Research On Spot Weld Model Of High Strength Steel Front Rail Based On The Crashworthiness

With the development of automobile industry, energy crisis becomes more and more important, and environmental pressures and other corresponding issues are also increasingly serious."Saving energy" is the one of three hot issues in automobile industry and widely studied in the21st century. Therefore, advanced high strength steel (AHSS) blank is well developed and widely used in the modern automobile body structure design. Compared with traditional steel, the advantage of AHSS is to satisfy the requirement for structure and lightweight simultaneously, Recently, domestic and foreign automobile manufacturers commonly used high strength steel to produce the beams of the car and other important structures, especially for the thin-walled front rail which can be regarded as the most effective energy-absorbing components.According to the advantages of spot welding, such as concentrating the energy in the welding process, smaller deformation, higher productivity, the spot welding is suitable for welding thin-walled components, etc. These make the spot weld become the most important connecting type for the auto body. In the manufacture procedure of the automobile body, the quality of welded joints, not only directly determines manufacturing deviation in the body welding assembly process, but also guarantees the reliability and security of the car. Thus, it is a critical point for simulation of compact procedure accurately. Moreover, the optimization for welding spots is also an important issue in real engineering design.According to the spot failure phenomenon in collision process and other previous studies, this paper combines the real experiment and finite element method (FEM) to analysis five different welding spot models based on the AHSS to study the influence for front member of automobile in crashworthiness. Moreover, the front rail trolley experiment is also implemented for verifying the simulation accuracy with different type weld spot models. Additionally, the distance between two spot joints has a very tremendous influence to the deformation and energy absorption of the front rail. According to above analysis the beam element is chosen to simulate, and build the carline trolley collision model. Sequentially, the OptiStruct is used for topology optimization and achieving the better spot distributed arrangement. Finally, the optimized spot distributed pattern is verified by the crash simulation. The result not only meets the energy absorption requirements, but also reduces the number of the spot welds.