News Column

Patent Issued for Holding Device for at Least One Fixture to a Cell Structure of an Aircraft Fuselage

July 8, 2014

By a News Reporter-Staff News Editor at Journal of Technology -- Airbus Operations GmbH (DE) has been issued patent number 8756769, according to news reporting originating out of Alexandria, Virginia, by VerticalNews editors.

The patent's inventors are Benthien, Hermann (Sottrum, DE); Soffker, Axel (Sottrum, DE).

This patent was filed on October 23, 2012 and was published online on June 24, 2014.

From the background information supplied by the inventors, news correspondents obtained the following quote: "According to the generally known state of the art, holding devices of interest at this point may be attached to the fuselage cell structure by means of screw connections. To this end, at least one fastening bore into the fuselage cell structure would need to be incorporated for each of the holding devices that are to be attached, in which a basic element of the holding device may be fastened by means of a fastening element.

"The multitude of fastening bores leads to a static weakening of the fuselage cell structure and, in addition, causes corrosion problems within the area of the bearing stress, which must be prevented by extensive corrosion protection measures such as, for example, sealing of the bearings applying suitable materials. Furthermore, every area exposed to bearing stress creates a preferred initiation point for fatigue cracks, the discovery and removal of which requires an increased inspection and maintenance effort over the whole lifecycle interval of the aircraft. In addition, any drilling of a fastening borehole taken as an individual process is quite extensive with regard to process technology, as the positioning of the usually manual drilling devices is usually carried out by using large-format master plates. The resulting drilling chips must also be carefully removed from the fuselage cell structure by means of suction to prevent short circuits and any additional corrosion problems.

"Therefore, DE 10 2007 061 425 A1 discloses a holding device for attaching a fixture at a fuselage cell structure of an aircraft, which may be affixed laterally to the fuselage cell structure without applying fastening bores. To this end, the crossing point between a stringer and a rib is used, into which a connecting angle of the holding device may be clamped. The holding device is embodied in two parts and comprises a lower part and an upper part, which may be connected thereto. The lower part may be slid onto the connecting angle. By fitting the upper part onto the lower part, the holding device assumes its fixed position after being fastened at the crossing point. Final fastening and positioning is obtained by connecting the holding device to a transverse circuit carrier by means of an expanding pin.

"DE 10 2008 041 259 A1 discloses another solution to provide a connection without fastening means of a holding device at the fuselage cell structure of an aircraft, which is based on adhesive bonding. An adhesive holder comprises a basic body, which is connectible to an attachment. The basic body and the attachment are each formed in one piece of a metallic material. At least three lugs are arranged at the basic body to provide an adhesive connection at the fuselage cell structure. In doing so, at least two lugs are positioned at one connection level, and at least one further lug is positioned at a second connection level to allow fastening at an edge of the structural component. To allow fastening at plane structural components, all three lugs are arranged at one connection level. As a consequence of the presence of at least three lugs, the adhesive holder is damage tolerant such that even in the event of failure of two adhesive lugs no loss of functionality occurs. However, the load-bearing capacity of said adhesive holder is limited and, therefore, not suitable for all kinds of fixtures.

"An embodiment of the present invention provides a holding device for attachment of at least one fixture at a fuselage cell structure of an aircraft not requiring any bore holes, which can be manufactured in a simple manner and which resists the high stress caused by the fixture."

Supplementing the background information on this patent, VerticalNews reporters also obtained the inventors' summary information for this patent: "An aspect of the invention includes the technical teaching that the basic element of a holding device is embodied as a fibre hook-and-loop element, the hook-and-loop bristles of which co-act with corresponding hook-and-loop bristles of at least one fixture which is also embodied as a hook-and-loop element thus forming a hook-and-loop connection, in the process of which the space between the interengaged hook-and-loop bristles is filled with an adhesive.

"The advantage of the solution according to an aspect of the invention is, in particular, that a composite part can be manufactured by applying prefabricated basic elements and fixtures made of fibre hook-and-loop semi-finished products, subsequently injecting an adhesive followed by hardening, which can be simply assembled locally and, after the hardening of the adhesive is completed, is highly resistant to static stress. The holding device according to an embodiment of the invention can be applied without chip-generating processing and without any additional connecting elements. A precondition for high stress resilience is obtained as the basic element is integrally connected with the fixture elements. By means of resorting to hook-and-loop technology, component tolerances can be compensated in a simple manner. Problems with respect to a differing thermal extension of the components to be fastened to one another, or with regard to electrochemical corrosion will not occur, because the holding device according to an embodiment of the invention does not need any metal. By means of a system comprising basic elements and fixture elements it is possible to offer a simple building block approach for the production of holding devices of different sizes and shapes.

"To this end, it is, therefore, suggested that the at least one fixture element shows in its cross section a polygonal or triangular shape having hook-and-loop bristles pointing to the outside. In the case of triangular fixture elements, several of those may be fastened to one another to form a lattice structure similar to a cross beam, wherein the space between the fixture elements, again, is filled with an adhesive.

"By means of such a lattice structure similar to a cross beam, which comprises individual triangles, almost any lattice surface may be formed in a simple manner, whereby the hook-and-loop connections of the individual components among one another guarantee a three-axial compensation of tolerance.

"In this process, a hardenable synthetic resin material may be applied as an adhesive, the hardening of which may be accelerated by microwaves. Besides that it is, however, also conceivable to use suitable cold curing adhesives as an adhesive to fill the space between the basic element and the fixture element, or between fixture elements among one another.

"Preferably, the fixture element arranged furthest from the basic element and the interior cross section together form a passage opening for guiding through the fixture. When triangular fixture elements are applied, the passage opening is triangular as well. Besides this it is also conceivable that a fixture may be attached by means of hook-and-loop tape at the fixture element on the outside. Said connection, however, may be protected against self-loosening, for example, by adhesive bonding.

"According to another measure of the invention it is proposed to attach the basic element of the holding device according to an embodiment of the invention to the fuselage cell structure by means of lamination. This measure is particularly applicable when the fuselage cell structure consists of a fibre-reinforced synthetic material. In this case, by lamination of the basic elements, the fastening points for the holding devices may already be defined during the process of production of the fuselage cell structure. Besides that, it is, however, also conceivable to bond the basic elements to the fuselage cell structure.

"The holding device according to an embodiment of the invention, which is generally described above, can be installed by the following production steps: Attaching of a basic element embodied as a hook-and-loop element to the fuselage cell structure such that its hook-and-loop bristles point to the outside, Fastening of at least one fixture element to the basic element by creating a hook-and-loop connection, and Filling of the space formed between the engaged hook-and-loop bristles with an adhesive, which will subsequently harden.

"Further fixture elements may be fastened in the manner described above to the fixture mounted such that a lattice structure is obtained, in the process of which the space between the hook-and-loop bristles, again, will need to be filled with an adhesive."

For the URL and additional information on this patent, see: Benthien, Hermann; Soffker, Axel. Holding Device for at Least One Fixture to a Cell Structure of an Aircraft Fuselage. U.S. Patent Number 8756769, filed October 23, 2012, and published online on June 24, 2014. Patent URL:

Keywords for this news article include: Technology, Airbus Operations GmbH.

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Source: Journal of Technology

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