I've been wondering about the Airbus A350 composite panel construction technique. If I understand correctly, at the moment they are planning to co-cure skin panels with stringers, window and door frames and other reinforcements. Then, they attach the panels to aluminum frames (hoops) and floor grid.
Would the panel approach enable a new approach, namely co-cured CFRP frames?
Since the frames don't carry much pressurization load, they can (and are) easily built out of separate arcs, bolted together. The pressurization hoop stresses go into the skin, and the frames "shear in" all the loads from the floor and interior fittings into the skin.
If you can build frames out of, say, four segments... would it be possible to co-cure CFRP frame segments directly with the skin panels? This would probably require at least two autoclave cycles, but the process is not unlike what is used for the A380 rear pressure bulkhead (cycle 1 is the CFRP bulkhead skin, cycle 2 co-cures foam-core CFRP ribs).
Co-curing the frames would do away with quite a few fasteners, making up for the extra fasteners on the longitudinal joints between the four sets of panels... and it is something that can uniquely be done in the panel approach, as opposed to the barrel approach where the mandrel interferes with the location of the frames.
Any thoughts on whether Airbus might actually pursue this approach?