Study On The Distribution Mode Of Residual Stress In Welded Hollow Spherical Joints And Its Influence On The Performance Of Joints

Welded hollow spherical joints are widely used in large space structures for their simple structure,convenient construction and reasonable force.Because the welded hollow ball joints are connected by the hollow ball and the steel pipe through the weld,the welding process will leave a lot of residual stress,even the residual stress of the welding exceeds the yield strength of the material.Therefore,the effect of welding residual stress on the performance of welded hollow ball joints can not be ignored.This paper mainly studies the distribution law of welding residual stress and the effect of welding residual stress on the ultimate bearing capacity and stiffness of welded hollow spherical joints.In this paper,finite element software ANSYS was used to simulate the welding process.The welding temperature field and welding stress field were calculated,and the distribution of welding residual stress in welded hollow spherical joints was summarized.Based on the distribution pattern of welding residual stress,the simulation load study under the condition of eliminating and not eliminating the welding residual stress was carried out respectively,and the influence rule of welding residual stress on the ultimate bearing capacity and stiffness of welded hollow spherical joints was revealed.The main research work of this article is as follows:(1)A finite element model of the welded hollow spherical joint was established.The transient thermal analysis was used to simulate the welding process.The reasonable unit was selected.The nonlinear characteristics of the material performance parameters with temperature were considered.Simulate the filling process of the weld seam using the life-and-death element method to obtain the cloud distribution of the temperature field at different times,and analyze the time-varying temperature field of the welding process.(2)Based on the analysis results of the welding temperature field,the instantaneous stress and welding residual stress at different moments of the welded hollow ball joint are calculated,and the distribution characteristics and rules of the welding residual stress on the weld,steel pipe and hollow ball are obtained.The influence of hollow sphere diameter,wall thickness,steel tube diameter and wall thickness on welding residual stress is analyzed parametrized.(3)Based on the distribution of welding residual stress,the ultimate bearing capacity of welded hollow ball joints under the influence of welding residual stress is compared and analyzed.The ultimate bearing capacity of welded hollow ball joints is analyzed with the changes of the diameter of the hollow sphere,the thickness of the wall,the diameter of the steel tube and the wall thickness of the welded hollow ball joints.(4)Based on the distribution of welding residual stress,the stiffness of the welded hollow ball joints under load is calculated,and the change of the joint stiffness of the welded hollow ball joints under the residual stress of welding is compared and analyzed.The influence of the welding residual stress on the stiffness of the welded hollow ball joints with the changes of the diameter of the hollow sphere and the thickness of the wall,the diameter of the steel tube and the thickness of the wall.