The Analysis Of Shear And Bending Failure Of Laser Welded T-Joint Of The Low Alloy Steel

Lightweight structure is one of the key factors for energy conservation and consumption reduction.As one kind of widely used lightweight structure,the metal sandwich panels is composed of two parallel face plates linked with vertical core plate.The sandwich panels links the parallel face plates with core plate by welding joint mainly through laser welding and arc fusion welding,and thus the mechanical properties of the joint are of great importance for the entire board,which could influence the stiffness,strength and failure mode,et al.In this paper,the CCS-B low alloy steel welded by laser beam and T-joint of BS960 sandwich plates were used to investigate the mechanical properties of these welding joint.According to the difference of stress condition,the strength,deformation and failure mode were studied in the case of shear stress and bend loading condition.The macro camera technology was employed to take photos simultaneously during loading process.Further,finite element analysis was adopted to clarify the force condition and failure mode of welding joints during the test of bending and shear.In the end,the fracture mode was confirmed by the observation of fracture surface of T-joint using scanning electron microscopy(SEM).The finite element model which is related to the T-joint with different linking width and gap was established.Meanwhile,the simulation analysis of bending test was applied to obtain the sensitive parameter greatly influencing the joint strength.The results of the study are as follows: when the T-joint serving under bending force,the failure path is starting from the outside of the gap at the joint at the both ends of the upper and lower sides of the neutral axis of the core plate,it will extend to the center of the weld in the wake of loading;When the T-joint serving under shear force,the relative movement between core plate and panels lead to the deformation of metal joint then causing failure.The observation of T-joint fracture by SEM reveals that the bend failure was mainly controlled by the coupling of shear force and normal stress,and the shear failure was controlled by shear force.Except for the analysis of force condition of the T-joint,the strength under bend and shear condition was also calculated,and the result shows that the joint strength of CCS-B sandwich panel is higher than BS960.Bending test of T-joint conducted using Abaqus finite element software shows that the T-joint follows 1/3 yield criterion.The bending strength of T-joint with different space and link width was also calculated by simulation analysis,the bending load increased with the increasing of link width;increasing the space distance,however,will reduce the yield strength.For the maximum bending strength,when the gap at the T-joint is at an appropriate value,the existence of gaps will increase the bending strength.Thus,for T-joint,the link width is much sensitive for joint strength than gap distance.In consequence,the link width between core plate and face plates has significant effect on joint strength.