SU1499221A1 - Apparatus for testing articles by its own frequencies - Google Patents

Abstract

The invention relates to non-destructive testing and can be used to control the stages of damage to materials of products during fatigue tests by acoustic emission (AE) signals. The aim of the invention is to improve the accuracy of monitoring the stages of damage to the product during fatigue tests by evaluating the stages of damage simultaneously by the parameters of the AE signals and by changing the resonant frequency of the product. The signals from the output of the mechanical vibration converter are separated by a low-pass filter 10 and a high-pass filter 11 and are used to maintain fatigue loading at the resonant frequency of the monitored product and to register AE signals arising from fatigue damage to the product. 1 il.

Description

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The invention relates to non-destructive testing and can be used to control the stages of damage to materials of products during fatigue tests by acoustic emission (AE) signals,

The aim of the invention is to improve the accuracy of monitoring the stages of damage to the product during fatigue tests by evaluating the stages of damage simultaneously using the parameters of the AE signals and the change in the resonant frequency of the product.

The drawing shows a device for testing products at their own frequencies.

The device contains an amplifier connected in series. J low frequencies, control unit 2, defining 20 oscillator 3, -attenuator 4, power amplifier 5 and vibration exciter 6, mechanical vibration converter 7, processing and recording unit 8, the input of which is connected to the output of 25 low-frequency amplifier 1, second output of the unit for linking jen-yen with the second input of the attenuator 4; the device is also equipped with a series-connected matching 30 unit 9 and a low-pass filter 10, the output of which is connected to the input of the low-frequency amplifier 1, connected in series by the upper 11 often 35 and the pulse amplifier 12, whose output is connected to a second input of the processing unit 8 and recording unit 9 matching input coupled to the converter 7 of mechanical vibrations, c avyhodom filter January 1st highpass;

The device works as follows.

The product, for example, the bin of the blade blade 13, is mounted on the working surface of the vibration exciter 6, on the blade 13 a mechanical oscillation transducer 7 is installed, executed, for example, in the form of a resonant type AE transducer. The frequency characteristic of the transducer 7 mechanical oscillations is selected with a flat section at the beginning of the frequency range, for example, up to

10 kHz, the electroacoustic conversion factor of which is less than the similar coefficient at the resonant frequency of the converter, for example, 360.kHz. Using the master

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the generator 3, the attenuator 4, the amplifier 5 mops and the vibration exciter 6 in the blade 13 excite mechanical oscillations at the resonant frequency of the blade lying in the low frequency range up to 10 kHz. These vibrations excite the mechanical vibration transducer 7, the electrical signal from its transducer goes through the matching unit 9 to the low-pass filter 10, then to the low-frequency amplifier 1 and to the control unit 2, which changes the frequency of the master oscillator 3 to find the maximum value of the oscillation amplitude i.e. until the resonant frequency of the blade 13 is found. The oscillation amplitude is set to the required value by using an attenuator 4. The loading frequency and the number of loading cycles are recorded by the processing and recording unit 8. In the process of fatigue loading of the blade 13, AE signals appear that are absorbed in the zone of damage to the material of the blade 13, they are received by the mechanical vibration converter 7, and the high-frequency filter 11 extracts the high-frequency component of the signals in the frequency range, for example, 100 kHz.

The high-frequency signals of the AE are amplified by the pulse amplifier 12, processed by the parameters of the AE, and recorded by the processing and recording unit. The parameters of the AE signals are correlated with the frequency and number of loading cycles; the parameters are controlled by the stages of fatigue damage of the blade material 13. ..

Thus, the proposed device allows to increase the accuracy of control, as well as to simplify the implementation of the device through use. mechanical vibration transducer for maintaining fatigue loading at the resonant frequency of the monitored product, as well as for recording AE signals arising from fatigue damage to the product.

Claims (1)

Invention Formula  - Device for testing products on their own frequencies, containing 5 14992216 connected in series by force-tests, it is equipped with a low-frequency connector, a control unit, sequentially matching the master oscillator, attenuator, low-frequency block and filter, power amplifier and vibration excitation ((the course of which is connected to the input of the amplifier, a converter of a mechanical low-frequency, sequence-oscillation, processing unit and a register-connected high-pass filter, whose input is connected to the output frequencies and a pulse amplifier, which is a low-frequency amplifier, whose second pass; The second input / output unit of the control unit is connected to the processing unit and the recording unit, the second input of the attenuator, and the matching unit is connected to the input unit so that, in order to use the transducer of the mechanical covari- top damage to the product at fatigue frequencies.