Prevention of defects in the process of superplastic forming and diffusion bonding sandwich panels of titanium alloys

Аuthors

Kolesnikov A. V.

Irkutsk National Research Technical University, 83, Lermontov str., Irkutsk, 664074, Russia

e-mail: Avk@istu.edu

Abstract

The experience of production of sandwich panels from titanium alloys via a method of superplasticforming and diffusionbonding (SPF/DB) shows that in the process of forming under certain conditions there are defects. The defects arise as a result of bending sheet of panel in excess of certain critical value. The bend of a sheet of the panel in the process of forming occurs in a free zone of the bottom sheet between diffusive welding of the next edges of the panel. The size of a bend of a forming in a free zone depends on a material of the panel, a mode of forming and a design of a filler panel.
In the work the values of critical height of a bend were determined by a method of modeling of process in the program «MSC Marc» depending on a design data of filler. Thanks to the received values the range of a choice of optimum constructive and geometrical parameters of sandwich panels was determined. The range is presented in the form of a plot for values thickness of sheet, width of the filler and panel height. Each plot shows that above the curve there is the recommended range of choices thickness sheet and filler for the forming of a sandwich panel of titanium alloy desired geometry without the defects.
Process is presented for a modeling and forming of the sandwich panel with the parameters chosen from the recommended range which confirmed a possibility of forming without manifestation of defects. To check of results of modeling the forming was done for the sandwich panel with the received parameters on the press of superplastic forming and diffusion bonding «FSP60T», in a laboratory of IRGTU. As a result of the forming the panel is received without any defects.
Thus, the results of modeling and natural production showed that when the recommendations, presented in this paper, are followed, there will be no defects in the process of forming of panels.
If its not possible to select the optimal structural and geometrical parameters of sandwich panels presented in the work, then its necessary to resort to special methods of forming, one of which is the use of supporting of sheets during the forming process to prevent the formation of bend and, as a consequence of defects.

Keywords:

superplastic forming, superplasticity, sandwich panels, titanium alloys

References

1. Chumachenko E.N., Smirnov O.M., Tsepin M.A. Sverkhplastichnost: materialy, teoriya, tekhnologii (Superplasticity: materials, theory, technology), Moscow, KomKniga, 2005, 320p.
2. Novikov I.I., Portnoi V.K. Sverkhplastichnost splavov sultramelkim zernom (Superplasticity ofalloys with anultrafine grain), Moscow, Metallurgiya, 1981, 168p.
3. Birjukov N.M., Smirnov V.A. Izvestija vysshih uchebnyh zavedenij. Aviacionnaja tehnika, 1988, no.3, pp. 38-42.
   
4. Khodyrev V.A. Proektirovanie, izgotovlenie iekspluatatsiya shtampov spoliuretanom (Design, manufacture and operation ofstamps with polyurethane), Perm, 1975, 365p.
5. Pashkevich A.G., Orekhov A.V., Smirnov V.A. Izvestija vysshih uchebnyh zavedenij. Aviacionnaja tehnika, 1985, no.4, pp. 90-93.
   
6. Kolesnikov A.V., Shmakov A.K. Vestnik Irkutskogo gosudarstvennnogo tehnicheskogo universiteta, 2013, no. 11(82), pp. 52-57.