Time Reversal Vibratory Wave Inspection for Defect Detection
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Solution Overview
Problem
Existing techniques for detecting defects in complex and non-uniform mechanical structures using vibratory waves face challenges due to strong interface echoes masking defect echoes, and require a high transducer-to-zone ratio, especially when accessing difficult zones.
Innovation Solution
A method involving two training stages to generate and store reference signals through time-reversal of vibratory waves, allowing for focused energy emission and comparison with diverging signals to detect defects, using a device with transducers and a processor to analyze and compare signals for defect detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If time reversal technique is used to amplify defect echoes, then defect detection sensitivity is improved, but interface echoes still mask defect echoes in complex structures
Solution Approach 1:
The method performs preliminary training stages to characterize the structure before actual inspection. During these training stages, the system learns the structure's acoustic properties and echo patterns without defects present, then uses this pre-acquired knowledge to subtract or compensate for interface echoes during subsequent defect detection, allowing defect echoes to be identified despite the masking effect
Solution Approach 2:
The system uses time reversal of received signals to create focused beams that return to the source location. By iteratively adjusting the excitation signals based on received echo patterns, the system optimizes the focusing effect and enhances defect signal strength relative to background interface echoes through feedback-driven signal refinement
2Area of stationary object
If more transducers are used to monitor more zones, then defect detection coverage is improved, but device complexity and cost increase
Solution Approach 1:
Each transducer in the array is designed to perform multiple functions: it can transmit excitation signals, receive echoes from multiple directions, and participate in time reversal focusing operations. This multi-functionality allows a smaller number of transducers to effectively monitor a larger area compared to systems where each transducer has a dedicated single function
Solution Approach 2:
The system uses time reversal to focus acoustic energy back to the source location in the temporal dimension, effectively adding a time-based dimension to the spatial inspection coverage. This allows the same physical transducer array to monitor multiple zones by sequentially focusing on different regions through signal processing rather than requiring additional transducers for each zone
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 effective detection of defects in complex structures with a lower transducer-to-zone ratio, improving accessibility and accuracy by isolating defect echoes from interface echoes, and allowing for periodic monitoring of structures in use or post-fabrication quality control.
Implementation Method 1
injecting a transient vibratory excitation into the inspection zone; picking up, at different locations of the inspection zone, the received signals
Implementation Method 2
time reversing the received signals and storing the time-reversed signals in order to constitute reference excitation signals; simultaneously emitting the reference excitation signals in order to focus them in the inspection zone
Data Source
AI summary
The present invention relates to a method of non-destructive inspection of mechanical structures (2) by using vibratory waves in order to detect local defects and/or changes of state. According to the invention, the method comprises:a first training stage in which a transient vibratory excitation is injected into an inspection zone (Z) and the received signals are picked up and time reversed in order to constitute reference excitation signals;a second training stage in which the reference excitation signals are emitted simultaneously and the resulting diverging signals are picked up in order to constitute reference response signals; anda stage of inspecting the mechanical structure (2), in which the reference excitation signals are emitted, the resulting diverging signals are picked up, and the diverging signals are compared with the reference response signals.