Analysis of tubes with rectangular section forming process by fluid-solid coupling method

Owing to the advantages of favorable forming stiffness, light weight, and high production efficiency, hydroforming technology has extensive application prospects in the automobile and aerospace fields. This study designs and develops an experimental test system, which continuously injects oil into a quartz tube with favorable transparency, and then captures the flow characteristics of the liquid in the tube in real time using an ultra-high-speed camera. The fluid-solid coupling method of the MSC.Dytran finite element software is used for the experiment. The correctness of the simulation analysis method is verified by comparing the experimental and simulation results. Thus, a hydraulic bulging experiment of 20# steel tube without axial feed and a simulation analysis of the hydraulic bulging process of the rectangular section tube through the fluid-solid coupling method were conducted. A comparison between the experimental and simulation results verified the correctness of the finite element modeling and numerical calculation. In addition, the effects of forming pressure, loading time, and hydraulic loading path on wall thickness change in fillet filling was studied. Results showed that pressure drop exists in the pipe, and the velocity of the fluid changes rapidly with the deformation. The forming pressure clearly influences the forming effect. The maximum thinning rate of the middle section wall thickness initially decreases and then increases given an extended hydraulic loading time. Therefore, the optimal loading time should be determined to achieve the optimal forming effect. The effect of hydraulic loading path on the thickness reduction of wall thickness is not apparent but significantly influences the uniformity of wall thickness distribution.