5 results about "Ultrasonic scattering" patented technology

The invention provides a method for detecting a welding seam by adopting an ultrasonic flaw detector, and belongs to the technical field of welding seam detection. The welding seam is divided into small welding sections, and each small welding section is subjected to multi-direction ultrasonic scanning; a scattering attenuation coefficient and a signal-to-noise ratio parameter are calculated to determine an optimal detection position direction vector group and an optimal time frequency group, and then a high-frequency narrow pulse probe is matched with a phased array focusing technology to carry out second detection according to the optimized parameter; and the identified defects are classified and evaluated according to the near surface blind area characteristic parameters, secondary verification is performed by adopting a surface wave supplementary detection algorithm, and finally a weld defect position distribution diagram is generated, so that the technical problem of low defect detection accuracy caused by serious ultrasonic scattering attenuation of a coarse grain structure weld material is solved.

The invention relates to the technical field of ultrasonic testing, in particular to a nondestructive testing method and device for inclusions in a titanium alloy bar. The method comprises the following steps: synchronously acquiring ultrasonic A scanning signals before and after multi-moment thermal imaging and thermal excitation by applying thermal pulse excitation; calculating a delay cooling factor based on the pixel temperature time sequence change, determining a hot spot existence rate in combination with the spatial distribution of the delay cooling factor in a multi-direction neighborhood, and screening a thermal abnormal region; in the region, a peak redundancy coefficient is determined by using time sequence volatility of ultrasonic signal amplitude, A scanning waveforms before and after thermal excitation are analyzed through window sliding cross-correlation to obtain a distortion degree, the two are fused to obtain an ultrasonic abnormal degree, and whether inclusions exist or not is judged according to the ultrasonic abnormal degree. According to the method, ultrasonic scattering noise caused by a titanium alloy coarse grain structure is effectively avoided, and the reliability of tiny inclusion detection is improved.

The invention provides an ultrasonic image reconstruction method. The method comprises the following steps: taking original radio frequency data received by an ultrasonic probe as an image reconstruction object; firstly, a sound field characteristic matrix of an ultrasonic probe in a two-dimensional plane is obtained through measurement of a hydrophone; according to the sound field characteristic matrix, a pulse-echo matrix corresponding to a two-dimensional plane is obtained through a classic sound field propagation rule, and probe excitation signals, probe response characteristics and sound field distribution prior are introduced into a reconstruction process; then, through a classic ultrasonic scattering echo model, a mapping relation among ultrasonic echo data, a pulse-echo matrix and an ultrasonic two-dimensional image is obtained; then, by introducing a multi-frame shared sparse constraint and optimization method, high-speed video reconstruction is realized instead of traditional single-frame reconstruction; the method has the beneficial effects that the signal-to-noise ratio and the signal-to-background ratio are remarkably improved, and meanwhile, side lobe and grating lobe artifacts are reduced.

This invention relates to the field of underwater weld technology and discloses a method and system for forward modeling of nonlinear ultrasonic scattering in the early stage of underwater welds. The method includes: obtaining material nonlinear parameters based on the ratio of second harmonic to fundamental wave amplitude; obtaining interface contact nonlinear parameters through the second harmonic amplitude in the reflected wave from the crack interface; establishing water-solid interface propagation conditions and constructing a sound velocity model; combining the sound pressure superposition relationship under multipath propagation and array excitation conditions to obtain the total fundamental wave sound pressure at any receiving point within the weld; and constructing a unified nonlinear ultrasonic forward scattering model by introducing equivalent local nonlinear parameters for unified characterization. This invention, by constructing a unified characterization model of material nonlinearity and contact acoustic nonlinearity, and combining the water-solid coupling propagation mechanism with Green's function forward modeling, can improve the completeness of the description of nonlinear ultrasonic scattering mechanisms and the accuracy and stability of the quantitative characterization of early-stage micro-damage in underwater welds.

A method and dedicated device for ultrasonic detection of microcracks in semiconductor silicon rings are disclosed, specifically comprising: selecting a piezoelectric crystal with a size of 6–10 mm and a frequency range of 1 MHz–15 MHz for a water immersion focusing ultrasonic probe; calculating the required incident angle for the ultrasonic waves to refract into transverse waves, surface waves, and creeping waves at the water / silicon interface; adjusting multiple sets of ultrasonic probes to emit ultrasonic waves at different tilt angles according to the incident angle value; the ultrasonic waves are refracted on the surface of the semiconductor silicon ring, resulting in waveform conversion; the refracted waves excited by ultrasonic waves at different incident angles in the semiconductor silicon ring propagate in the silicon wafer along a certain propagation path; when they encounter a defect, ultrasonic scattering occurs, and the reflected waves in the scattering return along the original path and are received by the ultrasonic probe; the ultrasonic probe converts the reflected wave signal into a detection electrical signal and transmits it to the ultrasonic instrument; the ultrasonic instrument uploads the result signal to an industrial control computer; the imaging software in the industrial control computer images the detection results and displays the distribution information of the microcracks in the entire semiconductor silicon wafer.