10 results about "Guided wave propagation" patented technology

The invention provides a frequency dispersion curve calculation method based on a decoupling type Legendre-Gauss-Labatto spectral element method, and belongs to the technical field of discrete solution of guided wave propagation in a thin plate, and the method comprises the following steps: S1, constructing a wave equation which comprises a Cartesian space coordinate system based on an orthotropic plate, and combining a constitutive equation, a geometrical relationship under the coordinate system and guided wave displacement to obtain a wave dispersion curve; substituting into a control equation when the volume force is zero to obtain an improved three-dimensional elastic wave equation; s2, a differential matrix is constructed, wherein discretization and decoupling are carried out on a wave equation on the basis of a Lagrange interpolation basis function of a Legendre-Gauss-Labatto node; s3, explicitly embedding the stress free boundary condition into the solving process through matrix line transformation, and solving to obtain a frequency dispersion curve, the derivation process is simplified, the boundary and the interior of the material are decoupled, and the physical significance is clearer. And meanwhile, the high-precision advantage of the spectrum method is maintained, and the calculation rate is remarkably improved.

The invention discloses an ultrasonic guided wave damage ellipse imaging positioning method and equipment for a layer decreasing composite material laminated plate. The method comprises the following steps: S1, acquiring thickness change direction information of the laminated plate and position coordinates of an excitation transducer and a receiving transducer; s2, according to the material characteristic parameters, simulating and calculating the propagation time of ultrasonic guided waves transmitted from an excitation transducer to any point to generate a first theoretical propagation time map, and simulating and calculating the propagation time of the ultrasonic guided waves transmitted from any point to a receiving transducer to generate a second theoretical propagation time map to generate a second theoretical propagation time map; coupling influence of thickness change and material anisotropy on guided wave propagation is considered in the simulation process; s3, transmitting an ultrasonic guided wave signal, and extracting the actual flight time of a damaged wave packet; s4, calculating theoretical total propagation time, and determining a candidate area where damage exists; and S5, on the basis of repeated operation of the multiple groups of transducer pairs, taking a plurality of candidate region intersections to determine a final damage position. The objective of the invention is to solve the positioning error problem caused by the structural characteristics of a laminated plate in a traditional algorithm, and to realize more accurate damage detection and positioning.

The application provides a performance evaluation method, device and equipment of a current transformer and a medium, and relates to the field of data processing. In the method, the current transformer is in a saturation edge excitation state through composite work excitation, and a magnetostrictive micro-vibration response signal and a guided wave propagation response signal are collected. Resonance modal variation characteristics, guided wave path propagation characteristics and local scattering characteristics are extracted to construct a magnetoacoustic modal feature vector sequence. The feature vector sequence is input into a magnetoacoustic-performance mapping model to obtain a ratio difference, a phase angle error, a saturation characteristic offset and a harmonic error prediction value, and to output a degradation category probability distribution. Based on the change trend of each performance prediction value over time and in combination with the degradation category probability distribution, a performance attenuation curve and a degradation category evolution track are generated, so that dynamic evaluation and degradation state judgment of the performance of the current transformer are realized. Implementation of the technical solution facilitates improvement of the performance evaluation accuracy of the current transformer.

The invention discloses a one-way horizontal shearing guided wave electromagnetic ultrasonic excitation device based on a double-V-shaped coil. The device comprises the double-V-shaped coil, a magnet, an electromagnetic shielding shell and a tested workpiece. The double-V-shaped coil is arranged right above a workpiece to be detected, and the magnet is arranged above the coil and packaged in the electromagnetic shielding shell with a downward opening. The double-V-shaped coil is horizontally and symmetrically arranged in an inflection manner; the upper layer coil and the lower layer coil are relatively staggered by 1 / 4 one-way horizontal shearing guided wave wavelength along the horizontal shearing guided wave propagation direction, and 90-degree phase difference excitation is kept; the magnet is composed of four bar magnets which are alternately arranged according to SN poles. The configuration can efficiently excite horizontal shear guided waves which are propagated unidirectionally, improves the detection sensitivity of defects on the surface of a workpiece and near the surface in a specific direction, and is suitable for a scene needing directional selectivity nondestructive detection.

The invention relates to the field of nondestructive testing, in particular to a milling cutter blade defect detection device and method. The method comprises the following steps of: firstly, calculating and drawing a wedge-shaped guided wave propagation group velocity frequency dispersion curve by establishing a milling cutter blade fluctuation mechanical model and adopting a double-Laguerre polynomial series analytical solution method; the optimal excitation frequency for milling cutter blade quality detection is selected according to the group velocity frequency dispersion curve, and implementation of wedge-shaped guided wave quality detection can be efficiently guided. The wedge-shaped guided wave quality detection device of the milling cutter blade is established, noise reduction processing and weak signal extraction are carried out on wedge-shaped guided wave signals obtained through detection, and rapid, convenient and comprehensive health condition detection on the milling cutter blade is facilitated. According to the detection method and device, the optimal excitation frequency of wedge-shaped guided wave quality detection can be efficiently found through a theoretical method, comprehensive quality detection can be conducted on milling cutter blade structures of different specifications through the wedge-shaped milling cutter fixing device, and the signal-to-noise ratio and reliability of quality detection of the milling cutter blade structures are improved.

The invention discloses a battery dendritic crystal monitoring method, system, equipment and product based on ultrasonic guided waves, and the method comprises the steps: employing a piezoelectric transducer to excite SH0 ultrasonic guided waves in a normal charging and discharging state of a battery, and enabling the SH0 ultrasonic guided waves to be transmitted along the surface of an electrode or a waveguide structure which is tightly coupled with the electrode, and high-precision acquisition and analysis are carried out on reflection and transmission echo signals. And carrying out guided wave feature extraction on the echo signal to obtain key parameters such as guided wave propagation time, speed drift and energy attenuation, so as to realize real-time and high-sensitivity monitoring of the process from early stage initiation and growth to irreversible accumulation of the crystal dendrites. And in combination with a signal processing algorithm and a threshold criterion, a quantitative characterization and early warning mechanism of crystal dendrite evolution is constructed, so that the safety risks that the crystal dendrite pierces the diaphragm and internal short circuit occurs are reduced. The nondestructive detection monitoring method can provide powerful technical support for battery safety management, life prediction and battery management system linkage control.

The invention discloses a method for determining guided wave frequency dispersion characteristics of a liquid-filled steel riser, which is characterized in that three-dimensional guided wave propagation is equivalent to a radial one-dimensional intrinsic problem under an axial symmetry condition, a relation between a complex wave number and frequency dispersion can be obtained only by dispersing the radial direction, and high degree of freedom of three-dimensional modeling is avoided. Internal fluid is not coupled through additional boundary terms, and is merged into the overall system by adopting a section contribution matrix, so that fluid-solid consistent assembly in the same system is realized, and error sources of coupling inconsistency are reduced. An external infinite water area does not use an absorption layer for approximation, and external water is equivalent to a wavenumber-related damping boundary by using radiation impedance meeting an infinite radiation condition; and the self-consistent complex wave number is solved through linearization and inverse iteration, so that the radiation modeling accuracy and solvability are improved.

This invention relates to the field of icing and snow accumulation detection technology, and discloses a method and system for detecting icing on overhead transmission lines. The method includes: deploying integrated torsional vibration and acoustic emission sensing units at both ends of the transmission line span to collect conductor angular velocity and acoustic emission signals; performing cross-correlation processing on the angular velocity signals within a time window to obtain the propagation delay of multi-band torsional guided waves, and calculating the group velocity in conjunction with the span length; comparing the group velocity with a baseline curve for an ice-free period, and inverting the icing thickness using a composite pole dispersion model; using the acoustic emission signals to detect sudden events; if the number and energy of events exceed a threshold and the group velocity rebounds, it is determined to be an icing shedding state; otherwise, it enters the thickness and event fusion stage, outputting the icing thickness, growth rate, icing shedding alarm, and confidence level through a confidence factor. This invention can realize dynamic monitoring and early warning of the entire process of icing on transmission lines.

The application relates to the technical field of image detection, and provides a multi-modal wafer defect detection system. The system comprises a guided wave collection module, a stress reconstruction module, a crack database construction module, a type identification module and a multi-modal data fusion module. Stress distribution information of a crack area is extracted through guided wave propagation parameters, and the propagation speed is corrected in combination with temperature, so that the depth positioning and spatial calibration of cracks in a multi-layer structure are realized. A crack database is constructed by using the wave speed characteristics generated by standardized indentation, a clear mapping relationship between the propagation characteristics and the crack types is established, the accuracy of crack property determination is improved, the crack identification result is spatially registered with a stripe abnormal area in an optical interference pattern, the identification blind area existing in image detection can be effectively covered, and then the guided wave detection result and the optical detection result are fused, and the defect coverage range and the identification integrity are enhanced.

This invention discloses a method for locating and imaging local micro-defects based on nonlinear ultrasonic guided wave mixing, belonging to the field of nondestructive testing technology. The method includes: screening guided wave modes on the material under test; exciting two fundamental frequency guided wave signals to form a mixing region in the material; measuring the propagation velocity of the fundamental frequency guided waves and calculating the mixing point position; adjusting the excitation delay to achieve mixing point movement and region scanning; acquiring signals and performing frequency domain analysis to extract the nonlinear mixing signal; and then performing defect determination and imaging. This invention utilizes the high sensitivity of nonlinear ultrasonic guided wave mixing to micro-damage, achieving precise location and imaging of early-stage micro-defects in materials, thus solving the problem of insufficient identification capability of traditional nondestructive testing methods for minute damage.