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CN-122021208-A - Mode filter, topology optimization method and ultrasonic guided wave damage imaging artifact suppression method

CN122021208ACN 122021208 ACN122021208 ACN 122021208ACN-122021208-A

Abstract

The invention relates to a mode filter, a topology optimization method and an ultrasonic guided wave damage imaging artifact suppression method, and relates to the field of ultrasonic detection and imaging, wherein the topology optimization method comprises the steps of obtaining initial design parameters, generating an initial population, and each chromosome individual in the initial population is formed by encoding a binary logic matrix which represents material distribution and meets design constraint; and (3) optimizing the population by adopting a genetic algorithm, constructing an fitness function in the genetic algorithm based on a mode purity index and an energy transmission index, wherein the mode purity index is the ratio of the in-plane displacement integral of a transmission area to the total displacement integral under finite element simulation added with a mode filter, the energy transmission index is the ratio of the relative energy of a transmission end to the relative energy of an S0 mode under finite element simulation added with the mode filter, and outputting the final optimized material distribution of the mode filter. Compared with the prior art, the invention has the advantages of effectively inhibiting background artifacts, and considering mode regulation performance and matrix structural integrity.

Inventors

  • SONG AILING
  • XIANG YANXUN
  • XUAN FUZHEN
  • TIAN XIAOCHUAN

Assignees

  • 华东理工大学

Dates

Publication Date
20260512
Application Date
20260415

Claims (10)

  1. 1. A topological optimization method of a mode filter suitable for ultrasonic guided wave damage imaging artifact suppression is characterized by comprising the following steps: Acquiring initial design parameters, and generating an initial population, wherein each chromosome individual in the initial population is encoded by a binary logic matrix which represents material distribution and meets design constraint; Optimizing a population by adopting a genetic algorithm, wherein an fitness function in the genetic algorithm is constructed based on a mode purity index and an energy transmission index, the mode purity index is the ratio of the in-plane displacement integral of a transmission area to the total displacement integral under finite element simulation added with a mode filter, and the energy transmission index is the ratio of the relative energy of a transmission end to the relative energy of an S0 mode under finite element simulation added with the mode filter; And outputting the final optimized material distribution of the mode filter by using the binary logic matrix corresponding to the optimal individual obtained based on the genetic algorithm.
  2. 2. The method of mode filter topology optimization for ultrasound guided wave lesion imaging artifact suppression of claim 1, wherein the design constraints comprise a bottom continuous constraint and an effective packing element number constraint.
  3. 3. The method of mode filter topology optimization for ultrasound guided wave lesion imaging artifact suppression according to claim 1 or 2, wherein the design constraints are expressed as: wherein, θ i,j represents the value of the ith row and j columns of cells in the mxn matrix, 1 represents the presence of material, 0 represents the removal of material, and N is the number of effective filling cells.
  4. 4. The method for optimizing a topology of a mode filter suitable for ultrasonic guided wave damage imaging artifact suppression of claim 1, wherein the transmission end relative energy is a sum of squares integral of transmission end cross-sectional in-plane displacement and out-of-plane displacement.
  5. 5. The method of optimizing a mode filter topology suitable for ultrasound guided wave lesion imaging artifact suppression according to claim 1, wherein the fitness function is expressed as: Wherein var1 is a mode purity index, f 1 (var 1) is an adaptive function based on the mode purity index, var2 is an energy transmission index, and w 2 (var 2) is a weight function based on the energy transmission index.
  6. 6. The method of optimizing a mode filter topology suitable for ultrasound guided wave lesion imaging artifact suppression according to claim 5, wherein the f 1 (var 1) is a piecewise nonlinear function expressed as: Wherein θ 1 、θ 2 is a key threshold value of the mode purity regulation stage, α 1 、ß 1 、α 2 、ß 2 、ß 3 is a reference level and a growth amplitude of a control piecewise function, and p 1 、p 2 、p 3 is a sensitivity regulation parameter of the fitness to the mode purity change.
  7. 7. The method of optimizing a mode filter topology suitable for ultrasound guided wave lesion imaging artifact suppression according to claim 5, wherein w 2 (var 2) is a piecewise decay function expressed as: Wherein b 1 、b 2 、b 3 is a deviation threshold, gamma 1 、γ 2 、γ 3 is a weight attenuation coefficient in different intervals, q 1 、q 2 、q 3 is a nonlinear index, and delta is a dimensionless deviation amount.
  8. 8. The method of optimizing a topology of a mode filter for ultrasound guided wave lesion imaging artifact suppression according to claim 1, wherein structural stability processing is performed each time a new population is generated.
  9. 9. A mode filter, characterized in that the mode filter is designed and obtained by adopting the topological optimization method of the mode filter which is suitable for suppressing ultrasonic guided wave damage imaging artifacts according to any one of claims 1-8.
  10. 10. An ultrasonic guided wave damage imaging artifact suppression method, characterized in that the mode filter according to claim 9 is stuck and arranged on an object to be detected, and an imaging result of artifact suppression is obtained.

Description

Mode filter, topology optimization method and ultrasonic guided wave damage imaging artifact suppression method Technical Field The invention relates to the field of ultrasonic detection and imaging, in particular to a mode filter, a topology optimization method and an ultrasonic guided wave damage imaging artifact suppression method. Background The platy structure is widely applied to the fields of aerospace, energy equipment, petrochemical industry and the like, is easy to generate structural damage such as cracks, corrosion, fatigue, creep and the like in the long-term service process, and forms a potential threat to structural safety. Therefore, the realization of high-precision nondestructive detection of the plate-shaped structure has important engineering significance. Ultrasonic guided wave technology is widely used because of advantages such as long propagation distance, high detection efficiency, etc., wherein lamb wave is the most commonly used guided wave form in plate structure detection. However, inherent multi-modal and dispersive characteristics of lamb waves often lead to mode aliasing in the actual acquired signals, thereby reducing lesion positioning accuracy and imaging quality. In order to solve the problem, various mode selective excitation methods based on an excitation end have been proposed, such as optimizing the size parameter of a piezoelectric sheet, adopting phased array excitation, designing a transducer with a special structure, and a non-contact excitation method. Although the above-described methods can improve modal purity to some extent, they generally rely on complex transducer structures, fine parameter matching, or higher system costs, limiting their engineering applications. In addition to excitation end improvement, another type of research focuses on mode separation and feature extraction at the signal post-processing level, such as wavelet transformation, short-time Fourier transformation, empirical mode decomposition, deep learning and other methods, which generally depend on higher signal-to-noise ratio data, complex algorithm parameter adjustment and stronger priori assumptions, and it is difficult to fundamentally eliminate the physical complexity introduced by multi-mode propagation. Reducing modal complexity from a physical level is more conducive to improving modal purity, and thus subsequent detection performance, than certain excitation modes and signal processing algorithms. In recent years, acoustic metamaterials have been gradually introduced into the field of guided wave regulation due to their unique advantages in terms of wave propagation regulation. The metamaterial has huge application potential in guided wave regulation, but early design depends on empirical configuration, structural form is limited, and related optimization is mostly parameter scanning or geometric fine adjustment, so that local optimization is easy to fall into. Under the premise of not depending on an empirical configuration, the topology optimization carries out global search on material distribution in a design domain, and an effective way is provided for complex wave regulation and control. However, the existing metamaterial design based on topological optimization still has certain limitations, such as single optimization target, complex structure and form, difficult manufacturing, damaged detected structure and the like. The patent application CN120951676A discloses a topological optimization-based double frequency filtering super-surface design method, which comprises the steps of establishing a two-dimensional simulation model comprising a double frequency filtering super-surface matrix and a scatterer, covering a double frequency target interval with a forbidden band frequency according to a preset target forbidden band to serve as an fitness function, encoding a binary matrix representing material distribution into a chromosome to perform optimization iteration of the chromosome, obtaining the chromosome with the largest fitness function value, constructing the material distribution corresponding to the chromosome on the two-dimensional simulation model in the optimization iteration, obtaining an energy band structure of the chromosome, calculating the fitness function value, outputting the final optimized material distribution of the double frequency filtering super-surface according to the binary matrix of the chromosome with the largest fitness function value, performing performance verification on the result through simulation, and obtaining the double frequency filtering super-surface with the baseband wave blocked through the double frequency wave. The method only considers the coverage intersection of the forbidden band frequency range and the target frequency band in the energy band structure, does not involve the restriction of the transmission loss, and optimizes the single target. Therefore, in order to achieve effective regulation and control of guided wave