The Study Of High-frequency Electro-hydraulic Vibration Exciter Using A Two Dimensional Valve

Vibration tests are widely used in the development of many high-technology products including rockets and satellites, automobiles and mobile machinery running on rough roads, and modern engineering materials. The progress of vibration table as a standard equipment in the vibration test directly impacts on various areas, as well as weighs the development of industry as an important symbol.A scheme for an electro-hydraulic vibrator excited by a two dimensional valve is proposed, which significantly extends the frequency range compared to that of vibrators excited by conventional servo valves. The structure and working principle of new Electro-hydraulic vibration exciter is first introduced particularly. And the mathematical model of the vibration exciter is also established in order to simulate and analyse it. Last the vibration-exciting force signals and the displacement signals are obtained by adapting card. The real excited waveforms are analyzed, compared and studied. Both simulation and experimental results show that the elastic force constitutes the main part of the load. And it was clarified that the change of the direction of the elastic force has a significant effect on the excited wave form. And the rate of throttling areas of the 2D valve varied in a triangular waveform approximately as the spool rotates. At lower frequencies the ascent and descent slopes of the output force show some inconsistency which becomes more significant above the critical valve linear opening but drops off with a reduction in the valve linear opening. In a higher frequency range, the vibration excited by the two-dimensional valve is mainly influenced by hydraulic resonance. As the input frequency approaches the hydraulic resonant frequency, the output excited vibration essentially becomes the hydraulic resonance. Therefore, the effective frequency range of the hydraulic vibration is not only decided by the frequency bandwidth of the two-dimensional valve, but also is influenced by the hydraulic resonance.The main tasks of this thesis are as follows. In chapter one, a summary of some relevant information about the history and trend of this research is made. The meaning, purpose and the main tasks of this thesis are given.In chapter two, the structure and working principle of this new Electro-hydraulic vibration exciter is introduced, analysis by establishing mathematical model of the vibration exciter is made.In chapter three, a non-linear Simulink model based on the real hydraulic pressure system is built, the simulation and analysis is made with different frequency of valve core input, and then the excited waveforms output is studied.In chapter four, an experimental platform was set up. And the hardware of the control system is selected. And the vibration-exciting force signals and the displacement signals are obtained by data acquisition system. The real excited waveforms are analyzed, compared and studied.In chapter five, a summary and a prospect of this thesis are put forward as the conclusion.