SU1527576A1 - Method of ultrasonic inspection of laminated articles - Google Patents

Abstract

The invention relates to non-destructive testing and can be used to control multilayer products, as well as in medical diagnostics. The purpose of the invention is to improve the accuracy and informativeness of the control by allowing independent measurement of the speed of acoustic oscillations in individual layers of the product and the thickness of its layers. Through the immersion medium, focused and unfocused acoustic waves are introduced into the layer under study and record the maximum amplitudes of the echo pulses of the focused wave from the back surface of the layer under study, and the unfocused wave from its front surface. The time Τ _fis and Τ flow in the test layer, respectively, of focused and _non- focused acoustic waves are _measured . The thickness of the layer and the speed of ultrasound are determined by the design formulas. 2 Il.

Description

The invention relates to non-destructive ultrasound testing of objects and can be used to control multilayer products, as well as in medical diagnostics.

The aim of the invention is to improve the accuracy and informativeness of the control

Fig. 1 shows an acoustic diagram explaining the essence of the method of ultrasonic testing of multilayer products; 2 is a simplified block diagram explaining the implementation of the method.

The block diagram includes a receiving-transmitting broadband focusing piezoelectric transducer 1 (damper not shown), which is coaxially connected with it mechanically receiving-transmitting nefo. a broadband piezo transducer 2 (damper not shown), contact medium 3 placed in cell 4, first 5 and second 6 layers of a multilayer product (other n layers are not shown), coordinate device 7, switch 8, amplifiers 9 and 10, pulse oscillator 11, test oscilloscope 12.

The essence of the method lies in the fact that the use of two types of transducers, focused and direct, allows measuring the thickness of the test layer and the speed of ultrasonic vibrations in it independently.

The method is carried out as follows.

A pulsed generator 11 through a switch 8 is sequentially excited by focused and unfocused piezoelectric transducers 1 and 2 mounted coaxially. The ultrasonic oscillations propagate in the direction of the multilayer product through a layer of contact liquid 3, of which

the cuvette is filled with the test layer 5 by moving the focusing transducer 1 in the coordinate device 7 to achieve a coincidence of focus with the rear border of the test layer 5 (boundary 5 - layer 6) according to the maximum echo of the echo signal by moving the two beams to the converters. the transducer with the front edge of the layer 5 under study at the maximum amplitude of the echo signal received by the unfocused transducer

The echograms on the oscilloscope 12 measure the time L, the passage of a pulsed signal by a focused wave, the distance 1 for the first layer 5 analyzed and the time C of the pulsed signal of a distance 1 unfocused for passing

 In the first

test layer 5 (Fig. 1) "At known ultrasonic velocity values from 1, in contact medium 3 and angle 0 of incidence of a focused impulse wave, cn (EG o signal at the transition boundary, contact medium 3 — the first layer 5 under study is determined the speed of ultrasound c in the first test layer 5 of the multilayer product LIN and thickness 1, (. riepBoro of the test layer 5

 / n "with sin (arccos ts

-1I4, V FIS

(one)

/ IIS

(arccos-X)

Serpe

(2)

For the determination of the subsequent tolpsin 1, | .j of the nth layers of the studied multilayer structure and the velocity of the ultraviolet with yf, they use the expressions (1) and (2), and, for the nth layer, in the sequential determination layer thickness and ultrasound velocity in it, instead of the value of c, use the predetermined value of c not (), and instead of the value of b, the offset arccos (- fis)

275764

Thus, with known values of the ultrasound velocity in a contact medium and the angle of incidence b of a focused ultrasonic wave of a pulsed signal when it passes through the boundary, the contact medium — the first layer under study or the layer under study — is the layer under study during subsequent measurements, as well as out of 10

five

0

five

0

five

Q

five

0

me fV (c.

According to expression (2), the thickness of the test layer is determined by the expression (2). According to the described measurement method, it is possible to determine the depth of the defect or foreign body in the test layer.

Claims (1)

Invention Formula The method of ultrasonic testing of multilayer products, concluding by introducing through the contact medium into the controlled object a focused transducer of acoustic pulses, receiving the same pulses of echo pulses reflected from the boundary between the layers with different acoustic impedances, and analyzing them, in that the aim of increasing the accuracy and informativeness of the control is by providing the possibility of independent measurement of the speed of acoustic oscillations in individual layers of the product and the crowd of its layers, acoustic impulses with an unfocused transducer are additionally introduced into the controlled product, moving the transducers relative to the product, record the maximum amplitudes of the echo pulses received by the focused and unfocused transducers from the back surface of the layer under study, measure time (and passage of the layer under study by pulses emitted by the focused and unfocused transducer) , and the speed of acoustic oscillations in the layer under study is determined from the with a cop. NIS h     ° Where - the speed of ultrasound, respectively, in the test layer and the contact medium; - the angle of incidence of the focused wave of pulsed signals on the front surface of the layer under study, 1527576 and the thickness iyg of the layer under study is determined from the extrusion s with a with kitty 2sin6 sin (arccos CfHC Tszig.1 11r.2 Compiled by S. Arbuzov Editor A. Shandor Tehred A. Kravchuk Corrector O. Kravtsova Building 7506/50 Circulation 789 VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, Raushsk nab. 4/5 Production and Publishing Combine Patent, Uzhgorod, st. Gagarin, 101 Subscription