JP2004053288A - Ultrasonic acoustic velocity measuring method, and method for obtaining young's modulus and poisson's ratio based on the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an acoustic velocity measurement method using ultrasonic waves for simultaneously measuring the acoustic velocity of a material (sample) with improved accuracy by a relatively simple operation by using a probe even in a thin and small sample, and to provide a method for obtaining Young's modulus and Poisson's ratio based on the acoustic velocity measurement method. <P>SOLUTION: In the case of the measurement of acoustic velocity, a bottom surface echo and a delayed echo are detected. The bottom surface echo that does not accompany any mode conversion and returns after being propagated by longitudinal waves in the sample and being returned by reflection from the bottom surface of the sample after ultrasonic waves are applied to the sample that is dipped into a medium from the probe. The delay echo is due to traverse waves being generated by mode conversion when being reflected from the bottom surface of the sample. Then a travel wave acoustic velocity C<SB>s</SB>is obtained from traverse wave propagation time obtained by subtracting the propagation time (T<SB>B</SB>/2) in the longitudinal waves of bottom surface echoes that do not accompany any mode conversion from propagation time (T<SB>X1</SB>) in the delayed echoes due to the mode conversion and a thickness (t) in the sample, where C<SB>s</SB>= t/(T<SB>X1</SB>-T<SB>B</SB>/2). <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method of measuring the speed of sound using ultrasonic waves, which can accurately measure the speed of sound of a material (sample) with a relatively simple operation, and a method of determining the Young's modulus and Poisson's ratio based on these methods.
[0002]
[Prior art]
At present, in material development at manufacturers, universities, research institutes, and the like, ultrasonic waves are frequently used for evaluating mechanical properties such as Young's modulus and Poisson's ratio.
The conventional method of measuring sound velocity using ultrasonic waves is to adjust the time axis of an ultrasonic flaw detector based on a standard test piece with a known sound velocity finished to a specified size, and to obtain a sample whose thickness is clear but whose sound velocity is unknown. The ultrasonic wave is incident by directly contacting the vertical probe and the vertical probe, and the beam path of the bottom echo, the thickness of the unknown sample, and the Usually, it is obtained from the known sound velocity.
[0003]
Also, there is a Sing Around method known as such a sound velocity measuring method, which also uses two types of vertical probes, a longitudinal vertical probe and a transverse vertical probe, and has a propagation time and a sample. The speed of sound is determined from the thickness.
In addition, there is also a method of measuring the speed of sound of longitudinal waves and transverse waves using a vertical echo and a delayed echo due to a bottom echo and a transverse wave and a cylindrical echo.
[0004]
As described above, the time axis of the ultrasonic flaw detector is adjusted based on the standard test piece, and the bottom echo obtained by directly contacting the vertical vertical and horizontal transducers and injecting ultrasonic waves. The method of obtaining the longitudinal and shear wave velocities from the beam path of the unknown sample, the thickness of the unknown sample, and the sound velocity of the standard test piece requires two types of vertical probes, one for the longitudinal wave and the other for the shear wave, and has a known sound velocity. Since a standard test piece is required, there is a problem that a test device and operation are complicated, and it is difficult to obtain an accurate measurement.
[0005]
As described above, in material development, ultrasonic waves are often used to evaluate mechanical properties such as Young's modulus and Poisson's ratio, but depending on the type of material and the content of research, a thickness suitable for the conventional ultrasonic method may be used. In some cases, it is difficult to prepare a sample having a pod size, and it is often difficult to evaluate a material.
Actually, there is a problem that a bottom echo cannot be obtained for a sample extremely smaller than the probe diameter and a sample thinner due to restrictions on pulse width, resolution, and the like. This is the same in the Sing Around method.
Furthermore, the above-mentioned method using a vertical echo and a delayed echo and a cylindrical echo due to a bottom echo and a transverse wave can be measured only when the sample is elongated or a round bar. There is a problem in that it is difficult to measure a thin and small sample because of the mechanical limitations.
[0006]
[Problems to be solved by the invention]
The present invention provides a sound velocity measuring method using ultrasonic waves, which can simultaneously measure the sound velocity of a material (sample) with a relatively simple operation with a relatively simple operation using a single probe, even for a thin and small sample. A method for determining Poisson's ratio is provided.
[0007]
[Means for Solving the Problems]
From the above, the present invention provides: An ultrasonic sound velocity measurement method that measures the transverse sound velocity of a sample, in which ultrasonic waves enter the sample immersed in a medium from a probe, propagate through the sample as longitudinal waves, and reflect back at the sample bottom surface. A bottom echo without conversion and a delayed echo due to a transverse wave generated by mode conversion when reflected on the bottom surface of the sample are detected, and the propagation time of the delayed echo due to mode conversion (T _X1 ) is used to detect the bottom echo without mode conversion. ultrasonic sound velocity obtaining the propagation time of the longitudinal wave _(T B / 2) a minus transverse propagation time and the thickness of the sample from (t) the shear wave velocity _{C S} as _{C S = t / (T X1} -T B / 2) Measurement method 2. An ultrasonic sound velocity measurement method for measuring the longitudinal wave velocity and the transverse wave velocity of a sample, in which ultrasonic waves are incident on a sample immersed in a medium from a probe, propagate in the sample as longitudinal waves, and are reflected at the bottom of the sample. A back echo without mode conversion and a delayed echo due to a transverse wave generated by mode conversion when reflected at the bottom of the sample are detected, and the propagation time (T _B ) of the bottom echo without mode conversion and the determined as the thickness (t) from the longitudinal acoustic velocity _{C L} to _C L = 2t / _{T B,} minus mode conversion due to the delay echo propagation time _{(T X1)} longitudinal wave propagation time from a _(T B / 2) transverse waves ultrasonic sound velocity measuring method 3 to determine the propagation time and the thickness of the tabular sample from (t) the shear wave velocity _{C S} as _{C S = t / (T X1} -T B / 2). When an ultrasonic wave enters a sample from a probe through a medium, a transverse wave generated by mode conversion is a transverse wave based on a propagation time ( _TX2 ) of a delayed echo of only a transverse wave reciprocatingly propagating in the sample and a thickness (t) of the sample. ultrasonic sound velocity measuring method for determining the speed of sound _{C S} as _{C S = 2t / T X2 4} . An ultrasonic sound velocity measurement method for measuring the longitudinal wave velocity and the transverse wave velocity of a sample, in which ultrasonic waves are incident on a sample immersed in a medium from a probe, propagate in the sample as longitudinal waves, and are reflected at the bottom of the sample. A back echo without mode conversion and a delayed echo due to a transverse wave generated by mode conversion when reflected at the bottom of the sample are detected, and the propagation time (T _B ) of the bottom echo without mode conversion and the thick (t) determine the longitudinal wave acoustic velocity C _L as C _{L =} 2t / T _B, the shear wave generated by mode conversion is only transverse wave through the sample was round trip delay echo propagation time (T _X2) and the sample ultrasonic sound velocity determined from the thickness (t) of the shear wave velocity _{C S} as _C S = 2t _{/ T X2} measurement method 5. 5. The ultrasonic sound velocity measuring method according to any one of the above items 1 to 4, wherein the measurement is performed by one probe. 6. The ultrasonic sound velocity measuring method according to any one of 1 to 5 above, wherein the ultrasonic probe is a focused vertical probe. 7. The ultrasonic sound velocity measuring method according to any one of 1 to 6 above, wherein the ultrasonic sound velocity measuring method is a flat sample. 8. The ultrasonic sound velocity measuring method according to any one of 1 to 7, wherein the medium is an inert liquid that propagates ultrasonic waves and does not damage the probe. 9. The ultrasonic sound velocity measuring method according to any one of 1 to 8 above, wherein the medium is water. The 1-9 respectively from longitudinal acoustic velocity _{C L} and transverse wave _{C S} and the density [rho obtained by the method, the method obtains the Young's modulus E and Poisson's ratio ν according to the following equation ^{_{E = ρ (3C S 2 ·}} C L 2 ^{_{-4C S 4) / (C L}} 2 -C S 2)
^{_{ν = (C L 2 -2C S}} 2) / 2 (C L 2 -C S 2)
I will provide a.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention will be specifically described with reference to the drawings. In FIG. 1, reference numeral 1 denotes a CRT monitor of an ultrasonic device, reference numeral 2 denotes a probe for transmitting and receiving ultrasonic waves (for example, a focus type vertical probe), reference numeral 3 denotes a sample to be measured, and reference numeral 4 denotes a probe. Indicates a medium such as water or an inert liquid that propagates until the transmitted ultrasonic wave reaches the sample. Such a medium is preferably an inert liquid that propagates ultrasonic waves and does not damage the probe, and usually uses water.
In the present invention, the sound speeds of the longitudinal wave and the transverse wave can be measured simultaneously using one probe, and a focus type vertical probe is used as the probe.
[0009]
In the conventional direct contact method in which a probe is brought into direct contact with a sample and ultrasonic waves are applied, the bottom echo is included in the transmitted pulse when the sample is thin, and the pulse width is used when the test frequency is low. Is too large to resolve close echoes.
However, the water immersion method of the present invention in which ultrasonic waves are incident through a medium such as water or an inert liquid has a feature that the bottom surface echo can be reliably detected because the transmission pulse is far from the sample surface. In addition, when a focus type vertical probe is used as in the present invention, there is an advantage that an ultrasonic beam is narrowed down and a bottom echo can be reliably obtained even with a sample which is much smaller than the probe diameter.
[0010]
That is, it is easy to simultaneously measure the longitudinal wave velocity and the transverse wave velocity even for a material having a thickness of 1 mm or less or a material having a very small area (a flat sample), which is difficult with the conventional measuring method. The effect was obtained.
For example, the focus type vertical probe with a frequency of 25 MHz, which is often used for ceramics, is said to have an ultrasonic beam diameter of 0.4 mm at a focal length of 20 mm and a beam diameter of 0.2 mm at a focal length of 10 mm. It is sufficient that the size is larger than this beam diameter.
Even if the thickness of the material is 1 mm or less, if it has a size of about 1 mm x 1 mm, the longitudinal wave velocity and the transverse wave velocity can be measured simultaneously with one focus type vertical probe, and the Young's modulus and Poisson's ratio can be measured from these. It has a remarkable effect that it can be obtained instantaneously.
[0011]
Next, specifically described method of obtaining the longitudinal wave acoustic velocity C _L and transverse wave C _S according to one probe of the present invention.
As shown in FIG. 1, a sample 3 is immersed in a medium 4 such as water or an inert liquid, and an ultrasonic wave transmitted from a focus type vertical probe 2 is incident on the sample 3. A waveform as shown appears.
The first waveform T is a transmission pulse, the next echo S ₁ is a surface echo, a bottom echo B ₁ in which a longitudinal wave reciprocates in the sample in order, and a transverse wave generated by mode conversion when the longitudinal wave is reflected on the sample bottom surface. A delayed echo X ₁ , a delayed echo X ₂ in which a transverse wave generated by mode conversion when an ultrasonic wave is incident on the sample reciprocates in the sample, and a bottom echo B ₂ reflected twice on the bottom surface.
[0012]
Propagation path of each echo, as shown in FIG. 3, bottom echo B ₁ represents a echo longitudinal wave expressed by the solid line is reciprocated in the sample, delayed echo X ₁ is one way that a longitudinal wave, the remaining one-way is by a broken line echoes transverse waves expressed is propagated, delay echo X ₂ are echoes transverse wave back and forth. The bottom echo B ₂ are echoes reciprocating longitudinal wave twice.
[0013]
Longitudinal acoustic velocity C _L reads the propagation time T _B which longitudinal waves through the sample from the bottom echo B ₁ is the reciprocal, when the sample thickness that is measured in advance and t, be obtained from the C L ₌ 2t / T _B Can be.
[0014]
From late echo X ₁ in order to determine the shear wave velocity C _S reads the propagation time T _X1 delay echo X ₁ consisting of transverse wave, the transverse wave obtained by subtracting the propagation time T _{B /} 2 of the way now by longitudinal waves The propagation time T _X1 −T _B / 2 is obtained, and the transverse sound speed C _S can be obtained from C _S = t / (T _X1 −T _B / 2).
Further, a method of the late echo _{X 2} Request shear wave velocity _{C S,} i.e. delayed transverse from the echo _{X 2} reads the propagation time _{T X2} which reciprocates in a sample, to obtain the _C S = 2t _{/ T X2} from shear wave velocity _{C S} You can also.
[0015]
Propagation time _{T B,} the propagation time _{T X1,} the reference position of the surface echo _{S 1} waveform when reading a propagation time _{T X2} from the CRT monitor 1, the waveform of the surface echo _{S 1} in the case of high sensitivity as shown in FIG. 4 Although several lines have the same height and it is difficult to determine the reference position, since the highest waveform appears as shown in FIG. 5 by lowering the sensitivity, each propagation time is set based on the highest waveform on the plus side. read.
From longitudinal acoustic velocity C _L and transverse wave C _S and the density ρ determined by the above, it is possible to determine the Young's modulus E and Poisson's ratio ν according to the following equation.
^{_{E = ρ (3C S 2 ·}} C L 2 -4C S 4) / (C L 2 -C S 2)
^{_{ν = (C L 2 -2C S}} 2) / 2 (C L 2 -C S 2)
[0016]
Fig. 6 compares the longitudinal wave velocity measured by one probe of the present invention and the longitudinal wave velocity measured by the conventional Sing Around method for various materials such as stainless steel, aluminum, zirconia, conductive sialon, and alumina. It can be seen that the values are almost the same.
FIG. 7 similarly compares the measured values of the shear wave velocity by the probe of the present invention with the conventional Sing Round method for various materials such as stainless steel, aluminum, zirconia, conductive sialon, and alumina. It is almost the same value.
FIG. 8 shows the results of the Young's modulus of the present invention and the Young's modulus according to the Sing Around method obtained based on the above measurement results. It can be seen that almost the same results were obtained for all the materials.
[0017]
Or delayed echo _{X 2} appears on either of the front and rear of the bottom echo _{B 2 is} determined by the ratio of _C S / C _L.
If delayed echo _{X 2} appears in front of the bottom echo _{B 2 is} made up relationship _{T B <T X2 <2T B} . And rearranging by substituting _{T B = 2t / C L T} X2 = 2t / C S in this inequality,
0.5 < _CS / _CL <1. Materials satisfying this condition include steel, alumina, zirconia, and quartz glass.
If delayed echo _{X 2} appears after the bottom echo _{B 2 is} made up relationship 2T B _{<T X2.} And rearranging by substituting _{T B = 2t / C L T} X2 = 2t / C S in this _inequality, the C _S / C L <0.5. Materials satisfying this condition include copper and the like.
Further, a delay echo _{X 2} appear at almost the same position as the bottom echo _{B 2 is} when the C _S / C L = 0.5, aluminum corresponds to this.
[0018]
【The invention's effect】
As described above, the ultrasonic sound velocity measuring method of the present invention makes it possible to easily simultaneously measure the longitudinal wave velocity and the transverse wave velocity even for a material having a thickness of 1 mm or less and a material having a very small area, which has been difficult until now. It has a remarkable effect that it can be done. In other words, according to the present invention, if a single focus type vertical probe has a size of about 1 mm × 1 mm even in a material having a thickness of 1 mm or less, its longitudinal wave velocity and transverse wave velocity can be measured simultaneously and accurately, There is an excellent feature that the Young's modulus and Poisson's ratio can be obtained instantaneously from these. As a result, the present invention can be expected to have a great effect on the evaluation of material properties in material development, and can greatly contribute to this field.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory view showing a configuration of an apparatus, a sample, and the like used in the present invention.
FIG. 2 is an explanatory diagram showing a state in which an ultrasonic echo used in the present invention appears on a CRT monitor of an ultrasonic device.
FIG. 3 is an explanatory diagram showing a form of each echo when an ultrasonic wave propagates in a sample.
FIG. 4 is an explanatory diagram showing a form of a surface echo when sensitivity is too high in measuring the propagation time of an ultrasonic wave.
FIG. 5 is an explanatory diagram showing a form of a surface echo when the sensitivity is lowered from a high state in measuring the propagation time of an ultrasonic wave.
FIG. 6 is a diagram comparing longitudinal wave velocities of various materials obtained by the method of the present invention and the Sing Around method.
FIG. 7 is a diagram comparing the shear wave velocities of various materials obtained by the method of the present invention and the Sing Around method.
FIG. 8 is a diagram comparing the Young's modulus of various materials obtained by the method of the present invention and the Sing Around method.
[Explanation of symbols]
1: CRT monitor 2: Focus type vertical probe 3: Sample 4: Medium

Claims (10)

An ultrasonic sound velocity measurement method that measures the transverse sound velocity of a sample, in which ultrasonic waves enter the sample immersed in a medium from a probe, propagate through the sample as longitudinal waves, and reflect back at the sample bottom surface. A bottom echo without conversion and a delayed echo due to a transverse wave generated by mode conversion when reflected on the bottom surface of the sample are detected, and the propagation time of the delayed echo due to mode conversion (T _X1 ) is used to detect the bottom echo without mode conversion. ultrasonic sound velocity obtaining the propagation time of the longitudinal wave _(T B / 2) a minus transverse propagation time and the thickness of the sample from (t) the shear wave velocity _{C S} as _{C S = t / (T X1} -T B / 2) Measuring method. An ultrasonic sound velocity measurement method for measuring the longitudinal wave velocity and the transverse wave velocity of a sample, in which ultrasonic waves are incident on a sample immersed in a medium from a probe, propagate in the sample as longitudinal waves, and are reflected at the bottom of the sample. A back echo without mode conversion and a delayed echo due to a transverse wave generated by mode conversion when reflected at the bottom of the sample are detected, and the propagation time (T _B ) of the bottom echo without mode conversion and the determined as the thickness (t) from the longitudinal acoustic velocity _{C L} to _C L = 2t / _{T B,} minus mode conversion due to the delay echo propagation time _{(T X1)} longitudinal wave propagation time from a _(T B / 2) transverse waves ultrasonic sound velocity measuring method for determining the shear wave velocity _{C S} from the propagation time and the thickness of the tabular sample (t) as the _{C S = t / (T X1} -T B / 2). When an ultrasonic wave enters a sample from a probe through a medium, a transverse wave generated by mode conversion is a transverse wave based on a propagation time ( _TX2 ) of a delayed echo of only a transverse wave reciprocatingly propagating in the sample and a thickness (t) of the sample. ultrasonic sound velocity measuring method for determining the speed of sound _{C S} as _C S = 2t _{/ T X2.} An ultrasonic sound velocity measurement method for measuring the longitudinal wave velocity and the transverse wave velocity of a sample, in which ultrasonic waves are incident on a sample immersed in a medium from a probe, propagate in the sample as longitudinal waves, and are reflected at the bottom of the sample. A back echo without mode conversion and a delayed echo due to a transverse wave generated by mode conversion when reflected at the bottom of the sample are detected, and the propagation time (T _B ) of the bottom echo without mode conversion and the thick (t) determine the longitudinal wave acoustic velocity C _L as C _{L =} 2t / T _B, the shear wave generated by mode conversion is only transverse wave through the sample was round trip delay echo propagation time (T _X2) and the sample ultrasonic sound velocity measuring method for determining the thickness (t) of the shear wave velocity _{C S} as _C S = 2t _{/ T X2.} The ultrasonic sound velocity measuring method according to any one of claims 1 to 4, wherein the measurement is performed by one probe. The ultrasonic sound velocity measuring method according to any one of claims 1 to 5, wherein the ultrasonic probe is a focused vertical probe. The ultrasonic sound velocity measuring method according to claim 1, wherein the ultrasonic sound velocity measuring method is a flat sample. The ultrasonic sound velocity measuring method according to any one of claims 1 to 7, wherein the medium is an inert liquid that propagates ultrasonic waves and does not damage the probe. The ultrasonic sound velocity measuring method according to any one of claims 1 to 8, wherein the medium is water. From longitudinal acoustic velocity C _L and transverse wave C _S and the density determined by the respective methods of claims 1 to 9 [rho, a method for determining the Young's modulus E and Poisson's ratio ν according to the following equation.
^{_{E = ρ (3C S 2 ·}} C L 2 -4C S 4) / (C L 2 -C S 2)
^{_{ν = (C L 2 -2C S}} 2) / 2 (C L 2 -C S 2)

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