| In order to satisfy the needs of mine with impact pressure and coal bumps inclination,the research and development of support equipment which had the rigid-flexible coupling characteristics have become a research hotspot.Structural dynamics problems of static load and impact load superposition are often encountered in many engineering fields.For example,in rock mass mechanics research,the impact characteristics should be considered when surrounding rock stress,which means the mining support equipment is subject to a large initial pressure at the initial state.When the power disaster occurs,along with the impact and ground pressure,the support equipment will suddenly lose stability under the superposition of static and dynamic loads.The supporting equipment could show quite different mechanical properties when under the action of static load and impact load.Due to the lack of large-tonnage impact test equipment for experimental research,the researches on the problems above were mainly based on theoretical calculations and numerical simulations by now.It is urgent to develop a test device to solve this problem according to the actual working conditions.In this study,according to the actual working conditions,a set of fast hydraulic impact testing machine has been designed,which could achieve the maximum impact,force of 2000kN and the maximum impact speed of 10m/s.In order to meet the technical requirements of the fast hydraulic impact testing machine,the key technologies such as high pressure,high speed,and large flow liquid release during impact were also investigated at different loading modes.The research and design of the fast hydraulic impact testing machine are mainly composed of a hydraulic loading system,test bench,and measurement and control system.Among them,the hydraulic loading system mainly provides loading energy for the testing machine and realizes static loading,impact dynamic loading and static-dynamic combined loading mode.The test bench can meet the vertical and horizontal test conditions of the impact tester,and complete the installation and fixation of the test piece.The measurement and control system realizes capabilities such as human-computer interaction in the test,individual or joint motion control of the impact tester system,attitude adjustment of the test machine,and high-speed acquisition and display of test data.In order to meet the release requirement of high-speed and large-flow requirements of the hydraulic loading system during an impact test,a super-large flow and quick-opening valve structure were designed.Based on the basic structure design,the valve orifice size calculation,steady-state hydrodynamic calculation,and transient hydrodynamic calculation were studied.A sealed protective sleeve was also designed to solve the dynamic seal problem under high speed and high pressure.In addition,the hydrodynamic force of the valve core was analyzed by the analytical method to optimize the structure further.The mathematical model and FLUNT simulation model of the ultra-large flow quick-opening valve were established.The optimal structure of the ultra-large flow quick-opening valve was obtained by simulation calculation and analysis.The analysis results showed that the structure could meet the ultra-large flow requirements of 48000L\min.The influence of the characteristics of the main hydraulic components on the output dynamic performance of the impact tester was analyzed by simulation.After analyzing the AMEsim simulation model which was established according to the hydraulic system schematic diagram,the accumulator parameters,load changes and the parameters of super-large flow quick-opening valve were calculated in detail,and the pre-charging pressure and the number of accumulators were finally determined according to the analysis results.The spool opening,spool quality and flow coefficient of the super large flow quick opening valve were obtained.The mechanical response characteristics of the main force frame under various typical stress conditions were analyzed to avoid the influence of the deformation caused by the main force frame of the test bench during the impact process.The static analysis of the ABAQUS/Standard general analysis module was carried out after the 3D solid modeling of the main force frame of the impact testing machine.The simplified model of the test truss strut in the impact process was established by using the analytical method,and then the general response of the test truss strut system under arbitrary excitation was analyzed.The impact spectrum and spectrum of different loading signals of the test system were also analyzed.Then the parameter range of the loading waveform has been obtained.The dynamic analysis of the ABAQUS/Explicit display dynamic analysis module was carried out according to the impact conditions.The analysis results showed that the maximum displacement of the impact tester under the static loading and impact dynamic loading of 2000KN were 0.86mm and 0.8917mm,respectively.The stress and strain of the main frame of the impact tester can meet the requirements under all conditions of the impact load.Based on the calculation results,the prototype was prototyped,and the test pieces of different structural forms were tested.The test included no-load test,static-dynamic composite loading shock test of the energy-absorbing box,impact test of the hydraulic strut,static tensile test and impact tensile test of anchor/anchor cable.The test results showed that the impact tester had been designed reasonably and could meet the test requirements of all different forms of loading.The test results proved the correctness of the dynamic simulation results.The design of 2000KN hydraulic impact testing machine provides necessary experimental means for the research of rigid-flexible coupling cushioning and energy-absorbing support equipment,and the test results can provide a reliable experimental basis for relevant research.This study laid the foundation for the development of impact testing machine on a larger energy level.The thesis has 91 pictures,15 tables,and 152 references. |
PDF Full Text Request