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San Diego state university. / Abdelouahab BENZERDJEB

Public ISBD Titre : San Diego state university. Type de document : texte imprimé Auteurs : Abdelouahab BENZERDJEB, Auteur Année de publication : 1984 Importance : 136 p. Langues : Anglais (eng) Catégories : Electronique:Génie Aérospatial Résumé : The purpose of this study is to analyze the effect of fluids heavier than air on the vibrational characteristics and on the radiated acoustic pressure of a sandwich panel. a sandwich panel consist of two face-plates (skins) and an inner soft viscoelastic layer (core). The differential equation governing the motion of the sandwich panel derives by Narayanan and Shanbhag is used in the present analysis. The characteristic equation governing the vibration of the sandwich panel derived in the present study is reduced to simpler form for the limiting conditions of zero fluid density and zero core thickness, the results obtained are compared to existing results for similar configurations. The roots loci of the fluid and the structural wave numbers are obtained dy solving the characteristic equation governing the motion of the structure. Finally, the acoustic pressure radiated from the structure into the far-field is approximated by the method of stationary phase. A comparison of the results obtained for the sandwich panel with two aluminum face-plates (1cm thick) to those obtained for the equivalent aluminum plate (2cm thick) shows that the far-field radiated acoustic pressure can be reduced by using an inner soft viscoelastic core between two face-plates. An analysis of the core properties and core thickness showx that a proper choice of the core properties and thickness can be selected to optimize the acoustical requirements of a particular problem. Directeur de thèse : PIERICCI San Diego state university. [texte imprimé] / Abdelouahab BENZERDJEB, Auteur . - 1984 . - 136 p. Langues : Anglais (eng) Catégories : Electronique:Génie Aérospatial Résumé : The purpose of this study is to analyze the effect of fluids heavier than air on the vibrational characteristics and on the radiated acoustic pressure of a sandwich panel. a sandwich panel consist of two face-plates (skins) and an inner soft viscoelastic layer (core). The differential equation governing the motion of the sandwich panel derives by Narayanan and Shanbhag is used in the present analysis. The characteristic equation governing the vibration of the sandwich panel derived in the present study is reduced to simpler form for the limiting conditions of zero fluid density and zero core thickness, the results obtained are compared to existing results for similar configurations. The roots loci of the fluid and the structural wave numbers are obtained dy solving the characteristic equation governing the motion of the structure. Finally, the acoustic pressure radiated from the structure into the far-field is approximated by the method of stationary phase. A comparison of the results obtained for the sandwich panel with two aluminum face-plates (1cm thick) to those obtained for the equivalent aluminum plate (2cm thick) shows that the far-field radiated acoustic pressure can be reduced by using an inner soft viscoelastic core between two face-plates. An analysis of the core properties and core thickness showx that a proper choice of the core properties and thickness can be selected to optimize the acoustical requirements of a particular problem. Directeur de thèse : PIERICCI

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2010	02-09-09	version papier	Bibliothèque USTOMB	Mémoire de Magister	Exclu du prêt