Dynamic characteristics of the neutron pulsing chopper rotor system based on the finite element method and the response surface method

The high-speed operation of neutron pulsing choppers often results in system instability caused by resonance, compromising reliability and safety. To address this, we conducted an in-depth study of the rotor dynamics of neutron pulsing choppers. A finite element model of the rotor system was developed to calculate its critical dynamic characteristics. Using central composite design and response surface methodology, we analysed the effects of bearing stiffness and position on critical speeds. Results show that the second critical speed is close to the operating speed, posing a resonance risk, with high vibration amplitudes observed near the chopper disk and the shaft's front end. Bearing stiffness positively correlates with critical speeds, showing the highest sensitivity for the first critical speed. The front and rear bearings significantly influence the second and first critical speeds, respectively. This study provides theoretical guidance for optimising high-performance rotors in neutron pulsing choppers and similar high-speed systems.