Electromagnetic Cavity Response Analysis for Aircraft Stiffener Inspection

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Solution Overview

Problem

Nondestructive inspection of composite fuselage stiffeners in aircraft is time-consuming and costly, particularly when detecting state changes such as delamination or fluid ingress, which are critical for assessing structural health after impacts.

Innovation Solution

Exciting the cavities of aircraft stiffeners with electromagnetic radiation and analyzing the resulting electromagnetic field responses to detect state changes, using transmit and receive antennas to measure and compare cavity responses against baseline data for health assessment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional nondestructive inspection methods (e.g., ultrasonic testing) are used on composite fuselage stiffeners, then inspection reliability is improved, but inspection time and cost increase significantly

Engineering Contradiction:

Improveinspection reliabilityVSAvoidinspection time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent replaces traditional mechanical inspection methods (ultrasonic testing) with electromagnetic field-based inspection. Electromagnetic waves are used to excite cavities in the stiffeners, and the resulting electromagnetic responses are analyzed to detect state changes. This substitution eliminates the need for complex mechanical scanning equipment and significantly reduces inspection time while maintaining reliability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the inspection parameter from mechanical wave propagation (ultrasonic) to electromagnetic field properties. By measuring electromagnetic cavity responses at specific frequencies and analyzing changes in these responses, the system can rapidly detect structural state changes without the time-consuming mechanical scanning required by traditional methods.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If traditional nondestructive inspection methods are used on composite fuselage stiffeners, then inspection reliability is improved, but inspection cost increases

Engineering Contradiction:

Improveinspection reliabilityVSAvoidinspection cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces expensive mechanical ultrasonic testing equipment with simpler electromagnetic field-based measurement systems. The inspection process uses standard electromagnetic wave generation and detection equipment, reducing the need for specialized costly infrastructure while maintaining the ability to reliably detect structural health issues.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent creates electromagnetic field responses that serve as digital copies of the physical structural state. By analyzing these electromagnetic responses rather than requiring direct physical measurement, the system reduces equipment costs and enables more efficient inspection processes.

Inventive Principle:

Principle #26Copying

3Productivity

If electromagnetic excitation is applied to stiffener cavities, then inspection speed is improved, but detection precision may be compromised

Engineering Contradiction:

Improveinspection speedVSAvoiddetection precision

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent employs feedback mechanisms where the electromagnetic cavity responses are continuously monitored and compared against baseline data. This feedback loop enables real-time detection of state changes, ensuring that rapid inspection does not compromise precision. The system adjusts measurement parameters based on the feedback from cavity responses to maintain high detection accuracy.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent uses periodic electromagnetic excitation at specific frequencies to elicit resonant responses from the stiffener cavities. By measuring the periodic responses and analyzing changes in these patterns, the system achieves both rapid inspection and high precision detection of structural state changes.

Inventive Principle:

Principle #19Periodic 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

Enables rapid and cost-effective detection of state changes in aircraft stiffeners, including delamination and fluid ingress, allowing for timely identification and addressing of potential issues before they become major problems.

Implementation Method 1

exciting cavities of the stiffeners with electromagnetic radiation

Methodology Applied

Scientific EffectElectromagnetic radiation: Electromagnetic Induction

Implementation Method 2

measuring its electromagnetic cavity response

Methodology Applied

Scientific EffectElectromagnetic radiation detection: Electromagnetic Induction

Data Source

PatentUS8499631B2Nondestructive inspection of aircraft stiffeners

Publication Date: 2013.08.06 THE BOEING CO

AI summary

Nondestructive inspection of a plurality of aircraft hat stiffeners includes exciting cavities of the stiffeners with electromagnetic radiation, and analyzing electromagnetic field responses of the cavities to detect state changes of the stiffeners.