Dynamic Power Cable Copper-Nickel Water Barrier
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Solution Overview
Problem
Submarine power cables face fatigue issues due to mechanical loads from wave motions and underwater currents, leading to moisture ingress and failure, with existing solutions like corrugated copper alloys increasing manufacturing costs and complexity.
Innovation Solution
A dynamic power cable with a water barrier layer made from a copper-nickel alloy using autogenous welding techniques, which minimizes microstructure changes and geometrical distortions during welding, providing improved fatigue resistance and reduced thickness, thus lowering costs and increasing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a lead water barrier layer is used, then flexibility and ease of manufacture are improved, but fatigue resistance deteriorates
Solution Approach 1:
The patent changes the material parameters by transitioning from lead to copper-nickel alloy, fundamentally altering the material's mechanical properties to achieve both manufacturability and fatigue resistance in the water barrier layer
Solution Approach 2:
The patent uses a composite copper-nickel alloy material that combines the advantages of both copper (ductility, ease of welding) and nickel (fatigue resistance, strength) to resolve the contradiction between ease of manufacture and fatigue resistance
2Reliability
If a corrugated copper alloy water barrier layer is used, then fatigue resistance is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent changes the material composition parameters by using copper-nickel alloy with specific nickel content (10-30 wt%), which provides sufficient fatigue resistance without requiring corrugation, thereby simplifying the manufacturing process
Solution Approach 2:
The patent extracts the corrugation step from the manufacturing process by using a material (copper-nickel alloy) that inherently provides fatigue resistance, eliminating the need for this complex additional processing step
3Stability of the object's composition
If conventional welding is used on CuNi alloy, then water barrier layer continuity is improved, but microstructure changes and geometrical distortion increase
Solution Approach 1:
The patent replaces conventional thermal welding processes with friction stir welding, which uses mechanical friction and stirring action instead of heat to join the copper-nickel alloy, thereby avoiding microstructure changes and geometrical distortion while maintaining water barrier continuity
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 results in a fatigue-resistant water barrier layer with reduced thickness, lowering production costs and time, while maintaining high weld quality and integrity, effectively addressing the fatigue issues in submarine power cables.
Implementation Method 1
A water barrier layer comprising a CuNi alloy exhibits higher fatigue resistance from cyclical mechanical loads caused by wave motions and water currents
Implementation Method 2
a metallic sheet comprising a CuNi alloy is made into a water barrier layer by autogenous welding
Data Source
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AI summary
The present invention relates to a method of manufacturing a dynamic power cable (1) comprising the steps of; - providing a cable core (2) comprising; an electrical conductor (3) and an electrically insulating layer (4) arranged radially outside of the electrical conductor (3), - wrapping a metallic sheet (7) radially around the cable core (2), the metallic sheet (7) comprising a copper-nickel alloy, - welding (8) together opposing edges of the metallic sheet (7) to form a continuous water barrier layer (5) around the cable core (2), wherein - the welding (8) is performed by autogenous welding. Furthermore, the invention relates to a dynamic power cable manufactured according to such a method, and the use of autogenous welding to form a water barrier layer (5) in a dynamic power cable (1).