Sample measuring device and method for measuring sample

Abstract

To provide a sample measuring device and a method for measuring a sample which can measure characteristics or properties of a sample such as the Q-value while reducing vibration losses caused by a supporting point.SOLUTION: A sample measuring device 100 is a sample measuring device 100 for measuring characteristics or properties of a sample SA, and includes a supporting device 20 for supporting a sample SA and a vibration excitation device 40 for causing vibrations in the sample SA supported by the supporting device 20. The vibration excitation device 40 extends the sample SA supported by the supporting device 20, in the longer direction of the sample SA and the supporting device 20 supports the sample SA in a state in which the sample SA can move in at least the longer direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a sample measurement device and a sample measurement method that support a sample and vibrate the sample to enable measurement of the vibration state of the sample. [Background technology]

[0002] Generally, when designing a vibration device, a vibration simulation using the finite element method is essential, followed by a process of evaluating the mechanical and electrical performance of the actual device. In this series of processes, the results of the simulation using the finite element method are extremely important for evaluating the performance of the device being designed. For this reason, when performing a simulation, in addition to elastic constants such as Young's modulus and density, the input value of the mechanical quality factor (Q value) is important. The Q value is a dimensionless quantity related to the internal friction of a material, and is an essential index when considering vibration damping inside a material. While precise measurement techniques exist for elastic constants and density, no method has been established for precisely measuring the Q value of a material.

[0003] There are many methods for measuring the vibration characteristics of materials. One of the most well-known methods is JIS G 0602 "Test method for vibration damping characteristics of vibration-damping steel plates" [1]. In this standard, electromagnetic exciters and impulse hammers are specified as excitation methods. Also, one-end fixing method, central support method, and simple support method are specified as material support methods. However, this measurement method has a problem in that vibration loss at the support point cannot be ignored. Therefore, if this measurement method is directly applied to vibration loss measurement of materials with high Q values, the vibration loss from the support point will have a large effect on the measurement results, making it difficult to measure the Q value precisely.

[0004] Although not directly related to the measurement of the Q value or elastic constant, a method is known for evaluating the soundness of adhesive anchors by using a device called an EMAT (electromagnetic acoustic transducer) to generate longitudinal vibrations in a non-contact manner in a sample and detecting the longitudinal vibrations with the same EMAT (Non-Patent Document 1). In this research, the vibration characteristics of an anchor bolt screwed into concrete are measured. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] K. Hasebe, Y. Mizuno, and K. Nakamura: "Non contact alignment free soundness evaluation of adhesive anchors by exciting / detecting longitudinal bolt vibrations using electromagnetic acoustic waves," Acoust. Sci. & Tech., Vol. 38, No. 4, pp. 225-228, 2017 Summary of the Invention

[0006] The present invention has been made in consideration of the above-mentioned background technology, and has an object to provide a sample measurement device and a sample measurement method that are capable of measuring sample characteristics and properties, such as the Q value, while reducing vibration losses caused by the support point.

[0007] In order to solve the above problems, the sample measurement device of the present invention is a sample measurement device that measures the characteristics or properties of a sample, and is equipped with a support device that supports the sample, and a vibration excitation device that induces vibrations in the sample supported by the support device, wherein the vibration excitation device expands and contracts the sample supported by the support device in the longitudinal direction of the sample, and the support device supports the sample in a state where it can be moved at least in the longitudinal direction.

[0008] In the above-mentioned sample measurement device, the support device supports the sample in a state where it can move at least in the longitudinal direction, so that the sample can be measured with reduced vibration loss caused by the support point, thereby improving the accuracy of sample measurement.

[0009] In order to solve the above problems, the sample measurement method of the present invention involves supporting a sample in a state where it can be moved in the longitudinal direction by a support device, and using a vibration excitation device to stretch and expand the sample supported by the support device in the longitudinal direction of the sample, and calculating the characteristics or properties of the sample from the relationship between the excitation frequency of the sample and the stretching state of the sample. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a conceptual diagram illustrating the structure of a sample measurement device according to the first embodiment. [Diagram 2] FIG. 2(a) is a side view illustrating the structure of the upper end portion of the support device, and FIG. 2(b) is a perspective view of the upper end portion shown in FIG. 2(a). [Diagram 3] FIG. 3(a) is a side cross-sectional view illustrating the structure of the excitation member, and FIG. 3(b) is a diagram illustrating a modified example of the device shown in FIG. 3(a). [Figure 4] FIG. 4(a) is a schematic cross-sectional side view of an excitation member, and FIG. 4(b) is a schematic perspective view illustrating a cross section of a sample. [Diagram 5] 5(a) and 5(b) are photographs of a system of an illustrative embodiment. [Figure 6] FIG. 6 is a chart showing the measurement points and the curves fitted to them. [Figure 7] 7(a) and 7(b) are diagrams showing the measurement results depending on the presence or absence of an input voltage to the Langevin transducer. [Figure 8] FIG. 8 is a diagram showing the relationship between the vibration velocity amplitude and the Q value of the Langevin transducer. [Figure 9] FIG. 9 shows the measurement results when another sample was supported in a non-contact manner. [Figure 10] FIG. 10 is a diagram showing the relationship between the input voltage to the coil and the measurement results. [Figure 11] FIG. 11 shows the results of measuring the frequency dependence of the Q value for a duralumin sample. [Figure 12] FIG. 12 is a conceptual diagram illustrating the sample measurement device of the second embodiment. [Figure 13] FIG. 13 is a conceptual diagram illustrating a modified sample measuring device. [Figure 14] FIG. 14 is a diagram for explaining the measurement results of the fundamental longitudinal vibration mode for a number of types of samples. [Figure 15] FIG. 15 is a diagram for explaining the change in the Q value depending on the mode order. [Figure 16] FIG. 16(a) is a diagram for explaining a modified example of the coil arrangement method, and FIG. 16(b) is a diagram for explaining the resonance peak of a higher mode of duralumin. [Figure 17] 17(a) and 17(b) are diagrams showing the measurement results when the sample is movably supported. [Figure 18] FIG. 18 is a graph comparing the admittance of a non-contact supported Langevin transducer before and after the installation of a horn. [Figure 19] FIG. 19 is a graph comparing the vibration velocity amplitude of the horn tip. [Figure 20] FIG. 20 is a diagram for explaining the adhesive effect of a support member provided at the tip of a Langevin transducer. [Figure 21] FIG. 21 is a diagram for explaining the adhesive effect of a support member provided at the tip of a Langevin transducer. [Figure 22] FIG. 22 is a diagram illustrating the characteristics of the Langevin transducer. [Figure 23] FIG. 23 is a diagram illustrating the effect of non-contact support of a sample by a Langevin transducer. [Figure 24] FIG. 24 is a diagram illustrating the effect of the input voltage to the Langevin transducer on the vibration of the sample. [Diagram 25] FIG. 25 is a diagram illustrating the effect of the input voltage to the Langevin transducer on the vibration of the sample. [Figure 26] FIG. 26 is a diagram for explaining the Q value measurement in a high-order mode. [Figure 27] FIG. 27 is a diagram for explaining the Q value measurement in a high-order mode. [Figure 28] FIG. 28 is a diagram for explaining the change in Q value due to the supporting method. [Figure 29] FIG. 29 is a diagram illustrating the relationship between vibration velocity and Q value. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] [First embodiment] A first embodiment of a sample measurement device and a sample measurement method according to the present invention will now be described with reference to the drawings.

[0012] 1 is a diagram illustrating a sample measurement device according to a first embodiment. The sample measurement device 100 includes a support device 20 that supports a rod-shaped sample SA, a vibration excitation device 40 that generates vibrations in the sample SA supported by the support device 20, a vibration measurement device 60 that measures the vibration state of the sample SA in the longitudinal direction, and a computer 90 that controls the overall operation.

[0013] The support device 20 supports the sample SA by utilizing the near-field ultrasonic levitation phenomenon. The support device 20 includes a pair of vibration members 21 and 22, and a driving power source 25 including AC power sources 23a and 23b for driving them. The support device 20 supports the sample SA in a state in which it can move at least in the longitudinal direction, which is the axial direction. The support device 20 uses Langevin vibrators as the vibration members 21 and 22, and supports two locations of the sample SA spaced apart along the axial direction, specifically both ends of the sample SA, so that the sample SA can move in the axial direction without contact against gravity. However, the sample SA supported by the support device 20 expands and contracts or vibrates in place, and remains in the same location overall or on average. The vibration member 21 is a pair of vibrators 21c such as PZT and a pair of electrodes 21d sandwiched between a horn 21a and a metal block 21b, and mechanically connected to them. The vibration member 22 has a structure similar to that of the vibration member 21.

[0014] FIG. 2(a) is a side view of the upper part of the horn 21a, and FIG. 2(b) is a perspective view of the upper end of the horn 21a. A circular plate-shaped support member 21u is provided at the upper end 21t of the horn 21a, and the part of the support member 21u that supports the sample SA has a shape that is an inversion of the partial shape of the part SS of the sample SA to be supported. Specifically, a groove 21v having a semicircular or U-shaped cross section is formed in the support member 21u. That is, the lower half of the part SS of the sample SA to be supported has a semicylindrical shape that is convex downward, and the space in the groove 21v has a semicylindrical shape that is convex downward. Correspondingly, the inner surface of the groove 21v has a semicylindrical side surface that is concave upward. This allows the lower part of the part SS of the sample SA to be accommodated in the groove 21v formed in the support member 21u. The width of the groove 21v is larger than the diameter of the sample SA, and the acoustic radiation force from the horn 21a causes the end SAa of the sample SA to float slightly above the bottom of the groove 21v and to separate from the inner surface of the groove 21v. That is, the support member 21u levitates the end SAa of the sample SA in a non-contact manner (more precisely, in a non-contact manner via air) and supports it so that it can move in the axial direction. When the end SAa of the sample SA is arranged so as to substantially coincide with the groove 21v of the support member 21u, the end SAa of the sample SA supported by one horn 21a and the end SAb of the sample SA supported by the other horn 21a receive a slight force toward the center of the sample SA, so that the sample SA can be stably held on the pair of vibration members 21, 22.

[0015] Support member 21u of horn 21a is replaceably attached to the body of horn 21a with double-sided tape or the like, but is not limited to this and may be formed integrally with the body of horn 21a, or may be firmly fixed to the body of horn 21a with an adhesive or the like.

[0016] 1, the vibration excitation device 40 includes an electromagnetic ultrasonic transducer 41 also called an EMAT, a signal processing device 42 having a frequency control function for controlling the frequency of a drive signal for driving the electromagnetic ultrasonic transducer 41, and an amplifier 43 for amplifying the drive signal. In this specification, the electromagnetic ultrasonic transducer 41 is also called an excitation member 141.

[0017] Fig. 3(a) is a side cross-sectional view illustrating the structure of the excitation member 141. Fig. 4(a) is a functional cross-sectional view of the excitation member 141, and Fig. 4(b) is a perspective view illustrating the YZ cross section of the sample SA.

[0018] 3(a), the excitation member 141 includes a first magnet 41a, a second magnet 41b, a coil holder 41c, and a coil 41d. The first magnet 41a, the coil 41d, and the second magnet 41b are arranged in this order parallel to the longitudinal direction of the sample SA. Here, the first magnet 41a and the second magnet 41b are permanent magnets, and the combination of the first magnet 41a and the second magnet 41b is called a magnetic field generating unit 41m. The magnetic field generating unit 41m is arranged so as to generate a magnetic field perpendicular to the eddy current, as will be described in detail later.

[0019] The first magnet 41a is arranged with its first magnetic pole, the N pole, facing the coil 41d, and the second magnet 41b is arranged with its second magnetic pole, the S pole, facing the coil 41d. In this case, the first magnet 41a and the second magnet 41b are magnetically connected to each other at a distance via the coil 41d. In this way, efficient excitation is possible when the first magnet 41a is arranged with one magnetic pole (specifically, the N pole) facing the coil 41d side and the second magnet 41b is arranged with the other magnetic pole (specifically, the S pole) facing the coil 41d side.

[0020] The first magnet 41a, the second magnet 41b, and the coil holder 41c are joined together, for example, using an adhesive, with the coil holder 41c positioned at the center and the axial centers of the members 41a, 41b, and 41c aligned, and are integrated. The members 41a, 41b, and 41c do not need to be joined together, and may be connected by the magnetic forces of the magnets 41a and 41b by providing fittings between the members 41a, 41b, and 41c. A hole 48a extending in the X direction, which is the longitudinal direction, is formed at the center of the excitation member 141. The inner diameter of the hole 48a is larger than the outer diameter of the sample SA by a predetermined amount, and a gap is secured to allow the sample SA to move in the axial direction and to deform or vibrate in such a way that it expands and contracts in a direction perpendicular to the axial direction.

[0021] The first magnet 41a and the second magnet 41b are both cylindrical permanent magnets extending in the ±X direction. The polarities of the first magnet 41a and the second magnet 41b are aligned as described above, and a magnetic field is formed in the space between them that is directed in the -X direction as a whole (see FIG. 4(a) for the state of the magnetic flux MF between the first magnet 41a and the second magnet 41b). As a result, a magnetic flux MF extending in the -X direction parallel to the axis of the hole 48a, that is, the axis of the magnets 41a, 41b and the coil holder 41c, is formed substantially uniformly in the sample SA inserted in the hole 48a.

[0022] The first magnet 41a and the second magnet 41b are not limited to being cylindrical and covering the entire circumference of the hole 48a, but may be formed, for example, only on the upper half of the hole 48a, or only on the lower half of the hole 48a.

[0023] The coil 41d is wound a predetermined number of times around a bobbin-shaped coil holder 41c to form a solenoid. The coil 41d is connected to an AC power source 46 consisting of a signal processing device 42 and an amplifier 43. The coil 41d generates an alternating magnetic field in the ±X direction parallel to the axis in the hole 48a, i.e., the sample SA, by the AC current supplied from the amplifier 43. As a result, a magnetic field is generated in the sample SA that is a sum of a large steady magnetic field component toward the -X direction and a small magnetic field component whose frequency fluctuates with an amplitude smaller than the magnitude of the steady magnetic field component. The material of the coil holder 41c is preferably a non-magnetic material with small loss at high frequencies and small magnetic permeability. Specific materials of the coil holder 41c are, for example, aluminum alloy and brass.

[0024] In this excitation member 141, when an AC current is applied to the coil 41d, a current change occurs in the coil 41d, and an induced current I, also called an eddy current, flows in the circumferential direction of the sample SA shown in FIG. 4(b). When an induced current I flows in the sample SA due to a current change in the coil 41d, a Lorentz force FL=I×B acts in the radial direction of the sample SA due to the influence of a magnetic flux density (magnetic field) B in the X-axis direction formed by the magnets 41a and 41b, which are the magnetic field generating unit 41m. This Lorentz force FL causes distortion in the radial direction of the sample SA, and a distortion occurs in the longitudinal direction, which is the axial direction of the sample SA, due to the Poisson's ratio, and a longitudinal vibration occurs in the sample SA. That is, the vibration excitation device 40 causes the sample SA to expand and contract in the longitudinal direction by the Lorentz force. As a result of the expansion and contraction of the sample SA, which increases and decreases the radius in the radial direction, the vibration excitation device 40 expands and contracts the sample SA in the longitudinal direction, and vibrates the sample SA at a frequency corresponding to the frequency of the AC current supplied to the coil 41d.

[0025] The longitudinal vibration of the sample SA is caused by the Lorentz force FL and is maximum at a portion corresponding to the position of the coil 41d. That is, the location or antinode where the stress amplitude of the longitudinal vibration of the sample SA is maximum is the center of the sample SA. It is preferable that the coil 41d of the excitation member 141 is disposed at the location where the stress amplitude is maximum in the resonance mode of the sample SA, but this is not limited to this. In this embodiment, the pair of ends SAa, SAb of the sample SA are supported in a non-contact manner by the pair of vibration members 21, 22, and the pair of ends SAa, SAb of the sample SA can be the location or antinode where the stress amplitude of the longitudinal vibration of the sample SA is maximum. The sample SA can resonate in a fundamental longitudinal vibration mode with the pair of ends SAa, SAb as antinodes and a high-frequency longitudinal vibration mode with a vibration frequency that is n times (n is an odd number) the frequency of the fundamental longitudinal vibration, and resonates at various frequencies depending on the way of excitation. At this time, the sample SA is not fixed at the positions of the vibration members 21 and 22, and the influence of vibration loss due to support can be reduced, and the vibration characteristics and physical properties of the sample SA can be determined more accurately.

[0026] 3(b) is a side cross-sectional view illustrating a modified example of the excitation member 141. The excitation member 141 includes a magnetic yoke 45 connected to the first magnet 41a and the second magnet 41b. The magnetic yoke 45 can increase the magnetic flux density formed in the hole 48a by the magnets 41a and 41b, thereby increasing the magnetic flux density passing through the sample SA in the axial direction.

[0027] Returning to FIG. 1, an end surface ES of one end SAa of the sample SA is processed into, for example, a flat surface, and reflects the laser light LL from the vibration measuring device 60 efficiently.

[0028] The vibration measuring device 60 includes a laser velocimetry device 61, and optically measures the displacement of the end SAa of the sample SA as the expansion / contraction state of the sample SA. The signal processing device 42 of the vibration excitation device 40 also functions as a part of the vibration measuring device 60. Although detailed description is omitted, the laser velocimetry device 61 is a laser Doppler vibrometer (LDV), and includes a laser light source, a photoelectric converter, and an amplifier, and can determine the Doppler frequency and calculate and output the velocity of the end face ES of the sample SA that is the target of irradiation with the laser light LL. The velocity of the end face ES of the sample SA is output to the signal processing device 42, making it possible to monitor the change in velocity with respect to the displacement of the end face ES of the sample SA in the X direction.

[0029] The computer 90 has an arithmetic processing circuit 91, an interface circuit 92, a storage device 93, and a user interface device 94. The computer 90, i.e., the arithmetic processing circuit 91, operates based on a program stored in the storage device 93, and controls the operation of the driving power supply 25 and the signal processing device 42. First, the computer 90 operates the driving power supply 25 to support the sample SA in a state in which it can move at least in the X direction, which is the longitudinal direction. After that, the computer 90 operates the amplifier 43 via the signal processing device 42 to apply an AC voltage to the coil 41d, and the sample SA can be brought into a state in which an eddy current is generated. As a result, a Lorentz force FL can be applied to the sample by the interaction between the magnetic flux density (magnetic field) B formed in the sample SA by the first magnet 41a arranged near the coil 41d and orienting its N pole to one end of the coil 41d, and the second magnet 41b arranged near the coil 41d and orienting its S pole to the other end of the coil 41d, and the eddy current, i.e., the induced current I generated in the sample SA. As a result, lateral vibration occurs due to radial strain of the sample SA, and longitudinal vibration occurs due to the Poisson's ratio due to longitudinal strain of the sample SA. In this state, the computer 90 operates the laser speed measuring device 61 via the signal processing device 42, and measures the expansion and contraction state of the sample SA, which expands and contracts in the longitudinal or vertical direction due to the Lorentz force FL, as the vibration velocity of the end surface ES. The computer 90 calculates the characteristics or properties of the sample SA from the relationship between the excitation frequency of the sample SA by the coil 41d and the vibration velocity of the end SAa of the sample SA. Here, the characteristics or properties of the sample SA include at least one of the vibration constant, Q value, and Young's modulus of the sample SA, and further include at least one of the temperature dependence and frequency dependence of the vibration constant, Q value, and Young's modulus. The vibration constant is information that provides information on the speed of sound, etc.

[0030] The first embodiment of the sample measurement apparatus 100 described above is a sample measurement apparatus 100 for measuring the characteristics or properties of the sample SA, and is equipped with a support device 20 that supports the sample SA, and a vibration excitation device 40 that induces vibrations in the sample SA supported by the support device 20, the vibration excitation device 40 expands and contracts the sample SA supported by the support device 20 in the longitudinal direction of the sample SA, and the support device 20 supports the sample SA in a state where it is movable at least in the longitudinal direction.

[0031] In the above-mentioned sample measurement apparatus 100, the support device 20 supports the sample SA in a state in which it is movable at least in the longitudinal direction, so that the sample SA can be measured with reduced vibration loss caused by the support point, thereby improving the accuracy of measurement of the sample SA.

[0032] The sample measurement device 100 is particularly suitable for measuring the Q value (mechanical quality factor). Furthermore, the sample measurement device 100 has a high S / N ratio even at a small voltage, and can improve the measurement accuracy of physical properties such as the Q value. Furthermore, the sample measurement device 100 makes it possible to measure physical properties such as the Q value with high power efficiency. The sample measurement device 100 makes it possible to measure physical properties such as the Q value in the band of several tens of kHz to several MHz, and makes it possible to measure physical properties such as the Q value in various vibration modes from low-order vibration modes to high-order vibration modes simply by changing the AC frequency.

[0033] By using the sample measurement device 100 to determine physical properties such as the Q value that are closer to the true value and applying this information in computer simulations, etc., it is possible to obtain results that are closer to reality and have fewer errors, enabling better material development and structural design.

[0034] Example 1 <1-1> Overview of the system proposed as the first embodiment In Example 1 embodying the first embodiment, the sample used for measurement is a thin rod-like object with a diameter of 1.5 mm and a length of 80 mm. Since the length of such a sample is considered to be sufficiently large compared to the diameter, it becomes possible to approximately consider only the vibration characteristics related to the longitudinal vibration mode.

[0035] In order to accurately measure the Q value, the sample measurement device 100 shown in FIG. 1 is used to make the excitation of the sample and the support of the sample non-contact. FIGS. 5(a) and 5(b) are photographs of the system proposed as Example 1. For the support of the sample, a support device 20 applying the near-field ultrasonic levitation phenomenon is used, and for the excitation of the sample, an electromagnetic ultrasonic transducer 41 is used. For the near-field ultrasonic levitation, a Langevin vibrator (FBL28302SSF-FC, Fujitsu Ceramics Co., Ltd.) is used. As shown in FIG. 1, the sample is placed on the tips of the vibrating members 21 and 22 which are Langevin vibrators. A semi-cylindrical groove 21v with a diameter of 1.6 mm is machined in the support member 21u provided at the tip of the Langevin vibrator to form a structure capable of supporting the sample. In the measurement of the Q value of the sample, the frequency and voltage of the voltage applied to the coil 41d of the excitation member 141 are controlled by a frequency analyzer (FRA5097, NF Circuit Design Block Co., Ltd.) which is a signal processing device 42, and the vibration velocity at the tip of the sample is measured by a laser Doppler vibrometer (LV-1800) which is a laser velocity measuring instrument 61. In this method, it is also possible to measure the Q value in the higher-order vibration mode by changing the frequency of the voltage input to the coil 41d of the excitation member 141.

[0036] The half-value width method is used for the measurement of the Q value. Let the resonance frequency of the n-th longitudinal vibration mode be f n and let the vibration velocity amplitude at the resonance frequency be A. Let the frequencies at which the vibration velocity amplitude becomes A / √2 be f1 and f2 (f1 < f2). Then, the Q value of this vibration mode can be calculated as shown in the following formula (1) [2]. TIFF2025028773000002.tif15158

[0037] Generally, for the longitudinal vibration of a distributed constant system thin rod, an LCR equivalent circuit can be considered, and the vibration velocity v(f) can be expressed by the following formula (2) [3,4]. TIFF2025028773000003.tif12158 However, x is as shown in the following formula (3). TIFF2025028773000004.tif14158The relationship between frequency f and vibration velocity amplitude v(f) is described by equations (2) and (3). The vibration velocity amplitude measured at each measurement point is fitted to the resonance curve of the above equivalent circuit using the nonlinear least squares method. The half-width is analytically calculated based on the fitted function v(f) to derive the Q value. Figure 6 shows the measurement points and the fitted curve. The coefficient of determination is 0.99.

[0038] In the thin rod longitudinal vibration mode, the resonant frequency of the nth longitudinal vibration mode is f n is expressed by the following equation [2]: TIFF2025028773000005.tif18158 where l is the length, E is Young's modulus, and ρ is density. Equation (4) can be transformed to In other words, by using the measurement system proposed in the first embodiment, the resonant frequency f n can be measured, and the Young's modulus E of the sample can also be measured using equation (5).

[0039] <1-2> Non-contact excitation of a sample using an excitation member In the first embodiment, an electromagnetic ultrasonic transducer 41 is used to excite a sample in a non-contact manner. The electromagnetic ultrasonic transducer 41 can generate a sound field inside the sample by using Lorentz force or magnetostrictive force, and can excite the sample in a non-contact manner [5, 6]. The advantages of the electromagnetic ultrasonic transducer 41 are: (1) It can transmit and receive ultrasonic waves without contact. (2) Various vibration modes can be excited by changing the arrangement of permanent magnets and electromagnetic coils. On the other hand, the electromagnetic ultrasonic transducer 41 has the disadvantage of having a small generating force. This disadvantage can be compensated for by using the ElectroMagnetic Acoustic Resonance (EMAR) method, which measures the vibration characteristics of the generated ultrasonic waves in a resonant state [7].

[0040] Conventional methods of exciting a sample by contacting it with a piezoelectric probe include the following: (1) Ultrasonic energy is absorbed by the probe and acoustic coupling agent, making it difficult to measure the energy loss inside the material. (2) Since ultrasonic waves are transmitted or reflected inside the probe or at the contact part, the reflection or transmission coefficient must be taken into consideration, making it difficult to improve accuracy. Since such problems are caused by the probe being in contact with the sample, it is possible to overcome such problems by exciting the sample in a non-contact manner using the electromagnetic ultrasonic transducer 41.

[0041] 4, the structure of the electromagnetic ultrasonic transducer 41 of the first embodiment is composed of two thick cylindrical permanent magnets (outer diameter 8 mm, inner diameter 3 mm, length 10 mm) and a hollow coil (inner diameter 3 mm). By applying an alternating current to the hollow coil 41d, an eddy current is generated in the circumferential direction in the sample, and due to the interaction with the magnetic flux density (magnetic field) B by the electromagnetic ultrasonic transducer 41, a Lorentz force FL (FL=I×B) acts in the radial direction of the sample, and the radial distortion generates an axial distortion, which excites longitudinal vibration. In the first embodiment, the permanent magnet has a residual magnetic flux density of 1.25-1.32 T in the catalog value, and the coil 41d has 50 turns. The self-resonant frequency of the coil 41d is around 40 MHz, which is a sufficiently higher frequency band than the frequency band for measuring the Q value in the first embodiment.

[0042] <1-3> Non-contact support using proximity ultrasonic levitation In Example 1, near-field ultrasonic levitation is used to support the sample SA in a non-contact manner. Near-field ultrasonic levitation is a levitation phenomenon that occurs when the levitation distance between the vibration surface and the levitating object is sufficiently small compared to the wavelength. A sound field is formed between the bottom surface of the levitating object and the vibration surface by sound waves emitted from the vibration surface, and acoustic radiation pressure is generated on the bottom surface of the levitating object, resulting in a levitation force [8]. Near-field ultrasonic levitation can levitate objects weighing in the kilograms, and technology has been reported that aims to apply it to the levitation and transportation of easily damaged or deformed materials such as semiconductor silicon substrates and display glass substrates [8, 9].

[0043] 1, in order to support the sample in a non-contact manner by near-field ultrasonic levitation, Langevin transducers (FBL28302SSF-FC, Fuji Ceramics Co., Ltd.) are used as vibration members 21 and 22. The resonant frequency of the Langevin transducer is about 27.8 kHz, and the vibration velocity at the resonant frequency is 10 V. p-p When this is done, it is about 0.9m. p-p / s. It has been confirmed that this vibration velocity amplitude is reduced to about one tenth by adhering a grooved support member to the tip of the vibrator. In addition, when measuring the tip vibration velocity amplitude of the sample, only the frequency component of the voltage applied to the coil 41d of the excitation member 141 is measured, so the vibration frequency component of the Langevin vibrator does not affect the measurement result.

[0044] In order to confirm the effectiveness of the non-contact support by the Langevin transducer, the Q value of a stainless steel (SUS304) sample was measured by changing the voltage applied to the Langevin transducer. Figure 7(a) shows the measurement result when the Langevin transducer was not driven, and Figure 7(b) shows the measurement result when 5V was applied to the Langevin transducer. p-p to 50V p-pThis is the measurement result when a voltage of 5V is applied to the Langevin transducer. This resonance curve is the resonance curve for the first mode. When no input voltage is applied to the Langevin transducer, the sample does not float and is in contact with the tip of the transducer, causing vibration loss from the contact point. Due to this vibration loss, the Q value and the vibration velocity amplitude at the resonance frequency are less than one-tenth of those when the Langevin transducer is driven. When a voltage is applied to drive the Langevin transducer, 5V p-p In this case, the peak value is about 0.3 mm. p-p / s, but the input voltage is increased to 20V p-p Above this, the peak value is 0.85 mm p-p The relationship between the vibration velocity amplitude of the tip of the Langevin transducer and the measured Q value of stainless steel (SUS304) is shown in Fig. 8. From Fig. 8, the input voltage to the Langevin vibration is set to 20V p-p The vibration amplitude is about 1.9m. p-p / s or more, it can be determined that sufficient non-contact support is being achieved.

[0045] Figure 9 shows the measurement results when the material of the sample was changed, the sample was supported non-contact by near ultrasonic levitation, and the sample was vibrated in the third longitudinal vibration mode. The sample used for the measurements was duralumin (A2017). In this case, the Q value was 46,000.

[0046] <1-4> Input voltage to the coil of an electromagnetic ultrasonic transducer In the first embodiment, the input voltage (current) to the coil 41d of the electromagnetic ultrasonic transducer, which is the excitation member 141, is one of the important parameters. If the input voltage to the coil 41d is too small, a sufficient generated force cannot be obtained, and a sufficient S / N ratio cannot be obtained. On the other hand, if an excessive voltage is applied, the coil 41d generates heat, which causes a temperature change or a temperature gradient in the sample SA, and there is a possibility that a correct result cannot be obtained.

[0047] FIG. 10 shows a resonance curve when the input voltage to the coil 41d is changed in the vibration of the first mode of a stainless steel (SUS304) sample. The input voltage to the coil 41d is 0.5V.p-p to 8V p-p The impedance of the coil 41d at the resonance frequency was 1.6Ω, and the input current to the coil 41d at this time was 0.31A. p-p from 4.95A p-p The vertical axis represents the vibration velocity amplitude per unit input voltage. The resonance frequency is between 32.84kHz and 32.86kHz, and the Q value is in the range of 1700 to 1950. However, at 4.0V p-p and 8.0V p-p At 1.0V, a rise in the coil surface temperature was confirmed, so it cannot be concluded that the results are accurate. p-p As a result of ten measurements, the average Q value was 1890 with a standard deviation of 96.

[0048] <1-5> Summary of Example 1 In Example 1, a method was devised that combines non-contact excitation by an electromagnetic ultrasonic transducer (excitation member 141) and non-contact support of a sample using the near-field ultrasonic levitation phenomenon in order to precisely measure the Q value of a metal material. The structure of the excitation member 141 is capable of exciting a longitudinal vibration mode in a thin rod-shaped sample with a diameter of 1.5 mm. The method proposed in Example 1 is particularly effective for measuring materials with high Q values. When a duralumin (A2017) sample was measured using the proposed method, a result of 46,000 was obtained. In order to confirm the effect of ultrasonic levitation of a sample using the Langevin transducer, the input voltage to the Langevin transducer was changed and measurements were taken of stainless steel (SUS304). p-p , vibration speed 1.9m p-p / s or more, the Q value fluctuates around 2000. On the other hand, if the vibration speed of the Langevin transducer is insufficient, the sample is not supported in a non-contact manner, and a low Q value is measured. These results show that non-contact measurement is very important for accurately measuring the Q value of metal samples. With the proposed method, the Young's modulus of the material can be calculated from the resonance frequency of the vibration mode. The Young's modulus of stainless steel (SUS304) was approximately 10% higher than the general value. Therefore, heat treatment was performed to remove the residual stress and work hardening that occurred during the machining of the sample. In particular, when solution treatment was performed at 1100°C, the Q value changed from 1930 to 6800 and the Young's modulus changed from 219.2 GPa to 198.8 GPa. In this way, the proposed method can also measure the Q value and Young's modulus of metal materials and their changes due to processing or treatment.

[0049] <1-6> Supplementary explanation for Example 1 Fig. 11 shows the results of measuring the frequency dependency of the Q value for the duralumin sample SA. It was confirmed that it was possible to measure the Q value in a high-order vibration mode by changing the frequency of the current input to the coil 41d of the electromagnetic ultrasonic transducer (excitation member 141). With the current structure, it was possible to measure the Q value up to the 1.5 MHz band.

[0050] Second Embodiment The sample measurement device and sample measurement method of the second embodiment will be described below. The sample measurement device etc. of the second embodiment are partially modified from the sample measurement device etc. of the first embodiment.

[0051] Referring to FIG. 12, the sample measurement device 100 uses a support member 222 that directly supports the sample SA as a support device 220 that supports the sample SA. The support member 222 supports the sample SA in a state in which it can move in the longitudinal direction. For this reason, the support member 222 includes a main body 22a and an abutment member 22b, and the abutment member 22b is attached to the upper surface of the tip portion 22t of the main body 22a. The abutment member 22b is a member with lower friction than the main body 22a, and is formed of a porous material that is elastically deformable, specifically, a sponge. In this case, the support member 222 supports the sample SA at a position where a node of vibration is formed, thereby reducing the influence on vibration. As a result, the ends SAa and SAb of the sample SA become antinodes, and the end surface ES of the end SAa of the sample SA, which is the measurement target by the laser speed measuring device 61, is located away from the support point.

[0052] 13 is a diagram illustrating a modified sample measurement device 100. In this case, a pair of support members 222 supporting the sample SA each have a hanging thread 22j with a loop 21i at its lower end and a support rod 22k supporting the upper end of the hanging thread 22j, and the support rod 22k is a common member. Here, the pair of support members 222 support the sample SA in a state in which it can move in the longitudinal direction. The hanging thread 22j including the loop 21i is a member with lower friction than the support rod 22k, which is the main body 22a.

[0053] Example 2 2-1 Measurement method in Example 2 In measuring the Q value, a sample measuring device 100 shown in FIG. 12 was used, which movably supports the sample SA with a low-friction porous elastic body. That is, an electromagnetic ultrasonic transducer 41 is used as an excitation member 141 to excite longitudinal vibration in the sample, and the vibration velocity of the tip of the sample is measured by a laser Doppler vibrometer (LV1800). The voltage frequency applied to the electromagnetic ultrasonic transducer 41 is controlled by a frequency characteristic analyzer (FRA5097). The coil used had 50 turns. The self-resonant frequency of this coil was around 40-50 MHz, which is sufficiently higher than the frequency band in which the Q value was measured in Example 2. The method of supporting the sample was to support the node points of the vibration of the third longitudinal vibration mode with sponge in order to minimize the influence of vibration damping. The sample had a diameter of 1.5 mm and a width of 80 mm, and was measured using a sample made of two types of materials, duralumin (A2017) and stainless steel (SUS304). The physical properties of the two materials are as shown in Table 1. [Table 1]

[0054] 2-2 Measurement results FIG. 14 shows the results of the frequency and vibration velocity amplitude when the sample was excited by the method of Example 2. The sample was made of duralumin with a length of 80 mm, and the results were obtained by measuring the fundamental longitudinal vibration mode. The measurement frequency interval was 0.2 Hz, and the input voltage to the coil 41d was 4 V.p-p The current flowing through the coil 41d when measuring the duralumin sample is 2.09A. p-p It was.

[0055] The resonant frequency f of the nth longitudinal vibration mode of a thin rod sample n is expressed by the above-mentioned formula (4). The resonance frequency measured by the method of Example 2 is 31.78 kHz in the case of duralumin. These values ​​match with the value of 31.88 kHz calculated by formula (4) with an error of 0.1 to 0.2 kHz. The Q value is calculated by taking the half-width from the resonance peak as shown in FIG. 14, and the Q value of the fundamental vibration mode is 10600 for duralumin.

[0056] Figure 15 shows the Q values ​​for each vibration mode of duralumin and SUS when the frequency is changed. For each material, the Q value of the fundamental vibration mode is smaller than the Q value of the higher modes. This is because the sample is supported at the node point of the 3rd mode in the measurement, and is particularly affected by vibration loss at the support point. Therefore, in this measurement, the results for the 3rd mode are less affected by vibration loss. In the 3rd mode, the Q value of duralumin was 28,000, and the Q value of SUS was 2200. The Q value of SUS is one order of magnitude smaller than the other two materials, and the S / N ratio is poor in the higher modes, so only the results up to the 3rd mode are shown in the figure.

[0057] 2-3 Measurement results In previous measurements, the coil 41d was placed at the center of the sample SA, and the width over which the sample was excited was always 8 mm. However, in order to measure the Q value of a higher mode, which has a shorter wavelength of the vibration mode, it is necessary to shorten the excitation amplitude. For this reason, the coil 41d was placed at the end of the sample as shown in Figure 16(a), and measurements were performed in an arrangement that allowed the excitation amplitude to be shortened. Reducing the excitation amplitude by 2 to 3 mm made it possible to measure a higher vibration mode. Figure 16(b) shows the resonance peak of the 35th mode of duralumin. Since the impedance of the coil 41d increases in proportion to the frequency, the input voltage to the coil 41d was 60V. p-pAt this time, the current flowing through the coil 41d is 1.22 A. p-p The peak value of the vibration velocity amplitude of this vibration mode was about 0.5 mm p-p / s, which is reduced to about one hundredth of the vibration velocity amplitude of the fundamental vibration mode. This results in a poor signal-to-noise ratio in the measurement. For this reason, in order to measure the Q value over a wide frequency band, it is necessary to excite the sample more strongly. In the structure of Example 2, the sample is excited by the Lorentz force. The amplitude of the Lorentz force is determined by the product of the induced current amplitude in the sample and the magnetic flux density due to the permanent magnet. For this reason, one effective way to increase the Lorentz force is to increase the magnetic flux density due to the permanent magnet. Methods such as strengthening the permanent magnet or introducing a yoke are effective.

[0058] 17(a) and 17(b) show the results of measurements taken by supporting the node points of the third-order longitudinal vibration mode with a thin thread (nylon, diameter 0.165 mm) and a thin sponge (2 mm). The sample SA used for measurements is made of duralumin (A2017), the same as in the first embodiment. Since support is provided at the node points of the third-order mode, the measurement results for the third-order mode are shown. The Q value when supported by thread is 13,000, and when supported by sponge is 33,000, showing that the Q value changes significantly depending on the support method. The same is true for the vibration velocity amplitude, and when supported by sponge, the vibration velocity amplitude at the resonant frequency is three times that when supported by thread.

[0059] 〔others〕 Although the sample measurement device and method according to the present invention have been described above as embodiments and examples, the sample measurement device and method according to the present invention are not limited to those described above.

[0060] The shape of the sample SA is not limited to a long, thin rod, and may be a cylinder, a cylinder, a rectangular parallelepiped, or the like. In the case of a rectangular parallelepiped, the circumferential direction in which eddy currents are generated means the direction perpendicular to the longitudinal direction of the rectangular parallelepiped. However, in consideration of the shape being such that the influence of the transverse elastic modulus is not large or is small, it is desirable for the shape of the sample SA to be, for example, a thin rod shape.

[0061] The material of the sample SA is not particularly limited as long as the Lorentz force acts on it.

[0062] Coil 41d is not limited to the one exemplified in the embodiment, but it is preferable that the self-resonant frequency of coil 41d can be clearly distinguished from the frequency band of the Q value to be measured.

[0063] The magnetic field generating unit 41m is not limited to including two magnets 41a, 41b, but may include only one of the magnets, or may include only three or more magnets.

[0064] From the viewpoint of ensuring positional accuracy of excitation, it is preferable that the width of coil 41d in the axial direction is equal to or less than half the wavelength of the vibration to be measured.

[0065] In the above embodiment, the sample SA is arranged to penetrate the center of the coil 41d, but when operating in a higher mode, only a part of the sample SA may be arranged to intersect with or be in the vicinity of the cross section of the coil 41d. In particular, when measuring in a high frequency band (short wavelength band) such as 1 MHz or more, it is preferable to arrange the sample at the end of the coil 41d from the viewpoint of narrowing the excitation region in the axial direction.

[0066] The laser speed measuring instrument 61 can use various methods capable of detecting axial movement or displacement of the end of the sample SA, including not only optical methods such as a laser Doppler vibrometer, but also acoustic methods such as a microphone, and electrical methods such as an eddy current sensor or a capacitance sensor.

[0067] The non-contact holding of the sample SA by the support device 20 is not limited to using a Langevin transducer, but may be performed by air pressure or electrostatic force, or may use other similar mechanisms or principles.

[0068] The sample SA may be a magnetic material. In the case of sample measurement device 100 for measuring a magnetic material, excitation member 141 does not include magnets 41a and 41b, and a magnetic field is applied to the sample SA made of a magnetic material by coil 41d. In this case, the magnetic flux formed in the sample SA by coil 41d directly expands and contracts the sample SA, so that the magnetostriction of the sample SA can be measured by monitoring the displacement of the tip of the sample SA.

[0069] The characteristics and / or properties of the sample SA that are the subject of measurement may be the degree of oxidation, deterioration, or corrosion on the surface or inside of the sample SA, and the effects of these on the sample SA (including prediction of the effects), or the state of the grain boundaries and atomic arrangement within the sample SA.

[0070] In the case of a thin rod-shaped sample SA, by attaching a substance such as a film that reacts with a specific substance to the tip of the rod, the Q value and other parameters change when the substance adheres to the rod. Therefore, the sample measurement device 100 of the embodiment can be applied to a highly sensitive sensor for determining the presence, concentration, and status of a substance. Specifically, if a sensitive film (PdNi film) that adsorbs hydrogen is attached to the tip of the sample, the resonant frequency decreases and the Q value also decreases due to the adsorption of hydrogen in the environment. It is expected that the device can be applied to a highly sensitive hydrogen leak detection sensor that ensures the safety of hydrogen stations necessary for fuel cell vehicles that reduce environmental load. In addition, by intermittently or continuously contacting the tip of the rod-shaped sample with the target, it may be possible to measure the hardness and viscosity of a living body or other target.

[0071] 18 to 29 show the results of measurements using Langevin transducers as vibration members 21 and 22 in the sample measurement device 100 shown in Fig. 1, from the viewpoint of confirming and estimating in advance the characteristics of the Langevin transducer and the Q value of the sample SA, etc. In the charts, "4049" and "4954" are the serial numbers of a pair of Langevin transducers with the same specifications.

[0072] <References> [1] Japanese Standards Association: JIS G 0602 (Test methods for vibration characteristics of vibration-damping steel plates), 1993. [2] Takeshi Morita: "Piezoelectric Phenomenon", Morikita Publishing Co., Ltd., 2017. [3] Hisayoshi Yanai and Masayoshi Yujo, "Measurement of Q and dielectric loss by the resonance curve area method", Journal of the Institute of Electrical Communication Engineers, Vol. 36, No. 3, pp. 121-125, 1953. [4] T. Miura, T. Takahashi and M. Kobayashi, "Accurate Q-factor Evaluation by Resonance Curve Area Methods and Its Application to the Cavity Perturbation," IEICE Trans. Elec., Vol. E77-C, No. 6, pp. 900-907, 1994. [5] PK Larsen and K. Saermark, "Helicon excitation of acoustic waves in aluminum," Phy. Lett, Vol. 24A, pp. 374-375, 1967. [6] ER Dobbs, "Electromagnetic generation of ultrasonic waves in metals," J. Phys. Chem. Solids, Vol 31, pp. 1657-1667, 1970. [7] M. Hirano, H. Ogi and H. Fukuoka, "Resonance EMAT systems for acoustelastic stress measurement in sheet materials," Rev. Sci. Instrum., Vol. 64, pp. 3198-3205, 1993. [8] Y. Koike, Y. Hashimoto and S. Ueda, "Acoustic levitation of planner objects using a longitudinal vibration mode," J. Acoust. Soc. Am., Vol. 16, pp. 189-192, 1995. [9] H. Tamura, R. Yano, M. Aoyagi and T. Takano, "A novel transfer method using near-field acoustic levitation and its application," Jpn. J. Appl. Phys., Vol. 50, No. 7S, 2011. [Explanation of symbols]

[0073] 20...support device, 21, 22...vibration member, 21a...horn, 21b...metal block, 21c...vibrator, 21d...electrode, 21t...upper end, 21u...support member, 21v...groove, 22a...main body, 22b...contact member, 23a, 23b...AC power supply, 25...driving power supply, 40...vibration excitation device, 41...electromagnetic ultrasonic transducer, 41a, 41b...magnet, 41c...coil holder, 41d...coil, 41m...magnetic field generating unit, 42...signal processing device, 43...amplifier, 45...magnetic yoke, 46...AC power supply, 48a...hole, 60...vibration measuring device, 61...laser speed measuring device, 90...computer, 91...arithmetic processing circuit, 92...interface circuit, 93...storage device, 94...user interface device, 100... sample measuring device, 141... excitation member, 220... support device, 222... support member, LL... laser light, SA... sample, SAa, SAb... end portions

Claims

1. A sample measurement device for measuring a characteristic or property of a sample, comprising: A support device for supporting the sample; a vibration excitation device for generating vibrations in the sample supported by the support device, The vibration excitation device expands and contracts the sample supported by the support device in a longitudinal direction of the sample, The support device supports the sample in a state where the sample is movable in at least the longitudinal direction. Sample measurement device.

2. The sample measurement device according to claim 1 , wherein the support device levitates and supports the sample in a non-contact manner.

3. 2. The sample measurement device according to claim 1, wherein the support device supports the sample via a low-friction member that is attached to a main body of the support device.

4. The sample measurement device according to claim 3 , wherein the support device supports the position of a vibration node in the longitudinal direction of the sample.

5. The sample measurement device of claim 1 , wherein the vibration excitation device comprises a coil connected to an AC power source.

6. The sample measurement device according to claim 5 , wherein the vibration excitation device further comprises a magnetic field generation unit.

7. The sample measurement device described in claim 6, wherein the expansion and contraction is caused by Lorentz force, the Lorentz force being caused by eddy currents in the sample caused by changes in current or voltage to the coil and a magnetic field generated by the magnetic field generating unit.

8. The magnetic field generating unit has a first magnet, The sample measurement device according to claim 7 , wherein the vibration excitation device has the first magnet and the coil arranged parallel to the longitudinal direction of the sample.

9. The magnetic field generating unit further includes a second magnet, 9. The sample measurement device according to claim 8, wherein the vibration excitation device includes the first magnet, the coil, and the second magnet arranged in this order parallel to the longitudinal direction of the sample.

10. The sample measurement device of claim 9, wherein the first magnet is arranged with a first magnetic pole facing the coil, and the second magnet is arranged with a second magnetic pole different from the first magnetic pole facing the coil.

11. The sample measurement device according to claim 10 , wherein the first magnet and the second magnet are magnetically connected directly or at a distance.

12. 2. The sample measurement device according to claim 1, wherein the portion of the support device that supports the sample has a shape that is an inverse of a partial shape of the supported portion of the sample.

13. 2. The sample measurement device according to claim 1, wherein the characteristics or properties of the sample include at least one of a vibration constant, a Q value, a Young's modulus, and a temperature dependence and a frequency dependence of a characteristic value of the sample.

14. The sample measurement device according to claim 1 , further comprising a vibration measurement device that measures a vibration state of the sample in the longitudinal direction.

15. In a state where the sample is supported by a support device in a state where the sample can be moved in the longitudinal direction, the sample supported by the support device is expanded and contracted in the longitudinal direction of the sample by a vibration excitation device; A sample measurement method, comprising: calculating a characteristic or property of the sample from a relationship between an excitation frequency of the sample and an expansion / contraction state of the sample.

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