JPS61271450A - Ae measuring apparatus - Google Patents

Abstract

PURPOSE:To enable accurate measurement of the rising-up time of an AE wave (acoustic emission), by measuring the first time as duration time of the AE wave and the second time up to the end time from the peak value to subtract the second time from the first time. CONSTITUTION:The peak value of an AE signal from an AE wave detection sensor 1 is outputted with an envelope circuit 3 as envelope signal and a comparator 5 outputs a high level signal only while the envelope signal exceeds a specified threshold. As a peak holding circuit 7 takes the maximum of the envelope signal to hold the peak value, the output of an AND gate 13 hold the high level thereof. Then, a counter 11 counts a clock pulse while the output signal of the comparator 5 is at the high level while a counter 15 counts a clock pulse while the output signal of the AND gate 13 is at the high level. Subsequently, the counts of the counter 15 is subtracted from the counts of the counter 11 with a subtraction circuit 17 to measure the rising-up time of the AE wave based on the number of the clock pulse.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention: Field of the Invention The present invention relates to an AP (acoustic electronic) measuring device.

B. Conventional technology When the AE wave detection sensor detects 9 AE waves to inspect the stress state of the target member, the rise time of the AE waves, that is, A
It is required to accurately measure the time from when the E wave exceeds the threshold until it reaches its maximum amplitude. On the other hand, it is also required to accurately measure the duration of the AE wave, that is, the time during which the AE wave exceeds a threshold value.

Problems to be Solved by the C0 Invention The rise time is normally on the order of several microseconds, and if the rise of the AE wave is steep, it becomes difficult to measure it. for example,
When enveloping the peak value of the AE wave detection sensor output to obtain an envelope signal and measuring the rise time and duration from the envelope signal, increasing the time constant of the envelope circuit allows accurate rise time measurement. , the duration cannot be measured accurately and vice versa.

Means for Solving the D0 Problem The present invention provides a sensor that detects the AE wave and outputs a signal, and an envelope that envelopes the peak value of the signal, in order to accurately measure the rise time and duration of the AE wave. means, first measuring means for measuring a first time during which the output of the envelope means exceeds a predetermined threshold value, detection means for detecting that the output of the envelope means has reached a peak value; a second measuring means for measuring a second time from the time the peak is detected to the end of the first time; and subtracting the second time from the first time to determine the AE.
and calculation means for calculating the rise time of the wave.

80 Effect In the present invention, the first time during which the enveloped sensor output is greater than or equal to a predetermined threshold is measured by the first measuring means, and the detection means detects that the enveloped sensor output has reached a peak value. Then, a second time period from the time when the peak value is detected to the end of the first time period is measured by the second measuring means. Then, the second time is subtracted from the first time by a subtraction circuit to calculate the rise time of the AE wave.

F. Embodiment FIG. 1 shows an embodiment of the present invention, and reference numeral 1 denotes an AE wave detection sensor that detects an AE wave and outputs an AE multiplied signal. For example, a piezoelectric type sensor can be used. The sensor 1 is followed by an envelope circuit, and the envelope circuit 3 is followed by a comparator 5, a peak hold circuit 7, and a comparator 9. A reference signal TH, which is a predetermined threshold value, is also applied to the comparator 5, and the output of the comparator 5 is il, which is ANDed with the clock signal.
1 is input. The output of the peak hold circuit 7 is connected to one input terminal of the comparator 9, and the output of the envelope circuit 3 mentioned above is connected to the other input terminal. The outputs of comparators 5 and 9 are connected to the inputs of AND gate 13, respectively.
The output is input to the AND gate 19 along with the clock signal, and the output thereof is input to the counter 15. therefore the power
The counters 11 and 15 are configured to count the pulses of the clock signal only while the output of the comparator 5 and 9 is at a high level. The output of each counter is connected to a subtraction circuit 17, and the subtraction circuit 17 is configured to output the result of subtracting the count value of the counter 15 from the count value of the counter 11.

The operation of this embodiment will be explained with reference to FIG.

As shown in FIG. 2(a), A from the AE wave detection sensor 1
The peak value of the H signal is enveloped by the envelope circuit 3 to become an envelope signal as shown in FIG. 2(b). The comparator 5 outputs a high level signal only while the envelope signal exceeds a predetermined threshold, that is, from time t1 to time t (FIG. 2(C)). The peak hold circuit 7 takes the maximum value of the envelope signal and holds the peak value after the peak value, so that the peak value shown in FIG. 2(b)
In the case of a signal like this, the peak value P at time tt is held from time t onwards (FIG. 2(d)). Therefore, the output of the AND gate 13 remains at a high level only between time points t and t, as shown in FIG. 2(e). The counter 11 is
The time t when the output signal of the comparator 5 is at high level,
~ Count the incoming clock pulses at t3, counter 1
5 counts incoming clock pulses at times t, ~t, when the output signal of the AND gate 13 is at high level. Then, the subtraction circuit 17 subtracts the count value of the counter 15 from the count value of the counter 11, and outputs the result. That is, the output of the subtraction circuit 17 is at time 1. Without changing the reference pulse number of −1°, the rise time of the envelope signal, that is, the AE wave, can be measured based on the pulse number. on the other hand,
Based on the output of the counter 11, the duration of the AE wave can be measured.

Note that the output of the counter 11 and the output of the subtraction circuit 17 can be displayed as the actual rise time and duration, and the high level duration of the comparator 5 and the AND gate 13 can be measured using a microprocessor. Time and duration can also be calculated.

G2 Effect of the Invention According to the present invention, the first time which is the duration of the AE wave is measured, and the second time from the time when the AE wave reaches its peak value to the end of the duration is measured. Since the rise time of the AE wave is measured by subtracting the second time from the first time, it is possible to accurately measure the rise time without adding a large time constant to the envelope circuit. Time can also be measured accurately.

[Brief explanation of the drawing]

Ru. 1... AE wave detection sensor, 3... Envelope circuit, 5.9... Comparator, 7... Peak hold circuit, 11.15... Counter, 13.18.19... AND gate , 17... Subtraction circuit.

Claims (1)

[Claims] A sensor that detects an AE wave and outputs a signal, an enveloping means that envelops the peak value of this signal, and a first measuring means that measures a first time during which the output of the enveloping means exceeds a predetermined threshold. a detection means for detecting that the output of the envelope means has reached a peak value; and a second time period for measuring a second time period from the time when the peak is detected by the detection means to the end of the first time period. 2. An AE measuring device comprising: second measuring means; and calculating means for calculating the rise time of an AE wave by subtracting the second time from the first time.