Composite Yoke for Rotor Systems
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Solution Overview
Problem
The high manufacturing costs and complexity of producing composite yokes for rotor systems, particularly due to the need for belted-blade retention straps, which increase material count and construction time.
Innovation Solution
A broad goods composite yoke construction method that reduces material count and eliminates the need for straps by using fewer plies of material, with plies extending continuously across all arms to act as both uniply and crossply, and additional layers for reinforcement in specific areas, allowing for automated layup and autoclave curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional composite yoke construction with belted-blade retention straps is used, then structural strength and blade retention are improved, but manufacturing cost and construction complexity increase
Solution Approach 1:
The patent removes the belted-blade retention straps from the traditional composite yoke construction. The straps are extracted as a separate component and eliminated entirely, relying instead on the integrated ply structure to provide blade retention functionality through the broad goods construction method
Solution Approach 2:
The patent merges the blade retention function into the main yoke structure by using continuous plies that extend across all arms. The retention functionality is combined with the structural strength function in a single integrated construction rather than being separate components
2Strength
If traditional composite yoke construction with multiple straps and pieces is used, then structural integrity is improved, but material count and manufacturing time increase
Solution Approach 1:
The patent segments the yoke into three main arms (leading arm, trailing arm, and tip arm) that are formed simultaneously in a single autoclave cycle using the broad goods construction method, eliminating the need for separate assembly of multiple strap components
Solution Approach 2:
The patent performs preliminary action by pre-positioning all necessary plies in their final configuration before autoclave curing. The broad goods construction method allows all plies to be laid up in place beforehand, eliminating subsequent assembly steps and reducing manufacturing time
3Productivity
If broad goods construction with fewer plies is used, then manufacturing cost and time are reduced, but structural strength may be compromised
Solution Approach 1:
The patent applies local quality by varying the ply orientation and reinforcement strategically in different areas of the yoke. Specific plies are oriented to provide enhanced strength where needed, such as at stress concentration points, while using fewer plies in less critical areas to reduce overall material count and manufacturing time
Solution Approach 2:
The patent uses composite materials with optimized fiber orientations and material properties to achieve high strength with fewer plies. The broad goods construction method utilizes advanced composite material characteristics to maintain structural integrity while reducing the total number of layers required compared to traditional construction
Data Source
AI summary
According to one embodiment, a rotorcraft yoke comprises a plurality of arms. The plurality of arms, in combination, comprise a plurality of fibrous plies extending continuously throughout all of the plurality of arms.