Large-amplitude vibration of thin plates and shells has been critical design issues for many engineering structures. The increasingly more stringent safety requirements and the discovery of new materials with amazingly superior properties have further focused the attention of research on this area. This thesis deals with the vibration problem of rectangular, circular and angle-ply composite plates. This vibration can be triggered by an initial vibration amplitude, or an initial velocity, or both. Four types of boundary conditions including simply supported and clamped combined with in-plane movable/immovable are considered. To solve the differential equation generated from the vibration problem, Lindstedt's perturbation technique and Runge-Kutta method are applied. In previous works, this problem was solved by Lindstedt's Perturbation Technique. This technique can lead to a quick approximate solution. Yet based on mathematical assumptions, the solution will no longer be accurate for large amplitude vibration, especially when a significant amount of imperfection is considered. Thus Runge-Kutta method is introduced to solve this problem numerically. The comparison between both methods has shown the validity of the Lindstedt's Perturbation Technique is generally within half plate thickness. For a structure with a sufficiently large geometric imperfection, the vibration can be represented as a well-known backbone curve transforming from soften-spring to harden-spring. By parameter variation, the effects of imperfection, damping ratio, boundary conditions, wave numbers, young's modulus and a dozen more related properties are studied. Other interesting research results such as the dynamic failure caused by out-of-bound vibration and the change of vibration mode due to damping are also revealed.

Les matériaux viscoélastiques sont utilisés dans tous les domaines de l'ingénierie et des systèmes mécaniques, de l'électroménager, spatial, l'automobile, l'aéronautique ou le génie civil (ponts...) grâce à leur capacité d’amortir les chocs ou de filtrer les vibrations. Ce travail constitue une contribution à l’étude du comportement dynamique non linéaire des composants viscoélastiques notamment les élastomères. Dans ce mémoire, on introduit, d’abord, les propriétés mécaniques des élastomères, pour les aspects viscoélasticité et friction. Un rappel des différents phénomènes physiques et une liste non-exhaustive des modèles existants dans la littérature sont présentés. Ensuite, on propose des techniques expérimentales afin de décrire le comportement dynamique sous sollicitations uniaxiales d’un élastomère. Une description des bancs d’essais, des chaines d’analyse vibratoire, des méthodes de traitement des données des essais et d’analyse des mesures expérimentales est détaillée dans ce manuscrit. Une nouvelle approche du modèle de Maxwell généralisé a été proposée pour décrire le comportement dynamique du composant viscoélastique. Ce modèle permet une description précise et une bonne connaissance du comportement dynamique des composants viscoélastiques en fonction de l’amplitude, de la précharge et de la fréquence. La dissipation d'énergie identifiée sous forme d'amortissement peut être issue de l'amortissement intrinsèque des matériaux polymère comme de la friction aux interfaces dans le cas de composants caoutchoucs non adhérisés sur les pièces, dans ce travail, un nouveau modèle visco-tribologique a été développé en couplant les propriétés rhéologiques linéaires du modèle de Maxwell généralisé et le modèle de frottement de Dahl pour la description du comportement de frottement hystérétique des liaisons viscoélastiques non adhérisées. / Viscoelastic materials are used in all areas of engineering and mechanical systems, appliances, aerospace, automotive, aerospace and civil engineering (bridges...) through their ability to absorb shock and vibration filtering. This work is a contribution to the study of nonlinear dynamic behavior of viscoelastic components particularly elastomers. In this dissertation, we introduced the mechanical properties of elastomers, for both viscoelasticity and friction aspects. A review of the different physical phenomena and a non-exhaustive list of existing models in the literature are presented. Then, we propose experimental techniques to describe the dynamic behavior under uniaxial stress of an elastomer. A description of test benches, vibration analysis chains, methods of processing data and analysis of experimental measurements is detailed in this manuscript. A new approach of generalized Maxwell model was proposed to describe the dynamic behavior of viscoelastic component. This model allows an accurate description and a good knowledge of the dynamic behavior of viscoelastic components depending on amplitude, frequency and preload. Energy dissipation identified as damping can be from intrinsic damping of the polymer as friction at the interfaces in case of not bonded rubber component to mechanical part, a new viscoelastic model tribological was developed by combining the rheological properties of linear generalized Maxwell model and the Dahl friction model for describing the behavior of viscoelastic hysteretic friction of not bonded connections.

La prédiction de l’amortissement des structures complexes se heurte actuellement à un certain nombre de difficultés. L'utilisation de matériaux métalliques dans les assemblages aéronautiques ne permet pas d'exploiter les faibles capacités d'amortissement interne des pièces de structure. Le potentiel d'amortissement de ces assemblages se trouve donc dans les interfaces de contact au niveau des liaisons fixes (vissées, rivetées) ou mobiles (rotules, pivots). La conception de jonctions fixes amortissantes demande de favoriser les micro-glissements, ce qui entraine l'apparition d'endommagements par fretting. Pour tenter de résoudre les problèmes de durée de vie liés au fretting, les traitements et revêtements de surface prennent de plus en plus d'importance. Ces travaux de thèse mettent en place des moyens expérimentaux (développement d’un banc haute température) et des méthodologies d'essais permettant de sélectionner des solutions palliatives au fretting avec un objectif de dissipation d'énergie maximale. L’approche énergétique mise en place permet de distinguer les différents régimes de glissement et d’identifier les configurations les plus favorables pour l’amortissement. Deux cas d'application (un à l'ambiante, un à 600°C) ont servi de base expérimentale, mettant en jeux différents alliages métalliques (aciers inoxydables 17.4-PH et XD15NW, Ti6Al4V, Inconel 718) protégés par des revêtements DLC, ou de l'implantation ionique de WS2 avec et sans traitement de sous-couche (CrN et CrC). / Predicting the damping behavior of complex mechanical assemblies faces many technical and scientific challenges. The internal damping of metallic materials is insufficient for aeronautical applications. The energy dissipation potential is located at the contacting surfaces of fixed (bolted, riveted) or mobile joints (pivot, ball-joint). Ensuring micro-slip is required to design dampening fixed joints, but it promotes fretting damage. Coatings and surface treatments are extensively used in order to tackle the ensuing durability issues. This work presents experimental means (newly designed high temperature test rig) and test methods for fretting palliatives selection with a maximum dissipated energy criterion. Energy based approaches enable the distinction between different sliding regimes and the identification of the most favorable ones. The experimental study was based on two industrial cases (at ambient temperature and 600°C) involving various metallic alloys (17.4-PH and XD15NW stainless steels, TI6Al4V and Inconel 718) protected with DLCs or WS2 ionic implantation (on raw substrate or CrC/CrN underlay).

by Lai Chun Yu. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 75-79). / Abstracts in English and Chinese. / LIST OF FIGURES --- p.vi / LIST OF TABLES --- p.ix / Chapter 1 --- INTRODUCTION --- p.1 / Chapter 1.1 --- Background --- p.1 / Chapter 1.1.1 --- Vibration Control of Suspension Systems --- p.1 / Chapter 1.1.2 --- Semi-active Devices --- p.3 / Chapter 1.2 --- Literature Review --- p.5 / Chapter 1.2.1 --- MR Fluid and Damper --- p.5 / Chapter 1.2.2 --- Vibration Control --- p.6 / Chapter 1.2.3 --- Robust Control --- p.8 / Chapter 1.3 --- Research Objective --- p.9 / Chapter 1.4 --- Organization of the Thesis --- p.9 / Chapter 2 --- MR DAMPER BEHAVIOR AND MODELING --- p.11 / Chapter 2.1 --- MR Damper --- p.12 / Chapter 2.2 --- Mathematical Model --- p.13 / Chapter 2.3 --- Experimental Setup --- p.15 / Chapter 2.4 --- Damper Characteristics --- p.18 / Chapter 2.5 --- Comparison Between Model with Experimental Data --- p.25 / Chapter 2.5.1 --- Graphical Study --- p.26 / Chapter 2.5.2 --- Quantitative Study --- p.26 / Chapter 2.5.3 --- Other Input Tests --- p.27 / Chapter 3 --- SEMI-ACTIVE VIBRATION CONTROL --- p.33 / Chapter 3.1 --- Dynamic Modelling of Suspension Systems --- p.33 / Chapter 3.2 --- Single-degree-of-freedom (SDOF) Passive Suspension System --- p.34 / Chapter 3.2.1 --- Viscous Damper --- p.34 / Chapter 3.2.2 --- MR Damper --- p.37 / Chapter 3.3 --- Single-degree-of-freedom (SDOF) Semi-active Suspension System --- p.41 / Chapter 3.3.1 --- Ideal Skyhook Control --- p.41 / Chapter 3.3.2 --- Semi-active Skyhook Control --- p.44 / Chapter 3.4 --- Semi-active Robust Control Development --- p.46 / Chapter 3.5 --- Sliding Mode Control --- p.47 / Chapter 3.6 --- Semi-active Damper Control --- p.51 / Chapter 3.6.1 --- On-off Control --- p.52 / Chapter 3.6.2 --- Continuous-state Control --- p.53 / Chapter 3.6.3 --- Comparison Between On-off and Continuous-state Controller --- p.54 / Chapter 4 --- SIMULATION STUDIES --- p.57 / Chapter 4.1 --- Transmissibility --- p.57 / Chapter 4.2 --- Different Base Excitations --- p.59 / Chapter 4.2.1 --- Bump Input --- p.60 / Chapter 4.2.2 --- Random Input --- p.62 / Chapter 5 --- CONCLUSION --- p.67 / Chapter 5.1 --- Summary --- p.67 / Chapter 5.2 --- Future Work --- p.68 / APPENDIX --- p.69 / Chapter A.1 --- Semi-active Control with MR Damper ´ؤ Main Program Listing --- p.69 / Chapter A.2 --- Sub-program Listing (Dynamic System) --- p.70 / Chapter A.3 --- Sub-program Listing (Sliding Mode Controller) --- p.73 / Chapter A.4 --- Sub-program Listing (MR Damper Model) --- p.73 / BIBLIOGRAPHY --- p.75

Thesis. 1978. M.S.--Massachusetts Institute of Technology. Dept. of Mechanical Engineering. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 117-121. / by Donald T. Darling. / M.S.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND AERO. / Vita. / Includes bibliographical references. / by John Shaw. / Ph.D.

Thesis. 1976. Ph.D.--Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics. / Microfiche copy available in Archives and Aero. / Vita. / Includes bibliographical references. / Ph.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by Bernard Dov Adelstein. / M.S.

Thesis. 1975. B.S.--Massachusetts Institute of Technology. Dept. of Mechanical Engineering. / Bibliography: leaf 39. / by Eric Hershler Bott. / B.S.

Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by Matthew Valentine Thompson. / B.S.