Acoustic Path Filtering for TFM Inspection
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Solution Overview
Problem
Conventional non-destructive evaluation techniques using acoustic methods, such as delay-and-sum and total focusing methods, face challenges in accurately focusing and resolving features within structures due to artifacts generated by unwanted acoustic propagation modes, which can limit the inspection's spatial extent and resolution, especially in complex structures like pipeline welds.
Innovation Solution
The implementation of a Path-Filtering Total Focusing Method (PF-TFM) that applies gain modulation to individual propagation paths based on desired modes, suppressing unwanted signals and enhancing signal-to-noise ratio (SNR) by weighting contributions from acoustic propagation paths outside a specified angular range, thereby improving image clarity and reducing artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional delay-and-sum or TFM techniques are used, then focusing can be achieved across a broad spatial region, but artifacts are generated by unwanted acoustic propagation modes
Solution Approach 1:
The patent segments the acoustic propagation paths into desired and unwanted modes, applying separate filtering operations to each. By dividing the full acoustic field into mode-specific components, the system can selectively enhance desired modes while suppressing unwanted ones, resolving the contradiction between achieving broad spatial focusing and eliminating artifacts.
Solution Approach 2:
The patent extracts unwanted acoustic propagation modes from the total acoustic field and removes them through filtering. By identifying and separating the harmful components (unwanted modes) from the useful signal, the system maintains focusing accuracy while eliminating artifacts that would otherwise contaminate the inspection images.
2Object-generated harmful factors
If beam aperture is physically limited to suppress artifacts, then unwanted mode conversion is reduced, but inspection sharpness and resolution are degraded
Solution Approach 1:
The patent applies local quality by implementing mode-specific filtering at each spatial location and propagation path, rather than applying a global beam aperture limitation. This allows the system to maintain full aperture benefits for resolution while locally suppressing unwanted modes through selective filtering, achieving both artifact reduction and high imaging quality simultaneously.
Solution Approach 2:
The patent changes the parameter space by filtering based on acoustic propagation mode characteristics (velocity, direction, conversion type) rather than spatial aperture. This parameter-based filtering approach allows suppression of unwanted modes without the spatial constraints that would degrade resolution, resolving the contradiction between artifact suppression and imaging sharpness.
3Manufacturing precision
If full aperture is used for scanning, then finer features can be resolved, but more unwanted acoustic modes contribute to the signal
Solution Approach 1:
The patent implements feedback by using knowledge of acoustic propagation characteristics (mode velocities, directions, conversion relationships) to dynamically filter received signals. This feedback mechanism allows the system to maintain full aperture operation for high resolution while using propagation-mode information to selectively suppress unwanted contributions, achieving both goals simultaneously.
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
The PF-TFM technique achieves a median 23-decibel SNR improvement in suppressing unwanted mode conversion artifacts while maintaining the integrity of useful signals, particularly in transverse-wave inspections, enhancing the sharpness and accuracy of imaging results.
Implementation Method 1
generating respective acoustic transmission events via selected transmitting ones of a plurality of electroacoustic transducers
Implementation Method 2
receiving respective acoustic echo signals using other receiving ones of the plurality of electroacoustic transducers
Implementation Method 3
Inhomogeneities on or within the structure under test can generate scattered or reflected acoustic signals in response to a transmitted acoustic pulse
Data Source
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AI summary
An acoustic technique can be used for performing non-destructive testing. For example, a method for acoustic evaluation of a target can include generating respective acoustic transmission events via selected transmitting ones of a plurality of electroacoustic transducers, and in response to the respective acoustic transmission events, receiving respective acoustic echo signals using other receiving ones of the plurality of electroacoustic transducers, and coherently summing representations of the respective received acoustic echo signals to generate a pixel or voxel value corresponding to a specified spatial location of the target. Such summation can include weighting contributions from the respective representations to suppress contributions from acoustic propagation paths outside a specified angular range with respect to a surface on or within the target, such as to provide an acoustic path-filtered total focusing method (PF-TFM).