Composite Tube Connector Assembly for Low-Stress Sealed Joints
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Solution Overview
Problem
Conventional methods for connecting composite fluid transfer conduits, such as those used in aerospace, often result in high localized stresses due to the use of metal end fittings and bolts, which are not suitable for composite materials, leading to inefficiencies in fluid flow and potential leakage.
Innovation Solution
A composite connector assembly that securely connects two composite tubular members without conventional flanges or bolts, utilizing a fibre redirecting member to redirect axial or helical fibres radially outward, combined with a tapered clamping surface and an overclamp, to distribute clamping forces effectively and reduce stress concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional metal end fittings and bolts are used to connect composite conduits, then the connection can be secured, but large localized stresses occur around the bolts and at the join between flanges and conduit body
Solution Approach 1:
The invention extracts and eliminates the conventional metal flange and bolt components from the connection system. Instead, it uses a continuous composite tube design with integrated clamping surfaces that distribute loads along the tube length, removing the sources of localized stress concentrations that occur with discrete fastening elements.
Solution Approach 2:
The invention incorporates clamping surfaces directly into the tube structure during manufacturing, before assembly. The axial fibres are oriented to provide clamping force along the length of the tube, pre-establishing the load distribution mechanism that prevents localized stress during operation.
2Strength
If metal end fittings are used for connection, then secure joining is achieved, but the overall weight of the conduit system increases
Solution Approach 1:
The invention uses homogeneous composite material throughout the entire conduit system, including the connection sections. The tubes are made from the same fibre-reinforced polymer material with consistent fibre orientation, eliminating the need for dissimilar metal fastening components and reducing overall system weight while maintaining connection strength.
Solution Approach 2:
The invention employs composite materials with specific fibre orientations (including axial fibres for clamping and hoop fibres for circumferential strength) to create lightweight yet strong connection structures that replace heavier metal alternatives, achieving weight reduction without sacrificing connection integrity.
3Weight of moving object
If composite end fittings are formed to replace metal, then weight is reduced, but large localized stresses occur and the approach is not suited for composite materials
Solution Approach 1:
The invention applies different fibre orientations in different regions of the tube to address local requirements: axial fibres are used in connection sections to provide clamping force and distribute loads along the length, while hoop fibres provide circumferential strength. This localized fibre orientation strategy prevents stress concentrations while maintaining lightweight composite construction.
Solution Approach 2:
The clamping surfaces and fibre reinforcement are integrated into the tube structure during the manufacturing process, before assembly. This preliminary integration ensures that load distribution mechanisms are built-in from the start, preventing localized stress development during service rather than attempting to address it through separate fastening components.
Data Source
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AI summary
A composite connector assembly 2 is provided comprising first and second tubular members 4, 6, each constructed from fibre-reinforced polymer and each comprising at least one layer of axial or helical fibre 26 and each comprising an end portion 8 with a clamping surface; an overclamp 27, which is arranged to at least partially enclose the end portions of the first and second tubular members and to apply a clamping force to the clamping surfaces so as to connect and hold the first and second tubular members together; and an elastomer O-ring 22 positioned between the first and second tubular members in a circumferential groove 20 cut into a facing surface 18 of one or both end portions. In each end portion, the at least one layer of axial or helical fibre is diverted radially outwards.