JPH0312552A - Method and device for measuring transversal sound wave speed in ultrasonic wave test - Google Patents

Abstract

PURPOSE:To measure the propagation time of a transversal wave with high accuracy by converting the output of a probe for reception to a frequency range, extracting a desired frequency component from the conversion output, and converting the extracted signal into a time-series signal again and displaying the waveform. CONSTITUTION:A Fourier transforming means(FFT) 12 transforms the output of the probe 11 for reception which is obtained in time series to the frequency range to obtain a transversal wave component on a low frequency side and a longitudinal wave component on a high frequency side. Therefore, a signal processing means (low-pass filter) 13 consisting of a proper filter extracts only the low-frequency side transversal component and an inverse Fourier transforming means(IFFT) 14 which retransforms the signal in the frequency range into a time-series signal and inputs the signal to a display means(oscilloscope) 15, so that the signal waveform of only the transversal wave component is obtained. Therefore, the speed and propagation time of the transversal wave can accurately be known.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to ultrasonic measurement used for quality control and deterioration testing of concrete structures, or non-destructive testing of timber, reinforced plastic FRP, etc. The present invention relates to a method and apparatus for measuring the sound velocity of transverse waves in ultrasonic tests, which enables accurate measurement of the sound velocity of transverse waves.

[Prior Art] In the fields of architecture and civil engineering, the i91 determination of the compressive strength of concrete, the determination of uniformity, and the detection of internal defects are usually performed by ultrasonic testing, the configuration of which is shown in Figure 5. be. In Figure 5 alb, 1 is a transmitting probe that oscillates ultrasonic pulses, 2 is a receiving probe that detects transmitted waves and reflected waves, and 3 is the concrete that is the subject of the test. .

FIG. 5a shows a configuration for determining the compressive strength of concrete. In this case, the transmitting probe 1 is placed on one side of the concrete 3, for example, the surface, and the receiving probe 2 is placed on the concrete 3.
They are respectively arranged on the other side, for example, the back side. The ultrasonic pulses emitted from the transmitting probe 1 pass through the concrete 3 as they are, and are reflected within the concrete 3, but the transmitted waves are detected by the receiving probe 2 and displayed on an oscilloscope (not shown). is displayed as the received waveform. The operator can determine the compression strength from the sound velocity of the ultrasonic pulse read from the received waveform and a caliplay scene curve created in advance. Furthermore, as shown in FIG. The position of the reflection source, that is, the position of the internal defect, can be estimated from the propagation time displayed above and read from the reflected waveform and the previously known speed of sound.

[Problems to be Solved by the Invention] However, the following problems have occurred in the conventional devices. In other words, there are longitudinal waves and transverse waves in the ultrasonic waves used in ultrasonic tests, and information on the sound speed of the transverse waves is especially essential when determining the elastic modulus, etc., which is an important factor in compressive strength.

Therefore, when determining the compressive strength, a shear wave probe is used. As shown in FIG. Since a vibration component is generated, a transverse wave component is generated due to slip deformation, and a longitudinal wave component is generated due to thickness deformation. For this reason, the received waveform displayed on the oscilloscope is, for example, a waveform in which the reflected transverse wave component 6 and the reflected longitudinal wave component 7 interfere, as shown in Fig. 7, making it difficult to read the propagation time of only the transverse wave. There is. Note that in FIG. 7, the horizontal axis indicates time. Therefore, it is not only difficult to measure the speed of sound with high precision, but also an obstacle to waveform analysis of only transverse waves.

The present invention solves the above-mentioned problems, and aims to provide a transverse wave sound velocity measuring method and apparatus in an ultrasonic test that can measure the propagation time of transverse waves with high precision.

[Means for Solving the Problems] In order to achieve the above object, the transverse wave sound velocity measurement method in ultrasonic testing of the present invention converts the output of the receiving probe into the frequency domain, and converts the output of the converted output into the frequency domain. The transverse wave sound velocity measurement device for ultrasonic testing of the present invention is characterized by extracting a desired frequency component of the signal, converting the extracted signal back into a time series signal, and displaying the waveform. a first signal converting means for converting the output of the receiving probe into a frequency domain; a signal processing means for extracting a desired frequency component from the output of the signal converting means; It is characterized by comprising a second signal conversion means for converting the output into a time-series signal, and a display means for displaying the output of the second signal conversion means in a waveform.

In the present invention, the longitudinal wave component and the transverse wave component can be clearly separated by converting the character sequence signal obtained by the receiving probe into the frequency domain, so only the transverse wave component can be easily extracted. This allows us to accurately know the sound speed and propagation time of transverse waves.

[Embodiment] As mentioned above, a transverse wave probe inevitably generates a longitudinal wave component, so in the present invention, the longitudinal wave component is generated by signal processing the output of the receiving probe while leaving the probe as it is. The purpose is to separate the transverse wave component and the transverse wave component. In other words,
Since longitudinal waves and transverse waves have different frequency components, the time-series signal output from the receiving probe is converted into the frequency domain to obtain only transverse wave components or longitudinal wave components.

Examples will be described below with reference to the drawings.

FIG. 1 is a diagram showing the configuration of one embodiment of the transverse wave sound velocity measurement method in an ultrasonic test according to the present invention. In the figure, 11 is a receiving probe, 12 is a FFT (fast Fourier transformer), etc. Fourier transform means, 13 signal processing means, 14 IF
Inverse Fourier transform means such as FT (inverse fast Fourier transformer), and 15 indicate display means such as an oscilloscope.

In the configuration shown in FIG. 1, it is clear from the above description that the signal detected by the reception probe 11 includes longitudinal wave components and transverse wave components.

Therefore, if the signal detected by the receiving probe 11 is displayed as it is on an oscilloscope, it will result in a waveform in which the transverse wave component 6 and the longitudinal wave component 7 interfere, as shown in FIG. 7, for example. Therefore, in the present invention, the receiving probe 1 obtained in time series is
The output is Fourier transformed by the Fourier transform means 12 and converted into the frequency domain. When the time series signal shown in FIG. 7 is converted into the frequency domain by the Fourier transform means 12, the output is as shown in FIG.
is obtained, and a longitudinal wave component 17 is obtained on the high frequency side. Therefore, as shown in FIG.
By extracting only the transverse wave component 6, and then converting the frequency domain signal back into a time series signal using the inverse Fourier transform means 14 and inputting it to the display means 15, a signal waveform of only the transverse wave component 6 can be obtained as shown in FIG. I can do it. Note that the horizontal axis in FIGS. 2 and 3 represents frequency.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment (and various modifications are possible. For example, means for converting a time series signal into a frequency domain, The inverse transform means is not limited to Fourier transform, but can be used as long as it has a similar function and operates at high speed.In addition, in the above embodiment, an example of extracting a transverse wave component was explained, but the If it is necessary to extract waves, a high-pass filter may be used as the signal processing means 13.Furthermore, in the above embodiment, a concrete test was taken as an example, but it is also possible to It is clear that this method can also be applied to destructive inspections.

[Effects of the Invention] As is clear from the above explanation, according to the present invention, in an ultrasonic test, a signal detected by a receiving probe can be separated into a longitudinal wave component and a transverse wave component, thereby reducing the propagation of transverse waves. It allows you to read the time with high precision.

[Brief explanation of drawings]

Figure 1 shows the transverse wave sound velocity 11 in the ultrasonic test according to the present invention.
Fig. 2 is a diagram showing a signal obtained by Fourier transforming the output of the receiving probe; Fig. 3 is a diagram showing the output of the signal processing means; Figure 4 is a diagram showing the output of the inverse Fourier transform means, Figure 5 is a diagram showing the general configuration of an ultrasonic test, Figure 6 is a diagram explaining the vibration of a transverse wave probe, and Figure 7 is a diagram showing the conventional FIG. 3 is a diagram showing an example of a signal waveform obtained by measurement. DESCRIPTION OF SYMBOLS 11... Receiving probe, 12... Fourier transform means, 13... Signal processing means, 14... Inverse Fourier transform means, 15... Oscilloscope. Figure 1 Figure 2 Applicant: Shimizu Corporation

Claims (2)

[Claims] (1) The output of the receiving probe is converted into the frequency domain, a desired frequency component is extracted from the converted output, and the extracted signal is converted back into a time series signal and displayed as a waveform. Transverse wave sound velocity measurement method in ultrasonic testing. (2) A receiving probe, a first signal converting means for converting the output of the receiving probe into a frequency domain, and signal processing for extracting a desired frequency component from the output of the signal converting means. an ultrasonic wave device comprising: a second signal converting means for converting the output of the signal processing means into a time-series signal; and a display means for displaying the output of the second signal converting means in a waveform. Transverse wave sound velocity measuring device used in testing.