Interlocking Diaphragm Coupler Structure for Crack-Resistant Drive Shafts
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Solution Overview
Problem
Existing flexible diaphragm couplers in drive shafts connecting an engine to a tail rotor in rotary wing aircraft suffer from fractures and wear in mechanical fasteners or welds due to operational stresses, leading to potential failure and requiring high-quality welds with additional costs and labor.
Innovation Solution
A flexible diaphragm coupler design featuring interlock elements with curvilinear, sawtooth, or semi-circular profiles and cylindrical inserts that form non-linear interfaces, inhibiting crack propagation and enhancing damage tolerance through welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If mechanical fasteners are used to join central hubs and annular plates, then assembly is simplified, but fractures occur in the fasteners over time leading to diaphragm failure
Solution Approach 1:
The patent removes mechanical fasteners from the design entirely, extracting the problematic component that caused fractures. The central hubs and annular plates are joined directly through welding without intermediate fasteners, eliminating the source of mechanical failure while maintaining assembly simplicity through direct welding procedures.
Solution Approach 2:
The patent replaces the mechanical fastening system with a welding-based joining system. Instead of using mechanical fasteners that are susceptible to fracture, the design employs welds to create a permanent, integrated connection between components, substituting mechanical assembly with metallurgical bonding.
2Strength
If welds are used to join central hubs and annular edges, then structural integrity is improved, but welds experience wear and crack propagation over time requiring exceptional weld quality
Solution Approach 1:
The patent divides the weld joint into multiple discrete weld locations rather than requiring continuous exceptional-quality welds. By segmenting the connection into multiple weld points, the design reduces the cumulative stress on any single weld and provides multiple load paths, improving overall joint reliability.
Solution Approach 2:
The patent incorporates design features that cushion and distribute operational stresses before they reach the weld joints. The diaphragm structure and connection geometry are designed to minimize stress concentration at weld locations, providing protective stress distribution that reduces wear and crack initiation in the welds.
3Ease of manufacture
If traditional diaphragm design is used, then manufacturing is simpler, but damage tolerance and crack resistance are insufficient under operational stresses
Solution Approach 1:
The patent incorporates curved and contoured surfaces in the diaphragm design, including curved connection surfaces and contoured diaphragm elements. These curved geometries distribute stresses more evenly throughout the structure, preventing stress concentration that leads to crack initiation, while the curvature is achieved through standard forming processes.
Solution Approach 2:
The patent employs a composite construction combining multiple metallic components (central hubs, annular plates, diaphragm elements) that are welded together to create a composite structure with enhanced damage tolerance. The combination of different structural elements creates a system that is more resistant to crack propagation than any single component alone.
Data Source
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AI summary
A flexible diaphragm coupler (52) includes a first flange (60) having a central support (67) and a first flange element (69) extending radially outwardly from the central support. The flange element includes a rim portion (76) having an axially facing surface (78). The axially facing surface includes a plurality of interlock elements (154). A diaphragm member (64) is disposed between the first flange (60) and the second flange (62). The diaphragm member (64) includes a diaphragm element (114). The diaphragm element includes a central support element (118) and a disc member (120) extending radially outwardly from the central support element. The disc member (120) includes a rim element (142) having an axially facing surface portion including a plurality of interlock members (154) that connect with the plurality of interlock elements (84).