Panel structure fabrication

Abstract

The structure and process for making a metallic panel structure from a plurality, e.g. two, core elements each comprised of a pair of sheets of superplastic material welded together along a plurality of weld lines, the weld lines of one core element being spaced differently or of different shape from the weld lines of the other core element. The core elements are joined together, with the weld lines of one core panel positioned at an angle, e.g., normal, to the weld lines of the adjacent core element. The resulting panel 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 elements, causing superplastic forming and expansion of the sheets of each core panel to form a first series of bulges between weld lines of one core element, and a second series of bulges dissimilar in shape, e.g. larger, than the first series of bulges, between weld lines of the adjacent core element, the bulges expanding inwardly toward each other. The two series of bulges are orthogonally disposed, the bulges from the two core elements 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, one series larger than the other, with face sheets connected to such bulges.