CN112326801A - Plate-shaped ultrasonic three-dimensional imaging detection method - Google Patents

Plate-shaped ultrasonic three-dimensional imaging detection method Download PDF

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CN112326801A
CN112326801A CN202011189245.5A CN202011189245A CN112326801A CN 112326801 A CN112326801 A CN 112326801A CN 202011189245 A CN202011189245 A CN 202011189245A CN 112326801 A CN112326801 A CN 112326801A
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ultrasonic
plate
dimensional
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detection
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郑钢丰
吴博林
吴振宇
安永莉
李泽
刘松峰
董浩
章皓天
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Anhui University of Science and Technology
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/04—Analysing solids
    • G01N29/06—Visualisation of the interior, e.g. acoustic microscopy
    • G01N29/0654—Imaging
    • G01N29/069—Defect imaging, localisation and sizing using, e.g. time of flight diffraction [TOFD], synthetic aperture focusing technique [SAFT], Amplituden-Laufzeit-Ortskurven [ALOK] technique
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/44—Processing the detected response signal, e.g. electronic circuits specially adapted therefor

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Abstract

The invention discloses a plate-shaped ultrasonic three-dimensional imaging detection method, which comprises the following steps: s1, carrying out ultrasonic detection on the surface of the plate-shaped workpiece, and receiving an ultrasonic pulse echo signal; s2, converting the collected echo signals into three-dimensional space coordinates; and S3, performing three-dimensional reconstruction on the three-dimensional space coordinate data, and smoothing the image by adopting a piecewise linear interpolation method or a local weighted regression scatter smoothing method in the three-dimensional reconstruction process. According to the invention, the three-dimensional data is reconstructed by adopting a piecewise linear interpolation method and a local weighted regression scatter point smoothing method, so that the three-dimensional shape of the defect in the plate can be visually displayed, a large amount of waveform data does not need to be analyzed and judged in the whole process, the processing difficulty of the data is greatly reduced, the calculation amount of reconstruction and visualization is also greatly reduced, and the detection cost is greatly reduced.

Description

Plate-shaped ultrasonic three-dimensional imaging detection method
Technical Field
The invention relates to the field of nondestructive testing, in particular to a plate-shaped ultrasonic three-dimensional imaging testing method.
Background
The metal plate has small plasticity, corrosion resistance and density, and is widely applied in the industrial fields of aviation, aerospace, ships and the like. However, the materials have inevitable defects in the processes of processing, transportation, use and storage, such as: folds, cracks, bubbles, lamellar inclusions, etc., which may cause severe damage over time, causing damage to the equipment. Whether a defect exists in the metal plate needs to be judged by selecting a proper method, so that safety accidents are avoided.
Ultrasonic detection is widely used in defect detection of metal plates, and with the continuous development of ultrasonic nondestructive detection technology, the general development trend is to develop from slow imaging to fast imaging, from black and white images to color images, and from two-dimensional images to three-dimensional images.
Disclosure of Invention
In order to avoid and overcome the technical problems in the prior art, the invention provides a plate-shaped ultrasonic three-dimensional imaging detection method. According to the invention, the three-dimensional data is reconstructed by adopting a piecewise linear interpolation method and a local weighted regression scatter point smoothing method, so that the three-dimensional shape of the defect in the plate can be visually displayed, a large amount of waveform data does not need to be analyzed and judged in the whole process, the processing difficulty of the data is greatly reduced, the calculation amount of reconstruction and visualization is also greatly reduced, and the detection cost is greatly reduced.
In order to achieve the purpose, the invention provides the following technical scheme: a plate-shaped ultrasonic three-dimensional imaging detection method comprises the following steps:
s1, carrying out ultrasonic detection on the surface of the plate-shaped workpiece, and receiving an ultrasonic pulse echo signal;
s2, converting the collected echo signals into three-dimensional space coordinates;
and S3, performing three-dimensional reconstruction on the three-dimensional space coordinate data, and smoothing the image by adopting a piecewise linear interpolation method or a local weighted regression scatter smoothing method in the three-dimensional reconstruction process.
As a further scheme of the invention: in step S3, two adjacent nodes (x, y values in three-dimensional coordinates) are selected as sample pointsi,yi),(xi-1,yi-1) Then in each interval [ x ]i-1,xi]This can be solved by the following equation:
Figure BDA0002752318040000021
and after the interpolation function is obtained, setting a sampling speed, selecting the acquired data to represent reconstruction data, and smoothing the reconstruction data by adopting a piecewise linear interpolation method.
As a still further scheme of the invention: in step S3, data requiring smoothing processing is determined by the x, y values in the three-dimensional coordinates, and a smoothed value of (x, y) is obtained by performing weighted regression by specifying a data range adjacent to x; definition of regression coefficients:
Figure BDA0002752318040000022
in corresponding smooth fitting equation
Figure BDA0002752318040000023
In (1), the gradient a and the constant b are defined as:
Figure BDA0002752318040000024
Figure BDA0002752318040000025
wherein
Figure BDA0002752318040000026
And
Figure BDA0002752318040000027
weighted averages of x and y, respectively;
and setting a sampling speed, selecting the acquired data to represent reconstructed data, and smoothing the reconstructed data by adopting a local weighted regression scatter point smoothing method.
As a still further scheme of the invention: in step S1, the workpiece surface is gridded, and the center of each grid is used as a detection point of the probe, and the detection points are detected point by the ultrasonic pulse echo method.
As a still further scheme of the invention: the grid is a square grid, and the side length L of the grid meets the formula:
Figure BDA0002752318040000028
wherein D is the ultrasound probe diameter.
As a still further scheme of the invention: in step S1, when performing ultrasonic detection, the output interface and the synchronous interface of the ultrasonic pulse transmitter/receiver are connected to the access interface and the synchronous interface of the digital oscilloscope through the coaxial cable; connecting the ultrasonic straight probe with a transmitting/receiving end of a pulse signal generator through a coaxial cable; and a coupling agent is coated between the ultrasonic straight probe and the plate-shaped workpiece.
As a still further scheme of the invention: in step S2, a spatial rectangular coordinate system is established with one vertex of the plate-shaped workpiece as the origin and the plate thickness direction as the z-axis, the x-axis coordinate and the y-axis coordinate of the defect point can be obtained according to the sequence index of the grid, and the thickness d of the plate-shaped workpiece measured by the probe at the detection point corresponds to the z-axis coordinate:
d＝vt/2
wherein t is the difference between the acquired primary echo time and the acquired secondary echo time, and v is the sound velocity of the ultrasonic wave in the plate-shaped workpiece.
Compared with the prior art, the invention has the beneficial effects that:
1. according to the invention, the three-dimensional data is reconstructed by adopting a piecewise linear interpolation method and a local weighted regression scatter point smoothing method, so that the three-dimensional shape of the defect in the plate can be visually displayed, a large amount of waveform data does not need to be analyzed and judged in the whole process, the processing difficulty of the data is greatly reduced, the calculation amount of reconstruction and visualization is also greatly reduced, and the detection cost is greatly reduced.
2. The plate body is divided into grids, the central point of each grid is the detection point, the detection points are detected point by point, the positioning precision is high, the detection difficulty is low, the data acquisition difficulty is reduced, and the detection efficiency is improved; the grid is designed into a square grid, and the side length of the grid is determined by the diameter of the probe, so that the requirement of ultrasonic detection on inspection grade is met.
3. According to the invention, the whole ultrasonic detection system is set up before detection, so that the efficiency is higher during detection.
4. According to the method, the plate body is divided into grids, the x-axis position and the y-axis position of the defect point can be directly obtained according to the grid points, the thickness of the plate-shaped workpiece corresponding to the detection point can be obtained through simple calculation, the thickness value is the z-axis coordinate corresponding to the defect point, the depth position of the defect point is effectively identified, the obtaining difficulty of the coordinate of the whole defect point is low, and the reconstruction efficiency is high.
Drawings
FIG. 1 is a three-dimensional data reconstruction diagram when the piecewise linear interpolation method is used in the present invention.
FIG. 2 is a three-dimensional data reconstruction graph when the local weighted regression scatter smoothing method is used in the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1-2, in an embodiment of the present invention, a plate-shaped ultrasonic three-dimensional imaging detection method includes the following steps:
s1, carrying out ultrasonic detection on the surface of the plate-shaped workpiece, and receiving an ultrasonic pulse echo signal;
before ultrasonic detection is carried out, in order to conveniently determine the positions of detection points, the surface of a workpiece is firstly meshed, the central point of each grid is the detection point of a probe, in order to enable the detection effect to be better, the grid is a square grid, and after the detection points are determined, point-by-point detection can be carried out on the detection points through an ultrasonic pulse echo method.
Taking a plate-shaped workpiece with the length of 200mm and the width of 100mm as an example, the frequency of the selected ultrasonic straight probe is 5Mhz, the diameter of the selected ultrasonic straight probe is 10mm, and in order to enable the inspection grade to be not lower than II grade, the side length of each grid needs to meet the following requirements:
Figure BDA0002752318040000041
wherein D is the ultrasound probe diameter.
Before detection, the detection equipment is installed, an output interface and a synchronous interface of an ultrasonic pulse transmitting/receiving instrument are connected with an access interface and a synchronous interface of a digital oscilloscope through a coaxial cable, the type of the ultrasonic pulse transmitting/receiving instrument can be selected from Model5800, an ultrasonic straight probe is connected with a transmitting/receiving end of a pulse signal generator through the coaxial cable, after a plate is tiled, a coupling agent is coated between the ultrasonic straight probe and the plate, and then detection can be started, wherein the coupling agent can be white vaseline;
during detection, a user can select to hold the probe by hand or fix the probe by other fixing devices, so that the probe traverses each detection point, a pulse emitter generates a longitudinal wave pulse signal in the detection process, the probe is caused to vibrate and generate ultrasonic waves to be emitted into a plate-shaped workpiece, the longitudinal waves generate echo signals after encountering defects in a plate and are received by a sensor, the echo signals are converted into electric signals to be received by a pulse receiver and recorded on a digital oscilloscope as time domain signals, wherein the digital oscilloscope is Tektronix DPO 3012 type, and the oscilloscope reproduces time domain waveforms through Deskchoice Top data acquisition software installed at a PC (personal computer) end.
S2, converting the collected echo signals into three-dimensional space coordinates;
in order to facilitate the transformation of coordinates, a spatial rectangular coordinate system is established by taking one vertex of the plate-shaped workpiece as an origin and taking the thickness direction of the plate body as a z-axis, the side length of a grid is determined after the plate body is gridded, the x-axis coordinate and the y-axis coordinate of a defect point can be directly obtained according to the sequence mark of the measurement point, and the thickness d of the plate-shaped workpiece measured by the probe at the detection point is the z-axis coordinate corresponding to the defect point:
d＝vt/2
wherein t is the difference between the acquired primary echo time and the acquired secondary echo time, and v is the sound velocity of the ultrasonic wave in the plate-shaped workpiece.
And S3, performing three-dimensional reconstruction on the three-dimensional space coordinate data, and smoothing the image by adopting a piecewise linear interpolation method or a local weighted regression scatter smoothing method in the three-dimensional reconstruction process.
Piecewise linear interpolation: selecting two adjacent nodes (x) by taking x and y values in three-dimensional coordinates as sample pointsi,yi),(xi-1,yi-1) Then in each interval [ x ]i-1,xi]This can be solved by the following equation:
Figure BDA0002752318040000051
and after the interpolation function is obtained, selecting the acquired data to represent reconstruction data at a uniform sampling speed of 1cm/s, and smoothing the reconstruction data by adopting a piecewise linear interpolation method.
Local weighted regression scatter smoothing method: determining data needing smoothing processing according to x and y values in the three-dimensional coordinates, and performing weighted regression by formulating a data range adjacent to x to obtain a smooth value of (x, y); definition of regression coefficients:
Figure BDA0002752318040000052
in corresponding smooth fitting equation
Figure BDA0002752318040000061
In (1), the gradient a and the constant b are defined as:
Figure BDA0002752318040000062
Figure BDA0002752318040000063
wherein
Figure BDA0002752318040000064
And
Figure BDA0002752318040000065
weighted averages of x and y, respectively;
and selecting the acquired data to represent reconstruction data at a uniform sampling speed of 1cm/s, and smoothing the reconstruction data by adopting a local weighted regression scatter smoothing method.
The two methods are operated based on a Matlab platform, collected data are converted into three-dimensional coordinates through Matlab software, a fitting model is established through a fit function, an interp1 function is called when a piecewise linear interpolation method is used, a lowess function is called when a local weighted regression scatter point smoothing method is used, so that fitting goodness is obtained, and finally three-dimensional reconstruction is completed.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims (7)

1. A plate-shaped ultrasonic three-dimensional imaging detection method is characterized by comprising the following steps:
s1, carrying out ultrasonic detection on the surface of the plate-shaped workpiece, and receiving an ultrasonic pulse echo signal;
s2, converting the collected echo signals into three-dimensional space coordinates;
and S3, performing three-dimensional reconstruction on the three-dimensional space coordinate data, and smoothing the image by adopting a piecewise linear interpolation method or a local weighted regression scatter smoothing method in the three-dimensional reconstruction process.
2. The ultrasonic three-dimensional imaging inspection method according to claim 1, wherein in step S3, two adjacent nodes (x, y) are selected by using x, y values in three-dimensional coordinates as sample pointsi,yi),(xi-1,yi-1) Then in each interval [ x ]i-1,xi]This can be solved by the following equation:
Figure FDA0002752318030000011
and after the interpolation function is obtained, setting a sampling speed, selecting the acquired data to represent reconstruction data, and smoothing the reconstruction data by adopting a piecewise linear interpolation method.
3. The ultrasonic three-dimensional imaging inspection method for plate-like according to claim 1, wherein in step S3, data to be smoothed is determined by x, y values in three-dimensional coordinates, and a smoothed value of (x, y) is obtained by performing weighted regression by specifying a data range adjacent to x; definition of regression coefficients:
Figure FDA0002752318030000012
in corresponding smooth fitting equation
Figure FDA0002752318030000013
In (1), the gradient a and the constant b are defined as:
Figure FDA0002752318030000014
Figure FDA0002752318030000015
wherein
Figure FDA0002752318030000016
And
Figure FDA0002752318030000017
weighted averages of x and y, respectively;
and setting a sampling speed, selecting the acquired data to represent reconstructed data, and smoothing the reconstructed data by adopting a local weighted regression scatter point smoothing method.
4. The ultrasonic three-dimensional imaging inspection method according to any one of claims 1 to 3, wherein in step S1, the surface of the workpiece is gridded, the center of each grid is used as the inspection point of the probe, and the inspection point is inspected point by an ultrasonic pulse echo method.
5. The plate-shaped ultrasonic three-dimensional imaging detection method as claimed in claim 4, wherein the grid is a square grid, and the side length L of the square grid satisfies the formula:
Figure FDA0002752318030000021
wherein D is the ultrasound probe diameter.
6. The method for detecting plate-shaped ultrasonic three-dimensional imaging according to any one of claims 1 to 3, wherein in step S1, when ultrasonic detection is performed, the output interface and the synchronous interface of the ultrasonic pulse transmitter/receiver are connected with the access interface and the synchronous interface of the digital oscilloscope through coaxial cables; connecting the ultrasonic straight probe with a transmitting/receiving end of a pulse signal generator through a coaxial cable; and a coupling agent is coated between the ultrasonic straight probe and the plate-shaped workpiece.
7. The method for detecting plate-shaped ultrasonic three-dimensional imaging according to any one of claims 1 to 3, wherein in step S2, a spatial rectangular coordinate system is established with one vertex of the plate-shaped workpiece as an origin and the thickness direction of the plate body as a z-axis, the x-axis coordinate and the y-axis coordinate of the defect point can be obtained according to the sequence labels of the grids, and the thickness d of the plate-shaped workpiece measured by the probe at the detection point corresponds to the z-axis coordinate:
d＝vt/2
wherein t is the difference between the acquired primary echo time and the acquired secondary echo time, and v is the sound velocity of the ultrasonic wave in the plate-shaped workpiece.
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Publication number Priority date Publication date Assignee Title
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CN105973988A (en) * 2016-07-05 2016-09-28 方大特钢科技股份有限公司 Method for detecting ultrasonic three-dimensional imaging of lamellarflaw distribution
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Patent Citations (3)

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Publication number Priority date Publication date Assignee Title
CN102129714A (en) * 2011-03-01 2011-07-20 哈尔滨工程大学 Interpolating method for reconstructing defected pipe three-dimensionally based on cubic spline function
CN105973988A (en) * 2016-07-05 2016-09-28 方大特钢科技股份有限公司 Method for detecting ultrasonic three-dimensional imaging of lamellarflaw distribution
CN110363767A (en) * 2019-08-09 2019-10-22 中国特种设备检测研究院 A kind of gridding ultrasound tomography detection method of shaft-like workpiece defect

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Application publication date: 20210205