Deformation Control of TC4 Titanium Alloy in Thin-Walled Hyperbolic Structures During Hot Forming Processes.

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.