Modeling the Super Plastic Forming of a Multi-Sheet Diffusion Bonded Titanium Alloy Demonstrator Fan Blade

The paper describes a finite element method in 2D and 3D to simulate the super plastic forming of a demonstrator jet engine fan blade made from Titanium alloy sheet. The fan blade is an assembly of three sheets in which a single inner (core) sheet is diffusion bonded to the two outer (skin) sheets at prescribed zones, which is then super-plastically formed to a desired fan profile. In the model, the diffusion bonded zones between the core and skin sheets are simulated using tied interfaces. The thickness of each skin sheet is not uniform and significant change in thickness can occur over a short distance as well as gradually over the entire skin sheet. The thickness of the core sheet which is smaller than the thickness of each skin sheet remains uniform. The paper describes the design for a scaled-down demonstrator fan blade and model build process. Selected results and evaluations of finite element simulations are presented and discussed.