Composite Drive Shaft Web Structure for Torsional Stiffness and Flexibility
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Solution Overview
Problem
Conventional drive shafts face a dilemma in needing to be both stiff and strong under torque while also being flexible under axial and bending deformations, which is typically achieved with metallic couplings and cylindrical shafts, resulting in high costs and weight due to the requirement for high-precision fabrication and high-quality control of metallic components.
Innovation Solution
A composite drive shaft design featuring a hollow shaft formed by a plurality of composite elements arranged at offset angles to create a web structure that allows flexibility under bending and axial loads while maintaining stiffness under rotational loads, utilizing fiber-reinforced polymer-matrix composites with undulations and axial/circumferential reinforcement, and a method of manufacturing involving automated fiber placement and washable mandrels to reduce costs and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If metallic couplings and cylindrical shafts are used to achieve flexibility under bending and axial loads, then the drive shaft can compensate for lateral and axial movements, but the manufacturing cost and weight increase due to high-precision fabrication requirements
Solution Approach 1:
The patent applies composite materials by using a composite shaft body made of fiber-reinforced polymer matrix composite material with spiral wound fibers, replacing the traditional metallic shaft body and coupling system. This composite construction provides the necessary flexibility under bending and axial loads while significantly reducing the overall weight of the drive shaft system compared to metallic alternatives.
Solution Approach 2:
The patent changes the structural parameters of the shaft body by introducing spiral wound fiber reinforcement at specific angles, creating a web-like internal structure that provides controlled flexibility. The spiral winding pattern and fiber orientation are optimized to achieve the desired balance between flexibility for movement compensation and weight reduction, eliminating the need for heavy metallic couplings.
2Ease of operation
If metallic couplings with high-precision fabrication are used to provide flexibility, then the drive shaft can accommodate shaft movements, but the manufacturing cost increases due to high-quality control requirements
Solution Approach 1:
The composite shaft body with spiral wound fiber reinforcement eliminates the need for separate metallic couplings and their associated high-precision machining and quality control processes. The composite structure is manufactured through winding and curing processes that are inherently more tolerant of variations, reducing both manufacturing cost and quality control complexity while maintaining the necessary flexibility.
Solution Approach 2:
The patent merges the functions of the shaft body and the coupling into a single integrated composite structure. The spiral wound fiber reinforcement within the composite shaft body provides the flexibility function previously requiring separate metallic couplings, simplifying the manufacturing process and eliminating the need for high-precision fabrication and assembly of multiple components.
3Strength
If a hollow cylindrical shaft with constant cross-section is used, then the shaft can provide torsional load transfer, but it cannot provide flexibility under bending and axial deformations
Solution Approach 1:
The patent uses composite materials with spiral wound fiber reinforcement to create a shaft body that simultaneously provides torsional strength and flexibility. The fiber orientation and composite construction allow the shaft to maintain rigidity for torsional load transfer while incorporating controlled flexibility for bending and axial deformations through the spiral web structure.
Solution Approach 2:
The patent applies local quality by varying the fiber reinforcement pattern and density in different regions of the shaft body. The spiral wound fibers are configured to provide enhanced torsional strength where needed while allowing flexibility in regions that accommodate bending and axial movements, creating a non-uniform internal structure optimized for multiple functional requirements.
4Weight of stationary object
If fiber-reinforced polymer-matrix composite materials are used, then the shaft weight can be reduced, but the manufacturing process becomes more complex
Solution Approach 1:
The patent applies preliminary action by pre-orienting and pre-positioning the fiber reinforcement in the desired spiral pattern before the curing process. This preliminary configuration of the fiber architecture ensures that the weight reduction benefits of composite materials are achieved while simplifying the manufacturing process, as the complex fiber orientation is established during the winding process rather than requiring post-manufacturing adjustments.
Data Source
Figure 1~2
Figure 3
Figure 4A~4B
AI summary
In accordance with at least one aspect of this disclosure, a composite shaft includes a plurality of composite elements (101) arranged about an axis to form a hollow shaft (100) with at least one undulation. The plurality of composite elements incudes a first group (102) of the composite elements arranged about the axis offset by an angle +α and a second group (104) of the composite elements arranged about the axis offset by an angle -α to form a web with the first group of composite elements. The first and second groups of the plurality of composite elements are configured to cooperate with one another to allow the hollow shaft to be flexible under axial load and stiff under rotational load.