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High-frequency guided ultrasonic waves for hidden defect detection in multi-layered aircraft structures
Bernard Masserey1, Christian Raemy1, Paul Fromme2
1Department of Mechanical Engineering, University of Applied Sciences, 1705 Fribourg, Switzerland.
Ultrasonics
|May 27, 2014
Summary
High frequency guided ultrasonic waves can detect hidden defects in aerospace structures. This non-destructive testing method shows potential for inspecting critical, hard-to-reach locations effectively.
Area of Science:
- Materials Science
- Non-Destructive Testing
- Aerospace Engineering
Background:
- Aerospace structures utilize multi-layered metallic components prone to hidden defects like fatigue cracks and disbonds.
- Non-destructive testing (NDT) is crucial for identifying these internal flaws without damaging the structure.
- Guided ultrasonic waves offer a promising NDT approach for inspecting complex geometries.
Purpose of the Study:
- To investigate the use of high frequency guided ultrasonic waves (HF-GUW) for detecting hidden defects in adhesively bonded multi-layered aerospace structures.
- To evaluate the propagation characteristics and defect detection capabilities of HF-GUW in aluminum plate structures.
- To assess the feasibility of detecting defects from a stand-off distance.
Main Methods:
- Generation of HF-GUW using standard wedge transducers in a two-layer aluminum plate model.
- Experimental measurement of wave propagation using laser interferometry.
- Comparison of experimental results with theoretical predictions and 2D finite element simulations.
- Investigation of HF-GUW interaction with artificial defects (notches) on internal and external surfaces.
- Pulse-echo measurements to determine detection sensitivity and stand-off distance effects.
Main Results:
- Achieved significant propagation distance with a strong, non-dispersive main wave pulse.
- Observed frequency-dependent variation in energy distribution through the thickness due to wave mode interference.
- Demonstrated successful detection of notches located on the sealant-facing aluminum layer and the bottom surface.
- Verified detection sensitivity and stand-off distance influence through pulse-echo measurements.
- Experimental and simulation results showed good agreement with theoretical predictions.
Conclusions:
- High frequency guided ultrasonic waves show significant potential for detecting hidden defects in multi-layered aerospace structures.
- The method is effective for inspecting critical and difficult-to-access locations.
- Detection is feasible from a stand-off distance, enhancing inspection safety and efficiency.
