Grid type fiber composite structure and method of manufacturing such grid type structure

Patent metadata

Field	Value
Publication number	US-9266303-B2
Application number	US-201314101458-A
Country	US
Kind code	B2
Filing date	Dec 10, 2013
Priority date	Dec 14, 2012
Publication date	Feb 23, 2016
Grant date	Feb 23, 2016

Abstract

The invention is related to a grid type fiber composite structure ( 1 ) comprising a grid of polygon cell modules ( 5 ) comprising at least three substantially u-shaped ribs made of fiber composite layer ( 8, 13 ) and a foam core ( 9 ) provided inside each cell module ( 5 ) for support of said u-shaped ribs. Said foam core ( 9 ) is along a base essentially in line with one of said flat cap sections ( 11, 12 ). At least one layer of strip ( 2, 3 ) is provided outside said flat cap sections ( 11, 12 ) and a skin sheet ( 4 ) is unilaterally attached to said cell modules ( 5 ) essentially in line with one of said flat cap sections ( 11, 12 ). The invention is as well related to a method of manufacturing such a grid type fiber composite structure ( 1 ).

First claim

What is claimed is:

1. A grid type fiber composite structure with longitudinal stiffening elements oriented in at least two directions, comprising:
a grid of polygon cell modules, each polygon cell module comprising:
two parallel polygon surfaces connected by peripheral surfaces perpendicular to the two polygon surfaces; and
at least three substantially u-shaped ribs, each rib having a transverse web section positioned along one of the peripheral surfaces and two flat cap sections integral with the transverse web section and each positioned along one of the respective polygon surfaces, at least one of the two flat cap sections extending only partially along one of the respective polygon surfaces;
wherein a foam core is provided inside of and its peripheral edges are fully encased by the at least three substantially u-shaped ribs for support of the transverse web sections and the flat cap sections, the foam core being delimited by the two parallel polygon surfaces and the peripheral surfaces and the foam core being in contact with the transverse web sections and the flat cap sections of each rib; and
wherein each of the cell modules is preassembled from the foam core and the ribs are made of fiber composite layer;
layers of intersecting strips; and
a skin sheet;
wherein the polygon cell modules are joined together along respective transverse web sections of equal length such that there is substantially no longitudinal or transversal offset between the adjoining transverse web sections of two cell modules;
wherein the layers of intersecting strips are provided outside the flat cap sections on at least one of the polygon surfaces, the layers of intersecting strips being aligned with the ribs in one direction of the longitudinal stiffening elements, at least one of the flat cap sections being allocated between the at least one layer of intersecting strips and the foam core;
wherein the skin sheet is directly attached to the layers of intersecting strips and/or to the flat cap sections and/or to a base of the foam core; and
wherein the longitudinal stiffening elements are provided by the polygon cell modules in cooperation with the layers of intersecting strips along the ribs.

2. The structure according to claim 1 , wherein the cell modules are triangular with ribs oriented in three different directions.

3. The structure according to claim 1 , wherein load introduction elements with radial lugs are provided at intersections of 8 or 12 ribs of adjacent cell modules.

4. The structure according to claim 3 , wherein there is a reduced thickness of the ribs at the intersections to compensate for the material thickness of the load introduction elements.

5. The structure according to claim 3 , wherein the load introduction elements are made of metal or of fiber composite.

6. The structure according to claim 1 , wherein the skin sheet is mechanical releasable affixed to the cell modules at the intersections.

7. The structure according to claim 1 , wherein the fiber composite layer is cut and textured.

8. The structure according to claim 1 , wherein the fiber composite layer is a dry semi-finished part or a semi-finished part pre-impregnated with resin.

9. The structure according to claim 2 , wherein the three ribs of each of the triangular cell modules are made of one tripartite fiber composite layer comprising three interconnected sections with two outer sections of the interconnected sections being pivotable relative to a central section.

10. The structure according to claim 2 , wherein the three ribs of each of the triangular cell modules are made of one quadripartite fiber composite layer comprising three lateral sections connected alongside a triangular central section, the triangular central section comprising one of the flat cap sections and the three lateral sections being pivotable relative to the triangular central section.

11. A method of manufacturing the grid type fiber composite structure with longitudinal stiffening elements oriented in at least two directions according to claim 1 , comprising:
providing textured fiber composite layers and polygon foam cores with peripheral supports, the polygon foam cores being delimited by two parallel polygon surfaces and by peripheral surfaces perpendicular to the two polygon surfaces;
sheathing each of the peripheral supports of the polygon foam cores with at least three substantially u-shaped ribs made of the textured fiber composite layers to provide polygon cell modules, each of the ribs having a transverse web section corresponding to one of the peripheral surfaces and two flat cap sections connected to the transverse web section, each of the two flat cap sections extending at least partially along one of the respective polygon surfaces;
joining together the polygon cell modules along respective transverse web sections of equal length to form a grid such that there is substantially no longitudinal or transversal offset between the adjoining transverse web sections of the cell modules;
inserting into the grid load introduction elements at intersections between at least four of the cell modules;
providing layers of intersecting strips;
attaching the layers of intersecting strips outside the flat cap sections in at least one of the polygon surfaces, each of the layers of intersecting strips being aligned with ribs in one direction of the longitudinal stiffening elements, at least one of the flat cap sections being allocated between the at least one layer of intersecting strips and the foam core;

providing the longitudinal stiffening elements by grid-wise mounting the cell modules to the layers of intersecting strips along the ribs;
providing a skin sheet;
and
mounting the longitudinal stiffening elements onto the skin sheet.

12. The method according to claim 11 , wherein sheathing is accomplished by arranging horizontally the textured fiber composite layer on a resilient central die part with separate peripheral die parts arranged alongside the resilient central die part,
arranging the foam core on the textured fiber composite layer on the resilient central die part,
pushing the resilient central die part along the peripheral die parts such that transverse web sections and flat cap sections of the textured fiber composite layer are pivoted by the separate peripheral die parts towards lateral faces of the foam core,
pressing the transverse web sections of the textured fiber composite layer with the lower separate peripheral die parts towards the lateral faces of the foam core,
pivoting and pressing the flat cap sections of the textured fiber composite layer with upper peripheral die parts towards the top faces of the foam core,
heating the transverse web sections and the flat cap sections of the textured fiber composite layer with the peripheral die parts for adhesive bond of the ribs for a triangular cell module

and
releasing the triangular cell module.

Assignees

• Airbus Helicopters Deutschland GmbH

Inventors

• Fink Axel

Classifications

• B29C70/68 Primary

  by incorporating or moulding on preformed parts, e.g. inserts or layers {, e.g. foam blocks (mould constructions therefor B29C33/12; joining preformed parts by moulding B29C65/70)} · CPC title

• B29D24/005

  the structure having joined ribs, e.g. honeycomb · CPC title

• B32B3/12 Primary

  characterised by a layer of regularly- arranged cells, e.g. a honeycomb structure · CPC title

• Y10T428/24157

  Filled honeycomb cells [e.g., solid substance in cavities, etc.] · CPC title

• Y10T428/24149

  Honeycomb-like · CPC title