Microstructured Optical Fibre Shear Load Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing microstructured optical fibre (MOF) structures for shear load sensing exhibit substantial cross-sensitivity to transverse load, making it difficult to precisely determine the actual level of shear load.
Innovation Solution
A microstructured optical fibre (MOF) design featuring a specific arrangement of holey structures with larger and smaller diameter holes, optimized to reduce sensitivity to transverse load while enhancing sensitivity to shear load. The fibre's core region is surrounded by side holey structures with distinct sub-grids, and the orientation of the fibre's mirror symmetry-axis is angled to optimize shear load detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional butterfly MOF structure is used for shear load sensing, then the fibre can detect transverse load based on birefringent properties, but the sensitivity to transverse load causes large cross-sensitivity between transverse load and shear load, making it difficult to precisely determine the actual level of shear load
Solution Approach 1:
The patent applies asymmetry by introducing side holey structures with a specific asymmetric arrangement relative to the core. The first sub-grid and second sub-grid are positioned at different orientations (first angle and second angle respectively) with respect to the core axis, creating an asymmetric microstructured optical fibre that preferentially responds to shear load while minimizing response to transverse load. This asymmetric geometry breaks the symmetry that causes equal sensitivity to both load types in conventional fibres.
Solution Approach 2:
The patent applies local quality by creating different hole arrangements in different regions of the fibre cross-section. The side holey structures have distinct sub-grids with different angular orientations and potentially different hole diameters (first diameter and second diameter) positioned at specific locations relative to the core. This local variation in hole structure creates regions with different stress sensitivity characteristics, allowing the fibre to selectively measure shear load while being less sensitive to transverse load in the core region.
2Measurement precision
If the MOF structure is optimized for shear load sensitivity, then shear load detection capability is improved, but the structure becomes more complex with multiple hole types and sub-grids
Solution Approach 1:
The patent applies segmentation by dividing the holey structure into distinct segments or sub-grids. The side holey structures are segmented into a first sub-grid and a second sub-grid, each with specific angular orientations (first angle and second angle) relative to the core. This segmentation allows independent optimization of each sub-grid's contribution to shear load sensitivity while managing the overall structural complexity through modular design.
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 MOF design achieves reduced cross-sensitivity to transverse load and improved sensitivity to shear load, enabling more precise measurement of shear load in composite structures.
Implementation Method 1
Microstructured optical fibres are known, and can be used for instance for sensing transverse load based on their birefringent properties
Data Source
Figure 1
Figure 2
Figure 3(a)~3(c)
AI summary
Microstructured optical fibre, composite structure, method and use for measuring shear load in a composite structure. A microstructured optical fibre (MOF), comprising a doped core region (2) embedded in a cladding layer (3), and comprising a plurality of longitudinal tubes, wherein a radial cross-section of the optical fibre comprises a central hexagonal portion (6) comprising a plurality of holes arranged according to a hexagonal grid surrounding a core section, each hole corresponding to a respective tube, within a hexagonal boundary (61-66) of said grid, the plurality of holes comprising holes of a first type (4) and holes of a second type (5) and arranged in a biaxial mirror-symmetric configuration, wherein said holes of said first type are arranged in two side holey structures comprising distinct sub-grids of said hexagonal grid, each of said side holey structures being defined by respective outer boundaries corresponding to portions of said hexagonal boundary of said grid and respective inner boundaries, wherein outer tangential lines (Til, T12) to said respective inner boundaries cross each other at the opposed side of said core with respect to the side of the respective side holey structure. Also claimed is composite structure including this fibre, a method and an use for measuring shear load in a composite structure.