Back to results
US 8,275,585 B2Granted
Spherical elastomeric bearing with improved shim thickness
AssigneeSikorsky Aircraft Corporation
InventorsRobert Cunningham, Francis Edward Byrnes
Life of this patent
Estimating the term…
Abstract
An elastomeric spherical bearing includes a multiple of shims, at least two of which have different thicknesses. In one exemplary embodiment, each of the shims has a different thickness with an essentially equivalent stress on each shim.
Claims8
A method of calculating a nonresilient shim thickness for a spherical elastomeric bearing comprising:
- determining a first thickness of a first of a multitude of nonresilient shim layers to satisfies a first set of criteria;
- determining a second thickness of a second of the multitude of nonresilient shim layers outboard of the first of the multitude of nonresilient shim layers to satisfies a second set of criteria, the second thickness different than the first thickness to produce a spherical elastomeric bearing generating an essentially equivalent stress to each nonresilient shim layer.
A method of calculating a nonresilient shim layer thickness for a spherical elastomeric bearing comprising:
- determining a first shim thickness of a first of a multitude of nonresilient shim layers in the spherical elastomeric bearing, each of the multitude of nonresilient shim layers sandwiched between a first pair of elastomeric layers;
- determining a elastomeric layer thickness for the first pair of elastomeric layers;
- and
- modifying the first shim thickness and the elastomeric layer thickness in response to an addition of a second a of the multitude of nonresilient shim layers and a second pair of elastomeric layers outboard of the first of the multitude of nonresilient shim layers and the first pair of elastomeric layers, the modifying continuing until each of the multitude of nonresilient shim layers have an essentially equivalent stress.
1 more element
A method of calculating a nonresilient shim thickness for a spherical elastomeric bearing comprising:
- determining a first thickness of a first of a multitude of nonresilient shim layers to satisfies a first set of criteria;
- determining a second thickness of a second of the multitude of nonresilient shim layers outboard of the first of the multitude of nonresilient shim layers to satisfies a second set of criteria, the second thickness different than the first thickness;
- adjusting the shim hoop stress for each of the multitude of nonresilient shim layers to satisfy:
- σ
- θ
- =
- 4
- ·
- (
- B
- I
- -
- (
- B
- o
- -
- β
- )
- )
- ·
- (
- γ
- a
- +
- γ
- r
- )
- ·
- G
- ·
- D
- ·
- π
- ·
- E
- ·
- cos
-
- (
- B
- s
- )
- ·
- R
- s
- 1800
- ·
- T
- e
- ·
- R
- s
- ·
- sin
-
- (
- B
- s
- )
- ·
- N
- s
- ·
- T
- (
- T
- T
- N
- s
- +
- 1
- )
- ·
- T
- T
- N
- s
- ·
- T
- ^
- s
- +
- T
- T
- ·
- [
- [
- E
- ·
- T
- s
-
- [
- cos
-
- (
- B
- s
- )
- ]
- 2
- 4
- ·
- E
- ·
- T
- s
- 3
- 12
- ·
- (
- 1
- -
- μ
- 2
- )
- ·
- [
- R
- s
- ·
- sin
-
- (
- B
- s
- )
- ]
- 2
- ]
- 1
- /
- 4
- ]
- -
- 3
- to produce a spherical elastomeric bearing which generates an essentially equivalent stress to each nonresilient shim layer,
- where:
- T
- ^
- e
- =
- Average
-
-
- Elastomer
-
-
- Thickness
-
-
- (
- T
- i
- +
- T
- i
- +
- 1
- )
- 2
-
- (
- in
- )
- Ts=Shim Thickness Tsj (in)
- {circumflex over (T)}s=Average Shim Thickness (in)
- μ=Shim Poison Ratio
- E=Shim Modulus of Elasticity (psi)
- Rs=Shim Median Spherical Radius Rj (in)
- G
- =
-
- Average
-
-
- Elastomer
-
-
- Shear
-
-
- Modulus
-
-
- (
- G
- i
- +
- G
- i
- +
- 1
- )
- 2
-
- (
- psi
- )
- BI=Bearing Inner Wrap Angle (deg)
- Bo=Bearing Outer Wrap Angle (deg)
- Ns=Total Number of Shims
- Bs=Outer Wrap Around Angle of Shim Bsj (deg)
- D=Shim Bending Stiffness Term (lb-in)
- BET=Shim Geometric Stiffness Term (in)
- γ=Average Elastomer Compression Induced Shear Strain (in/in)/100
- TT=Total Bearing Elastomer Thickness (in)
- Q=Averaging Coefficient of Bearing (non-dimensional)
- ν=Averaging Coefficient of Elastomer To Shim Context (non-dimensional)
- LL=Unsupported Spherical Arc of Shim LLi (see FIG. 4)
- YY=Radial Deflection of Shim YYi (see FIG. 4)
- σθ=Shim Hoop Stress σθi (psi)
- DP=Differential Resultant Pressure Load On Unsupported Spherical Arc of Shim LLi
- Tc=Axial Compressive Load (lb)
- θ=Torsional Motion Angle (deg))
- β=Cocking Motion Angle (deg)
- Tc·sin·β=Radial Load (lb)
- RI=Bearing Inner Radius (in)
- Ro=Bearing Outer Radius (in)
- Tei=Elastomer Thickness (in)
- α=Bearing Outer Taper Angle (deg).
218 more elements
Dependencies are inferred from the claim text.