Strength And Modal Analysis Of Large Capacity Composite Flywheel Rotor

China has put forward the goal of ’double carbon’ according to the problems existing in the development of thermal power and renewable energy,with the increasingly serious energy problem.Energy storage technology can realize the flexible adjustment of power system,and can solve the problem of grid flexibility adjustment caused by new energy power generation.As a physical energy storage technology,flywheel energy storage technology has the advantages of high power density,fast charge and discharge response,long life,high safety and reliability,and no environmental pollution.It has become an important direction for the development of energy storage technology in the future.Among them,the large-capacity power flywheel energy storage system is a high-quality frequency modulation resource of the power system,and the use of high-strength,low-density composite materials to manufacture flywheel rotors is the main method to improve flywheel energy storage.At present,most of the existing research on the strength of composite flywheel rotors has a small capacity,and the comparison between single-ring and multi-ring flywheel rotors is not sufficient.In this paper,the composite rotor of 100kW/25kWh flywheel energy storage system of Beacon Power Company is taken as the object,and the interference assembly strength and interference assembly dynamics are studied.The main research work of this paper is as follows:(1)Based on the anisotropic elastic mechanics and the principle of stress superposition,the analytical solutions of stress distribution of single-ring and multiring composite flywheel rotors with circumferentially wound fibers generated by centrifugal force,interference assembly and both are derived.The effects of the interference amount of the single-ring anisotropic flywheel rotor wound along the circumferential direction and the inner and outer diameters and anisotropy values under high-speed rotation on the stress distribution of the composite flywheel rotor were studied.The difference between the two-ring isomorphism and the two-ring heterogeneity was further verified.The analytical results and simulation results are applicable to the three-ring and four-ring composite flywheels.The results show that improving the inner and outer diameters and anisotropy values,setting heterogeneous structures and multi-ring structures can improve the radial stress distribution of the composite flywheel rotor.(2)Based on the progressive damage theory and Tserper criterion,the progressive failure process of single-ring and two-ring interference assembled composite flywheel rotors is compared and analyzed,and the influence of interference on the failure process of interference assembled composite flywheel rotors is discussed.The results show that the failure modes of composite flywheel rotors are different when the interference is different.Compared with the final failure speed of single-ring composite flywheel rotors,the failure speed of multi-ring composite flywheel rotors is generally lower than that of single-ring composite flywheel rotors.The final failure speed is first increased and then decreased,so the amount of interference can be used as an optimization parameter for related optimization analysis.(3)The dynamics of composite flywheel rotor with interference fit is studied by using modal analysis.The critical speed,vibration mode and other influencing factors such as interference and radial bearing stiffness are analyzed and compared.The results show that there is no critical speed in the working speed range,and the critical speed can be adjusted by adjusting the interference and bearing stiffness.