Two-Layer Cable Water Barrier for Buckling and Fatigue Resistance
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Solution Overview
Problem
Current water barriers for submarine power cables, primarily made of lead, are heavy, costly, and environmentally hazardous, with low fatigue resistance, making them unsuitable for dynamic applications.
Innovation Solution
A lightweight, lead-free water barrier comprising an inner layer of metal foil with an elastic modulus lower than 210 GPa, an intermediate adhesive layer, and an outer layer of polyethylene-based semi-conducting polymer, providing mechanical reinforcement and fatigue resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lead is used as water barrier material, then reliability and sturdiness are improved, but weight increases significantly and environmental harm worsens
Solution Approach 1:
The patent applies composite materials by combining aluminum foil (inner layer) with polyethylene polymer (outer layer) to create a water barrier that maintains reliability while reducing weight. The aluminum foil provides the necessary barrier properties, while the polyethylene layer provides mechanical protection, together achieving comparable or superior performance to lead with significantly reduced density and weight.
2Reliability
If lead is used as water barrier material, then water barrier function is achieved, but fatigue resistance deteriorates
Solution Approach 1:
The composite structure of aluminum foil surrounded by polyethylene provides both the water barrier function and enhanced fatigue resistance. The polyethylene layer acts as a protective jacket that absorbs mechanical stresses and prevents fatigue failure, while the aluminum foil maintains the water barrier integrity, together achieving superior fatigue resistance compared to lead alone.
3Strength
If lead is used as water barrier material, then mechanical protection is provided, but environmental harm increases
Solution Approach 1:
The patent changes the material parameter from lead to lead-free alternatives (aluminum and polyethylene), maintaining the necessary mechanical protection properties while eliminating the environmental harm associated with lead. The aluminum foil provides the required mechanical strength and barrier properties without the toxic characteristics of lead.
4Weight of moving object
If lead-free metal foil with low elastic modulus is used, then weight is reduced and flexibility is improved, but mechanical reinforcement is insufficient
Solution Approach 1:
The patent resolves this contradiction by creating a composite structure where the lightweight aluminum foil (low elastic modulus) is combined with polyethylene polymer. The aluminum provides weight reduction and flexibility, while the polyethylene layer provides the necessary mechanical reinforcement and protection, together achieving both lightweight and mechanically strong properties.
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 reduces weight and environmental impact while enhancing fatigue resistance, making it suitable for dynamic submarine power cables.
Implementation Method 1
an inner layer of lead-free metal foil... The metal foil can be welded or otherwise placed so that metal foil forms a waterproof barrier
Implementation Method 2
an intermediate layer of adhesive material, typically and preferably based on an organic polymer
Data Source
AI summary
A water barrier for encapsulating a cable core has an inner layer of lead-free metal foil having an elastic modulus lower than 210 GPa, an intermediate layer of adhesive material, and an outer layer of a polyethylene-based semi-conducting polymer having an elastic modulus higher than 0.5 GPa. A power cable is providing having such a water barrier.