Embedded Optical Fiber Checks for Composite Strength Members
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Solution Overview
Problem
Fiber-reinforced composite strength members, used in structures like overhead electrical cables, are difficult to detect for structural defects due to low ductility and the complexity of existing monitoring methods, which require precise alignment and coherent light sources, making them impractical for outdoor environments.
Innovation Solution
A system and method for interrogating fiber-reinforced composite strength members using embedded optical fibers and incoherent light sources, enabling simple and cost-effective detection of defects through light transmission and detection devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional monitoring methods (OTDR with coherent light sources) are used to detect structural defects, then measurement precision is improved, but device complexity and ease of operation deteriorate due to requiring precise alignment and complex equipment
Solution Approach 1:
The patent replaces expensive, complex coherent light sources (lasers) with inexpensive, simple incoherent light sources (LEDs). This substitution maintains adequate defect detection capability while dramatically reducing equipment complexity and cost, making the system suitable for field deployment without requiring precision alignment equipment
Solution Approach 2:
The patent substitutes the complex optical alignment system with a simple mechanical coupling system. The index-matching material creates automatic optical coupling between the LED and optical fiber, eliminating the need for precision mechanical alignment mechanisms while maintaining measurement effectiveness
2Device complexity
If incoherent light sources are used to simplify the system, then device complexity is reduced, but measurement precision deteriorates due to lower coherence
Solution Approach 1:
The patent introduces index-matching material as an intermediary between the incoherent light source and the optical fiber. This material optimizes light coupling efficiency, ensuring that sufficient light energy is transmitted through the optical fiber to detect defects with adequate precision, thereby compensating for the lower coherence of incoherent light sources
Solution Approach 2:
The patent changes the optical parameters of the system by using index-matching material with specific refractive index properties. This parameter optimization maximizes light transmission efficiency from the incoherent LED source through the optical fiber, maintaining adequate signal strength for defect detection despite using lower-cost light sources
3Reliability
If optical fibers are embedded within the composite strength member, then reliability of structural monitoring is improved, but manufacturing precision requirements worsen due to integration complexity
Solution Approach 1:
The patent incorporates optical fibers into the composite strength member during the manufacturing process itself, rather than as a post-manufacturing step. This preliminary integration ensures that the fibers are properly positioned and protected within the composite structure before the strength member is put into service, enhancing long-term reliability while managing manufacturing requirements
4Measurement precision
If complex alignment procedures are required for light source and optical fiber, then measurement precision is improved, but ease of operation deteriorates
Solution Approach 1:
The patent replaces complex mechanical alignment procedures with a simple chemical/optical coupling method using index-matching material. This material automatically optimizes light coupling when the LED is placed in proximity to the optical fiber, eliminating the need for precision mechanical alignment and making the system easy to deploy in field conditions
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
Facilitates the detection of structural integrity in fiber-reinforced composite strength members during manufacturing, installation, and post-installation, ensuring the structural integrity of cables like overhead electrical cables.
Implementation Method 1
at least a first optical fiber embedded within the fiber-reinforced composite and extending from a first end of the fiber-reinforced composite to a second end of the fiber-reinforced composite
Implementation Method 2
a light source that is configured to transmit light into the first end of the optical fiber
Data Source
AI summary
Systems, methods and tools for the interrogation of fiber-reinforced composite strength members to assess the structural integrity of the strength members. The systems and methods utilize the transmission of light through optical fibers that are embedded along the length of the strength members. The inability to detect light through one or more of the optical fibers may be an indication that the structural integrity of the strength member is compromised. The systems and methods may be implemented without great difficulty and may be implemented at any time in the life cycle of the strength member, from production through installation. The systems and methods have particular applicability to bare overhead electrical cables that include a fiber-reinforced strength member.