Spherical Elastomeric Bearing Shim Thickness Optimization
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Solution Overview
Problem
Conventional spherical elastomeric bearing optimization methods focus solely on elastomeric layers and single thickness non-extensible metal shims, failing to achieve the smallest and lightest package that meets design life requirements effectively.
Innovation Solution
The design incorporates multiple shims of varying thicknesses between elastomeric layers, with a method to calculate nonresilient shim thicknesses to ensure equivalent stress across all shims, optimizing the bearing's geometry and weight by staggering elastomer layers and adjusting shim and elastomeric layer thicknesses to enhance axial load-carrying ability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If single thickness non-extensible metal shims are used throughout the entire bearing, then the structure is simple, but the axial load-carrying ability is not optimized and the bearing size/weight cannot be minimized
Solution Approach 1:
The patent applies local quality by varying the thickness of non-extensible shims at different locations within the elastomeric bearing. Specifically, shims have different thicknesses (first thickness for inner shims, second thickness for outer shims) to create localized stress distribution optimization. This allows each region of the bearing to have the specific shim thickness needed for optimal load-carrying performance in that location, resolving the contradiction between structural simplicity and load-carrying optimization.
2Weight of moving object
If elastomeric layers are optimized alone, then the design process is simple, but the overall bearing package size and weight cannot be minimized effectively
Solution Approach 1:
The patent segments the bearing into multiple distinct components with different properties: elastomeric layers with varying thicknesses, non-extensible shims with different thicknesses, and reinforcing elements. This segmentation allows independent optimization of each component's contribution to load-carrying ability while minimizing overall weight. The segmented approach enables the bearing to achieve minimum weight by carefully selecting the thickness and material properties of each segment, resolving the contradiction between weight minimization and design complexity.
Solution Approach 2:
The patent employs composite materials by combining elastomeric layers with non-extensible shims and reinforcing elements in a multi-layered structure. This composite construction allows the bearing to leverage the advantages of different materials: the flexibility and damping of elastomers combined with the stiffness and dimensional stability of non-extensible shims. The composite structure enables optimized weight and size by selecting appropriate material combinations and thicknesses for each layer, addressing the contradiction between weight minimization and design complexity.
3Stress or pressure
If uniform thickness shims are used, then manufacturing is simple, but equivalent stress distribution across all shims is not achieved
Solution Approach 1:
The patent applies local quality by specifying different thicknesses for shims at different locations: inner shims have a first thickness while outer shims have a second thickness. This localized variation in shim thickness is designed to achieve equivalent stress distribution across all shims under axial load. The different thicknesses compensate for the varying stress concentrations that occur in different regions of the bearing, ensuring uniform stress distribution while maintaining manufacturability through a limited set of discrete thickness values.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in a minimized and optimized spherical elastomeric bearing size and weight, with improved axial load-carrying capacity and multi-directional rotation performance, applicable in various applications including aerospace and heavy machinery.
Implementation Method 1
an elastomeric spherical bearing includes a multitude of shims, each of said multitude of shims mounted between at least two of the multiple of elastomeric layers
Implementation Method 2
determining a first thickness of a first of a multitude of nonresilient shim layers to satisfies a first set of criteria
Data Source
Figure 1
Figure 2A~2B
Figure 3~4
AI summary
An elastomeric spherical bearing (30) includes a multiple of shims (38), at least two of which have different thicknesses. In one exemplary embodiment, each of the shims (38) has a different thickness with a generally equivalent stress on each shim (38).