U.S. patent application number 12/847126 was filed with the patent office on 2011-01-06 for thermoplastic last-stage blade.
Invention is credited to Christoph Ebert, Detlef Haje, Albert Langkamp, Markus Mantei.
Application Number | 20110002790 12/847126 |
Document ID | / |
Family ID | 42537775 |
Filed Date | 2011-01-06 |
United States Patent
Application |
20110002790 |
Kind Code |
A1 |
Ebert; Christoph ; et
al. |
January 6, 2011 |
Thermoplastic last-stage blade
Abstract
A turbine blade, a turbine and a method of manufacturing a
damping zone of a turbine blade are provided. The turbine blade
includes a damping zone with a damping layer and the damping layer
has a fiber matrix system. The fiber matrix system has a
thermoplastic matrix. Reinforcing fibers are embedded in the
thermoplastic matrix.
Inventors: |
Ebert; Christoph; (Dresden,
DE) ; Haje; Detlef; (Gorlitz, DE) ; Langkamp;
Albert; (Dresden, DE) ; Mantei; Markus;
(Pulsnitz, DE) |
Correspondence
Address: |
SIEMENS CORPORATION;INTELLECTUAL PROPERTY DEPARTMENT
170 WOOD AVENUE SOUTH
ISELIN
NJ
08830
US
|
Family ID: |
42537775 |
Appl. No.: |
12/847126 |
Filed: |
July 30, 2010 |
Current U.S.
Class: |
416/230 ;
416/241A |
Current CPC
Class: |
F01D 5/282 20130101;
F05D 2300/436 20130101 |
Class at
Publication: |
416/230 ;
416/241.A |
International
Class: |
F01D 5/14 20060101
F01D005/14 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 8, 2009 |
DE |
102009036018.2 |
Claims
1.-15. (canceled)
16. A turbine blade, comprising: a damping zone including a damping
layer with a fiber matrix system, wherein the fiber matrix system
has a thermoplastic matrix comprising reinforcing fibers.
17. The turbine blade as claimed in claim 16, wherein the
reinforcing fibers are embedded in the thermoplastic matrix.
18. The turbine blade as claimed in claim 16, wherein the damping
zone includes fiber layers, the fiber layers together with the
damping layer forming a laminar structure.
19. The turbine blade as claimed in claim 16, further comprising: a
blade region, wherein the blade region comprises a plurality of
further fiber layers, and wherein the plurality of further fiber
layers embodies a further laminar structure.
20. The turbine blade as claimed in claim 16, wherein the
reinforcing fibers are embedded in the thermoplastic matrix at an
angle between 1 degree and 90 degrees to one another.
21. The turbine blade as claimed in claim 16, wherein the
reinforcing fibers are embedded in the thermoplastic matrix
parallel to one another.
22. The turbine blade as claimed in claim 16, wherein at least one
of the reinforcing fibers includes a hybrid yarn, and wherein the
hybrid yarn comprises a thermoplastic material and a carbon fiber
material.
23. The turbine blade as claimed in claim 18, wherein the damping
layer has a lower elastic rigidity or a higher damping value than
the fiber layers.
24. The turbine blade as claimed in claim 18, wherein the damping
layer has a lower elastic rigidity and a higher damping value than
the fiber layers.
25. The turbine blade as claimed in claim 19, wherein the damping
zone has a lower elastic rigidity or a higher damping value than
the blade region.
26. The turbine blade as claimed in claim 19, wherein the damping
zone has a lower elastic rigidity and a higher damping value than
the blade region.
27. The turbine blade as claimed in claim 16, further comprising:
an enveloping layer, wherein the enveloping layer is wrapped around
a surface of the turbine blade such that the turbine blade is
protected against external influences, and wherein the enveloping
layer comprises non-reinforced thermoplastic material.
28. The turbine blade as claimed in claim 16, further comprising: a
further fiber matrix system with a thermoplastic matrix, wherein
the further fiber matrix system is disposed in the damping zone or
the blade region such that the further fiber matrix system is
exposed to external influences of the turbine blades, and wherein
the further fiber matrix system comprises reinforcing fibers which
are present as fiber mats with arbitrary main fiber directions.
29. The turbine blade as claimed in claim 16, further comprising: a
further fiber matrix system with a thermoplastic matrix, wherein
the further fiber matrix system is disposed in the damping zone and
the blade region such that the further fiber matrix system is
exposed to external influences of the turbine blades, and wherein
the further fiber matrix system comprises reinforcing fibers which
are present as fiber mats with arbitrary main fiber directions.
30. A turbine, comprising: a turbine blade, comprising: a damping
zone including a damping layer with a fiber matrix system, wherein
the fiber matrix system has a thermoplastic matrix comprising
reinforcing fibers.
31. The turbine as claimed in claim 30, wherein the turbine is a
steam turbine and the turbine blade is a rotor blade of the steam
turbine.
32. A method of manufacturing a damping zone of a turbine blade,
comprising: embedding reinforcing fibers into a thermoplastic
matrix in order to form a fiber matrix system of a damping layer;
forming the damping zone of the turbine blade by the damping
layer.
33. The method as claimed in claim 32, wherein, during the
embedding, the thermoplastic matrix is melted and the reinforcing
fibers are pressed onto the thermoplastic matrix.
34. The method as claimed in claim 32, further comprising deforming
the damping zone in order to match the damping zone to a predefined
shape of the turbine blade by a further melting of the
thermoplastic matrix.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority of German Patent
Application No. 10 2009 036 018.2 DE filed Aug. 4, 2009, which is
incorporated by reference herein in its entirety.
FIELD OF INVENTION
[0002] The present invention relates to a turbine blade. The
present invention also relates to a turbine, in particular a steam
turbine. The present invention further relates to a method for
manufacturing a turbine blade.
BACKGROUND OF THE INVENTION
[0003] Turbine rotor blades made of steel are predominantly used
nowadays in turbines, in particular in steam turbines. In
particular in large stationary steam turbines having large
diameters, the achievable rotational speeds for rotor blades made
of steel are limited due to the high dead weight. In this case
using rotor blades consisting of fiber-reinforced composite
materials would be conceivable in order to reduce the mass of the
blades significantly, which in turn enables the rotational speed to
be increased.
[0004] Furthermore, in stationary steam turbines that have large
diameters and consequently large blade lengths, undesirable
vibrations occur which have to be damped. In present-day
applications, therefore, vibration damping is produced by way of
additional damping wires or shrouding bands on the surface of the
blades. Owing to the blade geometry it is often extremely
labor-intensive, time-consuming and difficult to apply said damping
wires or shrouding bands to the blades, which in turn entails a
deterioration in efficiency and necessitates a complex
manufacturing overhead.
SUMMARY OF THE INVENTION
[0005] It is an object of the present invention to provide a
turbine blade having damping characteristics.
[0006] The object is achieved by means of a turbine blade, a
turbine, in particular a steam turbine, and a method for
manufacturing a turbine blade having the features recited in the
independent claims.
[0007] According to a first exemplary embodiment variant, a turbine
blade is provided wherein sub-regions of the turbine blade or the
entire turbine blade constitute or have a damping zone consisting
of a damping layer. The damping layer has a fiber matrix system.
The fiber matrix system has a thermoplastic matrix, in which matrix
reinforcing fibers are embedded.
[0008] According to a further exemplary embodiment variant, a
turbine is provided which has the above-described turbine
blade.
[0009] According to a further exemplary embodiment variant, a
method for manufacturing a turbine blade is provided. According to
the method, reinforcing fibers are initially embedded into a
thermoplastic matrix in order to form a fiber matrix system of a
damping layer. By means of the damping layer a damping zone of the
turbine blade is formed. The damping zone can embody sub-regions of
the turbine blade or the entire turbine blade.
[0010] By means of the term "damping zone" an area of a turbine
blade is described in which damping characteristics of the turbine
blade are integrated. The damping zone is installed in particular
in such regions of the turbine blade in which mostly higher
shearing or moment loads occur than in the remaining regions of the
turbine blade, with the result that damping is desirable in said
damping zones. Furthermore, greater vibrations can be damped in the
damping zone than in the remaining regions of the turbine blade.
The damping zone can define a specific section along the extension
zone or, as the case may be, along the length of a turbine blade.
The damping zone can also define a specific region in a
cross-section of the turbine blade. Thus, for example, an outer
region of a turbine blade can have a damping zone, while an inner
region can define an arbitrary blade region. In the damping zone it
is possible, for example, for high centrifugal forces, high bending
loads, high shearing stresses, high torsional loads or undesirable
vibrations to be applied which require damping and are damped in
the damping zone. For a turbine blade, in particular a
thermoplastic last-stage blade, the entire turbine blade forms the
damping zone. This means that the entire turbine blade can be
manufactured from a plurality of damping layers and consequently
can consist of the damping layers themselves.
[0011] A "layer", in particular a damping layer and/or a fiber
layer, is understood to mean a stratum of a damping layer or, as
the case may be, of a damping material and a stratum of a fiber
layer or, as the case may be, of a reinforcing fiber layer. A layer
can have a thickness of, for example, 0.1-1 mm, in particular a
thickness of 0.2 mm, 0.25 mm and/or 0.3 mm, for example.
[0012] The term "fiber matrix system" can be understood to mean a
fiber composite consisting of a matrix and reinforcing fibers. The
fiber matrix system can constitute, for example, the damping layer
in its entirety or a part thereof.
[0013] The term "reinforcing fibers" is understood to means fibers
which can pass on and transfer forces that act on the fiber matrix
system. In comparison with the matrix the fibers can exhibit a high
rigidity, in particular in respect of tension. The force flow is
mostly configured along the fiber in order to exploit the best
rigidity characteristics of a reinforcing fiber.
[0014] The term "matrix" is understood to mean a raw material which
embeds the reinforcing fibers. The term "embed" serves to define
that the reinforcing fibers are present spatially fixed in the
matrix and consequently can enable load to be introduced and load
to be directed out. The matrix can also protect the reinforcing
fibers, for example, against compression in the event of pressure
parallel to the fibers. The reinforcing fibers and the matrix are,
for example, glued or, as the case may be, fused to one another so
that load can be transferred between the matrix and the reinforcing
fiber, whereby shearing forces can also be transferred.
[0015] The term "thermoplastic" matrix serves to define the
material of the matrix. A thermoplastic material or, as the case
may be, a thermoplastic matrix has in particular damping
characteristics. The thermoplastic material of the matrix has a
lower rigidity and a higher damping value in relation to a
reinforcing fiber that is subject to tension. Accordingly, the
thermoplastic matrix can have a damping effect, whereas the
reinforcing fiber has a stiffening effect. The thermoplastic matrix
can also be reshaped or fused subsequently. The thermoplastic
matrix can consist, for example, of polyetheretherketone (PEEK), of
polyamide (PA), of polypropylene (PP), of polycarbonate (PC) or of
polyethylene (PE).
[0016] The reinforcing fibers can consist, for example, of
synthetic fibers, such as e.g. carbon fibers, aramid fibers,
polyester fibers, polyamide fibers or polyethylene fibers. As well
as these organic reinforcing fibers, inorganic fibers such as glass
fibers, natural fibers or metallic fibers can equally well be
used.
[0017] By means of the present invention a turbine blade which
consists in particular of fiber composite materials can be
selectively damped without the turbine blade's stability or
rigidity being reduced to such an extent that an instability is
created. Through the use of a thermoplastic matrix material a
selectively adjustable, advantageous potential for vibration
damping can be achieved by means of the material itself. In other
words, the material-side vibration damping is improved through the
use of a material combination consisting of thermoplastic and
reinforcing fiber in the critical damping zones or in the entire
turbine blade. Furthermore, different combinations of different
thermoplastic fiber matrix systems can be provided for damping
zones subject to different loads in order to adapt the turbine
blade in a targeted manner to a predefined load.
[0018] Furthermore, owing to the use of the thermoplastic fiber
matrix system the turbine blade can be subject to a subsequent
reshaping of the profile of the turbine blade, this being achieved
by reheating and consequently partly fusing or, as the case may be,
melting the thermoplastic fiber matrix system. In this way a
targeted subsequent deformation or, as the case may be,
readjustment or fine adjustment to suit specific turbine blade
profiles or to match different load stresses is possible. A
targeted detuning or, as the case may be, deformation of individual
blades on the blade ring can be achieved in this way.
[0019] According to a further exemplary embodiment variant, the
damping zone has fiber layers, the fiber layers and the damping
layer forming a laminar structure.
[0020] The term "laminar structure" is understood to mean, for
example, a laminate which describes a stacking of the different
layers, in particular the damping layers and the fiber layers, on
top of one another. A laminar structure describes a layer-by-layer
fabrication or, as the case may be, the layer-by-layer construction
of the damping zone or also other regions of the turbine blade,
such as the other blade regions, for example. The laminar structure
or, as the case may be, the laminar structure materials consists or
consist of layers superimposed on one another or, as the case may
be, different numbers of layers. The individual strata or, as the
case may be, the individual layers can be glued, for example, or
they can mutually interlock due to the open-cell nature of the
materials. For example, the laminar structure can be immersed in
resin in order to bond the layers to one another. The laminar
structure forms the integral configuration of a component such that
forces that act on the component can be transferred via the laminar
structure. The laminar structure additionally has the homogeneously
running surface of the component. In other words, fixtures glued
onto the surface of a component externally do not count as part of
the laminar structure of the component or, as the case may be, of
the turbine blade.
[0021] In this context the term "fiber layer" describes a layer
consisting of fibers that can have no thermoplastic material. The
fiber layers can, for example, exhibit a high rigidity or, as the
case may be, a higher rigidity than the damping layers and consist
of different reinforcing fiber materials, as described above.
[0022] According to another exemplary embodiment variant, the
turbine blade has a blade region, the blade region consisting of a
plurality of further fiber layers. The plurality of further fiber
layers embodies a further laminar structure. The blade region or,
as the case may be, the blade regions can adjoin the damping zone
or zones of the turbine blade. The blade regions can consist of the
plurality of further fiber layers that exhibit a higher rigidity
and load-bearing capability by comparison with the damping zone.
Vibrations can be transmitted, for example, from the blade region
onto the damping zone, the damping zone being able to damp or, as
the case may be, absorb the vibrations by means of the
thermoplastic fiber matrix system. By means of the present
exemplary embodiment a turbine blade can be provided which along
its extension direction has, for example, a plurality of blade
regions which in turn adjoin a plurality of damping zones. The
damping zones can be arranged at predefined regions having a high
loading or, as the case may be, having a high damping requirement.
The blade regions can be arranged at areas at which vibration are
non-critical or, as the case may be, at which a high rigidity is
required. Thus, a turbine blade can be individually adapted to suit
the loads to which it is subject and consequently tailored to a
detailed requirements profile in terms of costs and efficiency.
[0023] According to a further exemplary embodiment variant, the
reinforcing fibers are embedded into the matrix at an angle of
between 1.degree. (degree) and 90.degree. (degrees) to one another.
More particularly with complex loads or, as the case may be, load
directions, individual reinforcing fibers can be arranged at
different angles to one another. In this case the damping layer or
the fiber layer can be produced, for example, as a woven fabric, as
a knitted fabric or as a mesh having oriented reinforcing fibers.
Depending on the alignment of the reinforcing fibers, the turbine
blade can be adapted to predefined load directions, with the result
that the turbine blade can be selectively matched to a predefined
requirements potential.
[0024] According to another exemplary embodiment variant, the
reinforcing fibers are embedded into the thermoplastic matrix
parallel to one another. In areas in which the turbine blade is
subject exclusively to tension, for example, reinforcing fibers
arranged in parallel can suffice. Complex interweaves and
alignments of reinforcing fibers are then unnecessary, so that a
manufacturing method having low manufacturing costs can be created
in these areas with parallel reinforcing fibers.
[0025] According to a further exemplary embodiment variant, at
least one of the reinforcing fibers has a hybrid yarn. The hybrid
yarn has a thermoplastic material and a carbon fiber material. Such
a hybrid yarn can consist, for example, of many yarns which are
twisted together with one another or interlaced with one another
and which together form the hybrid yarn. One part of said yarns can
consist of a thermoplastic material and the other of a reinforcing
fiber material, such as e.g. carbon fibers. Furthermore it is also
possible to form the hybrid yarn in such a way that the
thermoplastic material is embodied as yarn and the fiber yarn is
fused into the thermoplastic yarn. In this way a targeted damping
of the turbine blade can be provided in a simple manner already by
means of the use of the thermoplastic yarn as a reinforcing
fiber.
[0026] According to another exemplary embodiment variant, the
damping layer has a lower elastic rigidity and/or a higher damping
value than the fiber layer.
[0027] The term "damping value" describes the damping
characteristics of a material. The damping value `tan .delta.` can
lie between 0 and 1, for example.
[0028] The teen "rigidity" can describe the E modulus or G modulus,
for example. Thus, for example, a fiber can have a rigidity of 130
GPa in the longitudinal direction and only 8 GPa along the
transverse direction. In the case of a weft of fibers, rigidities
of 65 GPa, for example, can be achieved in each main fiber
direction. Each main fiber direction is aligned at an angle a
relative to each other. The thermoplastic matrix can have a
rigidity of 0.5 to 10 GPa, for example, yet in return exhibit
better damping characteristics than the reinforcing fibers.
[0029] According to a further exemplary embodiment variant, the
damping zone has a lower elastic rigidity and/or a higher damping
value than the blade region.
[0030] According to a further exemplary embodiment variant, the
turbine blade has an enveloping layer. The enveloping layer is
wrapped around a surface or, as the case may be, a surface region
of the turbine blade in such a way that the turbine blade is
protected against external influences. The enveloping layer has a
non-reinforced thermoplastic material which is identical to the
matrix material. Owing to the high damping effect of a
non-reinforced thermoplastic material the softness or, as the case
may be, the elasticity of the thermoplastic material can be greater
than the elasticity of the fiber layer. When external particles
strike the surface of the turbine blade, a surface made of
thermoplastic material erodes less than, for example, a fiber layer
consisting of reinforcing fibers having a higher rigidity.
Accordingly, the service life of a turbine blade can be increased,
since damage due to impingement of external particles is reduced.
Moreover, a thermoplastic material is generally more resistant to
humidity than a reinforcing fiber, so corrosion is reduced.
[0031] According to another exemplary embodiment variant, the
damping zone has a further fiber matrix system having a
thermoplastic matrix. The further fiber matrix system is disposed
in the damping zone and/or in the blade region such that said
system is exposed to external influences of the turbine blade. The
further fiber matrix system having a thermoplastic matrix has
reinforcing fibers which are present as fiber mats in arbitrary
main fiber directions. As a result of the arbitrary alignment of
the main fiber directions of the reinforcing fibers, the rigidity
characteristic of the further fiber matrix system is reduced and a
better absorption characteristic and a greater resistance toward an
impact of external particles are achieved. Moreover, the further
fiber matrix system can also be extended over the other areas of
the turbine blade, for example also over the blade regions. In
comparison with a non-reinforced thermoplastic matrix, the further
fiber matrix system having a fiber-reinforced matrix can have not
only a high absorption capability in respect of impinging particles
but also a higher rigidity, with the result that the further
thermoplastic fiber matrix system can likewise contribute toward
the overall rigidity of the turbine blade. Accordingly, a rigid
material can be provided for a turbine blade while at the same time
increasing the erosion resistance and also the corrosion resistance
toward liquids of a surface of the turbine blade. With steam
turbines in particular, erosion due to water droplets is critical.
A surface or, as the case may be, an outer layer of the turbine
blade consisting of non-reinforced thermoplastic or, as the case
may be, of a terminating layer consisting of thermoplastic matrix
material or, as the case may be, of a terminating layer of the
further thermoplastic fiber matrix system can provide an integrated
erosion layer without the necessity of applying additional sealing
layers.
[0032] According to a further exemplary embodiment variant, a
turbine, in particular a steam turbine, is equipped with the
above-described turbine blades. Steam turbines in particular have
large diameters, in particular in the first compressor stage and
the last turbines stage. High centrifugal forces, bending moments
and torsion forces act in particular in the case of blade wheels of
a steam turbine having a large diameter. Specifically in that
situation it is suitable to use the turbine blade according to the
invention in order to achieve adequate rigidity while improving
damping characteristics compared to conventional turbine blades.
Accordingly, turbine blades consisting of a composite material can
be employed even for steam turbines having large diameters.
[0033] According to a further exemplary embodiment variant of the
method, the thermoplastic matrix is melted during the embedding
process and the reinforcing fibers are pressed onto the matrix.
Thus, an economical manufacture using the hot-press method can be
provided in that the thermoplastic material present in the matrix
is melted. Long infiltration and curing times as in the case of
conventional fiber composite layers, for example, can be dispensed
with.
[0034] According to a further exemplary embodiment variant of the
method, the damping zone is reshaped by means of a further fusing
or melting of the thermoplastic matrix in order to match a
predefined shape of the turbine blade. Owing to this fusibility or
meltability of the fiber matrix system or, as the case may be, of
the thermoplastic matrix the definitive shaping of the turbine
blade, e.g. a twisting of the turbine blade, can be carried out
directly after the manufacturing process, e.g. a hot-press process.
This can be useful above all in the case of special turbine
requirements, in particular in the case of special requirements in
terms of the twisting angle, etc. Furthermore, a subsequent
reshaping or, as the case may be, readjustment helps in the case of
specific problems with an oscillation frequency. By means of the
remelting the damping zone can be subsequently reshaped or, as the
case may be, fine-adjusted, for example, to a changed or, as the
case may be, unanticipated oscillation frequency.
[0035] Furthermore, the property of the remeltability of the fiber
matrix system also permits a subsequent blade repair. For example,
an additional thermoplastic material can be applied in order to
rectify damage to the fiber matrix system. Accordingly, the
possibility of a repair is created. In other words, an additional
thermoplastic can be applied locally in order to repair damage to
the turbine blade.
[0036] It is pointed out that embodiment variants of the invention
have been described with reference to different subject matters of
the invention. In particular some embodiment variants of the
invention are described by means of device-related claims and other
embodiment variants of the invention by means of method-related
claims. However, it will become immediately clear to the person
skilled in the art when reading this application that, unless
explicitly stated otherwise, in addition to a combination of
features that belong to one type of inventive subject matter, an
arbitrary combination of features that belong to different types of
inventive subject matter is also possible.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] Further advantages and features of the present invention
will emerge from the following exemplary description of currently
preferred embodiments.
[0038] FIG. 1 shows a turbine blade having a damping zone according
to an exemplary embodiment of the present invention;
[0039] FIG. 2 shows a plan view onto a fiber matrix system in a
damping layer according to an exemplary embodiment variant of the
present invention; and
[0040] FIG. 3 shows a schematic view of a fiber matrix system in a
damping layer according to an exemplary embodiment variant of the
invention.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENT VARIANTS
[0041] The same or similar components are labeled with the same
reference numerals throughout the figures. The depiction in the
figures is schematic and not to scale.
[0042] FIG. 1 shows an exemplary embodiment variant of the turbine
blade 100 according to an exemplary embodiment of the present
invention. The turbine blade 100 has a damping zone 101 having a
damping layer 103. The damping layer 103 has a fiber matrix system
200 (see FIG. 2). The fiber matrix system 200 has a thermoplastic
matrix 201 (see FIG. 2), in which thermoplastic matrix 201
reinforcing fibers 202 (see FIG. 2) are embedded.
[0043] The turbine blade 100 has, as shown in FIG. 1, two blade
regions 102 which surround the damping zone 101. The blade region
102 is formed, for example, from a further laminar structure 107
which can consist of a plurality of further fiber layers 105. If
the further fiber layers 105 consist, for example, of reinforcing
fibers 202 consisting of carbon fibers or other stiffening
composite fibers, the further laminar structure 107 embodies an
extremely rigid blade region 102.
[0044] The fiber layers 104 in the damping zone 101 can transition
seamlessly into the blade regions 102. In the case of a seamless
or, as the case may be, constant transition of the fiber layers 104
from the damping zone 102 into the blade regions 102, the fiber
layers 104 together with the further fiber layers 105 form a
continuously running layer. Furthermore, the damping zones 101 can
be manufactured as semifinished products, wherein the fiber layers
104 do not run beyond the damping zone 101 or, as the case may be,
do not protrude into the blade regions 102. The fiber layers 104
are truncated, for example, at the border regions of the damping
zones 101.
[0045] In the damping zone 101, the vibration damping can be
produced in that a laminar structure 106 forms the damping zone
101, the laminar structure 106 consisting of at least one damping
layer 103 and of further fiber layers 104. Owing to the
layer-by-layer structure by means of the damping layer 103 the
damping zone 101 can be less rigid than the blade regions 102, with
the result that in this case vibration damping is produced by means
of the laminar structure 106, i.e. by means of the material
itself
[0046] Furthermore, an enveloping layer 108 can be molded around
the turbine blade 100, the enveloping layer 108 protecting at least
the damping zone 101 but also in addition the blade regions 102
against external influences. In this arrangement the enveloping
layer 108 can consist, for example, of a non-reinforced
thermoplastic material. A non-reinforced thermoplastic material can
embody a soft enveloping layer 108 such that impacts of foreign
particles onto the turbine blade are cushioned and can rebound by
virtue of the soft enveloping layer 108. As a result of the low
rigidity of the thermoplastic enveloping layer 108, the impact of a
foreign particle causes the enveloping layer 108 to deform slightly
such that the impact energy is absorbed without this resulting in
fissures or other forms of damage being produced.
[0047] Furthermore, the damping zone 101 or in addition also the
blade regions 102 can have a further thermoplastic fiber matrix
system 109 which can protect the turbine blade 100 against external
influences. The further fiber matrix system 109 can have a
thermoplastic matrix 201 into which reinforcing fibers 202 are
embedded. If the reinforcing fibers 202 are arbitrarily present in
the thermoplastic matrix 201, this can be referred to as a fiber
mat. The fiber mats have a lower rigidity than fiber matrix systems
with directed composite fibers, with the result that in turn a
greater softness or, as the case may be, elasticity can be created
with the further fiber matrix system 109. This leads in turn to a
protection against external impacts of foreign particles and
against erosion of the surface of the turbine blade 100.
[0048] FIG. 2 shows a fiber matrix system 200 which consists of a
thermoplastic matrix 201. Reinforcing fibers 202 are embedded into
the thermoplastic matrix 201. As shown in FIG. 2, the reinforcing
fibers 202 can be aligned in parallel. Accordingly the reinforcing
fibers, which are subject to tension, can provide a high degree of
stiffness of the fiber matrix system 200. High damping
characteristics are possible transversely to the fiber direction of
the reinforcing fibers 202 owing to the low rigidity of the
reinforcing fibers 202.
[0049] FIG. 3 shows a further exemplary embodiment variant of a
fiber matrix system 200, in which reinforcing fibers 202 are
embedded into a thermoplastic matrix 201. The reinforcing fibers
200 are in this case embedded at a specific angle a between further
reinforcing fibers 201. In other words, the reinforcing fibers 201
are not present parallel to one another. By means of this
multidirectional alignment of the reinforcing fibers 202 a high
rigidity of the reinforcing fibers 202 in a plurality of predefined
directions can be achieved in a targeted manner. The damping
characteristics are in this case primarily produced by means of the
thermoplastic matrix 201. This means that a damping zone 101 can be
provided which can have reinforcing properties or, as the case may
be, rigidity properties on the one hand and damping characteristics
on the other.
[0050] For completeness it should be pointed out that "comprising"
excludes no other elements or steps and "one" or "a" does not
exclude a plurality. Let it furthermore be pointed out that
features or steps that have been described with reference to one of
the above exemplary embodiments can also be used in combination
with other features or steps of other above-described exemplary
embodiments. Reference signs in the claims are not to be regarded
as limiting.
* * * * *