Modular Rotor Hub Discrete Elastomeric Bearings
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Solution Overview
Problem
Existing fully articulated rotor hub systems face challenges in accommodating high-frequency and high-amplitude oscillatory motion under high thrust loading, with non-friction and strap pack systems requiring frequent maintenance, being difficult to detect failures, and having low damage tolerance, while elastomeric bearings require significant design and analysis efforts for implementation.
Innovation Solution
A modular rotor hub system with fully articulated rotor arm assemblies featuring discrete elastomeric bearings for each degree of freedom, including pitch and flap bearings, which facilitate movement about multiple axes without relying on a single bearing element, allowing for easier maintenance and reduced complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If non-friction bearing systems (ball or roller bearings) are used, then rotational freedom is provided, but lubricants and seals are susceptible to moisture extrusion and leakage requiring frequent maintenance
Solution Approach 1:
The patent replaces traditional friction-based ball or roller bearing systems with an elastomeric bearing system that uses elastic deformation to accommodate rotational movements. This substitution eliminates the need for lubricants and seals, thereby eliminating moisture extrusion and leakage issues that require frequent maintenance.
Solution Approach 2:
The patent changes the fundamental operating parameter from friction-based contact (ball/roller bearings) to elastic deformation (elastomeric bearings). This parameter change allows the bearing to accommodate high-frequency and high-amplitude oscillatory motion through material elasticity rather than mechanical contact, improving reliability under high thrust loading.
2Ease of operation
If strap pack hub systems are used, then rotational freedom is accommodated, but severe and complicated loadings result in strict damage criteria and frequent replacement
Solution Approach 1:
The patent employs composite material construction for the elastomeric bearings, combining multiple material properties to achieve both flexibility for rotational movement and high damage tolerance. The elastomeric material itself provides inherent damping and stress distribution capabilities that prevent the severe stress concentrations experienced by strap pack systems.
Solution Approach 2:
The patent changes the structural approach from rigid strap pack construction to flexible elastomeric construction. This allows the bearing to accommodate complicated loadings through elastic deformation rather than rigid stress transfer, significantly improving damage tolerance and reducing replacement frequency.
3Weight of moving object
If spherical elastomeric bearings are used to consolidate flap and pitch motions, then weight is eliminated and maintenance is minimized, but dynamic qualities require careful modeling and control increasing design complexity
Solution Approach 1:
The patent divides the bearing system into discrete elastomeric bearings for each degree of freedom (flap, lead-lag, and pitch) rather than using a consolidated spherical bearing. This segmentation simplifies the dynamic modeling and control requirements while maintaining the weight and maintenance advantages of elastomeric materials.
Solution Approach 2:
The patent changes from a consolidated spherical bearing design to discrete elastomeric bearings for each motion degree. This parameter change reduces the complexity of dynamic modeling and control while preserving the benefits of eliminated lubrication and minimized maintenance.
4Ease of operation
If non-friction and strap pack hub systems are used, then rotational freedom is provided, but failure detection is difficult and damage tolerance is low leading to aircraft damage or failure
Solution Approach 1:
The patent incorporates visual indicators (such as color-coded elements or visible wear indicators) into the elastomeric bearing system that change appearance when the bearing approaches failure or experiences abnormal conditions. This makes failure detection straightforward and immediate, unlike the difficult-to-detect failures in non-friction and strap pack systems.
Solution Approach 2:
The elastomeric bearing system provides self-diagnostic capabilities through its inherent material properties and integrated indicators, allowing the system to communicate its own status and potential failures without requiring complex external monitoring systems.
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
The modular system provides improved dynamic stability, reduced maintenance needs, and cost-effectiveness by using common aerospace materials, with elastomeric bearings that can handle high loads and are easier to detect for failure, thus enhancing the reliability and efficiency of rotor hub systems.
Implementation Method 1
The plurality of bearings are elastomeric bearings configured to facilitate movement of the rotor arm assembly about a plurality of degrees of freedom
Implementation Method 2
high thrust loading created by the centrifugal force of the rotating blades
Data Source
AI summary
A rotor arm assembly for use in a rotor craft rotor hub system includes a pitch shaft and a plurality of discrete bearings coupled to the pitch shaft. The plurality of bearings are elastomeric bearings configured to facilitate movement of the rotor arm assembly about a plurality of degrees of freedom. A respective one of the plurality of bearings is configured to accommodate a single degree of freedom.