Elastic Wave Guide Imaging via Modal LSM
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Solution Overview
Problem
Existing methods for non-destructive testing of mechanical structures, such as elastic wave guides interconnected by junctions, are limited in their ability to image complex structures without access to the interior and do not effectively account for junctions of any shape.
Innovation Solution
A method based on modal Linear Sampling Method (LSM) that uses surface-mounted elastic wave sensors to acquire measurements, determine guided propagation modes, convert measurements into a wave field scattering matrix, and apply numerical inversion to generate an image of the structure, including defects, without internal access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional imaging methods are used, then the structure can be imaged, but the frequency is limited to lower frequencies and defects cannot be effectively detected
Solution Approach 1:
The patent changes the frequency parameter from conventional low-frequency methods to high-frequency guided waves, enabling both high-resolution defect detection and effective imaging of complex structures. The modal LSM methodology is specifically designed to operate at high frequencies where multiple guided propagation modes exist, thereby resolving the contradiction between detection precision and operating frequency.
Solution Approach 2:
The patent employs multiple guided propagation modes dynamically across different frequencies to image the structure. By utilizing the dynamic characteristics of various modes (fundamental and higher-order modes) and their different propagation behaviors, the method achieves superior defect detection capability at high frequencies while maintaining effectiveness for complex junction geometries.
2Adaptability or versatility
If modal LSM is applied to plate or guide structures, then imaging is achieved, but the method does not account for junctions of any shape
Solution Approach 1:
The patent extends the modal LSM methodology to universally handle junctions of any shape by formulating a generalized scattering matrix approach. The method uses surface-mounted sensors that can detect scattered waves from any junction configuration, making the imaging method universally applicable to T-junctions, cross-junctions, and other complex geometries without requiring internal access or shape-specific modifications.
Solution Approach 2:
The patent transitions from two-dimensional plate imaging to three-dimensional junction imaging by incorporating the spatial complexity of multiple wave guide intersections. The scattering matrix formulation accounts for wave propagation in multiple dimensions and directions, enabling the method to handle arbitrary junction shapes while maintaining measurement completeness through surface-mounted sensor arrays.
3Measurement precision
If access to the cross section of the guide is required, then theoretical principles can be applied, but internal access is not always possible
Solution Approach 1:
The patent introduces surface-mounted sensors as intermediaries that bridge the gap between the external accessible surface and the internal defect regions. These sensors detect guided waves propagating along the wave guide surfaces and scattered waves from defects, enabling accurate imaging without requiring internal access to the wave guide cross-sections or junction interiors.
Solution Approach 2:
The patent replaces the mechanical requirement of internal cross-section access with a wave-based measurement system. By using elastic guided waves that propagate along the structure and interact with defects, the method substitutes direct mechanical access with indirect wave field measurements, achieving the same imaging objective without physical intrusion into the structure.
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 high-frequency imaging of complex-shaped structures with surface-mounted sensors, effectively detecting and imaging defects in structures composed of interconnected elastic wave guides, even when junctions have complex shapes.
Implementation Method 1
acquiring a plurality of measurements of signals propagating in the structure by means of a plurality of pairs of non-colocalized elastic wave sensors
Implementation Method 2
the structure supporting elastic wave guided propagation modes
Implementation Method 3
converting the measurement matrix M into a wave field scattering matrix U
Implementation Method 4
determining a plurality of propagation modes guided by the structure
Data Source
AI summary
A method for imaging a structure composed of at least one wave guide connected to a junction, the structure supporting elastic wave guided propagation modes, the method includes the following steps: for at least one operating frequency, acquiring a plurality of measurements of signals propagating in the structure by means of a plurality of pairs of non-colocalized elastic wave sensors, determining a plurality of propagation modes guided by the structure, correcting the measurements on the basis of ultrasound signals measured or simulated for the same structure in the absence of any defect, converting the measurement matrix M into a wave field scattering matrix U, determining, at each point of a sampling grid, a test vector F characteristic of the structure without any defect, applying a numerical inversion method to determine a vector H of modal components such that U.H=F at each point of a sampling grid, determining an image of the structure on the basis of the vector H.