Fibre-Reinforced Thermoplastic Sheath for Submarine Cable Buckling
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Solution Overview
Problem
Submarine power cables face challenges with buckling of water barrier sheaths and laminated metal sheath structures due to mechanical loads, leading to reduced operational lifetime and increased weight and handling difficulties.
Innovation Solution
A dynamic power cable design featuring a fibre reinforced thermoplastic composite sheath with wound fibres embedded in a polymer, which reduces buckling and enhances fatigue life, while also eliminating the need for additional armouring layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the thickness of the outer thermoplastic sheath or its polymer properties are increased to improve buckling resistance, then the buckling resistance is improved, but the cable becomes heavier and more difficult to handle
Solution Approach 1:
The patent applies composite materials by embedding wound fibres (such as glass fibres, carbon fibres, or aramid fibres) within the thermoplastic polymer matrix to create a fibre-reinforced composite sheath. This composite structure provides enhanced buckling resistance and mechanical strength without significantly increasing the sheath thickness or cable weight, as the high-strength fibres provide structural reinforcement efficiently.
Solution Approach 2:
The patent applies local quality by strategically placing wound fibres in specific orientations and densities within the thermoplastic sheath to provide localized reinforcement where buckling resistance is most needed. This allows the sheath to have varying mechanical properties in different regions, optimizing performance while minimizing overall weight increase.
2Strength
If the thickness of the inner thermoplastic core sheath is increased to improve buckling resistance of the LWS, then the buckling resistance is improved, but the cable diameter increases making it heavier and more difficult to handle
Solution Approach 1:
The patent applies composite materials in the inner thermoplastic core sheath by incorporating wound fibres within the polymer matrix. This composite construction enhances the buckling resistance of the longitudinally welded steel (LWS) water barrier without requiring an increase in sheath thickness, thereby maintaining a compact cable diameter.
Solution Approach 2:
The patent applies parameter changes by modifying the mechanical properties of the inner core sheath through fibre reinforcement, which alters the stiffness and strength parameters of the composite material. This allows the sheath to provide superior buckling resistance at the same thickness, avoiding cable diameter increase.
3Strength
If additional radial metallic armouring sheath is added underneath the outer thermoplastic sheath to prevent buckling, then the buckling resistance is improved, but the device complexity and handling difficulty increase
Solution Approach 1:
The patent replaces the traditional separate metallic armouring sheath with a fibre-reinforced thermoplastic composite sheath. This composite structure integrates the armouring function directly into the existing sheath layers, eliminating the need for additional separate components and simplifying the overall cable construction while maintaining buckling resistance.
Solution Approach 2:
The patent merges the armouring function with the existing thermoplastic sheath by embedding wound fibres within the polymer matrix. This integration combines the protective and structural functions into a single composite layer, reducing device complexity and eliminating the need for separate metallic armouring components.
4Power
If the power phase diameter is increased to deliver higher power, then the power transmission capacity is improved, but the cable becomes more prone to buckling during bending
Solution Approach 1:
The patent applies composite materials with wound fibres embedded in thermoplastic polymer to create a sheath with enhanced mechanical properties. This composite structure provides the necessary buckling resistance for larger diameter power phases, enabling higher power transmission capacity without compromising structural stability during bending and dynamic movements.
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 fibre reinforced thermoplastic composite sheath significantly improves the stiffness and fatigue life of submarine power cables, allowing for increased power phase diameter without buckling, and reduces the cable's weight and handling complexity.
Implementation Method 1
an inner thermoplastic composite core sheath arranged radially outside the water barrier sheath comprising wound fibres embedded in a thermoplastic polymer
Data Source
Figure 1~2
AI summary
The invention relates to dynamic power cables for submarine applications, wherein the dynamic power cable comprises at least one fibre reinforced thermoplastic composite sheath radially around a water barrier sheath providing reduced buckling of the water barrier sheath and wherein the at least one fibre reinforced thermoplastic composite sheath comprises wound fibres embedded in a thermoplastic polymer.