Fiber Optic Composite Joint Inspection for Strain Detection

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Solution Overview

Problem

Conventional non-destructive inspection methods, such as ultrasonic waves and X-ray CT, are inefficient and costly for inspecting composite joints with complex geometries and materials like noodles due to inconsistent signal reflection and high equipment costs.

Innovation Solution

A composite joint inspection system using fiber optic cables embedded within composite fillers to detect strain by measuring reflectivity indices of light waves, allowing for non-destructive, cost-effective, and consistent inspection of composite joints.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional ultrasonic inspection methods are used to inspect composite joints with complex geometries and materials, then the inspection can be performed with existing equipment, but the inspection is costly, time consuming and inconsistent due to complex geometry and location

Engineering Contradiction:
Improveinspection consistencyVSAvoidinspection time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent replaces conventional ultrasonic mechanical inspection methods with an optical sensing system using fiber optic cables. The fiber optic cable senses strain through optical properties (reflectivity index changes) rather than mechanical wave propagation, eliminating the inconsistencies caused by complex geometries and material variations that affect ultrasonic wave reflection.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The fiber optic cable acts as an intermediary element embedded within the composite filler material. It indirectly measures joint integrity by detecting strain through optical property changes, providing consistent measurements without direct contact with the complex geometric surfaces that problematic for ultrasonic inspection.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If conventional ultrasonic inspection methods are used to inspect composite joints, then the inspection can be performed, but it is costly and time consuming

Engineering Contradiction:
Improvestrain detection accuracyVSAvoidinspection cost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The fiber optic cable serves dual purposes: it is both a structural component (part of the composite joint assembly) and a sensing element. The existing fiber optic infrastructure is utilized for both communication/data transmission and structural health monitoring, eliminating the need for separate expensive inspection equipment and reducing overall system cost.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The fiber optic cable performs multiple functions simultaneously: it provides structural support as part of the composite assembly, transmits data, and senses strain through optical property changes. This multi-functionality reduces the need for dedicated inspection equipment, lowering costs while maintaining measurement precision.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Reliability

If fiber optic cables are embedded within composite fillers to detect strain, then accurate and efficient inspection is achieved, but the manufacturing process becomes more complex

Engineering Contradiction:
Improveinspection accuracyVSAvoidsystem integration complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The fiber optic cable is embedded within the composite filler material during the manufacturing process itself, before the structure is put into service. This preliminary integration ensures proper positioning and bonding of the sensing element, simplifying subsequent inspection operations while maintaining manufacturing feasibility through standardized embedding procedures.

Inventive Principle:
Principle #10Preliminary action

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

Provides accurate and efficient inspection of composite joints with complex geometries, reducing costs and time compared to traditional methods by integrating fiber optic cables to detect strain and inconsistencies.

Implementation Method 1

A light wave is sent through a fiber optic cable running through a cavity of the composite joint... A reflectivity index of the light received from the fiber optic cable is measured

Methodology Applied
Scientific EffectOptical reflection: Reflection

Data Source

PatentEP4667890A1Composite joint inspection
Publication Date: 2025.12.24 THE BOEING CO
  • EP4667890A1 patent drawingFigure 1
  • EP4667890A1 patent drawingFigure 2
  • EP4667890A1 patent drawingFigure 3

AI summary

A composite joint inspection system and methods of use and forming are presented. A composite joint inspection system comprises a cavity formed by at least two composite components; a composite filler within the cavity; and a fiber optic cable running through the cavity extending out from at least one of a first end of the cavity or a second end of the cavity. The fiber optic cable is in contact with the composite filler.