Static structures (e.g. – buildings) – Openwork; e.g. – truss – trellis – grille – screen – frame – or... – Outside corner or peripherally bordered
Reexamination Certificate
2001-08-14
2004-09-14
Friedman, Carl D. (Department: 3635)
Static structures (e.g., buildings)
Openwork; e.g., truss, trellis, grille, screen, frame, or...
Outside corner or peripherally bordered
C052S271000, C052S783100, C052S783110, C052S783170, C052S783180
Reexamination Certificate
active
06789367
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to methods of joining sandwich panels and to sandwich panels themselves having means to connect to other sandwich panels or structural or non structural units.
2. Discussion of Prior Art
Sandwich panels comprise a core material (such as honeycomb) sandwiched between plates of stiff material. These composite panels have application in a wide variety of areas due to significant mass savings and their high strength/stiffness to weight ratio and thus their use in lightweight structures. Thus they have application in the construction, aerospace and other fields.
It is a requirement that these panels be joined so as to form a structure and in such a way that they are able to withstand and transmit loads.
Alternative methods of joining sandwich panels have been developed.
FIG. 1
a
shows a simple way of joining two panels at 90°. This is done by extending one of the plates of one of the panels and using adhesive to connect to the cut end of the other. This joint is however extremely weak in many modes.
Alternatively cleats are known which produce fairly strong jointing between panels. These cleats consist of shaped plates which are used in a variety of modes.
FIGS. 1
b
and
1
d
show two panels joined at 90° and a “T” joint respectively. The panels of
FIGS. 1
b
and
d
are joined in each case by two L-shaped cleats
7
. The interfaces between the panels and the joining surface of the cleats are provided with adhesive. Alternatively the cleats may be mechanically fastened or a combination of both. In an alternative mode the cleats are shaped to provide a slot for insertion of the panels as shown at
8
in
FIG. 1
c
. This has the advantage in providing a stronger connection. However the use of cleats is not without problems. Firstly there is the problem that cleats are additional components which add to the cost as well as the increase in time in joining and assembling sandwich panels. Cleats having slots for insertion of the panels have to be accurately sized which is problematic. Heat or cold will often complicate accurate fitting as there is frequently thermal mismatch. In addition the use of cleats does not provide smooth joining. These may reduce aerodynamic performance in particular applications as well as making it more difficult to install units internally.
An alternative method of joining sandwich panels is disclosed in DE-A-2166396. The sandwich panels are provided with recesses formed from shell connectors which are embedded within the panel at the edge of a joint between shell halves. A latching profile is provided which may either plug the recess to provide structural support at the joint and protect the recess or provide connection between two or more panels having appropriately contoured recesses.
It is an object of the invention to provide a method of joining sandwich panels which is simple, effective and provides a good joint whereby forces are transmitted across members efficiently.
SUMMARY OF THE INVENTION
The invention comprises a sandwich panel comprising a core material sandwiched between plate members, and an insert member locally replacing the core and having a profiled side so as to intermesh with an appropriately profiled member on a second sandwich panel to which it is to be connected.
The insert is preferably corrugated. It is preferably fabricated from a high strength lightweight material such as carbon fibre reinforced plastic.
The advantages are that the corrugated sections interlock on assembly providing additional surface areas for adhesive in shear. No matching of honey comb or other filler material is required. The joining gives a lightweight structure with give good compression strength, excellent distribution of forces (especially shear). The appropriate use of a potting compound is preferred.
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Friedman Carl D.
Katcheves Basil
McDonnell & Boehnen Hulbert & Berghoff
QinetiQ Limited
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