Hidden Damage Detection in Multilayer Composites via Wavefield Energy Analysis
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Solution Overview
Problem
Current nondestructive evaluation (NDE) techniques cannot detect hidden or 'shadowed' damage in multilayered materials, particularly in aerospace composites, when only single-sided access is available, as they are limited to detecting near-surface damage and cannot identify or quantify the full extent of damage, including damage located beneath overlapping near-surface defects.
Innovation Solution
A method involving the generation of ultrasonic guided waves using piezoelectric transducers and laser doppler vibrometers to collect and process wavefield data, comparing measured energy data to simulated data to detect and quantify hidden damage by analyzing energy trapping patterns at the surface, allowing for the identification of internal defects even in scenarios with limited access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current NDE techniques are used for single-sided access inspection, then near-surface damage can be detected, but hidden damage below the surface cannot be detected
Solution Approach 1:
The patent transitions from traditional single-point ultrasonic measurement to full-field optical measurement using laser Doppler vibrometry. By measuring surface velocity across the entire specimen surface and calculating cumulative energy in the out-of-plane direction, the method accesses additional dimensional information that reveals hidden damage not visible from the accessible surface alone.
Solution Approach 2:
The patent replaces contact-based ultrasonic transducers with non-contact optical measurement systems (laser Doppler vibrometers). This substitution eliminates the limitations of mechanical coupling and allows for comprehensive surface measurement, enabling detection of hidden damage through optical field analysis rather than mechanical wave propagation.
2Reliability
If ultrasonic scans are used for internal damage detection, then near-surface damage can be identified, but shadowed damage overlapping near-surface defects cannot be detected
Solution Approach 1:
The patent segments the damage detection process into distinct energy analysis components by calculating cumulative energy in specific directional components (out-of-plane, in-plane x, in-plane y). This segmentation allows isolation of energy signatures from hidden damage that would otherwise be obscured by near-surface defects in traditional ultrasonic scans.
Solution Approach 2:
The patent changes the measurement parameter from traditional ultrasonic amplitude or time-of-flight to cumulative energy integrated over the wavefield. This parameter transformation converts the undetectable shadowed damage into a measurable energy signature that can be distinguished from near-surface defects through directional energy decomposition.
3Ease of operation
If single-sided access inspection is performed with conventional methods, then accessible surface damage can be detected, but full damage extent cannot be quantified
Solution Approach 1:
The patent creates a universal measurement system using laser Doppler vibrometry that can detect both near-surface and hidden damage from a single accessible surface. The out-of-plane velocity measurement and cumulative energy calculation provide multi-functional detection capability, eliminating the need for separate inspection methods for different damage types or locations.
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 the detection and quantification of hidden damage in multilayered materials, such as aerospace composites, by analyzing energy trapping patterns, effectively overcoming the limitations of existing NDE methods that rely on single-sided access and near-surface inspections.
Implementation Method 1
The transducer may comprise a piezoelectric transducer
Implementation Method 2
a laser doppler vibrometer (LDV) may be utilized to collect guided wavefield data from the surface of the item
Implementation Method 3
The transducer is actuated to generate an ultrasonic guided wavefield in the material, including on a surface of the item, such that energy is trapped near the surface of the item above any existing damage
Data Source
AI summary
A method of detecting internal defects in composites or other multilayer materials includes generating a wavefield on a surface of the material. Wavefield data is collected from the wavefield on the surface, and the measured wavefield data is processed to provide measured energy data. The method may include generating simulated or predicted energy data for the multilayer material that is compared to the simulated energy data to determine if the multilayer material has internal defects or damage below the surface. The method can be utilized to detect and/or quantify damage or other defects that are “hidden” by damage that is closer to the surface of the material.