U.S. patent application number 11/416172 was filed with the patent office on 2007-02-08 for containment casing.
This patent application is currently assigned to ROLLS-ROYCE plc. Invention is credited to Caetano Peng.
Application Number | 20070031246 11/416172 |
Document ID | / |
Family ID | 34834534 |
Filed Date | 2007-02-08 |
United States Patent
Application |
20070031246 |
Kind Code |
A1 |
Peng; Caetano |
February 8, 2007 |
Containment casing
Abstract
A containment casing 1 is provided in which tubular composite
layers 2, 3 are arranged in an angular staggered relationship to
minimise overlap between the interstitial spacing between tubes in
each respective layer 2, 3. In such circumstances, with a
continuous planar layer 4, 5 on one or both sides, operational
integrity is maintained with a lightweight containment casing 1 in
comparison with prior arrangements but retaining resistance to
fragment penetration.
Inventors: |
Peng; Caetano; (Derby,
GB) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC
P.O. BOX 19928
ALEXANDRIA
VA
22320
US
|
Assignee: |
ROLLS-ROYCE plc
London
GB
|
Family ID: |
34834534 |
Appl. No.: |
11/416172 |
Filed: |
May 3, 2006 |
Current U.S.
Class: |
415/173.1 |
Current CPC
Class: |
F05D 2250/231 20130101;
Y02T 50/60 20130101; F05D 2300/702 20130101; Y02T 50/672 20130101;
F05D 2250/313 20130101; F05D 2300/603 20130101; F01D 21/045
20130101; F05D 2240/14 20130101 |
Class at
Publication: |
415/173.1 |
International
Class: |
F01D 11/08 20060101
F01D011/08 |
Foreign Application Data
Date |
Code |
Application Number |
May 24, 2005 |
GB |
0510540.8 |
Claims
1. A containment casing for a rotating assembly, the casing
comprising a first tubular composite layer comprising a plurality
of tubular members and a second tubular composite layer comprising
a plurality of tubular members, the first tubular composite layer
and the second tubular composite layer angularly staggered relative
to each other to limit overlap of interstices between tubular
members in each respective composite layer with the other composite
layer.
2. A containment casing as in claim 1, wherein the rotating
assembly is part of an aircraft engine.
3. A casing as claimed in claim 1, wherein a continuous planar ring
is secured to one side of the casing.
4. A casing as claimed in claim 3, wherein continuous planar rings
are secured either side of the casing with the first tubular
composite layer and the second tubular composite layer sandwiched
between them.
5. A casing as claimed in claim 1, wherein the tubular members are
hollow.
6. A casing as claimed in claim 1, wherein the tubular members are
filled in order to alter at least one mechanical property of the
tubular composite layer overall or in selective parts thereof.
7. A casing as claimed in claim 6, wherein the or each mechanical
property altered by filling the tubular member is selected from the
list consisting of: acoustic damping, vibration damping, mechanical
stiffness of the composite layer.
8. A casing as claimed in claim 1, wherein the casing is
cylindrical.
9. A casing as claimed in claim 1, wherein the angular stagger
between the first composite layer and the second composite layer is
perpendicular.
10. A method of forming a containment casing for a rotating
assembly, the method comprising: a) forming a first composite
tubular layer of tubular members and a second composite tubular
layer of tubular members, associating the first composite tubular
layer with the second composite tubular layer with an angular
stagger relation between them; and, b) fixing the first composite
layer and the second composite layer with the angular stagger
relation between them to limit overlap of interstices between
tubular members in each respective composite layer with the other
composite layer.
11. A method as claimed in claim 10, wherein the method also
includes association securing a continuous planar ring to one side
of the casing.
12. A method as claimed in claim 11, wherein a continuous planar
ring is secured upon both sides of the casing.
13. An aircraft engine incorporating a containment casing as
claimed in claim 1.
14. An aircraft engine incorporating a containment casing
manufactured in accordance with the method of claim 10.
Description
[0001] The present invention relates to containment casings and
more particularly to containment casings utilised with respect to
aircraft engines as well as methods of manufacturing such
casings.
[0002] Metal and non-metal tubular structures have been used in
automobile, aircraft, train systems (i.e. locomotive and coach
structural bodies) and nuclear containers for several years. There
are many academic publications about the mechanical behaviour of
single tube and closely packed tubular structures. These tubes have
very high load bearing, crushing and energy absorption
capabilities. The energy absorbing process is either by axial
tubular buckling (i.e. concertina buckling) or lateral tubular
crushing. They can withstand high impact load levels. The impact
resistance and energy absorption efficiency of the tubular systems
depend on the cell wall solid material properties, cross-section
shape, diameter/length to thickness ratio, loading direction,
packing arrangement and whether they are internally empty or
filled. They can be made of monolithic metals, metal or non-metal
composites or both. Composites materials, cellular and structural
materials are known to have low density and high mechanical
strength and stiffness. Because of the high specific mechanical
properties (i.e. strength per unit mass or density), they are ideal
materials for lightweight structures and components. Polymeric
based composites (i.e. fibreglass, carbon fibre and Kevlar in
polymeric matrix) are also resistant to corrosion.
[0003] It will be understood that containment casings for different
situations will have different objectives. However, generally by
reason of the necessity for containment it is important that these
casings provide a high penetration resistance in order to prevent
release of projectile fragmentary material. Thus, for example with
respect to aircraft engine casings it will be understood that the
rotating blades may fracture and therefore the containment casing
must resist penetration of those fragments through the casing
whereby the fragments at high velocity may injure persons in the
vicinity or an associated aircraft body fuselage or wing. In such
circumstances there is a tendency to utilise monolithic plate like
structures in order to create sufficient resistance to fragment
penetration. Unfortunately, planar structures whether formed by
laminates or single layer material are generally solid and
therefore may have a higher weight than desirable.
[0004] In accordance with the present invention there is provided a
containment casing for a rotating assembly, the casing comprising a
first tubular composite layer comprising a plurality of tubular
members and a second tubular composite layer comprising a plurality
of tubular members, the first tubular composite layer and the
second tubular composite layer angularly staggered relative to each
other to limit overlap of interstices between tubular members in
each respective composite layer with the other composite layer.
[0005] The rotating assembly may be part of an aircraft engine.
[0006] Preferably a continuous planar ring is secured to one side
of the casing. Additionally, continuous planar rings are secured
either side of the casing with the first tubular composite layer
and the second tubular composite layer sandwiched between them.
[0007] Normally, the tubular members are hollow. Alternatively, the
tubular members are filled in order to alter the mechanical
properties of the tubular composite layer overall or in selective
parts thereof. Typically, the mechanical property altered by
filling the tubular member is acoustic damping or vibration damping
or mechanical stiffness of the composite layer.
[0008] Also, in accordance with the present invention there is
provided a method of forming a containment casing for a rotating
assembly, the method comprising;
[0009] a) forming a first composite tubular layer of tubular
members and a second composite tubular layer of tubular members,
associating the first composite tubular layer with the second
composite tubular layer with an angular stagger relation between
them; and,
[0010] b) fixing the first composite layer and the second composite
layer with the angular stagger relation between them to limit
overlap of interstices between tubular members in each respective
composite layer with the other composite layer.
[0011] Typically, the method also includes association securing a
continuous planar ring to one side of the casing. Typically, a
continuous planar ring is secured upon both sides of the
casing.
[0012] Generally, the casing is cylindrical.
[0013] Typically, the angular stagger between the first composite
layer and the second composite layer is perpendicular.
[0014] Embodiments of the present invention will now be described
by way of example only with reference to the accompanying drawings
in which
[0015] FIG. 1 is a schematic front perspective view of a
containment casing with a quarter section removed;
[0016] FIG. 2 is a more detailed schematic representation of the
containment casing structure depicted in FIG. 1; and
[0017] FIG. 3 is a schematic depiction of tubular members utilised
in accordance with the present invention to provide tubular
composite layers.
[0018] Prior planar laminate composite structures as indicated can
create sufficiently robust component structures to act as
containment casings for aircraft turbines and blades. Nevertheless,
there is a constant desire to reduce component weights within an
aircraft in order to improve efficiency. In such circumstances the
present invention comprises combining tubular composite layers in a
sandwich with, if necessary, a continuous planar ring or layer to
provide the containment casing.
[0019] The tubular composite layers are formed from tubular members
secured adjacent each other generally in alignment. At least one
further tubular composite layer is associated with the first
tubular composite layer in an angular staggered relationship in
order to minimise the overlap of the interstices between the tubes
in each tubular composite layer. Normally, a continuous planar
layer is secured either side of the tubular composite layers in
order to create the casing.
[0020] Referring to FIGS. 1 and 2 of the attached drawings, these
illustrate a containment casing in accordance with the present
invention. A first tubular composite layer 2 comprises a number of
tubular members arranged longitudinally, parallel to the engine
axis, and a second tubular composite layer 3 comprises a number of
tubular members arranged circumferentially to form rings. A thin
planar layer 4, 5 is provided either side of the tubular composite
layers 2, 3. The angular stagger between the tubular composite
layers 2 and 3 provides a robust containment casing in which the
interstices 6, 7 between the tubes of the tubular composite layers
2, 3 have the minimum overlap. It will be appreciated that it is at
these overlapping interstices that there is less resistance to
fragment penetration.
[0021] As depicted the angular stagger is generally perpendicular,
that is to say there is a ninety degree angular variation in the
orientation of the tubes in the respective tubular composite layers
2, 3. However, it will be appreciated that other angular
presentations of the tubes in the composite layers 2, 3 could be
provided as required particularly if several more levels of
composite containment layer are provided again to further minimise
the stacked overlap of the interstices between the tubes in the
respective composite layers 2, 3.
[0022] The planar continuous ring 5, 6 acts to provide an
aerodynamic and corrosion resistance to the containment casing, but
these planar continuous layers 4, 5 will be relatively thin and so
normally will not be sufficient to provide fragmentation
containment as required by a casing to resist penetration of
shattered fragments from a high speed rotating blade or other
member. Clearly, solid planar layers are relatively heavy so their
thickness should be minimised to reduce weight with aircraft
components.
[0023] As can be seen in FIGS. 1 and 2, the tubular containment
layers 2, 3 can be formed from individual extruded or monolithic
tubes which may be of a polymeric, ceramic or metal nature.
Alternatively, these tubes may be wound from fibre to form the
tubes in accordance with known techniques. Nevertheless, all the
tubes within each tubular composite layer 2, 3 are generally
aligned with each other.
[0024] In addition to single rows of tubes to form the respective
tubular composite layers 2, 3 it is possible to provide multiple
rows of smaller tubes also aligned to form each individual
composite layer 2, 3. FIG. 3 illustrates some examples.
[0025] FIG. 3a illustrates bundles of micro cylindrical woven tubes
arranged in staggered rows in order to create a tubular composite
layer defined with a depth 10. Although all cylindrical it will be
appreciated that different sized diameter cylindrical tubes may be
used with differing wind angles for the tubes when formed as woven
structures from filaments in order to achieve the desired
structural performance.
[0026] FIG. 3b illustrates combinations of rectangular tubes in
order to provide a tubular composite layer. It will be appreciated
that these rectangular tubes provide closer and therefore stronger
association between the individual tubes in forming the layer with
less interstitial spacing in order that thereby greater resistance
to fragment penetration is achieved.
[0027] FIG. 3c illustrates hexagonal tubes again utilised in order
to create a tubular composite layer in accordance with the present
invention and again through the flat sides of the hexagonal tubes
greater tube to tube contact and therefore assembly strength is
achieved.
[0028] As indicated above, generally woven tubes formed from micro
fibre can be used in accordance with the present invention. It is
appreciated that the angle of wind as well as the depth of tube can
be thereby adjusted to form highly robust tube structures with
great strength but with a hollow centre thereby reducing
containment casing weight in comparison with an equivalent
performing solid wall containment casing. Nevertheless, these
hollow tubes may be filled with a foam or other material in order
to adjust their mechanical properties or provide acoustic damping
or vibration damping as required. It will also be understood that
localised mechanical performance may be altered to meet localised
requirements. For example, it may be that increased fragment
penetration resistance is required at certain parts of the
containment casing as a result of the normal expected position of
persons who may be injured by such fragments or the location of
sensitive control or operational features which may be damaged by
such fragments. In such circumstances, weight in the casing
material is optimised in terms of achieving a lightweight
containment casing for the remainder of the casing with higher
protection but higher weight only in necessary parts of the
casing.
[0029] In accordance with the present invention the tubular
composite layers are constructed from hollow or filled composite
tubes made of either polymeric, metal based composites, ceramic or
both. These tube members can have different cross-sectional shapes,
orientation, wall thickness, diameters, cell length and varying
thickness. The tubes can be monolithic, multi layered tubes or both
in the same composite layer. The tubes can also be fibre woven
tubes at any chosen orientation in order to achieve the best
performance in relation to weight required for a particular
containment casing. Furthermore, as indicated, the tubes can be
filled with polymeric, metal, foam or both or liquids in order to
vary the mechanical performance or other factors such as vibration
damping. Generally, the tubes are positioned and arranged to be
loaded laterally under impact load conditions. The tubular
composite layers are generally fixed in a matrix and possibly fibre
stitched together. If the tubes are formed from a metal they can be
welded or encased in a similar fashion to roller bearings in order
to retain their position.
[0030] The objective with a containment casing is to design a high
strength and high impact resistance lightweight composite to
achieve higher engine efficiencies.
[0031] By utilising the hollow nature of tubes these objectives of
high strength and impact resistance whilst achieving a lightweight
construction are readily achievable. Furthermore, by combination of
infill within these tubes as required to adjust mechanical and
other properties of the containment casing as well as variations in
geometries and use of differing materials, it will be understood
that containment casings more tuned to particular requirements for
an engine are achievable in comparison with prior arrangements.
[0032] With regard to aircraft engines, typically the casing will
be substantially cylindrical such that by providing flexibility as
well as stiffness within the containment casing, absorption of
fragments from a high speed disintegrating blade can be achieved.
As indicated, the tubes may be filled with foam or elastomeric
materials or solid infill to achieve this absorption and variation
in stiffness along with acoustic and vibration damping.
[0033] It will be appreciated that particularly when the tubular
composite layers 2, 3 are sandwiched between continuous planar
layers 4, 5, utilisation of the differential thermal expansions of
these continuous ring layers 4, 5 may be utilised in order to
compress the sandwiched tubular composite layers 2, 3 therebetween
in order that further variation in the mechanical properties,
resistance to fragment penetration and deformation can be achieved
along with alterations dependent upon vibration and/or acoustic
requirements for the containment casing 1. Furthermore, the
utilisation of tubular composite layers 2, 3 between the inner
continuous ring layer 4 and the outer continuous ring layer 5 may
be utilised in order to accommodate for the possibly high
temperature differential between that experienced by the inner
continuous ring 4 and the outer continuous ring 5 without creating
overstressing therebetween. It will be understood in these
circumstances the tubular composite layers 3, 4 will essentially
allow for expansion and contraction by their deformation to
accommodate such variations in temperature experienced by the
layers 4, 5.
[0034] Modification and alterations to the embodiments of the
invention will be understood by those skilled in the technology.
Thus, for example the tubular multi-layered containment casing can
be made of more than two tubular layers. The materials used to form
the layers may include polymeric fibres and matrix, monolithic
metals, metal fibres and matrix, a ceramic or combination of these
dependent upon operational requirements. The skin to the components
may be a metal, erosion resistant material, polymeric or laminated
surface skins.
[0035] Such containment casings may be used, of course, in other
applications than aircraft engines, where a rotating assembly
requires a protective casing around it. Such assemblies include,
but are not limited to: flywheels; impellers; armatures or other
rotating assemblies in electrical motors or generators.
[0036] In terms of manufacturing, typically the processes will
involve one or more of the following, namely injection moulding
techniques, weaving/stitching, fibre wrapping around lateral blade
profiles, tubular systems embedded in polymeric, metal or ceramic
matrixes or use of ferrules to locate the tubes and to provide
additional lateral strength and stiffness. Essentially, what is
required is creation of the desired shaping by appropriate
techniques whilst maintaining sufficient structural strength and
profile under load for operational performance.
[0037] Whilst endeavouring in the foregoing specification to draw
attention to those features of the invention believed to be of
particular importance it should be understood that the Applicant
claims protection in respect of any patentable feature or
combination of features hereinbefore referred to and/or shown in
the drawings whether or not particular emphasis has been placed
thereon.
* * * * *