Fabrication of panel structure

Abstract

The structure and process for making a metallic panel structure from a plurality of core panels each comprised of a pair of sheets of superplastic material welded together along a plurality of weld lines. The core panels are joined together, with the weld lines of one core panel positioned normal to the weld lines of the adjacent core panel. The resulting assembly is placed in a die. The die is heated to superplastic forming temperature, and gas pressure is applied to the spaces between the sheets of the respective core panels, causing superplastic forming and expansion of the sheets of each core panel to form a series of bulges between weld lines of one core panel, and a series of similar bulges between weld lines of the adjacent core panel, the bulges expanding inwardly toward each other. The two series of bulges are orthogonally disposed, the bulges from the two core panels contacting and forming around each other. Further pressurization is applied to cause diffusion bonding at the contacting areas of the two series of bulges. The resulting structure is formed of two normally disposed series of bulges, with face sheets connected to such bulges. According to another embodiment, three core panels can be employed, resulting in a structure following superplastic forming and diffusion bonding, formed of two outer series of inwardly extending parallel bulges and an intermediate series of bulges between the two series of outer bulges.