SU1562846A1 - Method of ultrasonic through-transmission flaw detection of laminated articles - Google Patents

Abstract

This invention relates to acoustic methods of non-destructive testing. The aim of the invention is to improve the accuracy of determining the boundaries of the defect by eliminating the effect of fluctuations in the quality of acoustic contact due to the use of the dependence of the amplitude of ultrasonic (UL) oscillations passed through the product in the area of the defect obtained by means of a regression analysis. Ultrasonic transducers are coaxially mounted on opposite surfaces of the product. With their help, they emit and receive ultrasonic vibrations. Linear step-by-step scanning of the product is performed and the amplitude of the received ultrasonic vibrations is measured. When the amplitude reaches the threshold level, the presence of a defect is recorded. Using a regression analysis of the measurement results at several points, the amplitude of the received ultrasonic vibrations is determined and the location of the defect boundary is found. 2 Il.

Description

The invention relates to the field of acoustic methods of non-destructive testing and can be used in ultrasonic (US) inspection of multilayer products.

The aim of the invention is to improve the accuracy of determining the boundaries of the defect by eliminating the effect of fluctuations in the quality of the acoustic contact due to the use of the dependence of the amplitude of the ultrasonic oscillations transmitted through the product to determine the boundaries in the area of the defect obtained by regression analysis.

Figure 1 shows a graph of the amplitude U of received oscillations from the current coordinate, calculated on the basis of experimentally obtained points (UMOKC is the maximum amplitude value in the quality section of the product; U; amplitude of oscillations received at the point with coordinate Xjj U0 is the threshold the level reached at the point with the coordinate X0; XQ is the coordinate of the defect boundary (YI is the magnitude of fluctuations of the amplitude of the received oscillations on the quality section of the product when the quality of the acoustic contact changes); figure 2 - the results of the ultrasound control and preparations

SP

about

No

Sya

sample with a defect (X, 5Xoot Hooh - coordinates of points at which, with repeated scanning, the amplitude of received oscillations reached a threshold level; Hot, Hog, X03 - coordinates of points at which the boundary of the defect was recorded during repeated scanning by means of ultrasonic shadow flaw detection of multilayer products) ,,

The method of ultrasonic shadow flaw detection of multilayer products is as follows

On opposite sides of the product, the radiating and receiving transducers are acoustically aligned. Ultrasonic vibrations are emitted into the product by a radiating transducer, and ultrasonic vibrations transmitted through the product are received by the receiving transducer. 2

The product is scanned coaxially with the transducers and the amplitude of the received ultrasonic vibrations is measured. When the amplitudes of the received oscillations reach the threshold level U0, the X0 2 coordinate of the transducers is determined and the presence of a defect is recorded.

The amplitude U is also measured when the transducers are located at points with coordinates Xj, which are located on a straight line passing through a point with coordinate X0. Defect boundaries are determined using

U A exp (-kX),

Where X is the current coordinate;

U is the amplitude of the received ultrasonic oscillations along the current coordinate; / A; k are the coefficients determined by

in the regression analysis of the resulting set Xj, X0, U-, U0

The ultrasonic shadow flaw detection method of multilayer products is implemented as follows.

On opposite surfaces of products made, for example, of 45 mm laminate, transducers are installed at a frequency of 400 kHz with a contact area width of 22 mm. The transducers are connected to the ultrasonic flaw detector, for example, UD-22 of the AM and perform step-by-step scanning of the product along the coordinate axis X (the step is 10 mm). Over the threshold level U0, the average level is taken | its signal on the defect-free area of the product (U - / JU) / 2 minus 25 dB.

fAWK-Cu

Until an amplitude U is reached

the signal at the point with the coordinates X0 X7 select the points with the coordinates X 1 - XfЈ and determine the amplitudes C, .. U {3 signals received at these points. The least squares method finds the minimum of the function N

f. (A, k) Z (In U. + kX2 - InA),

where N is the number of pairs of involved measurements X, Uf;

A, k - coefficients.

As a result, the following values are obtained: w

N51 (xhnU) - rxf .InUi, 1

 T | 1gg- GO

 exp

 N, N1

k 21 (x) + 5: inu: i

N

From the obtained values of the coefficients A and K, the calculated functions are calculated.

U A exp (-kX).

Using the values of the function U.x) calculated, for example, on a DVK-2 computer, the boundary of the defect is determined. According to the results of the opening, the defect boundary for the monitored product is the point with the x2 coordinate (figure 1) at which the amplitude of the received signal decreases.

Claims (1)

Invention Formula The method of ultrasonic shadow flaw detection of multilayer products, consisting of installing acoustically coaxial emitting and receiving transducers on different sides of the product, emitting and receiving ultrasonic oscillations with corresponding transducers, coaxially scanning the product with transducers, measuring the amplitude of received oscillations, determining the X position of the transducers when the measured the amplitude of the threshold level U0 and the determination using the measured amplitude and position of the presence and boundaries of the defect characterized in that, in order to improve the accuracy of determining the boundaries of the defect, upon reaching the threshold level measured by the amplitude, several positions X are additionally determined — converters located on the line passing through the position X0; and amplitudes 11 are measured positions Xj, and the boundaries of the defect are determined by taking into account the formula U A exp (-kX) de x u Af K ™ current coordinate; amplitude of received oscillations along the current coordinate; coefficients determined by regression analysis of the resulting population vo and,., and about i xi xs 4 $ fa I Xv s xTI it ty X 1 I