Modeling and Experimental Verification of a Semi-rotary Fluid Damper Based on an Improved Kelvin Model

Abstract

The semi-rotary fluid damper is a shock-absorbing device that is widely used for the protections of various mechanical structures. In this research, a new small semi-rotary fluid damper for vibration reduction of helicopter control system is introduced. The damping medium used in the damper is hydraulic oil with a high shear thinning rate, which has a high degree of nonlinear hysteresis and viscoelastic properties. The accuracy of the mechanical model of the damper is of great significance to the design of control strategies for effective vibration reduction. Based on the adaptive genetic algorithm, the parameter identification of the semi-rotary fluid damper is studied with the objective function of minimizing the square of the difference between the analytical force and the experimental force. The Kelvin and generalized Kelvin with friction models lack parameters to properly describe the frequency and amplitude dependence. Therefore, an improved Kelvin model which is based on generalized Kelvin is proposed to capture the nonlinear dynamic characteristics of the damper. Through error analysis, it is concluded that the improved Kelvin model can more accurately describe the nonlinear damping characteristics of the semi-rotary fluid damper subjected to different amplitudes and frequencies.