Research On Material Flow For Superplastic Forming Process Of A Box

With the development of the superplastic forming (SPF) and diffusion bonding technology,SPF/DB has become an important technology to promote the development of structure concept designin aviation and aerospace. Comparing with traditional manufacturing process, SPF/DB has a lot ofirreplaceable superiority, such as improving the performance, reducing vehicle in weight, lowmanufacturing cost and so on.It is well known that the SPF/DB structure has been used in the aircraft. However, there are somedefects in the actual production, which need to be improved. And one of the common problems is thatthe wall thickness of the component will be uniform after SPF/DB forming. Thereby a research wasconducted on this problem with the aim to solve it by the forward pre-forming process.The main contents are as follows：(1) Superplasticity of TC4was tested by speed mutation method to obtain the value of strain ratesensitivity coefficient m.(2) One-stage superplastic forming process of TC4box was numerically simulated byMSC.MARC software. Experiments were carried out according to the load curve which was evaluatedby the simulation. Finite element model was proved to be rational by comparing its results withexperiments results on the shape and thickness. Moreover, eight-node shell element was found to bebetter for simulation than other elements. Thus, material flow of the TC4box in the process of metalsuperplastic forming was summarized.(3) Based on the material flow above, an exploratory research was demonstrated on thepre-forming process of the TC4box. Two-stage forming process was simulated by MSC.MARCsoftware. According to how pre-forming process affected material flow, an effective preformingmould was obtained by the optimization of its shape, which can improve the uniformity of thethickness. Finally, the two-step forming process was experimented.