Angled Boundary Composite Laminate for Stress Distribution
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Solution Overview
Problem
The manufacture of composite members, such as extendable tubes, faces challenges in controlling layer placement and positioning to achieve desired properties while withstanding coiling and extension stresses, which can lead to damage and premature failure due to stress concentration at discontinuities.
Innovation Solution
A composite member with angled boundary layers, where at least one layer does not extend the full length, is designed to distribute stresses and strains evenly, allowing for tailored properties along the length and reduced risk of failure during coiling and extension. This includes using braided or woven fibre reinforced layers with combed-out fibres to reduce intermeshing and align fibre ends with the longitudinal axis for strain relief.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous layers of material are used throughout the member, then the member has uniform structural properties, but stress concentration occurs at discontinuities during coiling and extension leading to premature failure
Solution Approach 1:
The patent divides the continuous layer into multiple discrete layers with different longitudinal extents. At least one layer has a boundary partway along the member, creating segments that can be independently optimized. This segmentation allows stress distribution across multiple interfaces rather than a single discontinuity, reducing stress concentration and preventing premature failure during coiling and extension cycles.
Solution Approach 2:
The patent applies local quality by having different layers extend to different lengths along the member. Each layer can be tailored to provide specific properties at specific locations - for example, providing reinforcement where needed while allowing other regions to be more flexible. This local differentiation optimizes the member's performance throughout its length while managing stress distribution.
2Manufacturing precision
If layers are placed to achieve desired material properties, then the member has optimized performance, but controlling layer placement and positioning becomes difficult during manufacture
Solution Approach 1:
The patent employs preliminary action by pre-forming the layers with their boundaries and orientations established before final assembly. The layers can be prepared separately with precise boundary definitions, then bonded together to form the laminate. This preliminary preparation of individual layers with defined extents and orientations simplifies the overall manufacturing process while maintaining high precision in layer placement.
3Ease of manufacture
If the boundary of a layer is perpendicular to the transverse axis, then the layer placement is simple, but stress and strain are concentrated in one location during coiling and extension
Solution Approach 1:
The patent applies asymmetry by angling the boundary of at least one layer with respect to the transverse axis, rather than using a perpendicular (symmetric) boundary. This asymmetric angular boundary distributes the stress and strain more evenly across the layer interface during coiling and extension, preventing concentration at a single location and improving the member's reliability under cyclic loading.
Data Source
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AI summary
The present application relates to composite members and to methods of manufacturing a composite member. In an aspect, a composite member (10) is formed as a longitudinal structure capable of being coiled about an axis transverse to the longitudinal axis of the member. The composite member (10) comprising plural layers (p1 -p5) of material bonded together to form a laminate. At least one layer (p3) of material has a boundary (30) partway along the longitudinal extent of the member and extending between the sides of the member. The boundary (30) is angled with respect to the transverse axis (18) of the member.