Deformation And Damage Behaviour Of CCS-B Laser Welding Joint In Sandwich Panels

As a result of the need for the modern automotive design to address energy savings and environmental issues, the sandwich structures has been applied widely. The welded joints were basic elements in sandwich structures. It costs a large amount of manpower and money to perform the deformation, damage and destruction of the various joints. Finite elemen t simulation can economize effectively the cost such as adopting, raising the efficiency, plus the validation of key experiments.The microstructure and mechanical properties of weld joints were nonuniform. Before carrying on finite element simulation, it was necessary to assess local mechanical properties of welded joint for accurate results. Local mechanical properties were measured accurately for the assessment of the mechanical properties of the whole welded joints to improve welding technique. This paper aims at the weld joint analysis of microstructure, hardness and mechanical properties of CCS-B low alloy steel laser-welded sandwich structrues, meanwhile a new method,double-shearing stamp test,was presented to measure strain-stress curves for weldbeams of sandwich structures. Its basic principle:the material resistance curves of local material,extracted from the welded joint by means of double-shear test. Boundary conditions, which is consistent with actual double-shear test, were established in ABAQUS. A special revised iterative process was applied to work out true strain-stress curves. This technique was available in mechanical property assessment for sandwich structures and got an advantage over the conventional tensile test.Based on the research above, double-shear test was used to characterize the local mechanical properties of CCS-B low alloy steel laser-welded joints. Data acquired was used in simulation to predict nonaffine deformation,damage initiation and fracture process under tensile load. Research shows that the nonuniform deformation of CCS-B low alloy steel weld joints is related with its nonuniformity of mechanical properties.As for high-matching deformation is mainly focused on base metal away from weldseam.G-T-N damage model was adopted in ABAQUS to predict damage evolution and failure process, indicate that damage occurred in the base metal of low strength during simulated tensile process, which is consistent with experiment. This paper provides references for failure analysis of key weld joints for sandwich structures.