The Mechanical Behavior Studies On Welded Joint Of Orthotropic Steel Deck

A host of one side welding joints are used to filled a weld groove of orthotropic steel deck,since its U-shaped ribs is the closed structure.During these structure of bridge in the using term,the welded joints are force in main girder directly.A lot of welding residual stresses concentrated in weld root with incomplete fusion defects,which bring the local fracture evolution shows,and result in degrading of structure performance.In order to more systematically study the mechanical behavior of welding seam of the different welding parameters,combined with welding numerical simulation and acoustic emission technique,which allows to separately the effects of components performance by these welding defect.This study in view of partial penetrated butt weld of the commonly used among welding construction.Based on Q345 qE structural steel as the main research material,which generally applied in the bridge engineering,and possesses excellent physical and welding properties.The deformation and fracture characteristics of this type of welding seam are analyzed according to tensile test of fillet welded joint,which is based on its equivalent force analysis.And it consists of numerical simulation of welding residual stress and AE signals parameter analysis to different fracture model of welding specimens:(1)through the infrared temperature and residual strain specimen test,welding process is obtained by accurate numerical simulation of the welding residual stress distribution characteristics,to prone to cracking of welding,weld toe area to the root of the hot spot stress for the characteristic values of weld is analyzed and the degree of fusion of parent metal,welding process parameter selection for the influence of residual stress distribution.(2)test the welded specimen tensile fracture process of the acoustic emission signal characteristics,combined with microscopic microstructure and macro mechanics test,the weld seam and heat affected zone of brittle fracture of ductile fracture,parent metal three typical fracture mode characteristics of acoustic emission signal process and distribution analysis.The results show that tired ringing count rate and cumulative rate can effectively evaluate damage process;the concept of plastic damage index is introduced to evaluate the damage characteristics of different penetration and groove welds,further optimizing the welding parameters and providing a reference for the evaluation of weld quality.