SU819685A1 - Method of measuring ultrasonic wave damping - Google Patents

Description

(54) METHOD FOR MEASURING THE DROP OF ULTRASOUND WAVES

The invention relates to non-destructive testing and can be used in the control-attenuation coefficient in materials with high sound absorption, such as glass-reinforced plastics with various fillers and binders. .

A known method for measuring the attenuation of ultrasonic waves is based on comparing the amplitudes of ultrasonic pulses that have traveled various paths in the sample ij.

However, this method does not allow detuning from interference and account for temporal and other instabilities of the amplifying tract, which leads to errors in the measurement of the attenuation of ultrasonic waves.

The closest to the invention according to the technical essence and the end-to-end result is a method for measuring the attenuation of ultrasonic waves, which in the test sample is excited using a Pulse ultrasonic oscillator generator, adopts a sequence of ultrasound pulses that pass the test sample, combine the second ultrasonic pulse sequence with signal and

with respect to the amplitudes of these signals, attenuation is judged 2.

However, this method has a number of drawbacks leading to errors in the attenuation determination. Thus, different generators are used to determine the amplitude of the working signals, and therefore, the parameters of the pulses may differ. The pulses of the ultra-sound generator undergo changes in the acoustic path of the system, while the measuring pulses go directly to the input of the amplifier from the output of the additional

5 generator, min acoustic path in which the spectral composition of the initial pulse changes uncontrollably.

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The aim of the invention is to improve the accuracy.

This goal is achieved by noting that in the sample under study the same generator re-energizes the impulse

5 ultrasonic vibrations, take the first, passed through the test sample, an ultrasonic pulse and

it is used as a gauge, and calibrated and gauge

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Claims (2)

the pulses stand out against the background of noise using the time sensitivity adjustment. Fig. 1 shows a device for carrying out the method according to the invention. 2 - diagrams of acoustic pulses. The device consists of synchronizer 1, generator 2, radio pulses of system 3 for time sensitivity adjustment, amplifier 4, indicator device 5 and piezo transducers b and 7, and the sample 8 is heard. The proposed method is implemented as follows. The synchronizer 1 generates sync pulses applied to the generator 2 radio pulses and the system 3 of the time sensitivity adjustment associated with the amplifier 4 and introducing a variable attenuation to the amplification path. From the output of amplifier 4, the signal arrives at the indicator device 5. Piezo transducers 6, 7 are connected to the input of system 3 and the output of the generator 2 radio pulses. From the output of synchronizer 1, the synchronization pulse AQ is fed to the input of system 3 to start it, and output a- synchronously with A receives a pulse for the initial start of the generator of 2 pulses, or a pulse held relative to d for a selected time t. Both pulses can be sent to the generator 2 radio pulses for the primary and secondary start of generator 2. These pulses correspond to the sequence. Af and AZ From system 3, the voltage Ag is supplied to amplifier 4. Technically, the measurement is carried out as follows. From the synchronizer 1 output 1, a pulse A is sent to system 3, and from a, to the radio pulse generator 2, which excites a sequence of ultrasonic pulses A. Having determined the location of the first pulse from this series, from the output of the synchronizer 1 to the generator 2 serves two signal, which excite in the sample under study two sequences of ultrasonic pulses A, (and Ag. Then combine the different pulses of these sequences A and Ag by varying the delay time. The registration accuracy is determined by the interference Now, when the pulses A and An are located at the same distance from the beginning of the clock, the action of the system 3 on them is the same. By measuring the amplitude of these pulses, you can measure the attenuation value. The proposed method allows you to improve the measurement accuracy when controlling the attenuation coefficient in materials with a high absorption coefficient. Claim 1. A method for measuring the attenuation of ultrasonic waves, which consists in the fact that a pulse of ultrasonic oscillations is excited in the sample under test by means of a generator They take a sequence of ultrasonic pulses that have passed the sample under investigation, combine the second ultrasound pulse of the sequence with a calibration signal, and determine the attenuation with respect to the amplitudes of these signals, characterized in that, in order to improve the accuracy, the ultrasonic pulse is excited by the same generator vibrations, take the first, passed through the sample, the ultrasonic pulse and it is used as a calibration. 2. Method POP1, characterized in that the calibrated and calibration pulses are distinguished from the background of noise using a temporal sensitivity adjustment. Sources of information taken into account in the examination 1. USSR author's certificate number 576537, cl. G 01 N 29/00, 08.30.74 .. 2. Truel R. et al. Ultrasonic methods in solid state physics. M., Mir, 1972, p. 51-52 (prototype). s .one ff