WO2009079164A2 - Uniform fatigue life spherical elastomeric bearing - Google Patents
Uniform fatigue life spherical elastomeric bearing Download PDFInfo
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- WO2009079164A2 WO2009079164A2 PCT/US2008/084452 US2008084452W WO2009079164A2 WO 2009079164 A2 WO2009079164 A2 WO 2009079164A2 US 2008084452 W US2008084452 W US 2008084452W WO 2009079164 A2 WO2009079164 A2 WO 2009079164A2
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- WIPO (PCT)
- Prior art keywords
- layer
- strain
- bearing
- elastomeric
- calculating
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64C—AEROPLANES; HELICOPTERS
- B64C27/00—Rotorcraft; Rotors peculiar thereto
- B64C27/32—Rotors
- B64C27/35—Rotors having elastomeric joints
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F1/00—Springs
- F16F1/36—Springs made of rubber or other material having high internal friction, e.g. thermoplastic elastomers
- F16F1/40—Springs made of rubber or other material having high internal friction, e.g. thermoplastic elastomers consisting of a stack of similar elements separated by non-elastic intermediate layers
Definitions
- the present invention relates to an elastomeric bearing.
- elastomeric spherical bearing design is the smallest/lightest package that meets the desired design life requirements.
- the design life is typically determined through a single motion strain.
- One conventional elastomeric bearing design methodology discloses how to develop a bearing with a uniform steady compression induced strain, ⁇ Tc , and a uniform strain distribution for one motion pitch ⁇ ⁇ or flap ⁇ o.
- Such conventional elastomeric bearing design methodology does not account for coupled load and motion or for the fatigue damage from additional motion strains. That is, the actual life of each layer is not dependent exclusively on pitch or flap strain as pressured by this conventional methodology.
- the conventional methodology generates a bearing that does not provide uniform life at each layer and may therefore result in a relatively inefficient elastomeric bearing.
- An elastomeric spherical bearing according to an exemplary aspect of the present invention includes a multiple of elastomeric layers, each of said multiple of elastomeric layers having an essentially equivalent fatigue life.
- a method of calculating a uniform life spherical elastomeric bearing according to an exemplary aspect of the present invention includes adjusting each layer thickness to produce a uniform fatigue life of each bearing layer.
- Figure 1 is a perspective view a rotor head assembly utilizing an elastomeric bearing according to one non-limiting embodiment of the present invention
- Figure 2A is an enlarged broken-away perspective view of the elastomeric bearing in combination with a rotor assembly yoke and shear segment of the rotor hub assembly of Figure 1;
- Figure 2B depicts an enlarged view of the elastomeric laminates of the elastomeric bearing of Figure 2A;
- Figure 3 is a schematic view of a section of one segment of an elastomeric layer of the elastomeric bearing
- Figure 4 is graph representing the shear modulus and elastomer thickness of one elastomeric bearing with three layers according to one non-limiting embodiment of the present invention.
- Figure 5 is a graph of the elastomeric bearing of Figure 4 illustrating an essentially equivalent elastomeric layer life.
- a rotor hub assembly 10 typical of a rotary- wing aircraft includes a hub retention member 12 which drives a plurality of rotor blade assemblies 14 about an axis of rotation 16.
- the hub retention member 12 includes a plurality of radial spokes 20 and shear segments 22.
- the yoke 24 is generally C-shaped and circumscribes, in looped fashion, the respective shear segment 22.
- the yoke 24 is disposed in combination with a cuff structures 28 which, in turn, mount to the root end of each rotor blade assembly 14.
- a spherical elastomeric bearing assembly 30 is interposed between each rotor assembly yoke 24 and the respective shear segment 22 to accommodate the multi-directional displacement of the rotor blade assembly 14.
- the spherical elastomeric bearing 30 is shown in combination with a rotor assembly yoke 24 and a respective shear segment 22.
- the spherical elastomeric bearing 30 includes a central bearing element 32 having a spherical bearing surface 32s which defines a bearing focal point 3Of.
- the bearing focal point 3Of defines the flap, lead-lag and pitch axes, Fa, La, and Pa, respectively, about which the rotor blade assembly articulates.
- To the spherical surface 32s is bonded discrete spherical elastomeric elements 34 about the bearing focal point 3Of.
- each spherical elastomeric element 34 includes a multiple of alternating layers (see Figure 2B) of elastomer 36 and nonresilient shims 38, respectively, which are disposed at increasing radii from the bearing focal point 3Of and have a center of curvature C. sub. c which is coincident therewith.
- Each elastomeric layer 36 of the elastomeric spherical bearing 30 provides a uniform fatigue life as will be further described below. It should be understood that although a particular rotor hub application is illustrated in the disclosed non-limiting embodiment, elastomeric bearing for any application including but not limited to aerospace, heavy machinery, and civil engineering (bridges, buildings, etc.) will benefit herefrom.
- Each spherical elastomeric bearing layer 36 has a fatigue curve with alternating strain (S) as the ordinate, and cycles to failure (N) as the abscissa (S-N).
- S alternating strain
- N cycles to failure
- the fatigue life of each elastomer bearing layer 36 can be approximated from the S- N curves by the following equations (1) - (5):
- the life of a layer is calculated from the combined cumulative damage of the two motions and the shear load.
- a section of one layer 36A of the elastomeric spherical bearing 30 is schematically illustrated such that nomenclature may be defined.
- the section 36A includes an outwardly facing convex surface 40 and an inwardly facing concave surface 42. It should be understood that the section 36A is representative of a single layer of an elastomeric material which may be attached to another layer (not shown)
- ⁇ c is the compression load .
- G 1 is the elastomer layer shear modulus
- G 1 - I is the previous elastomer layer shear modulus (starting at the layer closest to the focal point);
- R 1 is the mean radius of the layer
- R 1 . ! is the mean radius of the previous layer (starting at the layer closest to the focal point).
- a 1 is the Inner Angle and B 1 is the outer angle.
- one calculation procedure according to one non-limiting embodiment of the present invention is as follows: Determine Loads and Motions.
- the axial load acts in a direction parallel to the Z axis of rotation. For helicopters, this is generally the centrifugal force from the rotor blade.
- the radial load acts in the R, radial direction. This is usually the shear load on the rotor blade.
- Shear Modulus Is Calculated From The Geometry To Achieve A Uniform Torsional Strain. (See Equation #6 For Shear Modulus) Calculate Flapping Strain
- an elastomeric bearing 3OA with three layers has inputs delineated in the chart below: ⁇ np ⁇ & ⁇ &
- Flapping Stiffness ( ⁇ n-lb/rad) 1 ,079,065
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Aviation & Aerospace Engineering (AREA)
- Architecture (AREA)
- Support Of The Bearing (AREA)
- Sliding-Contact Bearings (AREA)
Abstract
An elastomeric spherical bearing includes a multiple of elastomeric layers with an essentially equivalent fatigue life.
Description
UNIFORM FATIGUE LIFE SPHERICAL ELASTOMERIC BEARING
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT This invention was made with Government support under N00019-06-C-
0081 awarded by The United States Navy. The Government has certain rights in this invention.
BACKGROUND OF THE INVENTION The present invention relates to an elastomeric bearing.
One goal of elastomeric spherical bearing design is the smallest/lightest package that meets the desired design life requirements. The design life is typically determined through a single motion strain. One conventional elastomeric bearing design methodology discloses how to develop a bearing with a uniform steady compression induced strain, γTc , and a uniform strain distribution for one motion pitch γθ or flap γo. Such conventional elastomeric bearing design methodology, however, does not account for coupled load and motion or for the fatigue damage from additional motion strains. That is, the actual life of each layer is not dependent exclusively on pitch or flap strain as pressured by this conventional methodology. Furthermore, the conventional methodology generates a bearing that does not provide uniform life at each layer and may therefore result in a relatively inefficient elastomeric bearing.
SUMMARY OF THE INVENTION An elastomeric spherical bearing according to an exemplary aspect of the present invention includes a multiple of elastomeric layers, each of said multiple of elastomeric layers having an essentially equivalent fatigue life.
A method of calculating a uniform life spherical elastomeric bearing according to an exemplary aspect of the present invention includes adjusting each layer thickness to produce a uniform fatigue life of each bearing layer.
BRIEF DESCRIPTION OF THE DRAWINGS
The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently disclosed embodiment. The drawings that accompany the detailed description can be briefly described as follows:
Figure 1 is a perspective view a rotor head assembly utilizing an elastomeric bearing according to one non-limiting embodiment of the present invention;
Figure 2A is an enlarged broken-away perspective view of the elastomeric bearing in combination with a rotor assembly yoke and shear segment of the rotor hub assembly of Figure 1;
Figure 2B depicts an enlarged view of the elastomeric laminates of the elastomeric bearing of Figure 2A;
Figure 3 is a schematic view of a section of one segment of an elastomeric layer of the elastomeric bearing; Figure 4 is graph representing the shear modulus and elastomer thickness of one elastomeric bearing with three layers according to one non-limiting embodiment of the present invention; and
Figure 5 is a graph of the elastomeric bearing of Figure 4 illustrating an essentially equivalent elastomeric layer life.
DETAILED DESCRIPTION OF THE DISCLOSED EMBODIMENT
Referring to Figure 1, a rotor hub assembly 10 typical of a rotary- wing aircraft includes a hub retention member 12 which drives a plurality of rotor blade assemblies 14 about an axis of rotation 16. The hub retention member 12 includes a plurality of radial spokes 20 and shear segments 22. Each shear segment 22, in combination with its respective radial spokes 20, form a structural loop for accepting a rotor assembly yoke 24. The yoke 24 is generally C-shaped and circumscribes, in looped fashion, the respective shear segment 22. The yoke 24 is disposed in combination with a cuff structures 28 which, in turn, mount to the root end of each rotor blade assembly 14.
A spherical elastomeric bearing assembly 30 is interposed between each rotor assembly yoke 24 and the respective shear segment 22 to accommodate the multi-directional displacement of the rotor blade assembly 14.
Referring to Figure 2A, the spherical elastomeric bearing 30 is shown in combination with a rotor assembly yoke 24 and a respective shear segment 22. The spherical elastomeric bearing 30 includes a central bearing element 32 having a spherical bearing surface 32s which defines a bearing focal point 3Of. The bearing focal point 3Of defines the flap, lead-lag and pitch axes, Fa, La, and Pa, respectively, about which the rotor blade assembly articulates. To the spherical surface 32s is bonded discrete spherical elastomeric elements 34 about the bearing focal point 3Of. Furthermore, each spherical elastomeric element 34 includes a multiple of alternating layers (see Figure 2B) of elastomer 36 and nonresilient shims 38, respectively, which are disposed at increasing radii from the bearing focal point 3Of and have a center of curvature C. sub. c which is coincident therewith.
Each elastomeric layer 36 of the elastomeric spherical bearing 30 provides a uniform fatigue life as will be further described below. It should be understood that although a particular rotor hub application is illustrated in the disclosed non-limiting embodiment, elastomeric bearing for any application including but not limited to aerospace, heavy machinery, and civil engineering (bridges, buildings, etc.) will benefit herefrom.
Each spherical elastomeric bearing layer 36 has a fatigue curve with alternating strain (S) as the ordinate, and cycles to failure (N) as the abscissa (S-N). The fatigue life of each elastomer bearing layer 36 can be approximated from the S- N curves by the following equations (1) - (5):
Pitch Angle Motion +/- θ
Nθ J = lL?
^ ) ( D where γQ equals the pitch strain as a percentage and NΘ equals the number of cycles to failure. C and α are constants (general values below) that are derived from curve fitting methods to approximate the particular S-N curve.
C ~ 5000; α ~ 3.5 to 5.0
Where γs is the shear strain
The life of a layer is calculated from the combined cumulative damage of the two motions and the shear load.
1 1 1
NN =
N iN 0θ N iN Rβ R iNγ,s (4)
Such that fatigue life: i
NN (5)
Referring to Figure 3, a section of one layer 36A of the elastomeric spherical bearing 30 is schematically illustrated such that nomenclature may be defined. The section 36A includes an outwardly facing convex surface 40 and an inwardly facing concave surface 42. It should be understood that the section 36A is representative of a single layer of an elastomeric material which may be attached to another layer (not shown)
Fatigue Loading: Pitch Angle Motion +/- θ-
Flap Angle Motion +/- β.
Shear Loading +/- τc sinfy
Where τc is the compression load .
Initial Practice Design Constraints: Shear Modulus GlstL = 24φsi
Compression Shear Strain γTc = ioo% For the first layer
Pitch Strain +/- γQ = 35% For All Layers First Layer:
Compressive Shear Strain: Jj0 = 100% Calculate Pitch Strain γQ and Flap Strain γ™ Normalize Pitch Strain γQ to 35%
Calculate Normalized γo to $] γn = f (Tc ύn βt )
Calculate
Adjust layer thickness, tj to obtain desired life [iterate using approach 1, "Local Flow chart Methodology" (below)].
Repeat until Pitch Strain, γQ = 35% For all layers
Local Flow Chart Methodology - Approach #1 - Constant +/- γθ Pitch Strain Percentage
Design Bearing for a Uniform Vibratory Pitch Shear Strain by varying the layer shear modules by:
(6) Where
G1 is the elastomer layer shear modulus;
G1-I is the previous elastomer layer shear modulus (starting at the layer closest to the focal point);
R1 is the mean radius of the layer;
R1.! is the mean radius of the previous layer (starting at the layer closest to the focal point); and
= covA . I-v&iA l ~ -+• 2-cβsA , \ - εe>%B, 1 sinB 3i ~ — l-cosB, a
(7) Where A1 is the Inner Angle and B1 is the outer angle.
For a given fatigue Life
Using Equations (1) - (8)
Adjusting the layer thickness such that the actual bearing shear strain equals the above calculated shear strain constraint (equation 10), will produce a uniform fatigue life for each bearing layer. Utilizing the Equations described above, one calculation procedure according to one non-limiting embodiment of the present invention is as follows: Determine Loads and Motions.
Determine the axial load. The axial load acts in a direction parallel to the Z axis of rotation. For helicopters, this is generally the centrifugal force from the rotor blade.
Determine the radial load. The radial load acts in the R, radial direction. This is usually the shear load on the rotor blade.
Determine the vibratory pitch motion (theta) angle. This motion rotates about the Z axis and is sometimes referred to as the torsional rotation. This motion is a vibratory motion. The angle is a plus or minus motion from the origin. Determine the flapping (cocking) motion angle. Determine Fatigue Life Desired (In Number Of Cycles Or Hours). Enter Bearing Dimensions.
Inner radius (Ri), Inner Angle (Bi), Inner Angle (Ai), Side Angle (Alpha) sometimes referred to as outer taper angle, and Side Angle (Blpha) sometimes referred to as inner taper angle.
Enter Shim thickness Enter Bearing Elastomer Material Properties.
Enter Bulk modulus of elastomer, (Kb, psi). A value of 200,000 psi is good practice.
Enter the fist layer shear modulus (G, psi). A value of 240 psi is good practice. Calculate Geometries. Inner And Outer Angles, Inner And Outer Radius,
Mean Radius, Etc.
Calculate Shape Factors Per Layer.
Calculate Effective Compression Modulus (Ec)
Calculate Radial And Axial Strains To Get Compression Shear Strain. Change Layer Thickness To Achieve Compression Strain Allowable.
Calculate Stiffnesses (Radial, Axial, Flapping, And Torsional Stiffnesses)
Calculate Torsional Strain. Add More Layers To Achieve Allowable.
The Shear Modulus Is Calculated From The Geometry To Achieve A Uniform Torsional Strain. (See Equation #6 For Shear Modulus) Calculate Flapping Strain
Calculate Shear Strain Allowable V .
Calculate Life
Vary The Thicknesses Of Each Layer To Meet Shear Strain Allowable and to Achieve Uniform Life. It should be understood that the instructions are basically the same for a solid bearing and a bearing with a central opening. It should also be understood that an elastomeric bearing with any number of layers may be calculated by the method herein. By way of illustration, an elastomeric bearing 3OA with three layers according to one non-limiting embodiment, has inputs delineated in the chart below:
ϊnpϊ&{&
Bearinα Parameters
Side Angle, BLPHA (deg) 0
Inner Angle Ai (deg) 0
Design Life (hours) 2,000
Applied Loads
Radial Loads, Pradial (Ibf) 100
Axial Loads, Paxial (Ibf) 122,500
Torsional Rotation, theta (deg) 1 68
Flapping Rotation, beta (deg) 0 96
Shear Correction Factor 0 7
Bulk modulus of elastomer, Kb (psi) 200,000
Rotor Info
Rotor RPM, 100% NR 246
Frequency (omega) 4 1
To provide the following properties:
JFmal Bearing JPropsrtiss
Geometrv
Inner Radius Ri (in) 4 98
Outer Radius Ro (in) 5 43
Inner Angle Ai (deg) 0 00
Outer Angle Ao (deg) 0 00
Inner Angle Bi (deg) 60 00
Outer Angle Bo (deg) 57 01
Side Angle, ALPHA (deg) 27
Side Angle, BLPHA (deg) 0
Stiffnesses
Radial Stiffness (lb/ιn) 4,909,450
Axial Stiffness (lb/ιn) 14,815,628
Torsion Stiffness (ιn-lb/rad) 540,147
Torsion Stiffness (ιn-lb/deg) 9,427
Flapping Stiffness (ιn-lb/rad) 1 ,079,065
Flapping Stiffness (ιn-lb/deg) 18,833
Shim Thickness (in) 0 0355
Life (hours) 2,000
Number of Elastomer Layers 3
These properties provide a shear modulus and elastomer thickness by layer (Figure 4) such that each layer the elastomeric bearing 30 has an essentially equivalent life (Figure 5).
It should be understood that relative positional terms such as "forward," "aft," "upper," "lower," "above," "below," and the like are with reference to the normal operational attitude of the vehicle and should not be considered otherwise limiting.
It should be understood that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will benefit from the instant invention.
Although particular step sequences are shown, described, and claimed, it should be understood that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the present invention. The foregoing description is exemplary rather than defined by the limitations within. Many modifications and variations of the present invention are possible in light of the above teachings. The disclosed embodiments of this invention have been disclosed, however, one of ordinary skill in the art would recognize that certain modifications would come within the scope of this invention. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. For that reason the following claims should be studied to determine the true scope and content of this invention.
Claims
1. An elastomeric spherical bearing comprising: a multiple of elastomeric layers; and a shim mounted between at least two of said multiple of elastomeric layers, each of said multiple of elastomeric layers having an essentially equivalent fatigue life.
2. The elastomeric spherical bearing as recited in claim 1, wherein an inner layer of said multiple of elastomeric layers is mounted to a central bearing element having a spherical bearing surface.
3. The elastomeric spherical bearing as recited in claim 2, wherein an inner layer of said multiple of elastomeric layers is mounted to a rotor assembly component.
4. The elastomeric spherical bearing as recited in claim 2, wherein an outer layer of said multiple of elastomeric layers is mounted to a cuff structures of a rotor assembly.
5. A method of calculating a uniform life spherical elastomeric bearing comprising: adjusting each layer thickness of an elastomeric bearing having uniform pitch strain to satisfy:
to produce a uniform fatigue life of each bearing layer where: C and a are constants derived from curve fitting methods to approximate the particular S-N curve; Life is the desired fatigue life;
Yθ is the pitch strain; and Yβ is the flap strain.
6. A method as recited in claim 5, wherein the thickness of each layer is varied until the Pitch Strain, the Pitch Strain (JQ) is approximately 35% for all layers.
7. A method as recited in claim 5, wherein C is between 4000 and 6000.
8. A method as recited in claim 5, wherein C is ~ 5000.
9. A method as recited in claim 5, wherein uniform pitch strain is calculated to satisfy:
where: G1 is the elastomer layer shear modulus;
Gi-1 is the previous elastomer layer shear modulus (starting at the layer closest to the focal point);
R1 is the mean radius of the layer,
R1-1 is the mean radius of the previous layer (starting at the layer closest to the focal point), and φj = cosA j-(sinAj) + 2-cosA ^ - cosB j-(sinBj) - 2-cosB j where:
A1 is the Inner Angle and B1 is the outer angle. to produce a uniform fatigue life of each bearing layer.
10. A method as recited in claim 7, wherein the thickness of each layer is varied until the Pitch Strain (γe) is approximately 35% for all layers.
11. A method of calculating a uniform life for a spherical elastomeric bearing comprising the steps of:
1.) Determining Loads and Motions;
2.) Determining Fatigue Life Desired; 3.) Entering Bearing Dimensions;
4.) Entering Bearing Elastomer Material Properties;
5.) Calculating Geometries;
6.) Calculating Shape Factors Per Layer;
7.) Calculating Effective Compression Modulus (Ec) Per Layer; 8.) Calculating Radial And Axial Strains To Get Compression Shear
Strain Per Layer;
9.) Calculating Stiffnesses (Radial, Axial, Flapping, And Torsional Stiffnesses);
10.) Calculating Torsional Strain and add layers to achieve allowable torsional strain;
11.) Calculating the Shear Modulus to Achieve A Uniform Torsional Strain;
12.) Calculating a Flapping Strain;
13.) Calculating Shear Strain Allowable; 14.) Calculating Life; and
15.) Varying the Thicknesses Of Each Layer To Meet Shear Strain Allowable to Achieve Uniform Life.
12. A method as recited in claim 11, wherein said Determining Loads and Motions further comprise: a. Determine the axial load; b. Determine the radial load; c. Determine the vibratory pitch motion (theta) angle; d. Determine the flapping (cocking) motion angle.
13. A method as recited in claim 11, wherein said Entering Bearing Dimensions further comprise: a. Inner radius (Ri), Inner Angle (Bi), Inner Angle (Ai), Side Angle (Alpha); and Side Angle (Blpha); b. Enter Shim thickness.
14. A method as recited in claim 11, wherein said Entering Bearing Elastomer Material Properties further comprise: a. Entering Bulk modulus of elastomer, (Kb, psi); and b. Entering the fist layer shear modulus (G, psi).
15. A method as recited in claim 11, wherein said calculating radial and axial strains to obtain compression shear strain further comprises: a. changing a layer thickness to achieve allowable compression strain.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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EP08862065.3A EP2234881B1 (en) | 2007-12-19 | 2008-11-23 | Method of providing a uniform fatigue life spherical elastomeric bearing |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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US11/959,945 US8511997B2 (en) | 2007-12-19 | 2007-12-19 | Uniform fatigue life spherical elastomeric bearing |
US11/959,945 | 2007-12-19 |
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WO2009079164A2 true WO2009079164A2 (en) | 2009-06-25 |
WO2009079164A3 WO2009079164A3 (en) | 2009-10-22 |
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US (1) | US8511997B2 (en) |
EP (1) | EP2234881B1 (en) |
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Families Citing this family (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR101836992B1 (en) * | 2009-11-23 | 2018-03-09 | 로오드 코포레이션 | Elastomeric high capacity laminated rotary wing aircraft bearing for rotary wing aircraft |
US9327832B2 (en) | 2011-10-03 | 2016-05-03 | Bell Helicopter Textron Inc. | Elastomeric bearing with tapered shims |
US9657582B2 (en) | 2013-03-13 | 2017-05-23 | Bell Helicopter Textron Inc. | Gimbaled tail rotor hub with spherical elastomeric centrifugal force bearing for blade retention and pitch change articulation |
US9334048B2 (en) * | 2013-09-18 | 2016-05-10 | Bell Helicopter Textron Inc. | Elastomeric bearing having tapered layers |
US10214284B2 (en) * | 2013-09-30 | 2019-02-26 | Sikorsky Aircraft Corporation | Pitch bearing |
US9796469B2 (en) * | 2014-04-04 | 2017-10-24 | The Boeing Company | Modular rotor craft rotor hub system |
WO2016048783A1 (en) | 2014-09-22 | 2016-03-31 | Sikorsky Aircraft Corporation | Cylindrical elastomeric bearing with tapered shims |
FR3034400B1 (en) * | 2015-03-31 | 2018-05-25 | Hutchinson | DEVICE FOR AN AIRCRAFT WITH A ROTATING SAILBOAT PROVIDED TO PROVIDE INFORMATION RELATING TO THE FATIGUE DAMAGE LEVEL OF THIS DEVICE. |
US10161441B2 (en) * | 2016-11-01 | 2018-12-25 | Sikorsky Aircraft Corporation | Self-lubricated bearings |
DE102017206494A1 (en) | 2017-04-18 | 2017-06-14 | Carl Zeiss Smt Gmbh | Arrangement for mounting an optical element in a microlithographic projection exposure apparatus |
US10233992B2 (en) * | 2017-07-31 | 2019-03-19 | Aktiebolaget Skf | Elastomeric bearing component with wedge-shaped shims |
US11162553B2 (en) * | 2019-02-12 | 2021-11-02 | Deere & Company | Externally-damped electromechanical valve assemblies |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
USRE30262E (en) | 1971-05-27 | 1980-04-29 | Lord Corporation | Compressive load carrying bearings |
US4895354A (en) | 1985-05-13 | 1990-01-23 | United Technologies Corporation | Equalizing stress distribution in each laminate of an asymmetrically loaded elastomeric bearing |
US5601408A (en) | 1996-03-18 | 1997-02-11 | Sikorsky Aircraft Corporation | Axisymmetric elastomeric bearing assembly for helicopter rotors |
US20030235499A1 (en) | 2002-06-24 | 2003-12-25 | Schmaling David N. | Multi focus hemi-spherical elastic bearing |
Family Cites Families (33)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2066187A (en) * | 1933-09-21 | 1936-12-29 | Transit Res Corp | Spring device |
US2051864A (en) * | 1934-04-17 | 1936-08-25 | Harry A Knox | Suspension for vehicles |
DE680988C (en) | 1934-09-21 | 1939-09-13 | Getefo Ges Fuer Tech Fortschri | Elastic coupling |
US2127219A (en) * | 1935-02-21 | 1938-08-16 | Transit Res Corp | Spring |
US2069270A (en) * | 1935-05-23 | 1937-02-02 | Transit Res Corp | Elastic spring and method of making same |
US2068279A (en) * | 1935-05-27 | 1937-01-19 | Transit Res Corp | Elastic spring |
DE646964C (en) | 1935-10-10 | 1937-06-24 | Getefo Ges Fuer Tech Fortschri | Cushioning, especially for motor vehicles |
GB492517A (en) * | 1936-01-23 | 1938-09-21 | Max Goldschmidt | Improvements in and relating to springs comprising rubber and metal parts |
US2158028A (en) * | 1937-07-12 | 1939-05-09 | James P Burke | Spring |
US2149297A (en) * | 1937-09-20 | 1939-03-07 | Harry A Knox | Suspension for vehicles |
FR934336A (en) | 1946-09-25 | 1948-05-19 | Const Aeronautiques Du Ct Soc | Improvements made to the articulations of the blades of rotary lift wings and aircraft propellers |
GB828065A (en) | 1955-08-29 | 1960-02-17 | Joseph Ralph Holland | Improvements in or relating to resilient bushes |
US3216593A (en) * | 1962-07-06 | 1965-11-09 | Cellasto Inc | Draught gear for vehicles |
US3467353A (en) * | 1966-08-02 | 1969-09-16 | Lord Corp | Tube form mounting |
US3380557A (en) * | 1966-10-06 | 1968-04-30 | Gerald H. Peterson | Variable kinetic energy absorber |
US3700352A (en) * | 1971-03-05 | 1972-10-24 | Lord Corp | Rotor system |
US3679197A (en) * | 1971-05-27 | 1972-07-25 | Lord Corp | Compressive load carrying bearings |
US3759632A (en) * | 1972-07-05 | 1973-09-18 | United Aircraft Corp | Articulated helicopter rotor |
FR2497173A1 (en) * | 1980-12-26 | 1982-07-02 | Aerospatiale | LAMINATED SHOT OF CURVED SHAPE, IN PARTICULAR FOR ROTOR OF HELICOPTER |
US5092738A (en) * | 1990-04-06 | 1992-03-03 | United Technologies Corporation | Flexbeam helicopter rotor with improved snubber-vibration damper between the torque tube and the flexible spar member |
GB2250763B (en) * | 1990-12-13 | 1995-08-02 | Ltv Energy Prod Co | Riser tensioner system for use on offshore platforms using elastomeric pads or helical metal compression springs |
US5482406A (en) * | 1993-04-15 | 1996-01-09 | Continental Emsco Company | Variable spring rate compression element and riser tensioner system using the same |
US5641248A (en) * | 1993-04-15 | 1997-06-24 | Continental Emsco Company | Variable spring rate compression element and riser tensioner system using the same |
US5628586A (en) * | 1995-06-23 | 1997-05-13 | Continental Emsco Company | Elastomeric riser tensioner system |
US6803095B1 (en) * | 2000-09-28 | 2004-10-12 | Lord Corporation | Composite shims having a laminate structure |
US6481894B1 (en) * | 2001-02-23 | 2002-11-19 | Lord Corporation | Pitch bearing |
US6568906B2 (en) * | 2001-04-24 | 2003-05-27 | Sikorsky Aircraft Corporation | Conformal sliding bearing |
US6860015B2 (en) * | 2001-10-10 | 2005-03-01 | The Boeing Company | Method of forming opposing internally preloaded conical elastomeric bearing assembly |
US6889965B2 (en) * | 2001-10-10 | 2005-05-10 | The Boeing Company | Opposing conical preloaded elastomeric bearing assembly |
US6666648B2 (en) * | 2002-05-17 | 2003-12-23 | Sikorsky Aircraft Corporation | Directional elastomeric coupler |
US6695583B2 (en) * | 2002-05-30 | 2004-02-24 | Sikorsky Aircraft Corporation | Snubber-vibration damper system for a bearingless main rotor |
US6971853B2 (en) * | 2003-10-14 | 2005-12-06 | Barry Wright Corp. | Elastomeric bearing system |
US7097169B2 (en) * | 2004-08-04 | 2006-08-29 | Skf Usa Inc. | Elastomeric bearing with modified cylindrical core |
-
2007
- 2007-12-19 US US11/959,945 patent/US8511997B2/en active Active
-
2008
- 2008-11-23 WO PCT/US2008/084452 patent/WO2009079164A2/en active Application Filing
- 2008-11-23 EP EP08862065.3A patent/EP2234881B1/en active Active
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
USRE30262E (en) | 1971-05-27 | 1980-04-29 | Lord Corporation | Compressive load carrying bearings |
US4895354A (en) | 1985-05-13 | 1990-01-23 | United Technologies Corporation | Equalizing stress distribution in each laminate of an asymmetrically loaded elastomeric bearing |
US5601408A (en) | 1996-03-18 | 1997-02-11 | Sikorsky Aircraft Corporation | Axisymmetric elastomeric bearing assembly for helicopter rotors |
US20030235499A1 (en) | 2002-06-24 | 2003-12-25 | Schmaling David N. | Multi focus hemi-spherical elastic bearing |
Also Published As
Publication number | Publication date |
---|---|
WO2009079164A3 (en) | 2009-10-22 |
EP2234881B1 (en) | 2019-03-06 |
US8511997B2 (en) | 2013-08-20 |
EP2234881A2 (en) | 2010-10-06 |
EP2234881A4 (en) | 2017-05-24 |
US20090162201A1 (en) | 2009-06-25 |
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