Laser Ultrasonic Composite Inspection via FFT Analysis
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Solution Overview
Problem
Conventional non-destructive testing methods, such as ultrasound testing, face challenges in detecting wrinkles and compaction inconsistencies in composite structures, particularly due to the difficulty in differentiating these inconsistencies from the regular spacing of layers and the reliance on human experience, which can be costly and time-consuming, and often result in destructive testing.
Innovation Solution
A method utilizing a pulsed laser beam to generate wide-band ultrasonic signals in composite structures, which are then processed to form ultrasonic A-scans and compared to a standard structure signal, allowing for the detection of inconsistencies through frequency and width analysis, enabling the identification of wrinkles and compaction issues without destructive means.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ultrasound testing is used to inspect composite structures, then non-destructive inspection is performed, but wrinkles and compaction inconsistencies are difficult to detect due to regular layer spacing
Solution Approach 1:
The patent transforms the ultrasound inspection from conventional time-domain A-scans to frequency-domain analysis by applying Fast Fourier Transform (FFT). This dimensional change in signal processing allows the detection of wrinkles and compaction inconsistencies through frequency spectrum analysis, where these defects manifest as distinct frequency signatures that differentiate them from regular layer spacing patterns.
Solution Approach 2:
The patent changes the analysis parameters from conventional amplitude-time domain to frequency domain by applying FFT transformation. This parameter transformation reveals hidden frequency characteristics of wrinkles and compaction defects that are not apparent in conventional ultrasound inspection, enabling reliable detection despite regular layer spacing.
2Reliability
If conventional non-destructive testing methods are used, then inspection is performed without altering the part, but the process is costly and time-consuming
Solution Approach 1:
The patent replaces conventional mechanical contact-based ultrasound inspection with a laser-based ultrasonic generation system. The laser generates ultrasonic waves without mechanical contact, eliminating the need for coupling agents and reducing inspection time while maintaining non-destructive characteristics. This substitution significantly reduces inspection costs and time while preserving detection accuracy.
3Reliability
If conventional ultrasound testing is used, then non-destructive inspection is performed, but human experience is required which increases cost and time
Solution Approach 1:
The patent implements automated feedback-based defect detection by comparing the frequency spectrum of the inspected composite structure against reference spectra of known good and defective structures. This automated comparison and classification system eliminates reliance on human expert interpretation, reducing both cost and time while maintaining high detection reliability through objective, repeatable measurements.
4Reliability
If conventional ultrasound testing is used, then inspection is performed, but some inconsistencies are not conventionally detectable
Solution Approach 1:
The patent applies FFT transformation to convert ultrasound signals from time-domain to frequency-domain representation. This dimensional transformation reveals hidden frequency signatures of wrinkles and compaction inconsistencies that are invisible in conventional time-domain A-scans, enabling detection of defect types that were previously undetectable with conventional methods.
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 allows for the reliable and non-destructive detection of wrinkles and compaction inconsistencies, improving the accuracy and efficiency of composite structure inspection, reducing costs and time, and providing repeatable and confident measurements.
Implementation Method 1
Wide-band ultrasonic signals are formed in the composite structure when radiation of the pulsed laser beam is absorbed by a surface of the composite structure
Data Source
AI summary
A method of detecting inconsistencies in a composite structure is presented. A pulsed laser beam is directed towards the composite structure comprised of a number of composite materials. Wide-band ultrasonic signals are formed in the composite structure when radiation of the pulsed laser beam is absorbed by a surface of the composite structure. The wide-band ultrasonic signals are detected over a duration of time to form data. The data comprises an ultrasonic A-scan spectrum. The data is processed to identify a structure signal in a frequency domain of the ultrasonic A-scan spectrum. The structure signal of the ultrasonic A-scan spectrum is compared to a structure signal of a composite structure standard to determine whether the inconsistencies are present in the number of composite materials.