Lamb Wave Mode Decomposition via Symmetric Transducer Segments
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Solution Overview
Problem
Current non-destructive inspection methods for structures, particularly in aircraft, face challenges in accurately identifying Lamb wave modes due to the presence of undesirable modes, which complicates the interpretation of structural health and can lead to incorrect assessments of reworking or replacement needs.
Innovation Solution
A method involving transducer units with symmetric segments to generate and detect electrical signals, forming measured and scaling factor matrices to isolate Lamb modes, and using a pseudo-inverse to identify common factor matrices, allowing for precise identification of Lamb wave modes and structural inconsistencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lamb waves are used for non-destructive inspection of structures, then the inspection capability is enhanced, but the presence of multiple undesirable modes complicates the interpretation of structural health
Solution Approach 1:
The transducer is divided into multiple segments (first segment and second segment) with specific symmetric geometries. Each segment detects waves independently, and the signals are processed separately to isolate specific Lamb wave modes (symmetric and anti-symmetric modes) from the complex wave field, thereby resolving the mode complexity issue while maintaining inspection capability
Solution Approach 2:
The patent extracts and isolates specific Lamb wave modes (symmetric zero order and anti-symmetric zero order modes) from the complex wave field by using the geometric symmetry of the transducer segments. The processing steps (forming measured signal matrix, scaling factor matrix, and common factor matrix) selectively extract the desired modes while filtering out undesirable modes, thus reducing the effective wave mode complexity for interpretation
2Measurement precision
If multiple transducer segments are used to isolate Lamb modes, then mode identification accuracy is improved, but the transducer configuration and signal processing become more complex
Solution Approach 1:
The patent utilizes the contrast between symmetric and anti-symmetric geometries of the transducer segments. The first segment has a first geometric symmetry while the second segment has a second geometric symmetry. This deliberate use of symmetry differences allows the system to selectively excite and detect specific Lamb wave modes, improving mode identification accuracy while keeping the geometric design systematic rather than arbitrarily complex
3Measurement precision
If complex signal processing is applied to identify Lamb modes, then the accuracy of structural health assessment is improved, but the processing time and computational resources increase
Solution Approach 1:
The patent performs preliminary signal processing by forming the measured signal matrix, scaling factor matrix, and common factor matrix in a systematic sequence. The geometric symmetry of the transducer segments is used upfront to predict which modes will be excited, allowing the processing algorithm to focus only on extracting those specific modes rather than analyzing the entire spectrum, thus reducing processing time while maintaining accuracy
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
This approach enhances the accuracy and flexibility of identifying structural health by isolating desired Lamb modes, reducing the complexity of interpreting wave signals and improving the reliability of structural assessments.
Implementation Method 1
transducers are used to generate signals in the structure. These signals are detected and analyzed to identify the health of the structure.
Data Source
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AI summary
The different advantageous embodiments provide a transducer unit, a testing system, and a method for testing a structure. The transducer unit comprises a first segment configured to generate a first electrical signal in response to detecting a plurality of waves propagating in a structure. The transducer unit also comprises a second segment configured to generate a second electrical signal in response to detecting the plurality of waves propagating in the structure.