UA138394U - METHOD OF CAPACITIVE EXCITATION OF HIGH-FREQUENCY ULTRASOUND RELAY PULSE PULS IN ELECTRICALLY CONDUCTIVE PRODUCTS - Google Patents

Abstract

The method of capacitive excitation of pulses of high-frequency ultrasonic Rayleigh waves in electrically conductive products includes the formation of a pulsed high-frequency electric field of a given frequency in the surface layer of the metal product and the action on the same surface layer of the product by a constant polarizing electric field. Constant polarizing and high-frequency electric fields are formed in the surface layer of the product in the form of a group of parallel sections. Each adjacent plot is located at a distance from each other.

Description

The useful model belongs to the technique of quality control of materials, products, equipment, etc., more specifically to the technique of detecting defects, determining physical and mechanical characteristics, thickness measurement by ultrasonic Rayleigh surface waves using the capacitive method of excitation of ultrasonic pulses.

There is a known method (1) of excitation of ultrasonic pulses by a capacitive method, which includes the formation of a pulsed high-frequency electric field of a given frequency in the surface layer of an electrically conductive metal product and the effect of a constant polarizing electric field of the same polarity on the same surface layer of the product.

A significant drawback of this method is that it does not allow effective excitation of high-frequency surface Rayleigh waves.

The closest analogue of |2| according to the technical essence and according to the claimed result, there is a method that includes, with the help of a round electrode, the formation of a pulsed high-frequency electric field of a given frequency in the surface layer of an electrically conductive metal product and the effect of a constant polarizing electric field on the same surface layer of the product.

A significant disadvantage of this method is also that when using a round electrode, longitudinal waves are mainly excited, which do not allow to control the quality of the surface layer of the metalwork, and high-frequency surface waves are excited inefficiently.

In addition, longitudinal waves can form coherent interference, which will reduce the quality of control.

The useful model is based on the task of increasing the efficiency of excitation of high-frequency ultrasonic pulses of surface waves due to the addition of amplitudes with the same phase of ultrasonic pulses excited in local areas of the surface of the metal product.

The problem is solved due to the fact that according to the known method of capacitive excitation of pulses of high-frequency Rayleigh ultrasonic waves in electrically conductive products, which includes the formation of a pulsed high-frequency electric field of a given frequency in the surface layer of the metal product and the effect of a constant polarizing electric field on the same surface layer of the product, according to a useful model, constant polarizing and high-frequency electric fields are formed in the surface layer of the product in the form of a group of parallel sections, while each adjacent section is located at a distance of 2 from each other, which is determined by the expression о-пС/ where С is the speed of propagation of an ultrasonic Rayleigh surface wave in the material to be diagnosed, mm/μs; n - integer 1, 2, 3...;

It is the frequency of the high-frequency electric field, MHz. An increase in the excitation efficiency of high-frequency ultrasonic pulses of surface waves is ensured due to the addition of amplitudes with the same phase of ultrasonic pulses excited in local areas of the surface of the metalwork, which are located from each other at a distance that is a multiple of the length of the Rayleigh ultrasonic surface wave.

The drawing shows a simplified diagram to explain the principle of implementing the proposed method.

The following are marked on the drawing: 1 - object of control (OK); 2...t - areas of the surface of the OK, in which pulsed high-frequency and constant electric field are excited, E - distance between adjacent areas of the surface of the OK, where it is necessary to excite ultrasonic surface pulses. C - excited high-frequency pulses of Rayleigh surface waves. (t) is the sign of the polarity of the applied polarizing constant electric field, which is the same in all areas. (5) - the mark of the applied high-frequency electric field. Arrows show the directions of propagation of the resulting excited Rayleigh surface waves.

The method is implemented as follows. In the surface layer of OK 1, a constant polarizing electric field is formed in sections 2...t, for example with polarity (yh). A pulsed high-frequency electric field (7) is periodically formed in the same sections 2...t. The interaction of a constant polarizing electric field (5) and a pulsed high-frequency electric field (5) in sections 2...t leads to the excitation by each section 2...t of pulses of Rayleigh surface waves that propagate in the directions shown by the arrows. Since the sections 2...t are located at a distance of 9 - pol », which is equal to n lengths of the ultrasonic surface wave, where C is the speed of propagation of the Rayleigh ultrasonic surface wave in the material to be diagnosed, and i is the frequency of the high-frequency electric field, then each section is excited 2...t pulses of the Rayleigh waves will have the same phase and in the directions indicated by the 60 arrows, will add up in amplitude. The need to choose the distance is due to the high frequency of exciting ultrasonic vibrations. At short distances 9: adjacent areas affect each other, reducing the efficiency of converting electrical energy into ultrasonic energy. At significant values of Я, the dimensions of the surface of the OK, where pulses of high-frequency ultrasonic waves are excited, increase significantly. It is optimal to form adjacent areas of excitation, at high frequencies, at distances of several lengths of ultrasonic waves.

In this way, the efficiency of excitation of high-frequency ultrasonic pulses of Rayleigh surface waves is ensured by adding with the same phase the amplitudes of ultrasonic pulses excited in adjacent local areas of the surface of the metalwork, located from each other at an optimal distance.

Sources of information: 1. Non-destructive testing: Reference book: In 7 vol. Pod obsch. ed. V.V. Klyueva. T. 3:

Ultrasonic control / I.N. Ermolov, Yu.V. Lange. - M.: Mashinostroenie, 2006. - 864 p. 2. Nozdracheva E.L. Peculiarities of excitation of ultrasonic pulses by a capacitive transducer / Nozdracheva E.L., Suchkov G.M., Petrishchev O.N. // Scientific works of the Donetsk National Technical University. Series: "Computer technology and automation". -

Krasnoarmiysk. - 2015. - Mo 1(28). - P. 165-170.

Claims (1)

USEFUL MODEL FORMULA The method of capacitive excitation of pulses of high-frequency Rayleigh ultrasonic waves in electrically conductive products, which includes the formation of a pulsed high-frequency electric field of a given frequency in the surface layer of the metal product and the effect on the same surface layer of the product of a constant polarizing electric field, which is distinguished by the fact that the constant polarizing and high-frequency electric fields are formed in the surface layer of the product in the form of a group of parallel sections, while each adjacent section is located at a distance of 5, which is determined by the expression o-аС/l where С is the speed of propagation of an ultrasonic Rayleigh surface wave in the material to be diagnosed , mm/μs; n - integer 1, 2, 3...; It is the frequency of the high-frequency electric field, MHz. h m o x U x Y x 2 3 d more Kk and yo boi hi | a shchi / Sl | | and the EU in ! and t - la u ! and c 4 Z I pig K u i I a and a | Y x ;