JP2015172528A - Ultrasonic measuring device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic measuring device capable of measuring sonic velocity requiring no complicated work even when surface wave is not identified.SOLUTION: A transmission probe 1 emits an ultrasonic to a test piece 100. A reception probe 2 receives the ultrasonic propagating on the test piece 100. A signal processing section 14 calculates the sonic velocity on the test piece 100 based on a signal received by a reception probe 2 in a reception state in which the ultrasonic propagates via longitudinal waves from the transmission probe 1 to a bottom face of the test piece 100, and propagates via transversal wave from the bottom face of the test piece 100 to the reception probe 2.

Description

  The present invention relates to an ultrasonic measurement apparatus and an ultrasonic measurement method for measuring the speed of sound of a specimen using ultrasonic waves.

  In recent years, damage to structures has become obvious, and appropriate maintenance is required. Strength measurement is important for concrete structures. Since the strength of concrete can be expressed by Young's modulus, and Young's modulus can be expressed by sound velocity, a technique for obtaining the sound velocity of concrete is desired. In particular, a simple measurement technique that does not require complicated work is desired at the work site.

  Since ultrasonic waves propagating in concrete have a large attenuation, a frequency of about several tens of kHz to several hundreds of kHz is often used in sound velocity measurement. Since the wavelength in such a frequency band is long, it is difficult to receive the specimen bottom surface echo with a single probe, so a method using two probes is used. In a general sound speed measurement method using two probes, an ultrasonic wave is generated from a transmission probe, and this ultrasonic wave propagates through the specimen. Ultrasonic waves propagating in the bottom direction are mainly longitudinal waves. Longitudinal ultrasonic waves are reflected by the bottom surface of the specimen and received by a receiving probe. This signal is generally referred to as a bottom echo.

  If the bottom echo is a simple waveform, the propagation delay time can be easily measured, so the sound speed of the specimen can be easily obtained. However, depending on the distance between the transmitting probe and the receiving probe, measurement may be complicated. Further, a surface wave propagates along the surface of the specimen from the transmitting probe and is received by the receiving probe. Since the speed of sound of the surface wave is slower than that of the longitudinal wave, reception times may overlap. When the bottom surface echo and the surface wave overlap, it is not easy to measure the propagation delay time of the bottom surface echo.

  As a conventional technique for measuring the speed of sound in such a situation, for example, there is a measurement method described in Patent Document 1. In this measurement method, the measurement is repeated while changing the distance between the probes, and the sound speed or the thickness of the specimen is obtained by the aperture synthesis method. Further, as described in Patent Document 2, for example, there is a method in which a surface wave signal is subtracted from a received signal in order to suppress the influence of the surface wave.

JP 9-318607 A Japanese Patent Laid-Open No. 5-188043

However, among the conventional measurement methods described above, the method of repeating the measurement while changing the distance between the probes described in Patent Document 1 needs to perform data collection a plurality of times while changing the distance between the probes. For this reason, there was a problem of requiring complicated work.
Further, the measurement method described in Patent Document 2 has a problem that it is difficult to apply when the surface wave cannot be specified because the surface wave is subtracted from the received signal.

  The present invention has been made to solve the above-described problems, and provides an ultrasonic measurement apparatus and method capable of measuring sound speed without requiring complicated work even when surface waves cannot be identified. With the goal.

  An ultrasonic measurement apparatus according to the present invention includes a transmission probe that transmits ultrasonic waves into a test object, a reception probe that receives ultrasonic waves propagated through the test object, and an ultrasonic wave transmission probe. The sound velocity of the test object is calculated from the received signal of the receiving probe in the reception state where it propagates in the longitudinal wave from the probe to the bottom surface of the test object and is transmitted in the transverse wave from the bottom surface of the test object to the receiving probe. And a signal processing unit.

  In the ultrasonic measurement apparatus of the present invention, ultrasonic waves propagate in a longitudinal wave from the transmitting probe to the bottom surface of the test body, and in a reception state in which the ultrasonic wave propagates from the bottom surface of the test body to the receiving probe in a transverse wave, Since the sound speed of the specimen is calculated from the reception signal of the receiving probe, the sound speed can be measured without requiring a complicated operation even when the surface wave cannot be identified.

It is a block diagram which shows the ultrasonic measuring apparatus by Embodiment 1 of this invention. It is explanatory drawing which shows the sound field simulation result of the ultrasonic measuring apparatus by Embodiment 1 of this invention. It is explanatory drawing which shows the echo and simulation result which were received of the ultrasonic measuring device by Embodiment 1 of this invention. It is explanatory drawing which shows the process which produces | generates the spike-shaped waveform of the ultrasonic measuring device by Embodiment 1 of this invention. It is explanatory drawing which shows the result of the different probe distance of the ultrasonic measuring device by Embodiment 1 of this invention. It is explanatory drawing in the case of measuring a sound velocity using the longitudinal wave bottom face echo and the transverse wave bottom face echo of the ultrasonic measuring device by Embodiment 1 of this invention. It is explanatory drawing at the time of measuring a sound speed using only the transverse wave bottom face echo of the ultrasonic measuring device by Embodiment 1 of this invention.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing an ultrasonic measurement apparatus according to Embodiment 1 of the present invention.
The ultrasonic measurement apparatus shown in FIG. 1 includes a transmission probe 1, a reception probe 2, and a transceiver 10. The transmission probe 1 is a probe that is installed on the test body 100 and is driven by an electric signal from the transceiver 10 to transmit ultrasonic waves to the test body 100. The reception probe 2 is a probe that is installed on the test body 100 and receives ultrasonic waves transmitted from the transmission probe 1 and propagated through the test body 100, and transmits and receives reception signals. It is configured to output to the device 10. The transceiver 10 is a processing unit that drives the transmission probe 1 and measures the sound speed of the test body 100 based on the reception signal from the reception probe 2. The transmission unit 11, the reception unit 12, and the display Unit 13 and signal processing unit 14.

  The transmission unit 11 is a processing unit for supplying an ultrasonic electrical signal to be output from the transmission probe 1 to the transmission probe 1. The receiving unit 12 is a processing unit that receives an electrical signal from the receiving probe 2 and sends it to the display unit 13 and the signal processing unit 14. The display unit 13 is a display output unit for displaying the reception result of the reception probe 2, the processing result of the signal processing unit 14, and the like. The signal processing unit 14 is a calculation unit that calculates the sound speed of the test body 100 based on the received signal from the receiving probe 2 received by the receiving unit 12. Although not shown, the transmitter / receiver 10 has a built-in control unit, and the transmission unit 11, the reception unit 12, the display unit 13, and the signal processing unit 14 are controlled in operation by signals from the control unit. Is done.

Next, a basic operation principle in the ultrasonic measurement apparatus according to the first embodiment will be described.
First, what kind of signal is received when the sound velocity of an attenuation material such as concrete is measured will be described using the sound field simulation result of FIG. FIG. 2 shows an in-test body sound field obtained by performing a simulation using a probe with a frequency of 100 kHz on a concrete with a thickness of 120 mm as the test body 100 and a distance between the probes of 100 mm. The sound field is 10 μs to 80 μs after the transmission probe 1 is excited, and is arranged in time series. Longitudinal ultrasonic waves emitted from the transmission probe 1 propagate through the test body 100, but the signal received first by the reception probe 2 is transmitted to the surface of the test body 100. Longitudinal waves propagated along.
In the TOFD (Time of Flight Diffraction) method, this longitudinal wave is called a lateral wave, so it is also called a lateral wave here. From the sound field simulation result, it can be seen that the lateral wave is received after about 20 μs.

  The ultrasonic wave propagating along the surface of the test body 100 propagates not only a lateral wave but also a surface wave. It can be seen from the sound field simulation that the surface wave is received in about 40 μs.

  The longitudinal wave propagated toward the bottom surface of the test body 100 is reflected by the bottom surface and received by the receiving probe 2. However, as can be seen from the sound field simulation results, not only longitudinal waves but also transverse waves are generated by mode conversion when reflected. Therefore, not only the longitudinal bottom echo but also the transverse bottom echo is received.

From the sound field simulation results, when the received echoes are arranged in time series,
・ Lateral waves, surface waves, longitudinal wave bottom echoes, and transverse wave bottom echoes.

  FIG. 3 shows echoes obtained by the simulation superimposed on the experimental results. A solid line is an experimental result and a broken line is a simulation result. Since both are almost the same, the simulation results are considered reliable. FIG. 3 also shows the interpretation of echoes estimated from the sound field simulation results. As shown in FIG. 3, not only the longitudinal wave bottom echo is received, but four signals (lateral wave, surface wave, longitudinal wave, and transverse wave) are received, resulting in a complex waveform.

  If only the speed of sound is measured, the echo amplitude can be ignored. Therefore, it is shaped into a waveform that emphasizes only the phase of the echo, and will be described below. First, a waveform shaping method emphasizing only the echo phase will be described with reference to FIG. 4A, 4B, and 4C are an AC waveform, a saturation waveform, and a differential waveform, respectively.

  The signal from the receiving probe 2 has an AC waveform as shown in FIG. The AC waveform is saturated by amplification as shown in FIG. 4B to obtain a saturation waveform. Thereafter, the differential waveform is obtained by differentiating as shown in FIG. Note that such a calculation is performed by the signal processing unit 14. As shown in FIG. 4, the zero cross point of the AC waveform appears as a spike-like waveform in the differential waveform. If it is a spike-like waveform, it is considered easier to read the propagation delay time than the AC waveform. In the following, the sound velocity measurement will be described using this spike-like waveform.

  FIG. 5 shows received signals obtained by experiments with the inter-probe distances of 100 mm, 120 mm, and 125 mm as spike-like waveforms. As shown in the figure, at a probe distance of 100 mm, a spike-like waveform representing a surface wave, a spike-like waveform representing a longitudinal wave bottom echo (shown as “longitudinal wave” in the figure), and a transverse wave bottom echo Spike-shaped waveforms (shown as “lateral waves” in the figure) are separately received. However, when the distance between the probes is increased, the surface wave and the longitudinal wave begin to overlap at a distance of 120 mm, and both cancel each other at a distance of 125 mm. In such a case, sound velocity measurement using a longitudinal wave bottom echo cannot be performed.

  On the other hand, even when the surface wave and the longitudinal wave bottom echo overlap each other and the sound velocity cannot be measured, the transverse wave bottom echo is received as shown in FIG. Therefore, when the surface wave and the longitudinal wave bottom echo overlap, the sound velocity can be measured by using the transverse wave bottom echo. Therefore, the present invention is to perform sound velocity measurement using a transverse wave bottom echo. Hereinafter, the operation of the ultrasonic measurement apparatus will be described.

The transmission probe 1 is excited by the electrical signal from the transmission unit 11, and ultrasonic waves propagate in the test body 100. As shown in the sound field simulation result of FIG. 2, there are various propagation paths of ultrasonic waves in the test body 100, and there are signals that are reflected and received by the bottom surface of the test body 100. Some signals are propagated through and received. In FIG. 1, arrows are attached to indicate bottom surface echo and surface wave propagation paths. The ultrasonic wave propagated through the test body 100 is received by the receiving probe 2, converted into an electric signal, and sent to the receiving unit 12. The receiving unit 12 amplifies the received signal if necessary, and sends the result to the display unit 13. The display unit 13 displays the received signal.
The signal processing unit 14 generates a spike-like waveform based on the waveform generation process shown in FIG.

  As shown in FIG. 5, the surface wave and the longitudinal wave may overlap each other. As a result, the spike-like waveform due to the surface wave and the spike-like waveform due to the longitudinal wave cancel each other and disappear. However, a spike-like waveform due to the transverse wave remains. In this embodiment, the longitudinal wave bottom echo and the transverse wave bottom echo are multiplied by different gates to measure the sound velocity (see gate 20 and gate 21 shown in FIGS. 6 and 7). In the signal processing unit 14, the waveform of the gate 20 is processed as a longitudinal wave bottom echo, and the waveform of the gate 21 is processed as a transverse wave bottom echo to obtain the sound velocity. Note that these gates 20 and 21 are, for example, gates that target signals at a predetermined time interval with an amplitude of +. By having two gates in this way, even when the longitudinal wave bottom echo overlaps the surface wave, the sound velocity measurement using the transverse wave bottom echo can be performed.

  When longitudinal wave bottom echoes and transverse wave bottom echoes are received as shown in FIG. 6, spike-like waveforms are received in the gate 20 and the gate 21, respectively. The sound velocity measurement may use longitudinal wave bottom echoes or transverse wave bottom echoes. Alternatively, sound velocity measurement may be performed using both, and a reliable value may be adopted, or an average value may be adopted.

  On the other hand, as shown in FIG. 7, when the longitudinal wave bottom echo disappears, the transverse wave bottom echo is received, so that the sound velocity can be measured from the spiked waveform in the gate 21. That is, the signal processing unit 14 says that the ultrasonic wave propagated as a longitudinal wave from the transmitting probe 1 to the bottom surface of the test body 100 and as a transverse wave from the bottom surface of the test body 100 to the receiving probe 2. Based on the assumption, the sound speed of the test body 100 is calculated from the received signal of the receiving probe 2.

  Although the sound velocity measuring apparatus and method have been described here with a spike-like waveform as an example, an AC waveform may be used. Further, a DC waveform used in normal flaw detection may be used.

  As described above, according to the ultrasonic measurement apparatus of the first embodiment, a transmission probe that transmits ultrasonic waves into a test body and a reception probe that receives ultrasonic waves propagated through the test body. And the ultrasonic wave propagates from the transmitting probe to the bottom surface of the specimen with a longitudinal wave, and from the bottom surface of the specimen to the receiving probe with a transverse wave. Since it has a signal processing unit that calculates the sound speed of the test specimen from the received signal, even if surface waves and longitudinal waves interfere with each other and cancel each other, it is possible to measure the sound speed with a simple method without requiring complicated work. Can do.

  In addition, according to the ultrasonic measurement apparatus of the first embodiment, the signal processing unit causes the ultrasonic wave to propagate from the transmitting probe to the bottom surface of the test body by a longitudinal wave and to receive the probe from the bottom surface of the test body. Propagating with transverse waves to the child, and receiving with the longitudinal wave propagating from the transmitting probe to the bottom surface of the specimen and propagating with longitudinal waves from the bottom surface of the specimen to the receiving probe Since the sound speed of the specimen is calculated from the received signal of the probe, the accuracy of sound speed measurement can be improved.

  Further, according to the ultrasonic measurement method of the first embodiment, an ultrasonic wave is transmitted into the test body by the transmitting probe, and an ultrasonic wave propagated through the test body is received by the receiving probe, The sound velocity of the test specimen was calculated from the transmitting probe to the bottom surface of the test piece with longitudinal waves, and from the bottom face of the test specimen to the receiving probe with the shear wave propagated. Even when surface waves and longitudinal waves interfere with each other and cancel each other, no complicated work is required, and sound speed can be measured by a simple method.

Further, according to the ultrasonic measurement method of the first embodiment,
Ultrasound propagates from the transmitting probe to the bottom surface of the specimen with a longitudinal wave, propagates from the bottom surface of the specimen to the receiving probe with a transverse wave, and from the transmitting probe to the bottom surface of the specimen. The sound velocity of the test object is calculated from the received signal of the receiving probe in the reception state where it propagated by the longitudinal wave and propagated by the longitudinal wave from the bottom surface of the test object to the receiving probe. Measurement accuracy can be increased.

  In the present invention, any constituent element of the embodiment can be modified or any constituent element of the embodiment can be omitted within the scope of the invention.

  DESCRIPTION OF SYMBOLS 1 Probe for transmission, 2 Probe for reception, 10 Transmitter / receiver, 11 Transmission part, 12 Reception part, 13 Display part, 14 Signal processing part, 20, 21 Gate, 100 Test body.

Claims (4)

A probe for transmitting ultrasonic waves into the test body;
A receiving probe for receiving ultrasonic waves propagated through the test body;
In the reception state, the ultrasonic wave propagates from the transmitting probe to the bottom surface of the test body with a longitudinal wave and propagates from the bottom surface of the test body to the receiving probe with a transverse wave. An ultrasonic measurement apparatus comprising: a signal processing unit that calculates a sound speed of the test body from a reception signal of a touch element. A probe for transmitting ultrasonic waves into the test body;
A receiving probe for receiving ultrasonic waves propagated through the test body;
The ultrasonic wave propagates as a longitudinal wave from the transmitting probe to the bottom surface of the test body, propagates as a transverse wave from the bottom surface of the test body to the receiving probe, and the transmitting probe. In a reception state in which a wave propagates from a child to the bottom surface of the test body by a longitudinal wave and propagates by a longitudinal wave from the bottom surface of the test body to the reception probe, the test body receives a signal from the reception signal of the reception probe. An ultrasonic measurement apparatus comprising a signal processing unit that calculates the sound speed of the sound. Sending ultrasonic waves into the test body with the transmitting probe, receiving ultrasonic waves propagated through the test body with the receiving probe,
The reception probe receives the reception probe in a reception state in which it propagates in a longitudinal wave from the transmission probe to the bottom surface of the test body, and propagates in a transverse wave from the bottom surface of the test body to the reception probe. An ultrasonic measurement method, wherein the sound velocity of the test body is calculated from a signal. Sending ultrasonic waves into the test body with the transmitting probe, receiving ultrasonic waves propagated through the test body with the receiving probe,
Propagation from the transmission probe to the bottom surface of the test body is a longitudinal wave, propagation from the bottom surface of the test body to the reception probe is a transverse wave, and from the transmission probe to the test Calculates the sound velocity of the test object from the received signal of the receiving probe in a reception state that propagates to the bottom surface of the body by a longitudinal wave and propagates from the bottom surface of the test object to the receiving probe by a longitudinal wave. An ultrasonic measurement method comprising:

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