H_∞ DESIGN AND EXPERIMENTAL STUDY OF TWO TYPES OF DYNAMIC VIBRATION ABSORBERS WITH TUNABLE DAMPING

Dynamic vibration absorbers have attracted extensive attention from both academia and industry due to its excellent vibration absorption performance. However, the high sensitivity in resonance frequency and damping coefficient makes the system design and application a real challenge. The traditional oil-type viscous dampers are difficult to achieve effective damping adjustment, and the high cost of emerging magnetorheological dampers also limits the practical application of this technology. In recent years, the development of the adjustable electromagnetic shunt damping has provided new feasibility for on-site optimal tuning of dynamic vibration absorbers. In this paper, based on the structural characteristics of the translational electromagnetic shunt damper, the method of opposing permanent magnets is used to improve the electromechanical coupling efficiency of the damper. The electromechanical coupling coefficient and equivalent damping coefficient of the six-stage opposing electromagnetic shunt damper are obtained through numerical simulation. The electromagnetic shunt damper can achieve real-time adjustment of the damping force by adjusting the impedance of the external resistance. Then, the electromagnetic shunt damper is applied in the suspended dynamic vibration absorber system and ground-hooked dynamic vibration absorber system, achieving the optimal vibration absorption effect of the two types of dynamic vibration absorption systems based on the H_∞ optimization method, and suppressing the vibration response of the main system effectively. The maximum displacement response of the main system is minimized with the tuned natural frequency ratio and the adjustable damping ratio. Moreover, the experimental results of both dynamic vibration absorber systems match well with the theoretical results, which provides design criterion and a basis for further application of dynamic vibration absorber systems.