Analysis Of Mechanical Properties Of Remanufactured Column Of Hydraulic Support Based On Finite Element Method

The column is the main structure of the hydraulic support to bear the pressure of the top plate.Due to the influence of the harsh working environment in the well,the surface of the cylinder body is prone to damage such as coating peeling,scratches,and corrosion.Laser cladding remanufacturing technology can repair the surface damage of the column.However,the laser cladding process will cause thermal damage to the column base and cladding layer,thus affecting the mechanical properties of the remanufactured column.Residual thermal stress is an important cause of thermal damage.Based on the finite element method,this paper analyzes the influence of laser cladding process on residual thermal stress,and analyzes the mechanical properties such as column strength and fatigue durability under the influence of residual thermal stress,to provide a theoretical reference for the performance inspection of remanufactured columns.The specific research contents are as follows:First,a geometric model of iron-based alloy powder for column cladding was established,and the laser cladding process was simulated by finite element software.According to the actual cladding process parameters,a Gaussian moving heat source model is established and a command flow is generated,and the model is loaded to obtain the temperature field results.The thermal-mechanical coupling analysis of the column cladding model was carried out with the temperature field as the load,and the residual thermal stress results were obtained.The research shows that the cladding layer and the column base near the cladding layer have large residual stress,and the residual stress of the base and the cladding layer in the circumferential direction of the column are tensile stress.Secondly,a finite element analysis method for remanufactured columns is proposed.According to GB 25974.2—2010 "Technical Conditions for Hydraulic Support Columns and Jacks for Coal Mine" on the impact test of columns,the impact test of double telescopic columns is obtained through theoretical derivation and mathematical calculation.Under the load,the pressure of the cylinders at all levels is established,the geometric model and finite element model of the remanufactured column are established,and the static analysis is carried out,and the strength of the remanufactured column is analyzed comprehensively considering the influence of residual tensile stress and impact load.The results show that under the influence of residual tensile stress,the maximum stress of the cylinder cladding layers at all levels exceeds the yield limit of the material,and there is a risk of cracking and falling off.The local stress in the middle cylinder is close to the yield limit of the material,which is prone to strain fatigue.Finally,the loading mode,load size and fatigue life analysis process of column fatigue life calculation are determined according to the column working conditions.The stress-strain results of the column under cyclic load are obtained by finite element method,which is prepared for fatigue life estimation.Based on the local stress-strain method and considering the influence of residual tensile stress,the fatigue life of the remanufactured double telescopic column is calculated.The results show that the life of the fatigue dangerous part of the remanufactured double telescopic column is about 47000 times,while the fatigue life of the new column is about 68500 times.At the same time,a fatigue life estimation model of laser cladding remanufactured parts considering the influence of residual stress based on Chaboche uniaxial nonlinear fatigue damage accumulation rule is proposed.