Stranded Composite Cable Lay Angle Optimization
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Solution Overview
Problem
Existing helically stranded composite cables face challenges in achieving improved tensile strength and maintaining the helical arrangement of composite wires, particularly when using materials that are not plastically deformable, such as fiber-reinforced composites, which are primarily elastic in their stress-strain response.
Innovation Solution
The solution involves stranding composite wires in a common lay direction with specific lay angles and lengths, where the relative difference between inner and outer layer lay angles is minimal, typically no greater than 4°, to enhance tensile strength and maintain the helical arrangement, which is not typically observed in conventional ductile wire cables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If composite wires are stranded in a helical arrangement, then flexibility and round cross-sectional shape are improved, but tensile strength is reduced compared to parallel strand configurations
Solution Approach 1:
The patent applies parameter changes by optimizing the lay angle to a specific range (3-15 degrees) and controlling the lay length to be at least 10 times the cable diameter. These parameter optimizations minimize the reduction in tensile strength while preserving the flexibility benefits of helical stranding, resolving the contradiction between ease of operation and strength.
2Ease of manufacture
If ductile metal wires are used, then plastic deformation during stranding is achieved, but composite materials with improved mechanical properties cannot be readily deformed
Solution Approach 1:
The patent applies preliminary action by pre-coating the composite wires with a ductile metal coating before stranding. This preliminary protective coating enables the composite wires to withstand the mechanical stresses of helical stranding without breaking, while still achieving the desired helical arrangement and maintaining the superior mechanical properties of the composite core materials.
3Adaptability or versatility
If alternating lay directions are used in successive layers, then conventional cable construction is maintained, but tensile strength of composite cables is not maximized
Solution Approach 1:
The patent applies inversion by reversing the conventional approach: instead of using alternating lay directions in successive layers as is traditional, the patent uses the same lay direction for all layers. This inverted approach, combined with specific lay angle and lay length controls, maximizes tensile strength in composite cables while maintaining compatibility with conventional cable construction methods.
4Reliability
If composite wires are used in stranded cables, then corrosion resistance and environmental endurance are improved, but the wires cannot be plastically deformed to maintain helical arrangement
Solution Approach 1:
The patent applies preliminary action by pre-coating composite wires with ductile metal before stranding. This coating enables the wires to be plastically deformed during the stranding process to achieve and maintain the helical arrangement, while the composite core materials retain their superior corrosion resistance and environmental endurance properties.
Data Source
Figure 1A~1B
Figure 2A~2C
Figure 3A~3D
AI summary
Stranded composite cables include a single wire (2) defining a center longitudinal axis, a first multiplicity of composite wires (4) helically stranded around the single wire in a first lay direction at a first lay angle defined relative to the center longitudinal axis and having a first lay length, and a second multiplicity of composite wires (6) helically stranded around the first multiplicity of composite wires in the first lay direction at a second lay angle defined relative to the center longitudinal axis and having a second lay length, the relative difference between the first lay angle and the second lay angle being no greater than about 4°. The stranded composite cables may be used as intermediate articles that are later incorporated into final articles,, such as overhead electrical power transmission cables including a multiplicity of ductile wires stranded around the composite wires. Methods of making and using the stranded composite cables are also described.