Kedward. Des simulations par \u00e9l\u00e9ments finis ont confirm\u00e9es les r\u00e9sultats estim\u00e9s. Des valeurs plus \u00e9lev\u00e9es de la r\u00e9sistance hors plan des corni\u00e8res fabriqu\u00e9es par AFP ont \u00e9t\u00e9 discut\u00e9es en faisant la liaison au processus de fabrication, en particulier au mode de compactage.<\/p>\n

Publication<\/h3>\n

Influence of the manufacturing process on the interlaminar tensile strength of thick unidirectional continuous epoxy\/carbon fibre composites<\/em>
\nM. Grabow, V. Keryvin, A. Marchandise, J.-C. Grandidier, C. Baley, C. Le Guennec, O. Fagherazzi
\nin Composites Part A: Applied Science and Manufacturing, Elsevier, 03\/2022<\/p>\n

Abstract:<\/strong>
\nRacing yachts that fly over the sea level use appendices called hydrofoils made out of carbon fibre reinforced <\/span>plastics. This study discusses the influence of the manufacturing process on their interlaminar tensile strength <\/span>(ILTS). Indeed, ILTS is a key design parameter, since tensile out-of-plane stresses in the hydrofoil elbow may <\/span>cause the structure to fail by delamination. Hydrofoils are usually manufactured by traditional hand lay-up <\/span>and more recently by automated fibre placement technology (AFP). <\/span>Thick unidirectional L-beam specimens were manufactured from the same prepreg material, either by AFP <\/span>or by hand lay-up (MAN). AFP specimens were<\/span> 40%<\/span> stronger than MAN ones. The investigation of failure <\/span>locations as compared to estimated ones made us highlight that AFP specimens reach their highest possible <\/span>strength while MAN specimens fail prematurely, due to manufacturing-induced defects, such as localised <\/span>porosities. The key features of AFP technology, with respect to the traditional MAN process, are eventually <\/span>discussed.<\/span><\/p>\n

____________________________<\/p>\n

\u00b9 Budiansky, B. & Fleck, N. (1993). Compressive failure of fibre composites. Journal of the Mechanics and Physics of Solids, 41 (1), 183\u2013211.
\n\u00b2 Grandidier, J.-C., Casari, P., & Jochum, C. (2012). A fibre direction compressive failure criterion for long fibre laminates at ply scale, including stacking sequence and laminate thickness effects. Composite Structures, 94 (12), 3799\u20133806.
\n\u00b3 Yurgartis, S. (1987). Measurement of small angle fiber misalignments in continuous fiber composites. Composites Science and Technology, 30 (4), 279\u2013293.<\/p>\n","protected":false},"excerpt":{"rendered":"

Doctorante \u00e0 l\u2019Universit\u00e9 Bretagne Sud et \u00e0 l\u2019Institut de Recherche Dupuy de L\u00f4me \u00e0 Lorient, France Titre de la th\u00e8se : Contribution \u00e0 l\u2019\u00e9tude des r\u00e9sistances en compression et au d\u00e9laminage de composites stratifi\u00e9s \u00e0 fibres continues dans le contexte du nautisme de comp\u00e9tition. Mot cl\u00e9s : CFRP, r\u00e9sistance en compression, r\u00e9sistance hors plan, d\u00e9salignement..<\/p>\n

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