Response Study Of Nonlinear Plate-Type Structures

The plate-type structure is wildy used in the design of the fuel element assembly of reator,the flow-induced vibration characteristics of which will affect the structural safety of the fuel element assembly.The main works of this thesis are as follows:1. Reasonable nonlinear flow-induce dynamic model of a simply-supported plate-type beam in axial incompressible viscous flow with cubic stiffness for rigid rectangular tube boundary condition is established in this thesis.The Galerkin method is used to discrete the equation of motion of the plate-type structure. The fourth order Runge-Kutta method is utilize toanalyze the bifurcation forms of the original nonlinear system. Numerical integrations results show that, the response is stable while the fluid velocity is on the small side. As the increase of fluid velocity, the system loses its stability by flexure within a certain rang of fluid velocities, and along with more accretion of fluid velocity, system loses stability by stable limit cycle flutter. When the increase of nonlinear stiffness coefficient, the system amplitude of the system will be decreased..2. For the pinned-pinned plates in pulsating flow, the dynamic characteristics and nonlineas responses are studied. The response is stable while the fluid velocity is on the small side. As the increase of fluid velocity, the system undertakes bifurcation through the path of periodic3-periodic6and period-doubling bifurcation to chaos. As the increase of fluid velocity, the system turns to periodic motion after a narrow area of chaos. The system turns to chaos after quasi-periodic motion. As the increase of fluid velocity further, the system alternating periodic motion and chaos. Eventually, the system is in chaos.3. By means of nonlinear dynamic model of a simply-supported plate-type beam with piecewise linear stiffness with clearance vibrating in axial incompressible viscous flow in a rigid rectangular tube established, the emphasis focuses on the complex responses of nonlinear system.The response is stable while the fluid velocity is on the small side. As the increase of fluid velocity, the system loses its stability by buckling.