The Analysis Of Residual Stress Of Two Layers Of Plates' With Butt Welding And Different Thickness Plates' With Butt Welding

Referring to Chinese steel structure standard and German standard,it found about German standard DIN18800-1 proposed the requirements of butt-welding connection.It recommends that two layers of plates' butt connection with the upper steel plate's weld groove Angle of 20 °,the lower plate's weld groove Angle of 50 °.Chinese steel structure design standard GB 50017-2017 has no relevant content.In addition,China's steel structure design standard GB50017 regulated that two steel plates in different thickness which more than 4mm with butt-welding aligned at one side.Its connected component needs transition slope,which slope should no more than 1:2.5,and its weld groove should be taken according to the thinner plate requirements.German steel structure standard DIN 18800-1 recommends that two steel plates which thickness difference of more than 10 mm connected.Its connected component needs set the height difference at the welding toe should no more than 10 mm,and the slope on one or both sides of thicker steel plate should no more than 1:1 bevel angle.its weld groove should be taken according to the thinner plate requirements.At present,there have been relevant tests and finite element analysis studies on the butt weld of steel plate in China,but few studies on two layers of steel plate with butt-welding and different thickness of steel plate with butt-welding.In order to deeply study the residual stress field of two layers of steel plate with butt-welding and different thickness of steel plate with butt-welding,this paper simulated them with finite element software and designed three sets of specimens of two layers of steel plate with butt-welding,tested the residual stress field.The main research contents include:(1)In this paper,three groups of Q345 two layers of steel plate with butt-welding specimens were designed in accordance with the requirements of German standard,and the residual stress distribution of each group of specimens was obtained by blind hole test.Three identical specimens in each group showed similar stress results,which verified the accuracy of the blind hole test method.When compared the test results with the finite element results.It shows a good agreement with the finite element results,which verified the correctness of the finite element model of two-layers steel plate.By simulating the moving heat source,the temperature field of the double-layer steel plate model is obtained,which ensures that the simulation process of welding is the same as the real welding process,and obtains that the small weld groove Angle can reduce the heat input.(2)This paper used the finite element software,according to Germany standard requirement,to set up two layers of Q345 steel plates with butt-welding model,and obtained the residual stress distribution under different welding groove Angle.It is concluded that the double plate transverse residual stress distribution is asymmetric,and with the increase of weld groove Angle,the transverse residual stress peak value increases,the asymmetric distribution.To compare and analyze the residual stress field and temperature field of single-layer steel plate and two-layers of steel plate,the butt welding models of single-layer steel plate according to the requirements of Chinese standard with the same thickness are established.It is concluded that the peak value of transverse stress of two-layer steel plate is lower than that of single-layer steel plate.(3)The mechanical performance of Q345 two-layers of steel plates with butt welding in different thickness of steel plate and groove angles were analyzed by finite element software.The model of two-layers of steel plates were loaded its residual stress field result,and its load displacement curve under different weld groove angles was obtained.It is concluded that weld groove angle has indirectly effect on bearing capacity.(4)To analysis of distribution of Butt-Welding residual stress by Two different thickness steel plates aligned at one side with transition slope,some finite element models are created to analyze effect of such parameters as the thinner plates' thickness,the transition slopes,height differences of welding toe on performance of butt-welding.The result shows that the thick steel plate weld toe of transverse residual stress decreases obviously with the transition or the welding toe height difference decreases.(5)To analysis of butt-welding stress concentration by two different thickness steel plates aligned at one side with transition slope,some finite element models are created to analyze effect of such parameters as the plates' thickness,the transition slopes,height differences of welding toe,transition radius of welding toe on performance of butt-welding.The result shows that the stress concentration located atthe welding toe on thinner plate,and the thickness of thinner plates has great effect on stress concentration.When transition slope's value is greater than 1:2.5,the models' stress concentration factors significantly increased with the sharper slopes and.the models' stress concentration factors increases obviously with the increasing of height differences of welding toe.Increasing of transition radius of welding toe can decrease stress concentration.