Research On Vibration Aging Technology Of Antenna Structure

The antenna base is a typical large-scale welding structure.With the development of large-scale antennas,the base has the characteristics of complex welding structure,high rigidity,requirements for manufacturing precision and high manufacturing quality.How to adopt correct methods and measures to reduce its residual stress is one of the important links to ensure its welding quality.According to the structural characteristics of the antenna base and the welding process characteristics,especially for the lap joint,T-joint,corner joint and T-joint of the truss in the structural parts,the double ellipsoid heat source characteristics are adopted.After a series of test operations such as heat source check,database loading and correct setting of boundary conditions,the temperature field and stress field of the above typical structure during the welding process are carried out and the deformation is studied by numerical simulation.The simulation results show that the weld pool morphology is in line with the actual situation after the heat source calculation.Through the equivalent residual stress nephogram,the distribution of residual stress of various typical structures is analyzed.Combined with numerical simulation,the distribution of welding residual stress field is analyzed,and the residual stress of key nodes of typical structural parts is measured.The measured results are in good agreement with the simulation results.On the basis of simulation and experimental research,the corresponding points are selected for VSR treatment and stress analysis.The released strain is measured by strain gauge based on elastic principle,and the calculation formula of residual stress is derived.For four typical antenna structures,the stress at the measuring points before and after vibration is compared and analyzed by VSR treatment,and compared with annealing treatment.The results show that the residual stress of the workpiece can be removed by vibration aging treatment of 13 meter center body,and the degree of stress uniformity after removal is relatively concentrated.Although the stress changes greatly after vibration aging treatment,most of the stress values are distributed below 100 MPa.The removal rate of stress in vibration aging is also kept at a high level,and the removal rate of most points is more than 80%.The vibration aging of 6 meters center body not only removes the residual stress,but also shows a uniform distribution of residual stress.The residual stress distribution is less than 100 MPa after vibration aging,and the maximum difference between residual stress and residual stress is 70 MPa.The support e is fixed on the vibration table.Although the vibration aging treatment can remove the residual stress of the workpiece better,the stress amplitude after removal is small,and the degree of stress uniformity is relatively poor.The effect of vibration aging stress removal is not obvious,and the stress removal range is more than 50 MPa.The stress level of the radiation beam is not high before the vibration aging treatment,and the stress change is not obvious after vibration,which leads to the stress not showing uniform distribution after vibration treatment,and aging treatment fails to reflect the better removal of residual stress of the workpiece.The final results confirmed that the vibration aging treatment can better homogenize the residual stress of the work-piece,especially the peak stress removal was relatively complete,and the degree of stress homogenization after removal was relatively concentrated,which could get the level of annealing treatment.