Lamb Wave Phased Array Dispersion Pre-Compensation
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Solution Overview
Problem
Lamb wave phased array focusing methods face challenges with dispersion and low positioning accuracy, and are time-consuming, especially in detecting defects in large areas.
Innovation Solution
A Lamb wave phased array focus-imaging method based on a frequency response function, which involves arranging a piezoelectric sensor array, calculating frequency response functions, constructing dispersion pre-compensation signals, and post-compensating for dispersion to enhance detection speed and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pre-compensation design is conducted on excitation signals to achieve narrow-band focusing, then positioning accuracy and sensitivity are improved, but detection time increases significantly
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing frequency response functions for multiple focal points before actual detection. When detecting a specific focal point, the system directly retrieves and uses the pre-computed frequency response function, avoiding time-consuming real-time calculations while maintaining high positioning accuracy and sensitivity.
Solution Approach 2:
The patent implements partial action by computing frequency response functions only for predetermined focal points of interest rather than continuously for all possible locations. This selective pre-computation reduces overall processing time while ensuring accurate detection at critical monitoring points.
2Ease of manufacture
If narrow-band signals are directly excited for focusing, then implementation is simple, but positioning accuracy and defect sensitivity are low
Solution Approach 1:
The patent applies parameter changes by transforming the excitation signal from simple narrow-band signals to signals modulated with pre-computed frequency response functions. This modification incorporates dispersion compensation information into the excitation signals, significantly improving positioning accuracy and defect sensitivity while maintaining practical implementability through systematic signal processing.
Solution Approach 2:
The patent introduces frequency response functions as an intermediary element between the simple excitation signal and the focal point. These functions act as a mediator that carries dispersion compensation information, enabling the system to achieve high positioning accuracy without directly implementing complex real-time calculations during detection.
3Measurement precision
If signal design and excitation are conducted for each monitoring point, then sensitivity and positioning accuracy are enhanced, but detection speed decreases
Solution Approach 1:
The patent applies preliminary action by pre-computing and storing frequency response functions for multiple focal points in advance. During actual detection, the system directly retrieves the pre-computed functions rather than calculating them in real-time, dramatically improving detection speed while maintaining high defect identification accuracy.
Solution Approach 2:
The patent implements partial action by computing frequency response functions only for predetermined focal points rather than continuously for all possible locations. This selective approach reduces computational burden and increases detection speed while ensuring accurate monitoring at critical points.
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 method improves damage detection speed and positioning accuracy, reducing hardware requirements for data storage and overcoming the limitations of existing Lamb wave phased array focusing technologies.
Implementation Method 1
arranging a piezoelectric sensor array on a surface of a tested structure, sequentially exciting a full-band signal fm(t) by array elements Pm(m=1, . . . N) of the piezoelectric sensor array
Implementation Method 2
collecting a response signal umn(t) of the tested structure by other array elements Pn (n=1, . . . N, n≠m)
Implementation Method 3
Lamb waves are ultrasonic guided waves with high sensitivity and low attenuation propagating in thin plate structures
Data Source
AI summary
The disclosure discloses a Lamb wave phased array focus-imaging method based on a frequency response function. In the method, a piezoelectric sensor array is arranged on a surface of a tested structure, the frequency response function of an excitation and acquisition pair formed by an excitation array element and an acquisition array element is calculated according to a full-band response signal, and a dispersion pre-compensation signal is constructed; the dispersion pre-compensation signal and the frequency response function are multiplied in a frequency domain to obtain a frequency domain pre-compensation response signal; and according to a distance from the acquisition array element to a focal point at the coordinates, the dispersion of the frequency domain pre-compensation response signal is post-compensated, so as to obtain a frequency domain dispersion post-compensation signal until all sensor excitation and acquisition pairs are traversed.