GB2076102A

GB2076102A - Connecting strips to form a grid

Info

Publication number: GB2076102A
Application number: GB8015555A
Authority: GB
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 1980-05-10
Filing date: 1980-05-10
Publication date: 1981-11-25

Abstract

A grid consists of a plurality of intersecting strips (10, 11, 12) interconnected to cooperating slots 13, 14, 16, 17. Each intersection between strips is reinforced by the use of a tubular member (18) slotted to accommodate the intersecting strips and which embraces the intersection. To further reinforce the tubular member 18 a cap 21 engages with the slotted end of the tubular member. A further cap 22 may reinforce the other end of the member 18. The grid is used as a debris guard or spoiler for the intake of a gas turbine engine. <IMAGE>

Description

SPECIFICATION Cellular member This invention relates to a cellular member which is particularly useful as a debris guard or spoiler when mounted across the air intake of a gas turbine engine.

In the past such cellular members have been made of intersecting pluralities of metal strips which were welded at the intersections. The method of construction normally involved the strips being provided with slots extending half way across their width, the intersections being formed by the engagement of the remaining half of one strip engaging in the slot of the engaging strip and vice versa. The edge of the strips in which the slots commenced was thus weakened, and if the weld at an intersection failed this edge of the strip would be free to vibrate and bend locally and lead to failure of the entire assembly. If this occured, sections of the member could be ingested into the engine with possible damage to the engine.

The present invention provides a cellular member whose structure is such as to strengthen these intersections and which lends itself to manufactured from composite material which, if ingested, is less likely to damage the engine.

According to the present invention a cellular member consists of a plurality of intersecting strips, each strip lying with its width extending transverse to the plane of the member so that the strips define the cells between them, each intersection between strips being reinforced by a tubular member having longitudinal slots extending from one end thereof corresponding with the dispositions of the strips and within which the intersecting strips engage so that the tubular member embraces the intersection, and a capping member which engages with and supports said one end of said tubular member.

Preferably said tubular member is bonded to said strips.

There may be a plurality of intersecting sets of parallel strips which form said cells, and in one embodiment there are two said sets the strips of which are disposed at right angles to each other to form rectangular cells.

The invention will now be particularly described, merely by way of example, with reference to the accompanying drawings in which: Figure 1 is an exploded view of a portion of a cellular member in accordance with the invention, Figure 2 is a central section through the member of Figure 1, and Figure 3 is a section on the line 3-3 of Figure 2.

In Figure 1 the components of part of the cellular member in accordance with the invention are shown exploded apart so that the construction of the member may be understood more easily. In this drawing parts of three strips 10, 11 and 12 are visible, the strips 11 and 12 being parallel and at right angles to the strip 10. When assemblied together the strips 11 and 12 will intersectthe strip 10. The strips are disposed so that their widths will extend at right angles to the plane of the overall member so that the surfaces of the strips define the walls of the cells of the member.

In this instance the strips are made of composite material.

It will be seen that the strip 10 is provided with slots 13 and 14 while the strips 11 and 12 are provided with corresponding slots 1 5 and 16 each of these slots extends halfway across the width of the strip and is wide enough to accept the unbroken portion of the engaging strip. Thus when assembled the strips 10 and 11 are pushed together so that the unbroken portion of the strip 11 behind the slot 1 6 engages with the slot 13 while the unbroken portion of the strip 10 behind the slot 13 engages with the strip 1 This will be recognised as a well-known construction for a joint between two crossing members sometimes referred to as a cross halving joint.

The strips 10 and 12 engage in an exactly similar manner through the slots 14 and 1 7.

Once the strips are assembled together it will be appreciated that the joints provide areas of weakness and in order to strengthen these joints tubular members such as that shown at 1 8 are provided. The tubular member 1 8 consists in the present instance of a tube of composite material in which are cut two diametral saw cuts or slots 19 and 20. There are thus effectively four slots on the tube. The slots are sized to accommodate the thickness of the strips 10 and 12 and since the slots are at right angles as are the strips the tube may be pushed into engagement with the strips 10 and 12 at their intersection. The tube will then embrace this intersection. It may be desirable to provide some form of bonding between the tube and the strips in which case a suitable adhesive would be applied.

The joint between the strip is thus strengthened by engagement by tube but because the tube is slotted from one end it is weakened at that end. In order to strengthen this end a cap 21 is provided having an internal dimension which is the same as the external dimension of the tube 1 8. The cap 21 may therefore be pushed over the end of the tube 1 8 and prevents the separate fingers of the tube formed by the slots 1 9 and 20 from splaying out or otherwise deforming. In the present instance a second cap 22 exactly similar to the cap 21 is provided and engages with the unslotted end of the tube 1 8. Once again the cap 21 and 22 may be bonded to the tube.

Figure 2 shows one complete cell of the cellular member in central cross-section. It will be appreciated that in Figures 1 and 2 only a small section of the cellular member is shown and that in practice there will be a large number of strips disposed in two sets of parallel strips, the two sets being at right angles to one another. From Figure 2 it can be seen that any movement of the strips relative to one another at the intersections is -inhibited by the engagement with the tube 18.

Figure 3 illustrates how the tube 18 is in turn strengthened by caps 21 and 22. It will be seen that in order to accommodate the caps 21 and 22 is it necessary for a tubular member 1 8 to extend beyond the strips by a distance equal to the depth of the cavity within the caps.

As described above the cellular member is one having rectangular cells formed by two sets of parallel strips. This is a relative!y simple application of the present invention and it will be understood more complex cells could be formed by the use of more than two sets of strips. Indeed the present invention is applicable to members in which each cell is made up of separate strip portions in which case the joints between the strips would be simply bonded joints again strenthened by tubular members such as 18.

It will be seen that the structure described is very simple and can be made with standard shapes of ready available composite materials so as to provide a strong and light structure which will not cause damage if ingested into a gas turbine engine.

Claims

1. A cellular member consisting of a plurality of intersecting strips, each strip lying with its width extending transverse to the plane of the member so that the strips define the cells between them, each intersection between strips being reinforced by a tubular member having longitudinal slots extending from one end thereof corresponding with the dispositions of the strips and within which the intersecting strips engage so that the tubular member embraces the intersection and a capping member which engages with and supports said one end of said tubular member.

2. A cellular member as claimed in claim 1 and in which said tubular member is bonded to said strips.

3. A cellular member as claimed in claim 1 or claim 2 and in which there are a plurality of intersecting sets of parallel strips which form said cells.

4. A cellular member as claimed in claim 3 and in which there are two said sets of strips, the strips of which are disposed at right angles to each other to form rectangular cells.

5. A cellular member as claimed in any one of the preceding claims and in which at each intersection between strips the intersecting strips are provided with slots extending halfway across their widths and in which the remaining portion of the intersecting strip engages.

6. A cellular member as claimed in any one of the preceding claims and in which each said tubular member is supported at both ends by a capping member which engages with each said end.

7. A cellular member as claimed in any one of the preceding claims and comprising a composite material.

8. A cellular member substantially as hereinbefore particularly described with reference to the accompanying drawings.