Analytical Dynamics Of High Speed Rotating Flexible Disc In Computer Compact Disc Drive

As basic components of rotating machinery, rotating discs have been widely used in the areas of computer data access devices, disc saw blade, rotary disc dryers, disc brakes and elastic connection disc between the engine and the torque converter, etc. Vibration of the rotating disc in computer compact disc (CD) drive can cause some problems such as error-reading data, service life reduction of disc and CD drive. Therefore, a research on the dynamics of high-speed rotating flexible disc in CD drive is significant and valuable.Firstly, the mechanical structure and operating principle of the computer CD drive was analyzed. Three-dimensional models of computer CD drive and rotating flexible disc were established in CATIA on the basis of actual measurement. Stress and stiffness of computer CD drive were calculated in ANSYS. Natural frequency and vibrational mode of support device and disc were solved at condition of non-speed and high-speed (7200r/min,15000r/min) respectively. By considering the heat generation of drive motor, the heat convection coefficient at the disc surfaces and the heat flux at the disc inner edge were analyzed. The temperature distributions of the disc and support device were obtained by ANSYS. With the thermal stress and centrifugal stress, a research on the natural frequency and vibrational mode of the disc and support devices were carried out. These ANSYS finite element investigations can provide some reference and verification data for the following research on the analytical dynamics of the rotating flexible disc. Secondly, based upon the mechanical principles of plate and shell vibrations, the force equilibrium equations and corresponding boundary conditions were modeled by involving the centrifugal stresses of disc rotation, and then the stress distribution function at any point on the disc was solved. By analyzing kinetic and potential energies of the rotating flexible disc and applying Hamilton principle, partial differential equation of the transverse vibration deformation of rotating disc and its boundary conditions were obtained. With Galerkin’s method, the partial differential equation was discretized to obtain its ordinary differential equations. Effects of disc rotating speed on natural frequency and critical speed were studied with eigenvalue problem, and the influences of disc thickness, outer and inner diameters on natural frequency and critical speed of the disc were analyzed. Thirdly, according to the heat transfer characteristics of the rotating disc, the heat conduction equation and boundary conditions of the disc were established. In addition, the boundary condition at disc inner edge was classified as two types:temperature increment and heat flux. The disc thermoelastic internal force was analyzed with the influence of temperature. Force and moment equilibrium equations of thermoelastic disc were derived by applying D’Alembert principle, and then the thermoelastic transverse vibration equation and its corresponding boundary conditions of the rotating disc were established. The temperature field and thermal stress function were solved. The vibration equation was discretized with Galerkin’s method, and then a research of effects of temperature increment and heat flux at disc inner edge on dynamics of the thermoelastic rotating disc was carried out separately. Finally, a simplified supporting model of five degree of freedom was assigned at disc inner edge, and the kinetic and potential energies of the rotating disc were updated. According to Hamilton principle, transverse vibration equation of the rotating disc was deduced with the simplified supporting model. Similarly, vibration equations were discretized with Galerkin method again, and then a research on supporting stiffness on dynamics of thermoelastic rotating disc was carried out.This dissertation was supported by the National Natural Science Foundation of China (NSFC)"Thermoelastic coupling dynamics and vibration suppression principle of flexible disk rotating at super-critical speed (Project Grant No.51105164)". With the application context of computer CD drive, the analytical dynamics of high-speed rotating flexible disc was analyzed in this dissertation, and this work can provide a theoretical foundation and technical reference for the development of computer CD drive and other applications of the rotating disc.