Analysis of free vibration of hydraulic opposing cylinders controlled by a servo valve

Abstract

The fluid transmission medium has large compressibility and low rigidity, and its physical properties are extremely sensitive to state parameters such as flow, pressure, and temperature. Therefore, compared with the mechanical transmission system, the natural frequency of the fluid transmission system is relatively low and has time-varying characteristics. After a wide frequency range change in the load frequency and long-term operation, the excitation frequency of the fluid transmission system is more likely to approach its natural frequency and causes resonance. Therefore, based on the analytical relationship between the dynamic bulk modulus and the equivalent stiffness of the oil, the dynamics model of the system of the hydraulic opposing cylinders controlled by a servo valve was established by using the lumped parameter method. Through the free vibration analysis, the natural frequencies and main vibration modes of the system were determined, and the sensitivity changes of the natural frequencies to the design parameters were revealed. The maximum error between the theoretical modal frequency and the experimental one was 3.77%, which verified the correctness of the dynamics model. This research can provide a theoretical reference for the optimization of the dynamic performance of the hydraulic transmission system.

Analysis of Vibration Characteristics of Electro-hydraulic 3-UPS/S Parallel Stabilized Platform

“…To further improve the performance of parallel stabilized platform, it is important to study its vibration characteristics [13][14]. There are three methods to study the vibration characteristics: simulation analysis method [15][16][17], theoretical analysis method [18] and experimental analysis method [19].…”