Nonlinear Vibration Of Thermal Barrier Coatinngs Cantilever Beam And Laminated Beam Under A Moving Load

With the development of science and technology, it is difficult for single materialto meet the various needs of practical application during engineering production,especially in the field of aerospace engineering. The laminated composite structure isa new kind of materials which combines two or more kinds of materials with differentmechanics characteristics by physical or chemical methods. Then, the composedmaterial performs new mechanical properties. Nowadays, the laminated structure hasbeen widely used. And the analysis of the nonlinear vibration of these kinds ofstructure has won broad attention.In this thesis, the nonlinear vibration characteristic of laminated beam structurewas analyzed based on constrained layer damping theory and nonlinear dynamicstheory. There are mainly two types of mechanical model in this paper:(1) laminatedcantilever mechanical model with thermal barrier coating layer. Thermal barriercoating is a kind of high-temperature protective coating. It has been widely used in theblades of aero-engine and gas turbine. There are many papers about single materialblade, but the study on nonlinear vibration of the coating blade as laminated structureis relatively rare. Thus, it is worthy to research in detail.(2) Laminated simplysupported beam under a moving load. The model of beam under moving load hasbeen widely used in railways, bridges, and mechanical engineering. The vibration ofthe beam will reduce the accuracy, stability and even life time of the system. Thus, thenonlinear dynamics analysis of beam under moving load has been studied by moreand more scholars.The main content of this dissertation is divided into the following sections:(1) Firstly, the coated blade is simplified as a three-layer beam model, and thedamping characteristics of the laminated beam were studied based on complexeigenvalue. The loss factor of the coated beam was obtained based on RKU model.And the influence of the thickness and thickness ratio of beam on the loss factor wasanalyzed in detail.(2) Secondly, the nonlinear dynamics of the thermal barrier coated blade wasstudied. Here, the blade was simplified as a three-layer cantilever beam firstly. Then,the governing equation was conducted by considering the impact of aerodynamicforces and geometric nonlinearity. Galerkin’s method was employed to obtain theordinary differential equations of motion. Perturbation analysis was implemented bythe multiple scales method. Numerical simulation was introduced to analyze the effectof aerodynamic force on the vibration responses of the coated blade.(3) In the4thchapter, the dynamics of the simply supported beam with single layer and double-layer under a moving load has been compared based on the theory ofnonlinear dynamics. The equations of motion were derived by using Hamilton’sprinciple based on von Karman type equations. Galerkin’s method was employed toobtain the ordinary differential equations of motion. Critical speed of these twomodels was analyzed. Vibration responses with the influence of system parameterswere studied based on the engineering parameters for these two models. Especially,critical velocity is analyzed considering the effect of the structural parameters, themagnitude and velocity of the moving load. All the results of numerical simulationshow that double-layer laminated beam model has better vibration suppressionperformance than single-layer beam model.