RU2251688C1 - Acoustic emission signals registrar - Google Patents

Abstract

FIELD: non-destructive testing.

SUBSTANCE: registrar can be used as a part of automated acoustic-emission complex for measuring parameters of acoustic emission. Registrar has digital peak detector which measures pulsation amplitude if resolving level is available which level comes from comparator when pulsation exceeds discrimination voltage specified by reference voltage source. Measured peak voltage is recorded into buffer register and transmitted to computer through communication interface together with data from binary counter which counts number of clock pulses of master oscillator between two close pulsations. Control unit prevents overflow of counter. Control unit initiates arrival of "zero" amplitude pulsation if time interval between pulsations exceeds specified critical value.

EFFECT: widened functional abilities.

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Description

The invention relates to non-destructive testing and can be used as part of an automated acoustic emission complex as a recording device for measuring acoustic emission parameters (AE).

A device for recording acoustic emission signals is known that contains a daisy-chain analog-to-digital converter and a computer communication interface, through which the input voltage values are sequentially recorded with the arrival of each clock pulse from a clock having a frequency exceeding more than twice the frequency of the processed signal (Shalaginov Yu.V. A broadband signal recorder with accelerated data output // Instruments and experimental technique, 2001, No. 4, p. 83-87).

However, the known device has a low monitoring performance due to the fact that information is recorded at small discrete time intervals even when there is no input signal. This leads to inefficient use of memory and increase the processing time of the results.

Of the known technical solutions, the closest in technical essence to the claimed object is a device for recording acoustic emission signals, consisting of a digital peak detector that measures the amplitude of the ripple in the presence of a resolution level that comes from the comparator and occurs when the ripple exceeds the discrimination voltage, as well as the buffer register with computer communication interface, in the memory of which the code of the measured peak voltage is recorded (Drobot Yu.B., Lazarev A.M. Non-destructive testing of the mouth ostnyh cracks acoustic emission method -. M .: Izd Standards, 1987, 128)..

In this device, the measured values of the ripple amplitudes are stored in the form of a data array in random access memory and on their basis receive information about the amplitude distribution of pulses for the observation period, total AE count, AE count rate, etc. However, it does not allow to completely restore AE signals due to lack of information about the time of registration of each ripple.

The essence of the invention lies in the fact that in order to expand the functionality of the device for recording acoustic emission signals, it is supplemented with a binary counter that counts the number of clock pulses of the master oscillator between two adjacent pulsations. This information is transmitted through the computer communication interface along with the peak voltage value. To reduce the bit capacity of the counter and prevent its overflow in the absence of acoustic emission (the time interval between adjacent pulsations can be very large), a control unit has been introduced that initiates the arrival of pulses of “zero” amplitude if the time interval between them exceeds a predetermined critical value. As a result of each registered ripple, its amplitude and the time interval by which it lags behind the previous ripple are assigned. Considering that the AE ripple is a part of a sinusoid, based on these data for resonance sensors, a complete restoration of the initial AE signal is possible.

The invention is illustrated by the attached drawing, which shows a block diagram of a device for recording acoustic emission signals.

The device for recording acoustic emission signals consists of a digital peak detector 1, which measures the ripple voltage in the presence of an active resolution level at the input CS, which is connected to the output of the comparator 2. An active resolution level appears when the ripple voltage exceeds the discrimination voltage, which is set by the reference voltage source 3 connected to one of the inputs of the comparator. The measured peak voltage is recorded in the buffer register of interface 4 upon arrival of the pulsation termination signal at clock input C1 and is transmitted to the computer for further processing via the data bus. To register the time between adjacent pulsations, a binary counter 5 is connected to the buffer register of the interface, counting the number of clock pulses arriving at its input from the master oscillator 6. To prevent overflow of the counter, the control unit 7 is used, which initiates the arrival of a “zero” amplitude pulsation via clock input C2 if the counter value exceeds the specified critical value N _cr and the active signal at the output of the comparator is absent. The number N _{cr is} chosen so that, if there is an active level at the output of the comparator, the counter does not have time to overflow, i.e.

where N _max - the maximum value of the counter; τ is the duration of the pulsation (determined by the characteristics of the resonant acoustic emission sensor); T ₀ - the period of the rectangular pulses of the clock 6.

The practical implementation of the proposed device is carried out according to well-known schemes using domestic microcircuits (logic circuits and buffer registers of the 1533 series, ADC of the 1107 series, 554 series comparator) and foreign production (computer communication interface via USB-FT8U245BM bus).

The device for recording acoustic emission signals operates as follows. An electric signal from a resonant sensor amplified to the required level is supplied to its input. This signal is supplied to an analog input of a digital peak detector comparator 1 and 2. As soon as the input voltage U exceeds the threshold value _Rin U _pores defined by the reference voltage source 3, the output of the comparator 2 the active signal level that is input to the digital peak resolution CS detector and it starts the measurement process. The output of the comparator is also connected to the recording input in the buffer registers of interface 4, where the value of the measured voltage is stored at the time when U _in becomes less than U _then , i.e. voltage drop at the output of the comparator. At the same time, information is recorded from the output of counter 5, which counts the number of clock pulses from generator 6. Immediately after recording, a short reset signal appears, setting the peak detector to zero and the counter, which again starts to count clock pulses. From the buffer registers, the data is transferred to a computer for subsequent software processing. At the moment of arrival of the next ripple, the measurement process is repeated. Thus, the maximum voltage of each ripple and the time interval between them are measured. In the absence of acoustic emission, this time interval can be large. To prevent overflow of the counter 5, leading to the loss of useful information about the time, the control unit 7, which has two inputs, is used. On one of them a binary code is supplied from the counter, and on the other - a signal from the output of comparator 2, informing about the presence of ripple at the input of the AE signal registration device. If the counter reading exceeds some critical value N _cr and there is no active level at the output of the comparator, the device generates a signal for writing C2 to the buffer registers of the interface 4 for information on time and voltage. Since there was no ripple, the value of its voltage recorded in the register will be zero.

Claims (1)

The device for recording acoustic emission signals, consisting of a digital peak detector that measures the ripple amplitude in the presence of a resolution level that comes from the comparator and occurs when the ripple exceeds the discrimination voltage set by the reference voltage source, as well as the buffer register with the computer communication interface, into which code of the measured peak voltage, characterized in that a binary counter is added to the buffer register, counting the number of clock pulses a generator between two adjacent pulsations, and in order to prevent the meter from overflowing and reducing its bit capacity, a control unit has been introduced that initiates the arrival of pulses of “zero” amplitude if the time interval between them exceeds a predetermined critical value.