The thin-walled hyperbolic structures made from titanium alloy primarily encompass two typical forms: hyperbolic convex and hyperbolic concave (saddle). This paper addresses the technical challenges associated with the forming processes that frequently result in ripples or wrinkles in these configurations. Specifically, it investigates precision control techniques for the hot forming process of thin-walled hyperbolic skins from TC4 titanium alloy. The present study examines the relationship between the instability characteristics and defect features of the thin-walled hyperbolic skins, establishing a constitutive model for TC4 titanium alloy and conducting uniaxial tensile tests. For the hyperbolic convex skin and the hyperbolic saddle skin, small-margin coupled hot pressing and curved edge forming processes are employed, respectively. Results are analyzed to identify the forms and distribution patterns of forming defects across different geometries. Furthermore, the surface accuracy following the forming processes is compared, culminating in a summary of the relationship between the ratio of the sum of chord heights to the sum of chord lengths and the occurrence of ripples and wrinkles.

Due to the impact of temperature on springback in hot stretch bending(HSB) process, this paper proposed a modified hot stretch bending(MHSB) process in which a reheating process was added before post stretching. The reheating process was realized by controlling the current distribution in the straight region and the bent region of titanium extrusion. Prior to HSB tests, uniaxial tensile tests were carried out to determine the deformation behavior of extrusion under the temperature condition similar to the HSB processes investigated. The results of the tensile tests provided supporting evidence for that the temperature of post stretching strongly affected the forming accuracy of hot stretch bending parts. Particularly, much more joule heat generated in the bent region than in the straight region successfully reheated it to initial forming temperature by increasing current before post stretching. Accordingly, the springback was significantly reduced via the novel method compared to conventional hot stretch bending(CHSB) process. This method is proved to be an efficient and lower cost solution for reducing springback in HSB.

Titanium alloy profiles are widely applied as airframe parts due to its excellent mechanical properties and high compatibility of electrical potential with resin composite material. The electrical assisted forming is recognized as the effective approach to improve plasticity of titanium alloy profile. In this work, the electo-thermal uniaxial tension was performed to investigate the mechanical properties. The experiment results show that, the stress-strain curves increases sharply to the peak and declines quickly, exhibiting no stable deformation occurring. On basis of the obtained curves, a constitutive equation was established with consideration of the characteristic of self resistance heating, and the microstructure evolution was predicted. A comparison of the calculated stress-strain curves with the experimental ones was conducted, showing a reasonable agreement.