Ultrasonic Defect Detection with Eigenvector Noise Removal
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Solution Overview
Problem
Existing ultrasonic detection methods for material defects are hindered by spurious signals, particularly near-surface waves and structural noise, which mask defects in the first millimeters of material depth, leading to compromised detection quality and difficulty in identifying defects, especially at low depths.
Innovation Solution
A method involving a multi-element ultrasonic probe that successively emits and receives signals, forms a sampling matrix, calculates a covariance matrix, and subtracts projections onto eigenvectors to attenuate spurious signals, allowing for improved defect detection without requiring healthy reference areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional ultrasonic detection methods are used, then defects in deep material can be detected, but spurious signals (near-surface waves and structural noise) mask defects in the first millimeters of depth
Solution Approach 1:
The invention extracts and removes spurious signals (near-surface waves and structural noise) from the ultrasonic measurement signals through signal processing techniques. By separating and eliminating these harmful components, the method enhances the visibility of defects in the first millimeters of material depth while preserving the useful defect detection capability.
Solution Approach 2:
The invention applies a composite signal processing approach that combines multiple processing techniques (filtering, normalization, and statistical analysis) to handle the complex interaction between ultrasonic waves and material structure. This composite method effectively addresses both the spurious signals and defect detection requirements simultaneously.
2Loss of information
If Total Focusing Method (TFM) is used for processing ultrasonic signals, then cross-section images of material can be produced, but spurious noise greatly deteriorates the quality of these images
Solution Approach 1:
The invention converts the harmful spurious noise into a useful component for normalization. By using the spurious noise characteristics as a reference for normalization, the method transforms what was previously a detrimental factor into a tool for enhancing image quality and defect detectability.
Solution Approach 2:
The invention changes the parameters of the ultrasonic signals through normalization and filtering operations. By adjusting signal amplitude, frequency, and temporal characteristics, the method enhances the contrast between defects and spurious noise, thereby improving image quality without losing defect information.
3Measurement precision
If reference areas are used for normalizing noise, then defect detection accuracy can be improved, but additional tests are required which increases overall measurement duration
Solution Approach 1:
The invention enables the system to normalize and reduce spurious noise using only the measurement signals themselves, without requiring separate reference area tests. The method extracts noise characteristics directly from the acquired signals and applies normalization internally, making the system self-sufficient and eliminating the need for additional time-consuming reference measurements.
Solution Approach 2:
The invention performs noise normalization and filtering as preliminary processing steps on the measurement signals before defect analysis. By pre-processing the signals to remove spurious noise components, the method prepares the data for more efficient and accurate defect detection without requiring subsequent reference area comparisons.
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 method effectively attenuates spurious signals, enhancing the detection of material defects by reducing noise interference, thereby improving the accuracy and reliability of defect identification.
Implementation Method 1
a multi-element ultrasonic probe, comprising transducers, which are put alternately in emitting mode and in receiving mode of the ultrasonic measurement signals propagating in the material
Data Source
AI summary
The present invention relates to a method for detecting, by ultrasound, defects in a material (MS), comprising the steps of transmitting, by M transmitters of index i, and receiving, at sampling times n·Te, by means of M receivers of index j, signals x(n, i, j), forming a sampling matrix (AΔ) having N columns Yn formed by the signals x(n, i, j) for which a distance between the receiver of index j and the transmitter of index i is equal to the deviation Δ and rows Xi,j formed by the signals x(n, i, j), the pair i, j being different from one row Xi,j to the next, calculating a covariance matrix (CΔ) for the projections Xi,jproj,k of the rows Xi,j of the matrix (AΔ) on the K eigenvectors (Vk) corresponding to the K largest eigenvalues (λk), subtracting, from each row Xi,j, the K projections Xi,jproj,k to obtain residual measurement signals x*(n, i, j) for detecting defects.