Design of Variable Stiffness Liquid Inertial Vibration Eliminator

The high-speed co-axial rotorcraft is a new type of composite high-speed helicopter with good low-altitude maneuverability and a significant speed increase compared to ordinary configuration helicopters. High-speed helicopters with co-axial rotor configuration have two operating conditions: hovering and forward flying. Different rotor speeds under the two operating conditions bring new challenges to helicopter vibration control. The liquid inertial vibration eliminator (LIVE) is a high-efficient vibration isolation device with compact structure and light weight, which is widely used in helicopter vibration control. In this paper, a variable stiffness LIVE considering the principle of smart-spring is designed for a co-axial rotorcraft to control the vibration at different frequencies under different operating conditions. The mechanical model is established, and the equations of vibration isolation frequency and displacement transmission rate are obtained. The parameters that affect the vibration isolation performance are analyzed. The structural parameters are determined and dynamics simulation is carried out. The results show that the LIVE with variable stiffness can control the vibration under different operating conditions for high-speed helicopters. The analysis results verify the feasibility of the relevant design schemes.