| The hydraulic servo system is widely used in energy power,engineering machinery,aerospace and other fields due to its advantages of fast response speed,high power to weight ratio and compact structure.With the development of the national economy,large-scale engineering equipment and experimental devices emerge in endlessly,and hydraulic servo system is developing towards heavy load and large flow.In order to keep up with the trend of The Times,this paper studies deeply the subsystem of heavy load hydraulic servo system with the support of national natural science foundation project(NO.51275068).Based on the development experience of small and medium dynamic triaxial test apparatus,a large dynamic triaxial test apparatus with heavy load hydraulic servo system is developed,the axial load of the device can reach 10000 KN and the maximum displacement can reach 800 mm.The research contents and methods of this paper mainly include the following aspects:Firstly,through reading the relevant literature domestic and overseas,understands the current situation of hydraulic pipe,hydraulic servo system and triaxial test apparatus,and makes a detailed introduction to the theory of the theory of fluid-structure interaction.The design scheme of large-scale triaxial test apparatus is put forward.Secondly,establish mathematical models of each hydraulic components,theoretical analysis is carried out on each subsystem of hydraulic servo system,and understand its operation rule.The energy system,pipeline system,hydraulic auxiliary system and supporting structure of the heavy load hydraulic servo system are designed,and the simulation model is established to analyze the stability and design feasibility of the system.According to the analysis results,the overall design and selection of parts for large triaxial test apparatus are completed.Then,the large-scale triaxial test apparatus designed was used to test soil samples,the experimental data showed that the large-scale triaxial test apparatus could meet the practical engineering requirements.However,further studies have found that the frequency band width of the system is narrow.When the input signal frequency is high,the signal waveform has distortion,and the distortion problem is more serious when non-sinusoidal input.Considering that the non-sinusoidal periodic signal loaded by the system belongs to the periodic signal,it can be decomposed by Fourier series according to the conditions of dirichlet.A new method to improve non-sinusoidal periodic signal in hydraulic servo loading control is presented,solves the problem of distortion and distortion of non-sinusoidal periodic loading waveforms when the system frequency response characteristics are slightly poor,avoids the situation that only hardware upgrade can solve this problem.This method has been applied to the simulation analysis of the large-scale triaxial test apparatus,and has been verified experimentally on small equipment.Finally,during the test of the device,it was found that the return pipeline vibrated violently.In order to solve this problem,the pipeline of heavy-load hydraulic servo system was analyzed with the help of ANSYS Workbench software.Under the condition of fluid-structure interaction,the influence law of different supporting spacing and pipe thickness on pipe deformation,stress and strain and mode was studied;The vibration noise analyzer of LMS company was used to complete the modal experiment of the return pipeline of the large-scale triaxial test apparatus,the experimental results are consistent with ANSYS Workbench simulation results,It is proved that ANSYS Workbench analysis method is feasible to solve the vibration problem of return pipeline of the large-scale triaxial test apparatus. |
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