Welding Process Optimization Of Thin-walled Box Boom

Compared with other structural steel, high-strength structural steel has lots of advantages, such as high strength, good mechanical properties and so on. With the continuous development of steel, more and more engineering vehicles boom uses thin-walled box section, such as crane trucks, telescopic forklift trucks, aerial vehicles and so on. Thin-walled box boom is the core component of many engineering vehicles, and its main structure is composed of four thin high-strength structural steel sheets connected by welding. Due to the high carbon equivalent and poor weld ability of high-strength structural and the thin thickness of boom, the large welding deformation that exceeds requirements of geometric tolerances easily appears during welding, which seriously affects the carrying capacity and safety of engineering vehicles when operating. Therefore, the appropriate welding process should be chose in order to reduce residual stress and control residual deformation during welding.Based on the above research background, the main contents are as follows:(1) The welding thermal process features and the theoretical basis of temperature and stress analysis during welding is introduced.(2) Take a T-joint fillet weld as an example, and its finite element modeling process, heat source selection and load application are introduced in detail. The welding process is numerically simulated by using the software ANSYS in order to obtain temperature, stress and strain fields of T-joint at any time, and then the stress and strain distribution on the critical path is analyzed.(3) The welding process with different welding currents, welding speeds and effective heating radii is numerically simulated, and the influence of the three welding parameters on temperature, residual stress and residual deformation is obtained, and the optimal T-joint welding process is ultimately determined.(4) Take the first boom of 30m aerial vehicles as example, and the influence of different welding sequences for the thin-walled box boom on residual stress and residual deformation is analyzed. Firstly, take a T-joint fillet weld of the thin-walled box boom as the research object, and four welding sequences is selected and numerically simulated, and then the optimal welding sequence of a T-joint fillet weld is obtained by synthetically comparing welding residual stress and residual deformation. Secondly, take the whole four welds of the thin-walled box boom as the research object, and four welding sequences are selected, and then the optimal welding sequence of the thin-walled box boom is obtained by the same method.