JPH05126805A - Phase velocity curve measuring method and its measuring device - Google Patents

Abstract

(57) [Summary] [Object] The present invention easily realizes a configuration of a measurement system including an ultrasonic probe, and detects velocity dispersive ultrasonic waves of an object by only one ultrasonic excitation detection. Accurately measuring the phase velocity curve. A means 12b for injecting ultrasonic waves into a subject 11 having velocity dispersion at an appropriate incident angle and receiving ultrasonic waves propagating in the subject with an ultrasonic probe.
13b and 17, a filter 19 that corrects the frequency characteristic of the received signal, a frequency analysis unit 20 that obtains the frequency spectrum of the velocity dispersive ultrasonic signal after the frequency characteristic correction, and a peak that appears in this frequency spectrum. Frequency detecting means 21 for obtaining the peak frequency from the frequency
And a phase velocity curve measuring device 22 based on this peak frequency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention measures the phase velocity curve of velocity dispersive ultrasonic waves propagating in various materials such as plates and layered media (collectively referred to as "subjects" hereinafter), and The present invention relates to a phase velocity curve measuring method for measuring a characteristic of an object, for example, an elastic constant using a phase velocity curve, and a measuring apparatus therefor.

[0002]

2. Description of the Related Art Generally, when an ultrasonic wave is incident on an object to be inspected, such as a rolled steel sheet or other various plates or a layered medium moving in a rolled steel sheet production line, the ultrasonic wave propagating in the object is velocity dispersive. However, this velocity dispersibility has a plate thickness,
It has a certain relationship with frequency and phase velocity. That is, the velocity dispersibility means that it has the property of propagating only at a certain frequency at a certain plate thickness and a certain phase velocity.

For example, FIG. 4 is a diagram showing a phase velocity curve representing such a relationship, the horizontal axis of which is the product of the plate thickness d and the frequency f (hereinafter referred to as the fd value), and the vertical axis is the phase velocity, θi. Indicates the incident angle of ultrasonic waves. That is, although the phase velocity curve is shown in FIG. 4, the velocity dispersive ultrasonic wave propagates in the vicinity of this curve. There are plural kinds of velocity dispersive ultrasonic waves, and a plate wave or a Lamb wave propagating in a plate body and a Love wave propagating in a thin layer of a layered medium are typical.

However, the above phase velocity curve is
Since the position varies depending on the elastic constant of the subject, this phase
The elastic constant of the object can be measured by obtaining the velocity curve.
Wear. Now, for example, the phase of the plate wave of the subject, which is an elastic isotropic body
The speed curve is expressed by the following equations (1) and (2).
Therefore, after actually measuring the phase velocity curve, this
The longitudinal wave sound velocity CL and the transverse wave sound are calculated using the equations (1) and (2).
Equation (3) and (4) can be obtained by determining the speed CS.
The elastic constant of the plate can be obtained. tan (K1b) / tan (K2b) =-(KP² −K2² )² / (4KP² K1K2) ... (1) tan (K1b) / tan (K2b) =-(4KP² K1K2) / (KP² −K2² )² (2) However, K1 = {(ω / CL)² − (Ω / CP)² }^1/2  K2 = {(ω / CS)² − (Ω / CP)² }^1/2  ω = 2πf (ω: angular frequency, f: frequency) b = d / 2 (d: plate thickness) CL: longitudinal wave sound velocity, CS: transverse wave sound velocity, CP: phase velocity, KP = ω / CP E = μ (3λ + 2μ ) / (Λ + μ) ・ ・ ・ (3) σ = λ / {2 (λ + μ)} ・ ・ ・ (4) where E is Young's modulus, σ is Poisson's ratio, and λ = ρCL² -2
ρCS² , Μ = ρCS² , Ρ is the density.

By the way, heretofore, in the case of exciting and detecting velocity dispersive ultrasonic waves using a contact type ultrasonic probe, a principle structure as shown in FIG. 10 has been adopted. In the figure, 1a is an ultrasonic wave excitation probe, 1b is an ultrasonic wave detection probe, 2a and 2b are wedges, 3 is a subject, 4 is an oscillator, and 5 is a voltmeter. These ultrasonic wave excitation probes 1a
The angle of incidence of the ultrasonic wave due to and the angle of reception of the ultrasonic wave of the ultrasonic wave detecting probe 1b are set to the same θi. Furthermore, in the figure, 2
The principle of the transmission method using one probe is shown, but the principle is the same for the reflection method using one probe.

Therefore, in the above-mentioned contact type ultrasonic probe, since the phase velocity and the incident angle of the ultrasonic wave have a constant relationship, the relationship between the frequency of the ultrasonic wave and the incident angle is shown. By obtaining it, the relationship between the fd value and the phase velocity can be obtained.

Therefore, conventionally, by using such a principle configuration, f
As a method for obtaining the relationship between the d value and the phase velocity, a patent application has been proposed which has found the following two methods (Japanese Patent Publication No. 63-29220).

The first method is a method in which the incident angle of ultrasonic waves is variable while the frequency of ultrasonic waves is constant.
Specifically, while the frequency of the oscillator 4 is constant, the ultrasonic wave is incident on the subject 3 while changing the incident angle of the ultrasonic wave,
At this time, velocity dispersive ultrasonic waves propagating through the subject 3 are detected, and the detected intensity is measured by the voltmeter 5.

When the relationship between the incident angle of the ultrasonic wave and the intensity of the velocity dispersive ultrasonic wave propagating in the subject is examined in this way, the intensity becomes maximum at the phase velocity corresponding to the frequency, that is, at the incident angle. .. Therefore, the relationship between the fd value and the phase velocity CP can be obtained by obtaining the phase velocity CP from the following equation (5) using the incident angle θi that maximizes the intensity of the velocity dispersive ultrasonic wave. CP = CW / sin θi (5) where CW represents the speed of sound of the wedges 2a and 2b.

The second method is a method which is completely opposite to the first method, and is a method of varying the frequency while keeping the incident angle of the ultrasonic wave constant. That is, according to this method, the ultrasonic wave is incident on the subject 3 while varying the frequency of the oscillator 4 with the incident angle of the ultrasonic wave being constant, and the velocity dispersive ultrasonic wave propagated through the subject 3 at this time. Is measured with a voltmeter 5.

When the relationship between the frequency and the intensity of velocity dispersive ultrasonic waves propagated in the subject is examined in this way,
The intensity becomes maximum at the frequency corresponding to the incident angle, that is, the phase velocity. Therefore, the relationship between the fd value and the phase speed CP can be calculated by calculating the phase speed CP from the equation (5).

[0012]

However, the above two methods have the following problems.

In the first method, the intensity of velocity dispersive ultrasonic waves is measured while the incident angle is continuously changed, and at the same time the incident angle is accurately read to determine the incident angle and the velocity dispersiveness propagating through the object. It is necessary to find the relationship with the intensity of ultrasonic waves. However, in practice, in order to continuously change the incident angle, it is not only necessary to use a variable-angle probe, but also a mechanism for accurately reading the incident angle is required, which makes the probe structure extremely difficult. Becomes complicated. Moreover, since the intensity is measured while continuously changing the incident angle, there is a problem that the measurement time is long. This is not suitable for online measurement of a moving object such as a rolled steel plate production line, and there is a problem that a certain point cannot be measured.

In the second method, it is necessary to measure while continuously changing the frequency. In order to measure while continuously changing the frequency, the measurement time is long as in the first method. Therefore, like the first method, it is not suitable for online measurement.

The present invention has been made in view of the above-mentioned circumstances, and the phase-velocity curve of the velocity dispersive ultrasonic wave of the subject is measured accurately and in a short time by only one ultrasonic excitation detection, and the on-line measurement is performed. It is an object of the present invention to provide a phase velocity curve measuring method that can be sufficiently applied to measurement.

Another object of the present invention is to provide a phase velocity curve measuring device capable of easily realizing the configuration of a measurement system including an ultrasonic probe and capable of accurately measuring a phase velocity curve of a subject. To provide.

[0017]

First, in order to solve the above-mentioned problems, the invention corresponding to claim 1 applies a wide frequency at an appropriate incident angle from an ultrasonic probe to an object having velocity dispersion. A pulsed ultrasonic wave in a band is incident, and velocity dispersive ultrasonic waves propagating in the subject are received by an ultrasonic probe that is the same as or different from the ultrasonic probe, and the frequency is received from this received signal. By obtaining the spectrum and the frequency at which the peak value of this frequency spectrum appears,
It is a phase velocity curve measuring method for measuring a phase velocity curve of the velocity dispersive ultrasonic wave.

Next, in the invention according to claim 2, a pulse ultrasonic wave in a wide frequency band is made incident on an object having velocity dispersion from an ultrasonic probe at an appropriate incident angle, and The ultrasonic wave transmitting / receiving means for receiving velocity dispersive ultrasonic waves propagating through the subject by the ultrasonic probe which is the same as or different from the ultrasonic probe, and is also received by this ultrasonic wave receiving means. A filter for correcting the frequency characteristic of the ultrasonic wave transmitting / receiving means with respect to the generated signal, frequency analysis means for obtaining the frequency spectrum of the velocity dispersive ultrasonic signal after the frequency characteristic correction by this filter, and this frequency Peak frequency detecting means for obtaining the frequency of the velocity dispersive ultrasonic wave from the frequency of the peak appearing in the frequency spectrum obtained by the analyzing means, and the frequency of the velocity dispersive ultrasonic wave of the peak frequency detecting means A phase velocity curve measuring apparatus provided with a phase velocity curve measurement means for obtaining a Luo phase velocity curves.

[0019]

Therefore, according to the invention corresponding to claim 1, by taking the above-mentioned means, the ultrasonic wave is incident on the object having the velocity dispersion property from the ultrasonic probe at an appropriate incident angle. , The velocity dispersive ultrasonic wave propagating from the subject is received, and if the frequency spectrum is obtained, the phase velocity can be obtained from the incident angle and the known sound velocity, and from the thickness of the subject and the peak frequency of the frequency spectrum. The phase velocity curve can be determined.

Therefore, since only one incident angle is determined from the ultrasonic probe and the ultrasonic wave is incident, the phase velocity curve of the subject and the elastic constant of the subject can be measured in a short time, It is also suitable for measurement of.

In the invention according to claim 2, ultrasonic waves are incident on the subject from the ultrasonic probe at an appropriate incident angle, and velocity dispersive ultrasonic waves propagating from the subject are received. ,
After the frequency spectrum of the received signal is measured by the frequency analysis means, the phase frequency curve is obtained by the peak frequency detection means from the frequency of the peak appearing in the frequency spectrum, so that a special variable angle probe or a complicated variable angle probe is used. It is possible to measure in a short time without using a probe structure.

[0022]

EXAMPLE An example of the phase velocity curve measuring method will be described below. First, a subject having ultrasonic velocity dispersion is installed at a predetermined measurement position. After that, an ultrasonic probe is installed on the subject via a wedge, and then an electric pulse is applied to the ultrasonic probe from a pulse generator. As a result, a wideband ultrasonic pulse is transmitted from this ultrasonic probe, but when the wideband ultrasonic pulse at this time is incident on the subject at an appropriate incident angle that can be known in advance via the wedge, the subject Velocity dispersive ultrasound can be excited therein.

Therefore, the frequency of the velocity dispersive ultrasonic wave propagating in the subject can be obtained by detecting the velocity dispersive ultrasonic wave in the subject and analyzing the spectrum of the detection signal. Then, from the relationship between the frequency and the intensity of the velocity dispersive ultrasonic wave propagating in the subject, the intensity becomes maximum at the frequency corresponding to the phase velocity. Therefore, by obtaining the phase velocity CP from the frequency using the equation (5), the relationship between the fd value and the phase velocity, that is, the phase velocity curve can be measured. Then, for example, the phase velocity curve for the elastic isotropic object is measured, and the (3)
The elastic constant of the subject can be obtained by performing calculations using the equation and the equation (4). Therefore, according to this measuring method, the phase velocity curve can be measured without continuously changing the incident angle and frequency of the ultrasonic wave, and by extension, the elastic constant of the subject can be measured.

Next, an elastic constant measuring device using the above measuring method will be described with reference to FIG. In the figure, reference numeral 11 denotes a subject having a plate thickness d.
Trapezoidal wedges 12a and 12b having inclined surfaces with appropriate inclination angles are provided on opposite sides of one subject surface portion. An ultrasonic probe 13a for exciting ultrasonic waves and an ultrasonic probe 13b for detecting ultrasonic waves are provided on the inclined surfaces of the wedges 12a, 12b, respectively. The wedge 12a has a role of transmitting the ultrasonic waves excited by the ultrasonic probe 13a to the subject 11, while the wedge 12ba ultrasonically detects the ultrasonic waves propagated in the subject 11. The ultrasonic wave is transmitted to the child 13b, and the ultrasonic wave incident angle and the ultrasonic wave reception angle of each ultrasonic probe 13a, 13b are set to the same angle θi. Reference numeral 14 is a contact medium for acoustic coupling.

Reference numeral 15 is a trigger circuit for generating a trigger signal appropriately or at predetermined intervals. The trigger signal generated by the trigger circuit 15 is sent to the pulse generator 16. The pulse generator 16 applies an electric pulse to the ultrasonic probe 13a in synchronization with the trigger signal. Therefore, an ultrasonic pulse having a wide band frequency component is transmitted from the ultrasonic probe 13a, and the wedge 12a
Then, the light enters the subject 11 via the contact medium 14.

Reference numeral 17 is a wide band amplifier for amplifying the electric signal of the ultrasonic wave received by the ultrasonic probe 13b, and the amplified signal obtained here is sent to the gate circuit 18. The gate circuit 18 captures and outputs a signal of velocity dispersive ultrasonic waves in the subject in synchronization with the trigger signal from the trigger circuit 15. Reference numeral 19 is a filter for correcting the frequency characteristic of the measurement system, 20 is frequency analysis means for obtaining the frequency spectrum of the output signal from the filter 19, and 21 is a peak for obtaining the peak frequency of the velocity dispersive ultrasonic waves received from the frequency spectrum. The frequency detecting means 22 obtains the phase velocity from the peak frequency obtained by the peak frequency detecting means 21 using the equation (5), and the elastic constant is obtained from the phase velocity curve and the equations (3) and (4). This is an elastic constant calculating means for calculating. Reference numeral 23 is a display unit for displaying the value of the peak frequency, the phase velocity curve, and the elastic constant.

Next, the operation of the apparatus configured as above will be described. In the pulse generator 16, when a pulse signal is applied to the ultrasonic probe 13a in synchronization with the trigger signal from the trigger circuit 15, an ultrasonic pulse is sent from the ultrasonic probe 13a, and the wedge 12a and the contact medium. It is incident on the subject 11 via 14. At this time, the ultrasonic pulse has a broadband frequency component, and the wedge 1
It propagates at the phase velocity CP calculated by the above equation (5) based on the angle θi of 2a, and only the specific frequency component propagates in the subject 11 due to velocity dispersion.

Therefore, the velocity dispersive ultrasonic waves propagating through the object 11 having the above characteristics are contact medium 1.
4 and the wedge 12b to be received by the ultrasonic probe 13b, where it is converted into an electric signal. Since the angle θi of the wedge 12b is the same as that of the wedge 12a, the ultrasonic wave having the phase velocity CP excited by the ultrasonic probe 13a is received by the ultrasonic probe 13b. This ultrasonic probe 1
The electric signal 3b is amplified by the wide band amplifier 17 and sent to the gate circuit 18.

In the gate circuit 18, the trigger circuit 15
The gate is opened in synchronism with the trigger signal generated from, and the signal of the velocity dispersive ultrasonic wave propagated from the inside of the subject is selected and given to the filter 19. Here, the pulse generator 16
Since the measuring systems such as the electric pulse, the ultrasonic probes 13a and 13b, and the broadband amplifier 17 have frequency characteristics, the intensity of the amplified output at each frequency is not accurate.
Therefore, the filter 19 corrects the frequency characteristic of the measurement system described above with respect to the output of the gate circuit 18, and sends it to the subsequent frequency analysis means 20.

In this frequency analysis means 20, the filter 19 is used.
Obtain the frequency spectrum of the output signal of. Then, the peak frequency detecting means 21 can measure the frequency of the velocity dispersive ultrasonic wave propagating through the subject by obtaining the peak frequency from the frequency spectrum obtained by the frequency analyzing means 20.

The filter 19 and the frequency analysis means 20
The order of depends on the filtering method. For example, when filtering the electric signal itself, the filter 1
9 and the frequency analysis means 20 in this order. On the other hand, when the spectrum is obtained by the calculation of the FFT (Fast Fourier Transform) analyzer, it is possible to perform filtering by multiplying the filter characteristic at each frequency after the spectrum calculation.
In this case, the frequency analysis means 20 and the filter 19 are arranged in this order.

Incidentally, FIG. 2 shows that the ultrasonic wave is incident at an incident angle θ of 43 °.
It is a received waveform when it is incident on an aluminum plate having a thickness of 1 mm with i and is propagated as a plate wave in the aluminum plate. FIG. 3 is a diagram obtained by frequency-analyzing the waveform of FIG. 2 with an FFT analyzer, and as is apparent from this diagram, three peaks appear in the amplifier output. The frequencies showing these peak values are 2.87 MHz and 6.02, respectively.
MHz and 9.24 MHz. Furthermore, the longitudinal wave sound velocity of the aluminum plate is 6500 m / s, and the transverse wave sound velocity is 310.
0 m / s, and the phase velocity curve at this time is as shown in FIG.

Therefore, from FIG. 4, the angle θi = 43 °,
When CW = 2453m / s, the phase velocity is 3597m / s
Since the plate thickness is 1 mm, the fd values are 2.87 MHz · mm, 6.02 MHz · mm,
It is 9.24 MHz · mm, and when plotted as shown in (a) to (c) of FIG. 4, it can be seen that it is on the curve. Therefore, as is apparent from the above results, the phase velocity curve is obtained by the device of the present invention, and the elastic constant can be measured by the elastic constant calculating means 22 using the expressions (3) and (4). it can.

Next, FIG. 5 shows an ultrasonic wave with an incident angle θi of 20 °.
Is a received waveform when it is incident on an aluminum plate having a thickness of 1 mm and is propagated as a plate wave in the aluminum plate. FIG. 6 is a diagram obtained by frequency-analyzing the waveform of FIG. 5 with an FFT analyzer, and four remarkable peaks appear in the amplifier output. This peak frequency is 2.5 each
0MHz, 3.15MHz, 6.05MHz, 8.21
MHz, and the phase velocity is 7172 m / s from the incident angle θi = 20 °.
If you plot like, you can see that it is also on the curve.

Next, FIG. 7 is a diagram showing an example in which an ultrasonic wave is transmitted using one ultrasonic probe to measure a phase velocity curve, and thus an elastic constant. In the figure, 11 is a subject, 12 is a wedge, 13 is an ultrasonic probe, and 14 is a contact medium. In addition, ultrasonic waves are incident from the ultrasonic probe 13, the velocity dispersive ultrasonic waves reflected and propagated by the end face of the subject 11 are received by the same ultrasonic probe 13, and the high bandwidth amplifier 17 is used. Since the subsequent processing is the same as that in FIG. 1, the same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

Therefore, in synchronization with the trigger signal generated from the trigger circuit 15, the pulse generator 16 causes the ultrasonic probe 1 to move.
When a pulse signal is applied to 3, an ultrasonic pulse is output from this ultrasonic probe 13 and is incident on the subject 11 via the wedge 12 and the contact medium 14. This ultrasonic pulse has a broadband frequency component, propagates at the phase velocity CP obtained by the above equation (5) based on the angle θi of the wedge 12, and is specific to the subject 11 for velocity dispersion. Only frequency components propagate.

Therefore, although the ultrasonic wave is incident on the subject 11 with the above characteristics, the velocity dispersive ultrasonic wave of the plate wave that is incident and propagates in the subject 11 is the end face 1 of the subject.
It reaches 1 A, is reflected here, is received by the ultrasonic probe 13 through the couplant 14 and the wedge 12 which are the same structure, and is converted into an electric signal. After conversion into this electric signal, the same processing as in the embodiment of FIG. 1 is performed, and the frequency of the velocity dispersive ultrasonic wave propagated through the subject 11 can be obtained.

Incidentally, FIG. 8 shows that the ultrasonic wave is incident at an incident angle θ of 20 °.
incident on a 0.5 mm thick aluminum plate with i,
This is a received waveform when propagating as a plate wave in this aluminum plate. In FIG. 8, the portion A is the received wave reflected in the wedge 12 shown in FIG. 7, and the portion B is the plate wave propagated through the subject 11 and reflected back.

FIG. 9 is a diagram obtained by frequency-analyzing the received wave B of FIG. 8 with an FFT analyzer, and two peaks appear in the output of the amplifier. The frequencies at this peak are 5.00 MHz and 6.30 MHz, respectively.
Since the plate thickness d is 0.5 mm as described above, the fd values are 2.50 MHz · mm and 3.15, respectively.
MHz · mm, the same results as in FIG. 5 are obtained,
When plotted as (d) and (e) in FIG. 4, it can be seen that they are on the curve. Therefore, as is apparent from the above results, the phase velocity curve is obtained by the device of the present invention, and the elastic constant can be measured by the elastic constant calculating means 22 using the expressions (3) and (4). it can.

Therefore, according to the configuration of the above embodiment, the ultrasonic wave is incident on the subject 11 having the known plate thickness d from the ultrasonic probe 13a (13) at the known incident angle θi which is appropriately determined. , And receives the velocity dispersive ultrasonic signal of the plate wave propagating through the subject 11. Then, the frequency spectrum of the received signal is obtained by the frequency analysis means 20, and the frequency at which the peak of this spectrum appears is measured, so that the phase velocity can be grasped from the known incident angle θi and the known sound velocity CW of the wedge. Moreover, the fd value can be grasped from the known plate thickness d and the frequency at the peak, and thus the phase velocity curve can be obtained.

Moreover, it is not necessary to measure the intensity of the peak while continuously changing the incident angle θi or frequency of the ultrasonic wave, and the frequency of the peak intensity can be measured by only one ultrasonic excitation detection. Does not need measurement time. Further, since it is not necessary to change the incident angle θi of the ultrasonic wave, the structure of the probe and the structure related to the scanning of the probe can be realized very easily, and the phase velocity can be accurately obtained under the known incident angle θi. be able to.

In the above two embodiments, the subject 11
Although a plate was used as the above, it is not limited to this.
The same applies to any medium in which the propagation of ultrasonic waves has velocity dispersion. As such a medium, for example, a Love wave that propagates a medium of a thin layer of a sample having a two-layer structure including a thin layer and a thick layer is raised. Further, in the above example, the elastic constant of the elastic isotropic object was obtained, but by measuring the phase velocity curves in multiple directions by this method, the elastic constant of the elastic anisotropic object can be obtained. Is also possible. Furthermore, in the above-mentioned embodiment, the contact type ultrasonic probe was used for the ultrasonic wave excitation detection, but the electromagnetic ultrasonic method for exciting and detecting the ultrasonic wave by the electromagnetic induction using the eddy current or the laser heat. Thus, it can be easily carried out even by using a non-contact ultrasonic measurement method such as a laser ultrasonic method in which ultrasonic waves are excited on a subject and detected by an interferometer. Besides, the present invention can be variously modified and implemented without departing from the scope of the invention.

[0043]

As described above, according to the present invention, the following various effects are exhibited.

According to the first aspect of the present invention, the phase velocity curve of the velocity dispersive ultrasonic wave of the subject can be measured accurately and in a short time by only one ultrasonic excitation detection, and the online measurement is sufficiently dealt with. it can. Further, the elastic constant of the subject can be measured accurately and in a short time by only detecting the ultrasonic wave excitation once. Further, according to the invention of claim 2, the configuration of the measurement system including the ultrasonic probe can be easily realized, and the elastic constant of the subject can be accurately measured by only one ultrasonic excitation detection.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of an elastic constant measuring device according to the present invention.

FIG. 2 is a received waveform diagram of velocity dispersive ultrasonic waves of the subject when the ultrasonic waves are incident on the subject at a certain incident angle using the apparatus of the first embodiment.

FIG. 3 is a frequency spectrum diagram of the reception waveform of FIG.

FIG. 4 is a phase velocity curve diagram of a subject.

5 is a reception waveform diagram of velocity dispersive ultrasonic waves of the subject when the ultrasonic waves are incident on the subject at an incident angle different from that of FIG. 2 using the apparatus of the first embodiment.

6 is a frequency spectrum diagram of the reception waveform of FIG.

FIG. 7 is a configuration diagram showing a second embodiment of the elastic constant measuring device according to the present invention.

FIG. 8 is a reception waveform diagram of velocity dispersive ultrasonic waves of the subject when the ultrasonic waves are incident on the subject at a certain incident angle using the apparatus of the second embodiment.

9 is a frequency spectrum diagram of the reception waveform of FIG.

FIG. 10 is a configuration diagram illustrating a measurement principle of a conventional device.

[Explanation of symbols]

11 ... Subject, 12a, 12b, 12 ... Wedge, 13
a, 13b, 13 ... Ultrasonic probe, 14 ... Contact medium, 1
5 ... Trigger circuit, 16 ... Pulse generator, 17 ... Wide band amplifier, 18 ... Gate circuit, 19 ... Filter, 20 ... Frequency analysis means, 21 ... Peak frequency detection means, 22 ... Elastic constant calculation means, 23 ... Display device.

Claims (2)

[Claims] 1. A velocity-dispersive ultrasonic wave that propagates through a subject by injecting pulsed ultrasonic waves in a wide frequency band from an ultrasonic probe at an appropriate incident angle to the subject having velocity dispersiveness. The ultrasonic wave is received by the ultrasonic probe which is the same as or different from the ultrasonic probe, the frequency spectrum is obtained from this received signal, and the frequency at which the peak value of this frequency spectrum appears A method for measuring a phase velocity curve, which comprises measuring a phase velocity curve of dispersive ultrasonic waves. 2. A velocity dispersion in which a pulsed ultrasonic wave in a wide frequency band is incident from an ultrasonic probe at an appropriate incident angle to a subject having velocity dispersion and is propagated in the subject. Ultrasonic wave transmitting / receiving means for receiving the ultrasonic wave by the ultrasonic wave probe which is the same as or different from the ultrasonic wave probe, and the frequency spectrum of the velocity dispersive ultrasonic wave signal received by the ultrasonic wave receiving means. A frequency analysis means for obtaining the frequency dispersion means, a peak frequency detection means for obtaining the frequency of the velocity dispersive ultrasonic wave from the frequency of the peak appearing in the frequency spectrum obtained by the frequency analysis means, and the frequency of the velocity dispersive ultrasonic wave of the peak frequency detection means. And a phase velocity measuring means for obtaining a phase velocity curve from the phase velocity curve measuring device.