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US 8,911,153 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 a generally equivalent stress on each shim.
Claims7
An elastomeric spherical bearing comprising:
- a multitude of elastomeric layers defined about a bearing focal point;
- and
- a multitude of shims, each of said multitude of shims mounted between at least two of said multiple of elastomeric layers, a first shim of said multitude of shims having a first thickness and
- a second shim of said multitude of shims having a second thickness, said second thickness different than said first thickness such that said first and second shims are subject to substantially the same stress 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
- where:
- {circumflex over (T)}e=Average Elastomer Thickness
- (
- T
- i
- +
- T
- i
- +
- 1
- )
- 2
- (in)
- Ts=Shim Thickness Tsj (in)
- T{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)
- υ=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).
186 more elements
An elastomeric spherical bearing comprising:
- a multitude of elastomeric layers defined about a bearing focal point;
- and
- a multitude of shims, each of said multitude of shims mounted between at least two of said multiple of elastomeric layers, a first shim of said multitude of shims having a first thickness and
- a second shim of said multitude of shims having a second thickness, said second thickness different than said first thickness, wherein said multitude of shims are arranged relative to said bearing focal point such that each of said multitude of shims increase in thickness relative an adjacent inboard shim.
1 more element
Dependencies are inferred from the claim text.