Structural panel having a predetermined shape and an associated method for superplastically forming and diffusion bonding the structural panel

A method of fabricating a structural panel having a predetermined shape, the method comprising the steps of:

• joining first and second metallic core sheets along respective edge portions of said first and second core sheets to thereby form an inflatable envelope assembly;
• forming first and second reinforced titanium composite sheets into a shape corresponding to the predetermined shape;
• disposing the inflatable envelope assembly between the first and second reinforced titanium composite sheets following said forming step such that the inflatable envelope assembly is sandwiched therebetween;
• and
• diffusion bonding the inflatable envelope assembly to the first and second reinforced titanium composite sheets, said diffusion bonding step comprising the step of expanding the inflatable envelope assembly such that the inflatable envelope assembly contacts and bonds to the first and second reinforced titanium composite sheets to thereby integrally form said structural panel having the predetermined shape,
• wherein the first and second reinforced titanium composite sheets have a first predetermined flow stress and the first and second metallic core sheets have a second predetermined flow stress, the first predetermined flow stress being greater than the second predetermined flow stress such that said first reinforced titanium composite sheet increases the relative strength of the integral structural panel.

A method of fabricating a structural panel having a predetermined shape, the method comprising the steps of:

• forming an inflatable envelope assembly having first and second metallic core sheets sealed along respective edge portions and joined at interior portions by a discontinuous weld pattern;
• superplastically forming the inflatable envelope assembly to an intermediate state in which the inflatable envelope assembly is partially expanded and in which the inflatable envelope has a shape corresponding to the predetermined shape;
• halting said step of superplastically forming the inflatable envelope assembly once the inflatable envelope assembly is partially expanded to the intermediate state;
• superplastically forming first and second metallic face sheets into respective shapes corresponding to the predetermined shape, said step of superplastically forming the first and second metallic face sheets being a separate step from said step of superplastically forming the inflatable envelope assembly to the intermediate state;
• placing the partially expanded inflatable envelope assembly between the superplastically formed first and second metallic face sheets;
• and
• superplastically forming and diffusion bonding the inflatable envelope assembly and the first and second metallic face sheets to thereby integrally form said structural panel having the predetermined shape.