Composite Lobe Joint Drive Shaft Without Fastener Assembly
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Solution Overview
Problem
The challenge in manufacturing composite drive shafts for aircraft is to achieve a balance between weight efficiency and structural integrity while minimizing the use of fasteners, which adds weight and increases manufacturing complexity and cost.
Innovation Solution
The method involves using a removable mandrel with a lobe joint member and end flange assembly, applying composite materials via Automated Fiber Placement or Automated Tape Laying, and integrating lobe joint members into the composite drive shaft to eliminate the need for fasteners, allowing for efficient torque and axial force transmission without additional weight or complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If fasteners are used to join dissimilar materials in composite drive shafts, then structural integrity and load transfer are improved, but weight increases and manufacturing complexity increases
Solution Approach 1:
The lobe joint member is integrally formed with the composite shaft through automated fiber placement, merging the joint member and shaft into a single monolithic structure. This eliminates the need for separate fasteners while maintaining structural integrity and load transfer capabilities between dissimilar materials.
Solution Approach 2:
The invention extracts and eliminates the fastener component from the traditional joint assembly. By using an integral lobe joint member formed directly with the composite shaft, the fastener is removed entirely, reducing weight while preserving the structural function of connecting dissimilar materials.
2Strength
If fasteners are used to join components, then structural integrity is improved, but manufacturing time and complexity increase
Solution Approach 1:
The lobe joint member and composite shaft are formed as a single integrated component using automated fiber placement technology. This merging of components eliminates multiple manufacturing steps including drilling, countersinking, and fastener installation, significantly reducing manufacturing time while maintaining structural integrity.
Solution Approach 2:
The lobe joint member is formed integrally with the composite shaft during the initial manufacturing process rather than being assembled later. This preliminary formation of the joint structure eliminates subsequent assembly operations and reduces overall manufacturing time.
3Strength
If wall thickness is increased to improve structural integrity, then strength and stiffness are improved, but weight and cost increase
Solution Approach 1:
The lobe joint member features localized variations in material thickness and fiber orientation tailored to specific functional requirements. Material is concentrated at the lobes for torque transfer and at the flange for mounting, while other areas use thinner walls, optimizing the strength-to-weight ratio throughout the structure.
Solution Approach 2:
The lobe joint member employs asymmetric geometry with lobes and flanks of varying thicknesses oriented to match the directional load patterns. This asymmetric design places material strategically where stresses occur, improving structural integrity while minimizing unnecessary weight.
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
Methods of making composite drive shafts and manufacturing assemblies thereof are provided. The methods include providing a removable mandrel (412) having a cylindrical shape and assembling a lobe joint member (300) at an end thereof. The lobe joint member includes at least three lobes (310) equally distributed thereabout. A removable end flange (414) is assembled to the lobe joint member at an opposite end of the lobe joint member from the removable mandrel to form a manufacturing assembly. A composite material is applied to an exterior surface of the manufacturing assembly to form a composite tubular that includes the lobe joint member at an end thereof. The removable end flange is removed from the lobe joint member and the removable mandrel is removed from within the composite tubular to form a composite drive shaft comprising the composite tubular and the lobe joint member integrally formed at an end of the composite tubular.