Method for ultrasonically detecting weld quality of main loop pipeline of nuclear power plant by phased array

The invention discloses an ultrasonic detecting method of defects in a thick-wall composite tubular structure. The ultrasonic detecting method includes the steps that original signal data are obtained, final signal data are obtained with signal processing methods such as noise reduction, fast Fourier transforming and continuous wavelet transforming, and a wavelet-coefficient-amplitude-time graph is generated; according to the generated wavelet-coefficient-amplitude-time graph, the positions and the sizes of inside damage of a composite material layer and the positions and the sizes of the unsticking portions of the boundary between the composite material layer and a metal layer are extracted, and distribution of the thickness of the metal layer is calculated. The ultrasonic detecting method can be used for detecting the multiple defects of the tubular structure composed of composite materials and metal, damage positioning and size assessing are carried out through the corresponding signal processing technology, and quantitative analysis of the whole structure performance can be achieved; the ultrasonic detecting method is high in accuracy, free of reference signals, simple, easy to operate and capable of being used for field detecting.

Ultrasonic detecting method of defects in thick-wall composite tubular structure

The invention discloses a wavelet denoising method and a wavelet denoising system both oriented to an ultrasonic signal. The method includes the following steps, step I, obtaining a mathematical model of the noise-contained ultrasonic echo signal f (t) =s (t) +r (t), and the s (t) is an ultrasonic echo attenuated signal received by a probe, and r (t) is all noises including structural noise; step II, selecting a basic wavelet and calculating scale function and filter function of the basic wavelet; and step III, performing convolution of the mathematical model of the ultrasonic echo signal and the filter function of the wavelet, so as to obtain the denoised ultrasonic signal. The invention can denoise the ultrasonic echo, reduce the area of the device, and enhance the robustness of the device.

Wavelet denoising method and wavelet denoising system both oriented to ultrasonic signals

Defect classification method based on phased ultrasonic wave

The invention relates to a classification and assessment method of ultrasonic detection defects of an extrusion formed thick-walled seamless steel pipe, and belongs to the field of inspection and testing According to the method, common defects found in the longitudinal wave vertical incidence ultrasonic detection process of the extrusion formed thick-walled seamless steel pipe are classified and defined according to morphology and distribution states, and are collected into a unified standard for assessment In the longitudinal wave vertical incidence ultrasonic detection process of the extrusion formed thick-walled seamless steel pipe, a variety of distribution state defects comprising layering are found, in the prior art, only layering defects have assessment standards, other types of defects have no assessment basis and standards, types of defects cannot be effectively defined, and cannot be classified and assessed, the quality of the extrusion formed thick-walled seamless steel pipe cannot be judged to cause overstock or fraudulent use of the extrusion formed thick-walled seamless steel pipe

Classification and assessment method of ultrasonic detection defects of extrusion formed thick-walled seamless steel pipe

The invention discloses a recognition method for weld defect signals generated in ultrasonic testing of austenitic stainless steel, and relates to a recognition method for weld defect signals in ultrasonic testing The objective of the invention is to solve the existing problem that weld defect signals generated in ultrasonic testing of austenitic stainless steel are hard to recognize The recognition method comprises the following steps: detecting a weld joint to be measured on the austenitic stainless steel and obtaining a column of A scanning signals a, and detecting an adjacent weld joint and obtaining another column of A scanning signals b; respectively carrying out wavelet packet decomposition on a and b so as to obtain corresponding wavelet packet trees and details of all branches of a and b; carrying out multiplicative operation on the details of all branches of a and b so as to obtain multiplicative details and corresponding multiplicative wavelet packet trees; carrying out noise reduction on the multiplicative wavelet packet trees so as to obtain A scanning signals with abated noise, and recognizing defect signals through the A scanning signals The method provided in the invention has a good noise suppression effect, can effectively overcome the difficulty in recognition and quantificational measurement of austenitic stainless steel weld defects, and is applicable to the field of ultrasonic testing

Recognition method for weld defect signal in ultrasonic testing of austenitic stainless steel

An ultrasonic time-of-flight diffraction method by a cylinder focusing wedge relates to the field of ultrasonic detection and solves the problem that an existing time-of-flight diffraction method for detection is low in energy level of defective diffraction signals and needs improvement of detecting sensitivity. The ultrasonic time-of-flight diffraction method includes the specific steps: firstly, determining known conditions including the diameter of a probe wafer, the longitudinal wave velocity of the wedge, the longitudinal wave velocity of a detected workpiece and the velocity of longitudinal waves in water; secondly, setting needed conditions including the water path of an acoustic beam of a spindle, the refraction angle of longitudinal waves in the detected workpiece and the focusing vertical depth of the acoustic beam of the spindle in the workpiece; and thirdly, computing the curvature radius of a cylinder of the wedge according to the conditions and detecting by the ultrasonic time-of-flight diffraction method through the manufactured cylinder focusing wedge. The ultrasonic time-of-flight diffraction method is used for ultrasonic detection.

Libin Zhao

Papers

Recognition method for weld defect signal in ultrasonic testing of austenitic stainless steel

Ultrasonic time-of-flight diffraction method by cylinder focusing wedge