Elastic Wave Speed Estimation Using Mode-Specific Spectrum Analysis
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Solution Overview
Problem
Existing methods for estimating elastic wave speeds in industrial structures face challenges such as high calculation costs, convergence issues with non-uniform structures, speed determination errors, and difficulty in specifying spectrum peaks, particularly in materials with multiple reflection points, leading to insufficient accuracy.
Innovation Solution
A speed estimation apparatus and method that utilizes multiple reflection of elastic waves to extract spectrum information, determine a frequency range of plate thickness mode, and specify peak frequencies to accurately estimate elastic wave speeds by analyzing frequency spectra at multiple measurement points, accounting for internal voids and flexural vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If inverse analysis tomography method is used to estimate elastic wave speeds, then comprehensive speed distribution can be obtained, but calculation cost increases significantly and convergence fails in non-uniform structures
Solution Approach 1:
The invention segments the frequency spectrum into multiple frequency bands and performs separate spectrum analysis for each band. This allows the complex tomography problem to be divided into simpler sub-problems that can be solved more efficiently, reducing overall calculation cost while maintaining accuracy
Solution Approach 2:
The invention performs preliminary spectrum analysis and peak frequency extraction before conducting tomography reconstruction. By pre-processing the data to identify characteristic frequencies and modes, the subsequent tomography calculation becomes more efficient and converges faster, especially for non-uniform structures
2Measurement precision
If inverse analysis tomography method is used, then speed distribution can be obtained, but determination error of arrival time leads to speed error
Solution Approach 1:
The invention utilizes the vibration characteristics of elastic waves at different frequency bands to identify mode types (plate thickness mode vs. flexural mode). By analyzing frequency spectrum peaks and their correspondence to theoretical mode frequencies, the method reliably determines arrival times and wave speeds without being affected by small timing errors
Solution Approach 2:
The invention employs an iterative feedback mechanism where initial speed estimates are used to calculate expected mode frequencies, which are then compared with actual spectrum peaks. Discrepancies feed back into the reconstruction process to refine speed estimates, progressively reducing errors from arrival time determination
3Ease of manufacture
If multiple reflection of impact elastic waves is used for uniform material, then simple sequential analysis works, but it is difficult to specify spectrum peaks for non-uniform material with multiple reflection points
Solution Approach 1:
The invention applies different analysis strategies to different frequency bands and spatial regions. For each measurement point and frequency band, it locally determines the dominant wave mode based on spectrum characteristics, allowing the method to adapt to local structural variations (uniform or non-uniform) while maintaining overall analysis simplicity
Solution Approach 2:
The invention changes the parameter of frequency band segmentation to transform the complex non-uniform structure problem into multiple simpler uniform-band problems. By analyzing each frequency band separately with appropriate mode assumptions, the method can specify peak frequencies accurately even for non-uniform materials with multiple reflection 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
Improves estimation accuracy of elastic wave speeds by distinguishing between plate thickness and flexural modes, enabling precise determination of elastic wave speeds even in non-uniform structures with internal voids and multiple reflection points.
Implementation Method 1
one or more elastic waves generated due to an impact
Implementation Method 2
multiple reflection of impact elastic waves is used
Implementation Method 3
extracts spectrum information of one or more elastic waves
Implementation Method 4
determines a frequency range of plate thickness mode based on the one or more peak frequencies
Implementation Method 5
estimates an elastic wave speed at each measurement point based on the peak frequency specified for each measurement point and thickness information
Data Source
AI summary
According to one embodiment, a speed estimation apparatus includes a spectrum information extractor, a peak frequency extractor, a range determiner, a specifier, and an elastic wave speed estimation unit. The spectrum information extractor extracts spectrum information of one or more elastic waves generated due to an impact at different measurement points of a target member for each measurement point. The peak frequency extractor extracts one or more peak frequencies in each of the pieces of spectrum information extracted for each of the measurement points. The range determiner determines a frequency range of the elastic waves based on the one or more peak frequencies. The specifier specifies a peak frequency at each measurement point based on the spectrum information and the frequency range. The elastic wave speed estimator configured to estimate an elastic wave speed at each measurement point based on the peak frequency and thickness information of the target member.