3D Composite Tubular Structure for Delamination-Resistant Risers
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Solution Overview
Problem
Composite tubular elements used in subsea environments, such as risers and pipes, suffer from delamination phenomena, which limit their mechanical resistance and lead to failure, especially under mixed mode I-II loading conditions, with local toughening providing only incremental improvements.
Innovation Solution
A composite tubular structure is developed with first and second fibers oriented in the x and y directions, respectively, and third fibers extending through the wall thickness, embedded in a first thermoplastic polymer to consolidate the structure and a second polymer to fill porosity, enhancing adhesion and resistance to delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional composite tubular elements with layered fiber structures are used, then manufacturing complexity is reduced and ease of manufacture is improved, but delamination phenomena occur under mixed mode I-II loading conditions, limiting mechanical resistance and leading to failure
Solution Approach 1:
The patent transitions from a two-dimensional layered fiber structure to a three-dimensional tubular structure by adding fibers extending through the wall thickness. This dimensional enhancement creates interlayer connections that prevent delamination under mixed mode loading conditions, directly resolving the contradiction between maintaining ease of manufacture and improving resistance to delamination.
Solution Approach 2:
The patent employs a composite structure combining fibers oriented in multiple directions (circumferential, longitudinal, and radial) within a matrix material. This multi-directional fiber arrangement creates a more robust composite material that resists delamination while maintaining structural integrity under various loading conditions.
2Reliability
If fibers are added to extend through the wall thickness to prevent delamination, then resistance to delamination is improved, but structural complexity increases
Solution Approach 1:
The patent integrates radial fibers extending through the wall thickness into the manufacturing process rather than adding them as a separate complex assembly step. The fibers are incorporated during the forming process, allowing the three-dimensional structure to be created in a single operation, thus minimizing the increase in device complexity while achieving improved reliability.
3Strength
If local toughening is applied to improve resistance to delamination, then mechanical resistance is incrementally improved, but the overall structural integrity remains limited under mixed mode loading
Solution Approach 1:
The patent divides the fiber reinforcement into multiple directional components: circumferential fibers for hoop strength, longitudinal fibers for axial strength, and radial fibers for interlayer bonding. This segmentation of reinforcement functions throughout the wall thickness provides comprehensive protection against delamination and maintains overall structural integrity under mixed mode loading conditions.
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 solution provides strong adhesion across the tubular element's cross-section, significantly improving resistance to delamination and crack propagation under stress, reducing the risk of failure and allowing for simpler load transfer structures and smaller buoyancy devices, thus lowering costs.
Implementation Method 1
a first thermoplastic polymer arranged to further embed the fibres of the tubular structure and thereby consolidate the tubular structure
Implementation Method 2
The solution provides strong adhesion across the tubular element's cross-section, significantly improving resistance to delamination
Implementation Method 3
a second polymer arranged to fill residual porosity of the tubular structure and thereby form the tubular element
Data Source
Figure 1
Figure 2
Figure 3A~4
AI summary
The present invention relates to tubular structures for use in a subsea environment. More particularly, the invention relates to composite tubular structures for use in the oil and gas industry, such as production risers, and a method of manufacturing the same.