| Since the full implementation of the “Made in China 2025” plan,a series of great changes have been made to China’s industrial structure,taking the sustainable economic development as the key focus of China’s construction of the modern manufacturing power,vigorously promoting the popularization and application of energy-saving and environmentfriendly machinery and equipment,forming a green production and manufacturing system,reducing energy consumption and promoting intelligent manufacturing.In the coal industry,as an underground construction and excavation equipment without environmental pollution,horizontal directional drilling rig is widely used in underground operation of coal mine and engineering projects requiring drilling.In the actual work of rock breaking by bit,as the main load-bearing structure,the drilling rig substructure has complex stress and bad working environment.Therefore,it is very necessary to study the life evaluation and reliability of drilling rig substructure.Therefore,taking ZYL-15000 D crawler drill for coal mine as the research object,this paper calculates the service life and reliability of its base structure.Firstly,the material of drilling rig substructure is Q345 B.Through the fatigue tensile test of stress control on the sample,it is substituted into the power exponential model for fitting,and the fitting relationship between the maximum stress and life of Q345 B steel under pulsating cycle is obtained.Through the stress correction and the selection of safety factor,the function fitting relationship between stress amplitude and life of Q345 B steel under symmetrical cycle is obtained.Then,the damage degradation model is derived from thermodynamics.According to the fatigue tensile test data of Q345 B steel,it is fitted in MATLAB to determine the undetermined parameters in the model.Combined with the fitting relationship between stress amplitude and life,the damage degradation model of Q345 B steel is determined.Then,by simplifying the structural model of the drilling rig substructure,the finite element analysis is carried out in ABAQUS to determine the location of the dangerous point,and the appropriate electric bridge is selected according to the deformation at the dangerous point.Then,the indoor prototype loading test is carried out to measure the stress time history data at the dangerous point(i.e.the position with the largest stress).The measured results are preprocessed and statistically analyzed in MATLAB.After treatment,the life is calculated by the determined life evaluation model of Q345 B steel.Finally,by introducing the damage degradation model of Q345 B steel into the traditional stress strength interference model,the stress strength interference model based on the damage mechanics theory is obtained.The data is analyzed and calculated according to the improved first-order second moment method,and the reliability degradation curve of the drilling rig substructure structure is obtained for reliability evaluation. |
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