The Excited Waveform Analysis Of The Electrohydraulic Vibrator Based On 2D Valve

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. The rapid development of the industry, especially space area, the vibration frequency range and output are demanded higher and higher, and improving frequency range and increasing output are important themies that have run throughout the course of vibration table development.The working frequency of the electrohydraulic vibration exciter conventionally constructed by a servo valve and a hydraulic cylinder or a motor is to a large extent limited to fairly narrow range by the frequency response capability of the servo valve. A scheme of electrohydraulic vibration exciter using a 2D valve (two-dimensional control valve) to control a hydraulic actuator is therefore proposed to enhance the working frequency to a large scale. In this thesis, the working principle of the electrohydraulic vibration exciter is first introduced, and the mathematical model of the vibration exciter is also established. According to hydraulic machinery and dominant equations, the excited waveforms are solved in the analytical method. At last, the vibration-exciting force signals and the displacement signals are obtained by adapting card. The real excited waveforms are analyzed, compared and studied. The theoretical and experimental investigations were carried out to the case that the elastic force constitutes the main part of the load. It was clarified that the change of the direction of the elastic force has a significant effect on the excited wave form. Although the rate of throttling areas of the 2D valve varied in a triangular waveform approximately as the spool rotates, the ascent and descent slopes of output force or displacement wave demonstrated somewhat inconsistency because of the changing direction of the elastic force. The inconsistency becomes the most manifest as the linear opening of the 2D valve reaches a critical point and weakens it is reduced. When the opening over this point, the waveform will be a 'saturation phenomenon.' 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 electrohydraulic vibration exciter is introduced, analysis by establishing mathematical model of the vibration exciter is made.In chapter three, according to hydraulic machinery and dominant equations, the excited waveforms are solved in the analytical method. This part focuses on analyzing the typical excited waveforms.In chapter four, the vibration-exciting force signals and the displacement signals are obtained by adapting card under Delphi development. 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.