Nonlinear vibrations and stability of shells and panels in presence of fluid and flow

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The continuous advancement of material science and engineering along with the increasing demand for improved design, safety and energy efficiency requirements necessitates the establishment and verification of new nonlinear theories to describe the interaction between thin-walled structures and the surrounding fluid. The proposed research considers the study of nonlinear vibrations and dynamic stability of thin-walled structures with fluid-structure interaction. Thin shells, plates and curved panels (with single or double curvature) of traditional, laminated composite and functionally graded materials can be found in many engineering applications e.g. in aircraft, spacecraft, rockets, cars, computer disks (CD), DVD, hard-disks, submarines, boats, storage tanks and roof of buildings. Shell structures are also part of many biological systems such as the pulmonary passage and veins found in the human body. The objective of the research is twofold: (i) to develop a study approaching open problems with ground-breaking innovations in experimental, theoretical and numerical investigation, and (ii) to use an unifying approach to merge branches of research that have proceeded separately in the past but that present many common problems. This research also aims to improve existing theoretical models for the nonlinear mechanics of shells, e.g. by constructing a new consistent nonlinear shell theory including third-order shear deformation and rotary inertia, which is particularly important for advanced materials. The nonlinear analysis will be (i) performed numerically, by developing innovative numerical codes based on reduced-order models and, (ii) experimentally, by developing a sophisticated measuring system and procedure, including a laser Doppler vibrometer used on specimens placed in water and wind tunnels, in order to validate the numerical codes, study the complex dynamics and evaluate the effect of geometric imperfections. Specifically, the experimental procedure will also involve (a) experimental modal analysis with burst random or impact excitation; and (b) identification of the nonlinear response using feedback controlled step-sine excitation, altering the excitation frequency to induce hysteresis and jumps.