30 results about "Guided wave propagation" patented technology

A method for the in vivo non-invasive characterization of the material and architectural properties of a bone in which an ultrasonic wave is introduced into a bone in such way as to produce one or more guided wave modes within the bone, and the signals emerging from the bone are stored and analyzed to determine the propagation characteristics of the guided wave / s. These measured guided wave propagation characteristics are then processed to obtain estimates of desired bone properties such as cortical thickness, bone density and bone elastic constants. The invention also includes an unltrasound arrangement with movable transducers.

The invention provides an ultrasonic guided wave multi-damage identification method based on Bayesian updating and Gibbs sampling. The method comprises: arranging three sensors for ultrasonic guided wave signal acquisition, analyzing each sensor signal to obtain M propagation time ToF of M damage direct scattering, and obtaining M 3 * 1 ToF vectors corresponding to each possible combination mode;performing linearization processing on parameters in the nonlinear damage positioning model based on the guided wave propagation time; solving conditional posterior probability distribution of each parameter by utilizing a Bayesian theorem; using gibbs sampling to sample the conditional posteriori distribution of each parameter, performing Gibbs sampling on a plurality of ToF vector data corresponding to each possible combination mode, and finally, judging the grouping mode with the minimum sample point dispersion degree and reasonable speed parameters to be the finally identified damage position. According to the invention, ultrasonic guided wave multi-damage accurate positioning can be automatically realized based on ToF information of three sensors.

The invention discloses an ultrasonic guided-wave propagation distance sparse estimation method and a detection system thereof. The method comprises the steps of acquiring the frequency-wavenumber curve of a target modal ultrasonic guided wave of a to-be-tested structure, taking unit impulse response signals at different propagation distances as atoms to construct an over-complete dictionary library, acquiring the unit pulse response signal of the to-be-tested structure, adopting the over-complete dictionary database as a signal base to establish the sparse representation model of the unit pulse response signal, and solving a sparse representation model to obtain the distance spectrum of the ultrasonic guided wave propagation. Compared with the prior art, the obtained distance spectrum result has higher range resolution, higher accuracy and better anti-interference effect.

The present invention proposes a metal sheet defect location method based on active sweep frequency acoustic excitation, said method includes four steps: device layout, signal acquisition, signal processing, and defect location; the method can obtain defect position curves through time delay information , and then determine the defect position according to the intersection point of the defect position curve; the beneficial technical effect of the present invention is: a metal sheet defect location method based on active sweep frequency acoustic excitation is proposed, which can be realized without knowing the propagation velocity of the guided wave in advance Defect location, the positioning accuracy is high.

The invention discloses an electromagnetic ultrasonic excitation probe design method, according to the sound propagation principle, namely SH type guided wave propagation rule, in a solid plate, optimum excitation frequency is determined, and according to the frequency, an electromagnetic ultrasonic excitation probe is designed; enhancement of SH type 0 order mode guided wave and inhibition of 1 order mode guided wave in the plate can be realized, simplification of the mode of a guided wave excited in a particular frequency can be realized, the signal-to-noise ratio is improved, and defect detection probability and quantization accuracy can be effectively improved.

The invention discloses a method for judging the connecting compactness of an interface by using a spring stiffness coefficient. The method is mainly used for ultrasonic nondestructive testing of the interface compactness and comprises the following steps: (1) establishing a corresponding model according to actual conditions, and arranging a spring model at the interface; (2) deducing out a frequency dispersion equation of guided wave propagation according to a wave equation and boundary conditions; (3) drawing out a changing curve of phase velocity along with the tangential stiffness coefficient Kt under the condition that the normal stiffness coefficient Kn is infinitely great so as to obtain a tangential stiffness coefficient value with relatively sensitive phase-velocity change and a corresponding frequency-dispersion characteristic curve; (4) determining peeling-degree percentage values corresponding to different Kt values by simulation; (5) exciting and receiving ultrasonic guided wave signals on a tested object; (6) extracting parameters from actual testing signals to carry out inversion and further determine corresponding Kt values; and (7) judging the compactness degree of the interface by the tangential spring stiffness coefficient value. The method disclosed by the invention has the advantages that the connecting condition of the interface of a bonding part can be relatively well obtained and the quality monitoring and the maintenance can be carried out on the bonding part in a relatively effective manner.