Acoustic Emission Signal Processing for Composite Impact Damage Detection
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Solution Overview
Problem
Current methods for detecting impact damage in composite materials, such as those used in aircraft, are costly, time-consuming, and prone to overlooking damage, especially for low-velocity impacts that do not exhibit visible signs.
Innovation Solution
A system comprising a broadband, non-resonant piezoelectric sensor and a processor that detects and filters acoustic waves to differentiate between damaging and non-damaging impacts by identifying initial and secondary pulses, providing a damage rating based on amplitude ratios, and storing results for automated inspection and maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual inspection techniques are used to detect impact damage, then detection capability is provided, but the process becomes costly and time consuming
Solution Approach 1:
The patent replaces manual inspection techniques with an automated acoustic emission detection system. Sensors detect acoustic waves generated by impact events, and a processor automatically analyzes the signals to identify damage. This substitution of mechanical/manual inspection with an automated sensing and processing system resolves the contradiction by providing reliable damage detection while significantly reducing inspection time and cost.
2Reliability
If manual inspection techniques are used to detect impact damage, then detection capability is provided, but the risk of overlooking damaged areas increases
Solution Approach 1:
The automated acoustic emission system replaces manual inspection, eliminating human error and oversight. The system continuously monitors acoustic signals and uses automated processing to identify damage indicators, ensuring consistent and reliable detection without overlooking damaged areas.
Solution Approach 2:
The system incorporates feedback mechanisms where the processor analyzes acoustic emission signals in real-time, compares them against damage criteria, and provides automated identification of damaged areas. This continuous feedback loop ensures comprehensive detection and reduces the risk of overlooking damage.
3Extent of automation
If acoustic wave measurements are processed to identify impact damage, then automated detection is achieved, but noise interference may reduce measurement precision
Solution Approach 1:
The patent extracts the relevant impact signals from the noisy acoustic wave measurements through selective processing. The system identifies and isolates acoustic emissions characteristic of impact events while filtering out unrelated noise, thereby maintaining measurement precision in automated detection.
Solution Approach 2:
The processor acts as an intermediary that mediates between the raw acoustic wave measurements and the final damage identification. It applies signal processing techniques to enhance relevant features and suppress noise, preserving measurement precision while enabling automated detection.
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
This approach enables efficient, automated detection and classification of impact damage, reducing inspection costs and time, while identifying both visible and invisible damage, and providing a robust measure of damage severity, even in noisy environments.
Implementation Method 1
a broadband, non-resonant piezoelectric sensor detects the acoustic wave
Implementation Method 2
processing measurements of an acoustic wave within a member made of a composite material and caused, at least in part, by an impact to the member
Data Source
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AI summary
A method and apparatus for processing measurements of an acoustic wave, the acoustic wave being within a member (12) made of a composite material and caused by an impact to the member (12), the method comprising: analysing the measurements to detect an initial acoustic wave feature; analysing the measurements to detect the presence of further acoustic wave features, the further features occurring after the initial feature; if there are no further acoustic wave features, determining that the impact to the member (12) has not changed the structure of the member (12); if there are further features, determining a value of a function of the further acoustic wave features; if the determined value satisfies certain criteria, determining that the impact has changed the structure of the member (12); and if the determined value does not satisfy the criteria, determining that the impact has not changed the structure of the member (12). By doing so, impact induced damage is detected and quantified by processing separately acoustic data generated by the impact from acoustic data generated by acoustic emission due to damage generation.