Composite Elastic Torsion Element with Integrated Lead-Lag Hinge
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Solution Overview
Problem
Existing elastic torsion elements for connecting rotor blades to rotor hubs in rotary wing aircraft are complex, expensive, and require additional structures to prevent deformation, leading to high weight and low aerodynamic performance.
Innovation Solution
An elastic torsion element comprising two elastically deformable plates made of fiber-reinforced polymers with fibers oriented at specific angles to form an integrated lead-lag hinge, providing low lead-lag stiffness and high flapping stiffness, and featuring a U-shaped cross-section for reduced torsion resistance and buckling resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a torsion weak region with integrated lead-lag-soft region is arranged between the flapwise-soft region and rotor blade attachment, then lead-lag stiffness is reduced and flapping stiffness is increased, but the flexbeam element becomes complex and expensive to manufacture
Solution Approach 1:
The flexbeam is divided into distinct functional regions: a flapwise-soft region for flapping motion, a torsion weak region with integrated lead-lag-soft region for lead-lag motion, and a rotor blade attachment region. This segmentation allows each region to be optimized for its specific function while simplifying the overall manufacturing process by using standard composite beam techniques
Solution Approach 2:
The lead-lag-soft region is specifically positioned within the torsion weak region to provide localized lead-lag flexibility where needed, while maintaining high flapping stiffness in the flapwise-soft region. This local optimization allows the structure to have different stiffness characteristics in different directions without requiring complex overall geometry
2Reliability
If additional structures such as flap stops are added to prevent excessive deformation, then reliability is improved, but weight increases and manufacturing complexity increases
Solution Approach 1:
The integrated lead-lag-soft region within the torsion weak region provides inherent resistance to excessive deformation through its structural design, eliminating the need for additional flap stop structures. The region's geometry and material properties are optimized to naturally prevent buckling and excessive lead-lag motion under centrifugal and flapping loads
3Device complexity
If the lead-lag-soft region and torsion weak region are integrated, then device complexity is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The flexbeam is constructed using fiber-reinforced composite materials with fibers oriented in specific directions to achieve the desired anisotropic stiffness characteristics. The composite structure allows for precise control of mechanical properties through fiber placement, enabling the integrated lead-lag-soft region and torsion weak region to be manufactured as a single piece with controlled deformation behavior
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 solution allows for easy and cost-effective manufacturing of the elastic torsion element, reducing weight and improving aerodynamic performance by minimizing the need for additional structures and maintaining high resistance against buckling under flapping loads.
Implementation Method 1
two elastically deformable plates made of fiber-reinforced polymers
Implementation Method 2
Each one of the at least two elastically deformable plates comprises fiber reinforced polymers
Data Source
AI summary
An elastic torsion element for connecting a rotor blade to a rotor hub of a rotor, the elastic torsion element comprising at least two elastically deformable plates, wherein each one of the at least two elastically deformable plates comprises fiber reinforced polymers, wherein respective fibers of the fiber reinforced polymers of each one of the at least two elastically deformable plates are at least arranged along one of a first and a second dominant fiber directions, wherein the first dominant fiber direction crosses the second dominant fiber direction in a predetermined fiber direction crossing region, and wherein the elastic torsion element comprises an integrated elastic lead-lag hinge that is formed at the predetermined fiber direction crossing region.