SU1366936A1 - Simulator of acoustic-emission signals - Google Patents

Abstract

The invention relates to the field of non-destructive quality control of materials by acoustic methods and can be used to configure and calibrate equipment for the study of acoustic emission in materials. The aim of the invention is to improve the accuracy of reproduction of simulated signals by taking into account the distribution of real acoustic emission signals over the amplitudes. In the process of generating imitation signals in the device, it is possible to change the probability of their occurrence at given time intervals and the probability density distribution of the values of their amplitudes. The device contains two 3,4 random number generators, a memory block 8, a binary counter 9 and a decoder 10, which make it possible to form at the output of the electroacoustic converter 6 a series of rectangular pulses simulating an acoustic transmission signal, 1 slug. i (Л с:

Description

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The invention relates to non-destructive quality control of materials by acoustic methods and can be used to set up and calibrate equipment for the study of acoustic emission in materials.

The purpose of the invention is to improve the accuracy of reproduction of simulated signals by taking into account the distribution of real acoustic emission signals in amplitudes,

The drawing shows a block diagram of a simulator of acoustic emission signals.

The simulator contains a series-connected clock generator 1, a one-oscillator 2 and the first generator 3 random numbers, a second generator 4 random numbers, a digital-to-analog converter 5 emitting an electro-acoustic converter 6, connected i to the output of the first generator 3 random numbers linear converter 7 code - probably The output of which is connected to the input of the second 4 random number generator connected. to the output of the last memory block 8, the output of which is connected to the input of the digital-to-analog converter 5, the output of which is connected to the radiating electroacoustic converter 6, and connected to the output of the one-oscillator 2 serially connected binary counter 9 and the decoder 10, the first group of outputs of which is connected to the address inputs of the block 8 memory, and the second groups: outputs - to the control inputs of the linear converter; 7 code - probability. I

The simulator works as follows.

Let it be necessary to simulate the AE signal of the developing defect, the statistical characteristics of which are given in the table (P (j) the probability of the appearance of exciting pulses in the time interval l, -, where t, tn is the final and initial time interval /) j; Co4j (A) is the distribution density of the probabilities of the amplitude A values of the exciting pulses in the interval d; ; i - the number of the tact of forming a simulating signal

d, i IP (P J

tod j (A)

Initially using a decoder 10 in a linear converter 7

and memory block 8, parameters P (4) and to, (A) are set. Radiating electro-acoustic transducer 6 is installed on the surface of material sample I1.

With the help of generator 1, a sequence of clock pulses is formed, which are normalized in duration by one-oscillator 2 and fed to the clock input of the first generator.

Torah 3 random numbers. The number of clock pulses is counted by binary counter 9.

At the output of generator 3, a sequence is formed uniformly

distributed random numbers with a period of M 2 1 s- where m is the number of bits of the generator shift register 3. This sequence of random numbers is fed to the first input of the converter 7, which converts a sequence of n-bit uniformly distributed random numbers into a random sequence of square pulses , the likelihood of rm (lr

occurrences of which at clock i-e moments of time t. is determined by the control code defined by the decoder 10, where n is the converter's resolution. 7..

The resulting pulse sequence is clocking for generator 4, the output of which forms a sequence of randomly distributed numbers, which is converted into a sequence of random numbers, the values of which are distributed in accordance with - by distribution in potencies

U), (A) amplitudes reflecting the law of the distribution of the amplitudes of the stimulating impulses of the simulated defect on the interval, l ,.

A sequence of random numbers formed at the output of memory block 8 is fed to the input of a digital-to-analog converter 5, where it is converted into a random sequence of rectangular pulses whose appearance moments are distributed in accordance with the value of P (i) and the amplitude in accordance with ). The resulting pulse sequence is fed to the input of a radiating electroacoustic transducer 6, which excites in the sample. 11 of the material is a random sequence of elastic vibration pulses simulating an acoustic emission signal.

Binary counter 9 counts the number of pulses of a sequence of clock pulses and when the number 1, which determines the interval duration l, is reached, using the decoder 10, sets the value of P (l,) and s (A) for interval d, and The process of generating imitation signals is repeated in a similar way. The same is done on the interval L

Using the proposed simulator makes it possible, during the generation of imitating signals, to change the likelihood of their occurrence at given time intervals and the probability density of the amplitudes, which increases

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the accuracy of simulating acoustic emission signals, for example, from developing defects.

Claims (1)

Invention Formula An acoustic emission simulator containing a series-connected clock generator, a one-shot and a first and second random number generators, a digital-analog converter and an emitting electroacoustic converter, characterized in that, in order to improve the accuracy of reproduction of simulated signals by taking into account the distribution of real signals acoustic emission amplitude, it is equipped with a linear converter connected to the output of the first random number generator code - probability b, the output of which is connected to the input of a second random number generator connected to the output of the latter by a memory unit whose output is connected to the input of a digital-to-analog converter connected to an emitting electroacoustic converter 30 and connected to the output of the single-oscillator by a serially connected binary counter and a decoder , the first group of outputs of which is connected to the address inputs of the memory unit, and the second group of outputs - to the control inputs of the linear converter code - probability. 20 25 35