Composite Tube Connector Assembly With Distributed Clamping
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Solution Overview
Problem
Conventional methods for connecting composite fluid transfer conduits, such as aircraft fuel pipes, face issues with localized stresses due to the use of metal end fittings, 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 fibre redirecting members and a combination of circumferential and axial fibre reinforcement to distribute clamping forces evenly, reducing stress concentrations and enhancing the structural integrity of the connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional metal end fittings with flanges and bolts are used to connect composite tubular members, then secure connection is achieved, but localized stresses concentrate around bolts and at the join between flanges and conduit body
Solution Approach 1:
The patent replaces the conventional mechanical bolted flange connection system with a composite overclamp that applies distributed clamping force around the entire circumference of the tubular members. This substitution eliminates localized stress concentrations at bolt holes and flange joints by distributing the connecting force uniformly across the composite structure, while maintaining secure connection through the matched thermal expansion properties of the composite overclamp.
Solution Approach 2:
The patent employs composite materials for the overclamp that are specifically selected to match the thermal expansion properties of the tubular members being connected. This composite construction allows the overclamp to maintain consistent clamping force across temperature variations without creating thermal stress, while the composite structure itself distributes loads uniformly without the localized stress concentrations inherent in metal flange and bolt assemblies.
2Weight of moving object
If composite end fittings or flanges are formed to connect composite conduits, then weight savings are achieved, but large localized stresses occur around bolts and at the join between flanges and conduit body
Solution Approach 1:
The patent applies local quality by creating a tapered portion on the tubular members that concentrates the fibre reinforcement exactly where the overclamp applies clamping force. This localized fibre orientation change ensures that the composite structure has enhanced strength precisely at the connection zone without requiring heavy metal flanges, while the tapered geometry distributes the stress smoothly through the composite material rather than creating localized stress concentrations.
Solution Approach 2:
The patent uses composite materials throughout the connection assembly, including the overclamp and the tubular members with modified fibre reinforcement. This all-composite approach maintains weight savings while eliminating the localized stress problems associated with hybrid metal-composite flange connections, as the composite materials distribute loads uniformly and can be tailored to match thermal expansion properties.
3Strength
If fibre redirecting members are formed from hoop fibre to redirect axial fibre radially outwardly, then fibre strength is utilized effectively and structure is strengthened, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-forming the hoop fibre redirecting members and positioning them on the mandrel before laying the axial or helical fibre reinforcement. This sequence allows the hoop fibres to be cured in place first, creating a stable structural element that will reliably redirect the subsequent axial fibres radially outwardly. This preliminary positioning ensures proper fibre orientation for strength utilization while simplifying the overall manufacturing process compared to attempting to redirect fibres after complete assembly.
Data Source
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AI summary
From a first aspect of the present disclosure, there is provided a composite connector assembly 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 (10) with a clamping surface (16); and 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; wherein in each end portion, the at least one layer of axial or helical fibre is diverted radially outwards. The connector assembly can effectively and securely connect two composite tubular members without the use of conventional flanges or bolts. The assembly suffers fewer localised stresses and can thus form a secure connection between two composite tubes. Each end portion may have a fibre redirecting member formed underneath the axial or helical fibre which serves to divert the axial or helical fibre radially outwards. The fibre redirecting member may be formed from hoop fibre so as to build up a suitable profile before laying the axial or helical fibre over the top.