Laminated Elastomeric Journal Bearing for Combined Rotor Loads
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Solution Overview
Problem
Existing rotary-wing aircraft rotor systems face challenges in managing in-plane lead and lag forces, which can cause high strains and cocking issues in journal bearings, particularly when subjected to both rotation and axial loads, leading to inefficiencies and increased aerodynamic drag.
Innovation Solution
The development of laminated elastomeric journal bearings with elliptical or spherical cross-sectional shapes, featuring alternating layers of elastomer and metal, which provide improved resistance to cocking and axial loads, allowing for reduced strain and a lower-profile, lighter-weight rotor configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional cylindrical journal bearings are used in rotor systems, then the structure is simple and easy to manufacture, but the bearings experience high strains and cocking issues when subjected to both rotation and axial loads
Solution Approach 1:
The patent employs a composite bearing structure consisting of a rigid outer cage made from durable material and flexible laminated elastomeric elements made from rubber or polymer material. This composite construction allows the rigid cage to maintain structural integrity under combined rotational and axial loads while the flexible elastomeric elements accommodate strain and prevent cocking, thereby resolving the contradiction between reliability under combined loads and structural simplicity.
Solution Approach 2:
The bearing is divided into distinct segments: a rigid outer cage structure and multiple flexible laminated elastomeric elements. This segmentation allows each component to perform its specialized function - the rigid cage handles structural support and load distribution while the flexible elements handle strain accommodation - thereby improving reliability without requiring a completely complex monolithic structure.
2Strength
If heavier and higher-profile rotor configurations are used, then the structural strength is increased, but the aerodynamic drag and aerodynamic signature are increased
Solution Approach 1:
The flexible laminated elastomeric elements act as thin, compliant structures that provide necessary structural flexibility and strain accommodation without adding significant weight or profile height. These thin flexible elements allow the rotor to maintain structural strength while minimizing aerodynamic drag and signature, as they do not require the heavy, bulky construction of traditional rigid bearings.
Solution Approach 2:
The patent changes the material parameters from rigid metals to flexible elastomers, allowing the bearing to deform elastically under load rather than requiring heavy structural support. This parameter change enables the rotor to maintain strength through material properties rather than increased mass or profile, thereby reducing aerodynamic drag.
3Force
If more parts are used in the rotor-hub assembly, then the load transmission capability is improved, but the device complexity and weight are increased
Solution Approach 1:
The patent merges the functions of load bearing, strain accommodation, and rotational support into a single integrated bearing assembly consisting of the outer cage and elastomeric elements. This unified structure eliminates the need for multiple separate components while maintaining superior load transmission capability, thereby resolving the contradiction between force transmission and device complexity.
Solution Approach 2:
The bearing assembly serves multiple functions simultaneously: it supports radial loads from rotation, accommodates axial loads from blade forces, and provides strain relief through elastomeric deformation. This multi-functionality allows a single bearing component to replace what would traditionally require multiple specialized parts, reducing overall complexity while improving load transmission.
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
These improved bearings enhance the ability to react in-plane loads, reduce aerodynamic signature, and enable more efficient transmission of loads, resulting in a more stable and efficient rotor-hub assembly with a lower parts count.
Implementation Method 1
alternating layers of elastomer and metal located between the inner sleeve and the outer sleeve... improved resistance to cocking and axial loads... ability to react in-plane loads
Data Source
AI summary
A laminated elastomeric journal bearing has an outer sleeve having an inner surface, at least a portion of each end of the inner surface being a concave surface of revolution, and an inner sleeve having an outer surface, at least a portion of each end of the outer surface being a convex surface of revolution. Alternating layers of elastomer and metal are located between the sleeves, with adjacent surfaces of the layers and the sleeves being adhered to each other.