Flexible Composite Driveshaft Coupling With Sharp-Transition Diaphragms
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Solution Overview
Problem
Current composite driveshaft manufacturing methods are limited by the geometry of flexible elements, particularly in achieving small radius or sharp corner transitions, which restricts the design's ability to accommodate angular and axial misalignment and mass imbalance.
Innovation Solution
A method involving a mandrel with rigid and compressible elements is used, allowing for fiber placement with automated fiber placement (AFP) and a two-step curing process to form flexible composite driveshafts with sharp corner or small radius transitions by compressing fiber layers to conform to the mandrel's shape, eliminating the need for autoclaving.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If conventional composite manufacturing methods are used, then driveshaft strength and weight reduction are achieved, but the geometry of flexible elements is limited and cannot achieve small radius or sharp corner transitions
Solution Approach 1:
A mandrel is introduced as an intermediary tool with compressible material and rigid members that defines the desired final geometry. The mandrel enables AFP to produce complex shapes (small radius transitions, sharp corners) that would otherwise be impossible, while the mandrel itself is removed after curing. This resolves the contradiction by mediating between the AFP process limitations and the desired complex geometry.
Solution Approach 2:
The mandrel is prepared in advance with compressible material positioned at locations where small radius transitions are needed. Fiber tape is applied over this pre-prepared mandrel structure, allowing the complex geometry to be built in during the AFP process rather than requiring post-processing or complex tooling changes.
2Shape
If fiber tape is applied without selective curing, then complex geometries can be formed, but fiber breakage increases and manufacturing precision deteriorates
Solution Approach 1:
The curing process is applied periodically and selectively during the AFP operation. The laser cures fiber tape only in regions that do not require further deformation, while leaving regions over the compressible material uncured for subsequent shaping. This periodic, selective curing maintains manufacturing precision in cured regions while enabling geometry flexibility in uncured regions.
Solution Approach 2:
Different regions of the driveshaft receive different treatments: some regions are cured during AFP to maintain precision and structural integrity, while other regions remain uncured to allow for subsequent compression and shaping. This local differentiation of material properties resolves the contradiction between maintaining precision and forming complex geometries.
3Reliability
If autoclaving is used for curing, then complete curing is achieved, but the process time increases and productivity decreases
Solution Approach 1:
The traditional mechanical/thermal autoclaving system is replaced with an optical system (laser) for curing. The laser provides rapid, localized curing without requiring the lengthy autoclave process, thereby maintaining curing completeness while dramatically reducing cycle time and increasing productivity.
Solution Approach 2:
The curing process is rushed through by using laser irradiation that cures fiber tape almost instantaneously as the AFP head moves along the mandrel. This skips the time-consuming autoclave cycle while still achieving complete curing of the thermoplastic material through rapid thermal energy delivery.
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 method enables the production of driveshafts with increased bending flexibility and reduced weight, overcoming the limitations of existing AFP technology by allowing for complex geometries and minimizing fiber breakage.
Implementation Method 1
A plurality of strips of fiber tape are applied to a first longitudinally extending region of the mandrel adjacent to the one or more first and second rigid members using automated fiber placement with in-situ laser curing
Data Source
Figure 1~2
Figure 3
Figure 4~6
AI summary
A process for forming a flexible composite driveshaft includes providing a mandrel (10) having a rigid region and a compressible region, applying fiber tape (24) to the mandrel using automated fiber placement with in-situ laser curing in the rigid region and without in-situ laser curing the compressible region, and compressing the fiber tape and compressible material in the compressible region to form diaphragms that extend radially outward to a diameter that is at least twice the size of a diameter of the composite driveshaft in the rigid region.