Spherical Elastomeric Bearing Uniform Fatigue Life Design
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Solution Overview
Problem
Conventional elastomeric bearing designs do not account for coupled load and motion, leading to non-uniform fatigue life across layers and inefficient bearing performance, as they primarily focus on single motion strain without considering additional motion strains and fatigue damage.
Innovation Solution
The design involves multiple elastomeric layers with adjustable thickness to achieve uniform fatigue life, calculated using specific equations that account for pitch, flap, and shear strains, ensuring each layer has an equivalent fatigue life by varying the shear modulus and layer thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional elastomeric bearing design methodology is used focusing on single motion strain, then the bearing can be designed with simpler calculation, but the bearing does not provide uniform life at each layer and results in inefficient elastomeric bearing
Solution Approach 1:
The patent applies local quality by making each elastomeric layer have different thickness to achieve uniform fatigue life distribution. The thickness of each layer is specifically adjusted based on its position and the strain it experiences, so that although the layers are not identical, each contributes equally to the overall bearing life. This resolves the contradiction by accepting increased design complexity in exchange for achieving uniform reliability across all layers.
Solution Approach 2:
The patent changes the thickness parameter of each elastomeric layer to optimize fatigue life uniformity. By adjusting the thickness parameter of individual layers based on calculated strain distributions and fatigue considerations, the design achieves uniform life across layers. This parameter optimization approach resolves the contradiction between simple design and uniform reliability by systematically modifying layer parameters.
2Adaptability or versatility
If the bearing is designed to accommodate multi-directional displacement with coupled load and motion, then the bearing performance is improved, but the design and calculation become more complex requiring consideration of additional motion strains and fatigue damage
Solution Approach 1:
The patent segments the bearing into multiple elastomeric layers, each experiencing different strain conditions due to multi-directional displacement. By dividing the bearing into discrete layers, the complex coupled load and motion effects can be analyzed separately for each layer, then combined to determine overall bearing behavior. This segmentation approach manages the complexity of multi-directional displacement accommodation.
Solution Approach 2:
The patent addresses multi-directional displacement by considering strain in multiple dimensions and directions simultaneously. The design methodology calculates pitch strain, flap strain, and their coupled effects, adding dimensional complexity to the analysis. This multi-dimensional approach enables the bearing to accommodate complex motion while systematically managing the calculation complexity through structured analysis methods.
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 spherical elastomeric bearing with uniform fatigue life across all layers, enhancing the efficiency and performance of the bearing by accommodating multi-directional displacement and reducing the risk of premature wear.
Implementation Method 1
elastomeric spherical bearing includes a multiple of elastomeric layers
Implementation Method 2
adjusting each layer thickness to produce a uniform fatigue life of each bearing layer
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
An elastomeric spherical bearing includes a multiple of elastomeric layers with an essentially equivalent fatigue life.