The present invention relates to a pressure bulkhead for an aircraft fuselage, in particular a flat pressure bulkhead for a wide-body aircraft fuselage, as well as to an aircraft with an aircraft fuselage, in which such a pressure bulkhead is installed. The pressure bulkhead comprises a sandwich structure or is formed as a sandwich structure.
The sandwich structure extends between a circumferential edge area or region and defines a central axis with respect to this edge area. The central axis may be perpendicular to a plane between opposite sections of the edge area and may be parallel to the aircraft longitudinal axis of an aircraft fuselage when the pressure bulkhead is installed therein. The edge area is configured or adapted to be attached or secured to the fuselage structure of the aircraft fuselage and to maintain in this manner the pressure difference between the pressure side, i.e. the cabin, and the unpressurized rear section of the aircraft fuselage.
The sandwich structure comprises an inner cover or top layer facing towards the pressure side, an outer cover or top layer facing towards the rear and being disposed opposite the inner cover layer, and a core layer, which extends between the inner and the outer cover layers and connects them. The inner and outer cover layers extend transversely, such as perpendicularly, to the central axis and are may be made from fiber-reinforced composite material, in particular from Carbon-fiber-reinforced polymer (CFRP) or graphite fiber-reinforced polymer (GFRP), but may, however, also be made from a metallic material. The core layer may be made from foam material, such as polymethacrylimide (PMI), for example. The edge area can be formed either in a monolithic design, wherein the cover layers lie against one another and no core layer is provided, or formed in a sandwich design, wherein the core layer also extends through the edge area.
Several such pressure bulkheads or similar pressure bulkheads are known from the prior art. In the pressure bulkhead customarily used today, the skin element, together with the reinforcing elements attached thereto, has a dome-shaped pronounced curvature, in order to be able to absorb the pressure load between cabin pressure and ambient pressure acting on the pressure bulkhead as good as possible. The reinforcement elements are disposed in a radial manner on the convex surface of the skin element. However, the disadvantage with such a pressure bulkhead design is that, on the one hand, the pressure bulkhead takes up a lot of space due to the pronounced curvature, wherein the space inside the curvature is normally not utilized for safety reasons, and, on the other hand, the production of the pressure bulkhead as a fiber-reinforced workpiece is very costly and time-consuming, since disposing and attaching the reinforcement element on the curved skin element is a very complex undertaking.
For these reasons, the prior art includes various attempts to design non-curved pressure bulkheads, the skin elements of which thus extend substantially planar and which have no curvature or only a very slight curvature. Such pressure bulkheads are described in U.S. 2009/0242701 A1, U.S. 2001/0025903 A1 or DE 10 2010 018 933 A1, for example. Furthermore, similar flat pressure bulkheads are already known from smaller types of aircraft, such as the Fokker 100, for example.
At the same time, it has been found that it can be particularly advantageous to form or construct flat pressure bulkheads in a sandwich design with a lenticular or lens-shaped cross section because the pressure forces can be absorbed particularly effectively by such a structure, while a minimum weight of the pressure bulkhead is possible. Such a pressure bulkhead is described in DE 10 2012 005 451 A1, for example. In order to prevent the cover layers from detaching from the core layer and to prevent formation or expansion of cracks in the core layer in such a sandwich pressure bulkhead, it is known in the prior art to reinforce the sandwich structure by means of pins, which extend through the core layer from one cover layer to the other.
However, in the case of aircraft with a large fuselage diameter, so-called wide-body aircraft, such as the aircraft models A330, A340, A350 and A380 by Airbus, or similar types of aircraft, the problem arises that the large core thickness, and thus that of the sandwich structure, required to absorb the forces due to the large fuselage diameter can exceed the pin length which, due to the method for introducing the pins, is limited to approximately 90 mm, so that the pins would not extend from cover layer to cover layer and consequently could not be effectively used. The use of pressure bulk-heads in the form of lenticular sandwich structures is thus problematic in the case of wide-body aircraft and this design is rarely employed in practice.
USPTO Backgrounds
USPTO Backgrounds