Electromagnetic ultrasonic measuring apparatus and method

Abstract

The present invention aims to provide a measuring device and method for electromagnetic ultrasonic waves that can measure with measurement data having more appropriate attenuation characteristics. [Solution] The electromagnetic ultrasonic measuring device 1000 of the present invention comprises a data acquisition unit 1 that acquires measurement data measured using electromagnetic ultrasonic waves, and a measurement processing unit 22 that determines a predetermined physical quantity in the object to be measured based on the measurement data acquired by the data acquisition unit 1. The object to be measured is a member having a curved surface in which at least one of a predetermined first direction and a second direction intersecting the first direction is a tangential direction, and the measurement data is ultrasonic data obtained by incidenting the object to be measured with electromagnetic ultrasonic waves of transverse waves vibrating in one direction relative to the object to be measured.

Description

[Technical Field]

[0001] The present invention relates to an electromagnetic ultrasonic measurement device and a measurement method that use measurement data measured using electromagnetic ultrasonic waves. [Background technology]

[0002] Ultrasound is a known method for non-destructively measuring objects. Ultrasound probes (ultrasound transducers) that transmit and receive ultrasound can be broadly categorized into two types based on their ultrasound generation method: piezoelectric ultrasonic probes, which generate ultrasound through electroacoustic conversion of a piezoelectric element, and electromagnetic ultrasonic probes, which generate ultrasound through the electromagnetic interaction between a magnet and a coil. Compared to piezoelectric ultrasonic probes, electromagnetic ultrasonic probes have the advantage of not requiring an acoustic coupling agent for ultrasound transmission and reception, enabling non-contact measurement. Measurement techniques using such electromagnetic ultrasonic probes are disclosed, for example, in Patent Document 1. Ultrasound probes can usually receive ultrasound by reversing the ultrasound generation process. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2001-343368 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] Incidentally, ultrasonic waves incident on a measurement target usually attenuate as they propagate through the target. The inventor investigated the attenuation characteristics by incidenting various transverse wave electromagnetic ultrasonic waves on a measurement target and noticed that there were differences in the attenuation characteristics.

[0005] This invention was made in view of the above circumstances, and its purpose is to provide an electromagnetic ultrasonic measuring device and an electromagnetic ultrasonic measuring method that can measure with measurement data having more appropriate attenuation characteristics. [Means for solving the problem]

[0006] As a result of various studies, the inventors have found that the above objective can be achieved by the present invention as described below. That is, an electromagnetic ultrasonic measuring device according to one aspect of the present invention comprises a data acquisition unit that acquires measurement data measured using electromagnetic ultrasonic waves, and a measurement processing unit that determines a predetermined physical quantity in a measurement target based on the measurement data acquired by the data acquisition unit, wherein the measurement target is a member having a curved surface in which at least one of a predetermined first direction and a second direction intersecting the first direction is a tangential direction, and the measurement data is ultrasonic data obtained by incidenting the measurement target with transverse wave electromagnetic ultrasonic waves vibrating in one direction with respect to the measurement target. Preferably, in the above-described electromagnetic ultrasonic measuring device, the measurement data acquisition unit is an electromagnetic ultrasonic probe. Preferably, in the above-described electromagnetic ultrasonic measuring device, the measurement data acquisition unit is an interface circuit that inputs and outputs data to and from an external device, and the external device is a storage medium that stores the measurement data. Preferably, in the above-described electromagnetic ultrasonic measuring device, the data acquisition unit is an interface circuit that inputs and outputs data to and from an external device, and the external device is a drive device that reads data from a recording medium that stores the measurement data. Preferably, in the electromagnetic ultrasonic measuring device described above, the data acquisition unit is a communication interface circuit that sends and receives communication signals with an external device, and the external device is a server device connected to the communication interface circuit via a network and managing the measurement data.

[0007] The inventor noticed that the attenuation characteristics of ultrasound depend on the direction of vibration in transverse ultrasound. The above electromagnetic ultrasound measuring device uses ultrasound data obtained by incidenting transverse ultrasound vibrating in one direction relative to the object to be measured onto the object to be measured. Therefore, the measurement data will have the attenuation characteristics desired by the operator (user), and thus the above electromagnetic ultrasound measuring device can measure with measurement data that has more appropriate attenuation characteristics.

[0008] In another embodiment, in the above-described electromagnetic ultrasonic measuring device, the frequency of the electromagnetic ultrasonic is 4 MHz or higher. Preferably, in the above-described electromagnetic ultrasonic measuring device, the frequency of the electromagnetic ultrasonic is 4.5 MHz or higher or 5 MHz or higher.

[0009] The inventor noticed that the attenuation characteristics of ultrasound depend on the frequency of transverse ultrasound. Since the above electromagnetic ultrasound measuring device uses electromagnetic ultrasound with a frequency of 4 MHz or higher, the measurement data will have the attenuation characteristics desired by the operator (user). Therefore, the above electromagnetic ultrasound measuring device can measure with measurement data that has more appropriate attenuation characteristics.

[0010] In another embodiment, the electromagnetic ultrasonic measuring device described above includes a plurality of measurement data measured using electromagnetic ultrasonic waves of different frequencies, and further comprises frequency processing to determine the envelope of each of the plurality of measurement data, determine the exponential function that best fits the determined envelope, determine the error of the determined exponential function of the measurement data with respect to the envelope of the measurement data, select the smallest error from among the plurality of errors determined for each of the plurality of measurement data, and determine the frequency of the measurement data having the selected error. Preferably, in the electromagnetic ultrasonic measuring device described above, the frequency processing unit determines the mean squared error as the error based on the difference between the envelope and the exponential function determined at each timing corresponding to each peak in the measurement data.

[0011] The specified physical quantity can be obtained based on the attenuation constant, which is one of the parameters characterizing the attenuation characteristics. Since the electromagnetic ultrasonic measurement device obtains the frequency of the measurement data with the smallest error, it can obtain the frequency for obtaining measurement data with more appropriate attenuation characteristics.

[0012] In another aspect, in the electromagnetic ultrasonic measurement device described above, the measurement data includes a plurality of measurement data measured at intervals of a predetermined period, and each one direction in the plurality of measurement data is the same.

[0013] Such an electromagnetic ultrasonic measurement device aligns the vibration direction with respect to the measurement object for each different measurement, so that each measurement data for each measurement can be treated equally.

[0014] In another aspect, in the electromagnetic ultrasonic measurement device described above, the one direction is the axial direction.

[0015] Since such an electromagnetic ultrasonic measurement device has the one direction as the axial direction, it can measure with measurement data having even more appropriate attenuation characteristics.

[0016] In another aspect, in the electromagnetic ultrasonic measurement device described above, the one direction is the circumferential direction.

[0017] Since such an electromagnetic ultrasonic measurement device has the one direction as the circumferential direction, it can measure with measurement data having more appropriate attenuation characteristics.

[0018] In another aspect, in the electromagnetic ultrasonic measurement device described above, the physical quantity is at least one of hardness, creep damage degree, fatigue damage degree, remaining life, dislocation density, dislocation line length, and crystal grain size.

[0019] According to this, an electromagnetic ultrasonic measuring device can be provided that can measure at least one of the following: hardness (e.g., Vickers hardness), creep damage (e.g., creep damage life consumption rate), fatigue damage (e.g., fatigue damage life consumption rate), remaining life, dislocation density, dislocation line length, and grain size (e.g., average grain size).

[0020] In another aspect of the present invention, a method for measuring electromagnetic ultrasonic waves comprises a data acquisition step of acquiring measurement data measured using electromagnetic ultrasonic waves, and a measurement processing step of determining a predetermined physical quantity in a measurement target based on the measurement data acquired in the data acquisition step, wherein the measurement target is a member having a curved surface in which at least one of a predetermined first direction and a second direction intersecting the first direction is a tangential direction, and the measurement data is ultrasonic data obtained by incidenting the measurement target with transverse wave electromagnetic ultrasonic waves vibrating in one direction relative to the measurement target.

[0021] This electromagnetic ultrasonic measurement method uses ultrasonic data obtained by incidenting a transverse wave electromagnetic ultrasonic wave vibrating in one direction onto the object to be measured as measurement data. Since the measurement data will have the attenuation characteristics desired by the operator (user), this electromagnetic ultrasonic measurement method can measure with measurement data that has more appropriate attenuation characteristics. [Effects of the Invention]

[0022] The electromagnetic ultrasonic measurement device and electromagnetic ultrasonic measurement method according to the present invention can measure with measurement data having more appropriate attenuation characteristics. [Brief explanation of the drawing]

[0023] [Figure 1] This is a block diagram showing the configuration of an electromagnetic ultrasonic measuring device in an embodiment. [Figure 2] This diagram illustrates the positional relationship of the electromagnetic ultrasonic probe relative to the object being measured. [Figure 3] As an example, this is a diagram illustrating how to determine the damping constant. [Figure 4]As an example, this figure shows the simulation results used to explain the relationship between the vibration direction and damping characteristics of transverse electromagnetic ultrasound for a measurement target. [Figure 5] As an example, this figure shows the measured results to explain the relationship between the vibration direction and damping characteristics of transverse wave electromagnetic ultrasound for a measured object. [Figure 6] As an example, this figure shows the simulation results used to explain the relationship between frequency and attenuation characteristics in transverse electromagnetic ultrasound. [Figure 7] As an example, this figure shows the measured results used to explain the relationship between frequency and attenuation characteristics in transverse electromagnetic ultrasound. [Figure 8] As an example, this diagram illustrates the correlation between damping constant and Vickers stiffness. [Figure 9] This is a flowchart showing the operation of the electromagnetic ultrasonic measuring device. [Modes for carrying out the invention]

[0024] Hereinafter, one or more embodiments of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the disclosed embodiments. In each figure, components denoted by the same reference numerals are identified as identical components, and their descriptions are omitted where appropriate. In this specification, general reference numerals are used without subscripts, while individual components are indicated by subscripts.

[0025] The electromagnetic ultrasonic measuring device in this embodiment includes a data acquisition unit that acquires measurement data measured using electromagnetic ultrasonic waves, and a measurement processing unit that determines a predetermined physical quantity in the object to be measured based on the measurement data acquired by the data acquisition unit. The object to be measured is a member having a curved surface in which at least one of a predetermined first direction and a second direction intersecting the first direction is a tangential direction. The measurement data is ultrasonic data obtained by incidenting the object to be measured with transverse wave electromagnetic ultrasonic waves vibrating in one direction relative to the object to be measured. The electromagnetic ultrasonic measuring device and the electromagnetic ultrasonic measurement method implemented therein will be described in more detail below.

[0026] Figure 1 is a block diagram showing the configuration of an electromagnetic ultrasonic measuring device in an embodiment. Figure 2 is a diagram illustrating the arrangement of the electromagnetic ultrasonic probe with respect to the object to be measured. Figure 2A is a cross-sectional view of the object to be measured along the yz plane, viewed from the x-axis direction, when the xyz orthogonal coordinate system shown in Figures 2A and 2B is set up. Figure 2B is a cross-sectional view of the object to be measured along the zx plane, viewed from the y-axis direction. The x-axis direction is considered to be the axis direction of the object to be measured. Figure 3 is a diagram illustrating how to determine the attenuation constant as an example. Figure 3A shows the waveform of measurement data (ultrasonic echo waveform) obtained by the pulse echo method, and Figure 3B shows the waveform of measurement data (ultrasonic echo waveform) obtained by the resonance method. In Figures 3A and 3B, each horizontal axis represents time (elapsed time), and each vertical axis represents displacement. At a predetermined point (location) on the object to be measured, (displacement) = (position of the point when ultrasonic waves are propagating) - (position of the point when ultrasonic waves are not propagating). Figure 4 shows simulation results illustrating the relationship between the vibration direction and damping characteristics of transverse electromagnetic ultrasound for a measurement target, as an example. Figure 4A shows the case where transverse electromagnetic ultrasound vibrates along the circumferential direction of the measurement target Ob, and Figure 4B shows the case where transverse electromagnetic ultrasound vibrates along the axial direction (x-axis direction) of the measurement target Ob. In Figures 4A and 4B, each horizontal axis represents time (elapsed time) [s], and each vertical axis represents normalized displacement [au]. Figure 5 shows measurement results illustrating the relationship between the vibration direction and damping characteristics of transverse electromagnetic ultrasound for a measurement target, as an example. Figure 5A shows the case where transverse electromagnetic ultrasound vibrates along the circumferential direction of the measurement target Ob, and Figure 5B shows the case where transverse electromagnetic ultrasound vibrates along the axial direction (x-axis direction) of the measurement target Ob. In Figures 5A and 5B, each horizontal axis represents time (elapsed time) [s], and each vertical axis represents voltage [V] representing displacement. Figure 6 shows the simulation results illustrating the relationship between frequency and attenuation characteristics in transverse electromagnetic ultrasound as an example. Figure 6A shows the case where the frequency is 2 MHz, Figure 6B shows the case where the frequency is 5 MHz, and Figure 6C shows the case where the frequency is 10 MHz.In Figures 6A and 6C, the horizontal axis represents time (elapsed time) [s], and the vertical axis represents normalized displacement [au]. Figure 7 is a diagram illustrating, as an example, the measured results to explain the relationship between frequency and attenuation characteristics in transverse electromagnetic ultrasound. Figure 7A shows the case where the frequency is 3 [MHz], and Figure 7B shows the case where the frequency is 5 [MHz]. In Figures 7A and 7B, the horizontal axis represents time (elapsed time) [s], and the vertical axis represents voltage [V], which represents displacement. Figure 8 is a diagram illustrating, as an example, the correlation between the attenuation constant and Vickers stiffness. In Figure 8, the horizontal axis represents Vickers stiffness [HV], and its vertical axis represents the attenuation constant [ / μs].

[0027] The electromagnetic ultrasonic measuring device 1000 in this embodiment includes, for example, a data acquisition unit 1, a control processing unit 2, an input unit 3, an output unit 4, an interface unit (IF unit) 5, and a storage unit 6, as shown in Figure 1.

[0028] The data acquisition unit 1 is connected to the control processing unit 2 and is a device that acquires measurement data measured using electromagnetic ultrasonic waves according to the control of the control processing unit 2. This measurement data is ultrasonic data obtained by incidenting electromagnetic ultrasonic waves of transverse vibration in one direction relative to the measurement target Ob onto the measurement target Ob. The transverse electromagnetic ultrasonic waves propagate in a direction perpendicular to the direction of vibration of the transverse waves, and this perpendicular direction is the propagation direction. In this embodiment, the data acquisition unit 1 uses an electromagnetic ultrasonic transducer. This electromagnetic ultrasonic transducer (abbreviated as "EMAT" as appropriate) 1 is a transducer that generates a sound source directly inside the measurement target (measurement object) Ob by electromagnetic action and transmits and receives ultrasonic waves. It does not require an acoustic coupling agent for the transmission and reception of ultrasonic waves, and non-contact measurement is possible. There are Lorentz type and magnetostrictive type EMATs, both of which are composed of a magnet and a coil. A Lorentz-type EMAT comprises a magnet that forms a static magnetic field in a metal and a coil that generates eddy currents in the metal using a high-frequency current. The interaction between the static magnetic field and the eddy currents generates a Lorentz force in the metal, thereby producing ultrasonic waves, and the reverse action allows the ultrasonic waves propagating through the metal to be received. On the other hand, a magnetostrictive-type EMAT is applicable only to magnetic materials and transmits and receives ultrasonic waves by utilizing the magnetostrictive effect of the magnetic material.

[0029] Various types of EMATs are known. In addition to the classification based on the electromagnetic ultrasonic wave generation principle described above, when classified by the shape of the coil, three main types are known: spiral type, racetrack type, and butterfly type. Compared to the spiral type EMAT, which generates electromagnetic ultrasonic waves in all directions, the racetrack type EMAT and butterfly type EMAT can generate electromagnetic ultrasonic waves that vibrate in one direction, making them suitable for the measuring device 1000 of this embodiment.

[0030] The object to be measured, Ob, is a member that is the subject of measurement for which a predetermined physical quantity is measured. The object to be measured, Ob, can be any member as long as it has a curved surface in which at least one of a predetermined first direction and a second direction intersecting the first direction is the tangential direction. For example, in the examples shown in Figures 2A and 2B, when an xyz Cartesian coordinate system is set in which the tangential direction of the curved surface of the object to be measured, the tangential direction of the curved surface of the object to be measured, is the y-axis, the thickness direction of the object to be measured, which is perpendicular to the y-axis, is the z-axis, and the directions perpendicular to the y-axis and z-axis, respectively, are the x-axis, the object to be measured, Ob, is a cylindrical member (all of it) or a part of the cylindrical member. The x-axis direction is the axial direction of the object to be measured, which is the whole or a part of the cylindrical member, and the direction along the curved surface is the circumferential direction. In the example shown in Figure 2, the x-axis direction or the y-axis direction corresponds to an example of the first direction, and the y-axis direction or the x-axis direction corresponds to an example of the second direction.

[0031] On the surface of the object to be measured (on the front, back, outer, or inner surface), an EMAT1, which is an example of a data acquisition unit 1, is positioned so as to incident a transverse wave electromagnetic ultrasonic wave vibrating in one direction relative to the object to be measured (Ob) onto the object to be measured. For example, the one direction is the axial direction (the x-axis direction in the example shown in Figure 2), and the EMAT1 is positioned on the surface of the object to be measured so as to cause the transverse wave electromagnetic ultrasonic wave to vibrate in the axial direction and propagate in the thickness direction. The electromagnetic ultrasonic wave undergoes multiple reflections in the thickness direction depending on its incident intensity and the attenuation constant of the object to be measured. This generates measurement data obtained by incidenting a transverse wave electromagnetic ultrasonic wave vibrating in the axial direction relative to the object to be measured onto the object to be measured. Alternatively, for example, the one direction is the circumferential direction (the direction along the curved surface with the y-axis direction as the tangential direction in the example shown in Figure 2), and the EMAT1 is positioned on the surface of the object to be measured so as to cause the transverse wave electromagnetic ultrasonic wave to vibrate in the circumferential direction and propagate in the thickness direction. The electromagnetic ultrasonic waves undergo multiple reflections in the thickness direction, depending on their incident intensity and the attenuation constant of the object Ob being measured. This generates measurement data obtained by incidenting the object Ob with transverse waves of electromagnetic ultrasonic waves that vibrate in the circumferential direction.

[0032] Furthermore, the object to be measured, Ob, may be a component made of a magnetic material or a component made of a non-magnetic material. The object to be measured, Ob, may be a metal pipe made of any metal, such as iron, alloy steel (carbon steel, chromium-molybdenum steel, stainless steel, etc.), aluminum, copper, nickel, etc. This metal pipe may be used, for example, as plumbing in a building, and flowable fluids such as gases, liquids, and powders may flow through it.

[0033] Furthermore, the data acquisition unit 1 may not only be an EMAT that directly acquires measurement data from the object being measured, but may also be a device that acquires measurement data that has been measured in advance. For example, the data acquisition unit 1 may be an interface circuit that inputs and outputs data to and from an external device, in which case the external device is a storage medium such as a USB (Universal Serial Bus) memory and an SD card (registered trademark) that stores the measurement data. Alternatively, for example, the external device may be a drive device that reads data from a recording medium such as a CD-ROM (Compact Disc Read Only Memory), CD-R (Compact Disc Recordable), DVD-ROM (Digital Versatile Disc Read Only Memory), and DVD-R (Digital Versatile Disc Recordable) that records the measurement data. Alternatively, for example, the data acquisition unit 1 may be a communication interface circuit that sends and receives communication signals to and from an external device, in which case the external device is a server device that manages the measurement data and is connected to the communication interface circuit via a network (WAN (Wide Area Network, including a public communication network)) or LAN (Local Area Network). Furthermore, if the data acquisition unit 1 is an interface circuit or a communication interface circuit, the data acquisition unit 1 may also be used in conjunction with the IF unit 5 (i.e., the IF unit 5 may be used as the data acquisition unit 1).

[0034] The input unit 3 is connected to the control processing unit 2 and is a device that inputs various commands, such as a command to instruct the start of measurement, and various data necessary for operating the electromagnetic ultrasonic measuring device 1000, such as the name of the object to be measured Ob and the vibration direction of the electromagnetic ultrasonic waves relative to the object to be measured Ob. Examples of input units include a keyboard, mouse, and multiple input switches assigned to predetermined functions. The output unit 4 is connected to the control processing unit 2 and is a device that outputs commands and data input from the input unit 3, as well as measurement results, etc., according to the control of the control processing unit 2. Examples of output units include display devices such as CRT displays, LCDs (liquid crystal displays), and organic EL displays, and printing devices such as printers.

[0035] The input unit 3 and output unit 4 may be configured as touch panels. In this configuration, the input unit 3 is a position input device that detects and inputs the operating position, such as a resistive or capacitive touchscreen, and the output unit 4 is a display device. In this touch panel, a position input device is provided on the display surface of the display device, and one or more candidate input contents that can be input to the display device are displayed. When the user touches the display position showing the input content they want to input, the position input device detects that position, and the display content shown at the detected position is input to the electromagnetic ultrasonic measuring device 1000 as the user's operation input. With such a touch panel, the user can easily understand the input operation intuitively, thus providing an electromagnetic ultrasonic measuring device 1000 that is easy for the user to handle.

[0036] The IF unit 5 is connected to the control processing unit 2 and, in accordance with the control of the control processing unit 2, is a circuit that inputs and outputs data to and from external devices, for example. Examples include an RS-232C serial communication interface circuit, an interface circuit using the Bluetooth® standard, and an interface circuit using the USB standard. Alternatively, the IF unit 5 may be a communication interface circuit that sends and receives communication signals to and from external devices, such as a data communication card or a communication interface circuit conforming to the IEEE 802.11 standard.

[0037] The memory unit 6 is connected to the control processing unit 2 and is a circuit that stores various predetermined programs and various predetermined data in accordance with the control of the control processing unit 2. The various predetermined programs include, for example, a control processing program, and the control processing program includes, for example, a control program and a measurement processing program. The control program is a program that controls each part 1, 3 to 6 of the electromagnetic ultrasonic measuring device 1000 according to the function of each part. The measurement processing program is a program that determines a predetermined physical quantity at the measurement target Ob based on the measurement data acquired by the data acquisition unit 1. The various predetermined data include, for example, the name of the measurement target Ob, the vibration direction of the electromagnetic ultrasonic on the measurement target Ob, data during measurement processing, and physical quantities that are the results of measurement processing, which are necessary data for executing each of these programs.

[0038] Such a storage unit 6 may include, for example, a non-volatile memory element such as ROM (Read Only Memory) or a rewritable non-volatile memory element such as EEPROM (Electrically Erasable Programmable Read Only Memory). Furthermore, the storage unit 6 includes RAM (Random Access Memory) which serves as the working memory of the control processing unit 2, storing data generated during the execution of the predetermined program. The storage unit 6 may also be configured to include a hard disk drive or solid-state drive (SSD) with a relatively large storage capacity.

[0039] The control processing unit 2 is a circuit for controlling each part 1, 3 to 6 of the electromagnetic ultrasonic measuring device 1000 according to the function of each part, and for measuring a predetermined physical quantity. The control processing unit 2 is configured, for example, with a CPU (Central Processing Unit) and its peripheral circuits. The control processing program is executed within the control processing unit 2, which functionally configures the control unit 21 and the measurement processing unit 22.

[0040] The control unit 21 controls each of the parts 1, 3 to 6 of the electromagnetic ultrasonic measuring device 1000 according to the function of each part, and is in charge of the overall control of the electromagnetic ultrasonic measuring device 1000.

[0041] The measurement processing unit 22 determines a predetermined physical quantity in the object Ob based on the measurement data acquired by the data acquisition unit 1. More specifically, the measurement processing unit 22 determines the damping constant α of the object Ob based on the measurement data, and then determines the physical quantity based on the determined damping constant α. The physical quantity is set appropriately in advance, and in this embodiment, since the damping constant α is determined based on the measurement data, any physical quantity that correlates with the damping constant α is acceptable. In this embodiment, as will be described later, Vickers hardness [HV] is measured as an example of the predetermined physical quantity. The damping constant α is a numerical value that represents the rate of damping (degree of amplitude reduction) in the damping waveform, and in this embodiment, the envelope of the damping waveform is expressed using the exponential function e -αt It is defined as the coefficient of time t in the exponent when expressed as follows.

[0042] Therefore, in this embodiment, the measurement data represents the attenuation waveform, and the attenuation waveform is measured by EMAT, generating the measurement data.

[0043] For measuring this attenuated waveform, for example, the so-called pulse-echo method (pulse reflection method) is used. In this pulse-echo method, the EMAT transmits ultrasonic pulses with a short time width to the object to be measured, Ob. As shown in Figures 2A and 2B, the ultrasonic echoes that are reflected multiple times in the thickness direction (z direction) of the object to be measured are received by the EMAT. With each multiple reflection, the amplitude (intensity) of the ultrasonic (ultrasonic echo) is attenuated, and as a result, data of an attenuated waveform is obtained as measurement data, which has a gradually decreasing amplitude (intensity) and multiple peaks PK11, PK12, PK13, PK14, PK15, PK16, ... appearing alternately positive and negative in a time-series order, as shown in Figure 3A.

[0044] Alternatively, for example, the so-called resonance method is used to measure the attenuated waveform. In this resonance method, the EMAT excites the object to be measured, Ob, for a predetermined time so that it resonates with ultrasound at the resonance frequency. After excitation, the excitation is stopped, and the ultrasonic echo that is multiple-reflected in the thickness direction (z direction) of the object to be measured, Ob, by free vibration is received by the EMAT. As a result, data of an attenuated waveform, such as shown in Figure 3B, is obtained as measurement data, which has a gradually decreasing amplitude (intensity) and multiple peaks PK21, PK22, PK23, PK24, PK25, PK26, ... appearing alternately positive and negative in chronological order. The resonance method has a higher signal-to-noise ratio compared to the pulse echo method.

[0045] Measurement data of such attenuated waveforms may be generated and acquired by an operator (user) using the electromagnetic ultrasonic measuring device 1000 through manual operation using the pulse echo method, the resonance method, etc., or the control unit 21 of the control processing unit 2 may automatically generate and acquire the data using the pulse echo method, the resonance method, etc., with EMAT1 as an example of the data acquisition unit 1.

[0046] Based on the measurement data of such attenuated waveforms, the measurement processing unit 22 first determines the attenuation constant α, as described above. More specifically, for example, the measurement processing unit 22 determines the envelope of the attenuated waveform by so-called envelope detection, and then determines the exponential function e that best fits the determined envelope. -αt We find the exponential function e -αt The damping constant α is determined from this. As can be seen from Figures 3A and 3B, there are positive envelopes EV11;EV21 and negative envelopes EV12;EV22, so the exponential function e is determined based on the positive envelopes EV11;EV21. -α1pt ;e -α2pt The damping constants α1p;α2p were determined, and the exponential function e was calculated based on the negative envelope EV12;EV22. -α1nt ;e -α2ntFind the attenuation constants α1n and α2n, and the average values of the positive-side attenuation constants α1p and α2p and the negative-side attenuation constants α1n and α2n can be used as the final attenuation constants α1 and α2 (α1 = (α1p + α1n) / 2; α2 = (α2p + α2n) / 2). Alternatively, for example, the measurement processing unit 22 may use the exponential function e -αt to fit the absolute values of a plurality of peaks PK11, PK12, PK13, PK14, PK15, PK16, ···; PK21, PK22, PK23, PK24, PK25, PK26, ··· arranged in time series order in the measurement data of the attenuation waveform, and obtain the attenuation constant α from the obtained exponential function e -αt Alternatively, for example, the measurement processing unit 22 may use the exponential function e -αt to fit the absolute values of a plurality of peaks PK11, PK13, PK15, ···; PK21, PK23, PK25, ··· arranged in time series order on the positive side of the attenuation waveform, and obtain the attenuation constant α from the obtained exponential function e -αt Alternatively, for example, the measurement processing unit 22 may use the exponential function e -αt to fit the absolute values of a plurality of peaks PK12, PK14, PK16, ···; PK22, PK24, PK26, ··· arranged in time series order on the negative side of the attenuation waveform, and obtain the attenuation constant α from the obtained exponential function e -αt In this way, when obtaining a predetermined physical quantity, the attenuation constant α is obtained from the attenuation waveform through the envelope and its approximate exponential function. Therefore, it is inferred that if a more appropriate attenuation characteristic, that is, a more appropriate envelope, is obtained, a more appropriate physical quantity can be obtained.

[0047]

[0048] ​In this embodiment, the object to be measured, Ob, is a member having a curved surface where at least one of a predetermined first direction and a second direction intersecting the first direction is a tangential direction (a curved surface where the planes formed in the first and second directions are tangent planes). Since the shape in the first direction and the shape in the second direction are different, it is presumed that if the vibration directions of the transverse wave electromagnetic ultrasonic waves relative to the object to be measured are inconsistent, only inconsistent attenuation waveforms will be obtained. For this reason, it is necessary to align the vibration direction of the transverse wave electromagnetic ultrasonic waves in one direction relative to the object to be measured, Ob. Therefore, the spiral-type EMAT is undesirable.

[0049] Furthermore, since the measurement target Ob shown in Figure 2 has two directions, circumferential and axial, the attenuation waveform and its envelope for each direction were investigated through simulation (numerical experiment) and actual experimentation.

[0050] In this simulation, the received waveform (received waveform using the pulse echo method) obtained when a transverse wave electromagnetic ultrasonic pulse is incident on a cylindrical pipe with an outer diameter of φ50 [mm] and a wall thickness of 3.5 [mm] was analyzed using ultrasonic analysis software (ComWAVE®, manufactured by Itochu Techno-Solutions Corporation). In this case, firstly, the received waveform with the vibration direction of the transverse wave electromagnetic ultrasonic pulse set to the circumferential direction (circumferential received waveform) was analyzed, and the result is shown in Figure 4A. Secondly, the received waveform with the vibration direction of the transverse wave electromagnetic ultrasonic pulse set to the axial direction (axial received waveform) was analyzed, and the result is shown in Figure 4B. As can be seen from Figures 4A and 4B, by defining the vibration direction to one direction, an exponentially attenuating waveform is obtained. Note that in Figures 4A and 4B, the amplitude of each peak is normalized by the amplitude of the incident electromagnetic ultrasonic pulse (i.e., the amplitude of each peak is determined when the amplitude of the incident electromagnetic ultrasonic pulse is set to 1). Furthermore, comparing the circumferential received waveform shown in Figure 4A with the axial received waveform shown in Figure 4B, the axial received waveform exhibits more exponential attenuation than the circumferential received waveform. This is presumed to be because, when the vibration direction of the transverse wave electromagnetic ultrasonic is considered to be circumferential, significant mode conversion occurs at the reflective surface, causing the attenuation waveform to be distorted.

[0051] On the other hand, in the actual experiment, a 5 MHz transverse electromagnetic ultrasonic pulse was incident on a cylindrical pipe with an outer diameter of φ57.1 [mm] and a wall thickness of 3.5 [mm] using an EMAT, first with the vibration direction circumferentially, and second with the vibration direction axially, and the received waveforms were obtained using the EMAT. The received waveform with the vibration direction circumferentially (circumferential received waveform) is shown in Figure 5A, and the received waveform with the vibration direction axially (axial received waveform) is shown in Figure 5B. The exponential function (circumferential exponential function) Y approximates the envelope of the circumferential received waveform shown in Figure 5A. R (t) is Y R (t)=(7.564E-01)×e -1.565E+0.5t Therefore, the exponential function (axial exponential function) Y approximates the envelope of the axially received waveform shown in Figure 5B. A (t) is Y A(t)=(4.275E-01)×e -1.183E+0.5t As can be seen from Figures 5A and 5B, the attenuation constant α is smaller for the axially received waveform than for the circumferentially received waveform. Therefore, it is considered that setting the vibration direction of the transverse electromagnetic ultrasonic wave to the axial direction results in a lower base level of the attenuation constant α (attenuation constant α0 without material change) than setting the vibration direction of the transverse electromagnetic ultrasonic wave to the circumferential direction, allowing for more sensitive measurement of the change in the attenuation constant α due to material change in the object Ob. In other words, a smaller attenuation constant α0 without material change means that the influence of material change on the attenuation constant α (=|(actually observed attenuation constant αs)-(attenuation constant α0 without material change)|) among the actually observed attenuation constants αs becomes larger, making it easier to observe material changes. For this reason, it is preferable to set the vibration direction of the transverse electromagnetic ultrasonic wave to the axial direction rather than the circumferential direction.

[0052] Next, the frequency of transverse electromagnetic ultrasound was investigated. In the simulation, transverse electromagnetic ultrasound pulses were injected into a pipe similar to the one described above, with the vibration direction oriented towards the circumferential holes, at frequencies of 2 MHz, 5 MHz, and 10 MHz. The received waveforms obtained were then analyzed using the aforementioned ultrasound analysis software. The results for frequency 2 MHz are shown in Figure 6A, the results for frequency 5 MHz are shown in Figure 6B, and the results for frequency 10 MHz are shown in Figure 6C. As can be seen from Figures 6A to 6C, the received waveform at frequency 2 MHz (2 MHz received waveform) shown in Figure 6A did not exhibit exponential decay, while the received waveforms at frequency 5 MHz (5 MHz received waveform) shown in Figure 6B and at frequency 10 MHz (10 MHz received waveform) shown in Figure 6C exhibited ideal exponential decay as the frequency increased. In general, ultrasound has the property that its directivity increases with increasing frequency. On the other hand, it is presumed that at lower frequencies, ultrasound spreads out as it propagates, and each time it is reflected, the diffused ultrasound interferes with each other, causing the received waveform to become distorted.

[0053] Meanwhile, in the actual experiment, transverse electromagnetic ultrasonic pulses were incident on a pipe similar to the one described above using an EMAT, first at a frequency of 3 [MHz] and second at a frequency of 5 [MHz], with the vibration direction being circumferential. The EMAT then obtained the received waveforms for each frequency. The results for the 3 [MHz] frequency are shown in Figure 7A, and the results for the 5 [MHz] frequency are shown in Figure 7B. The exponential function (3MHz exponential function) Y approximates the envelope of the received waveform (3MHz received waveform) shown in Figure 7A. 3MHz (t) is Y 3MHz (t)=(6.436E-01)×e -1.614E+0.5t Therefore, the exponential function (5MHz exponential function) Y approximates the envelope of the received waveform (5MHz received waveform) shown in Figure 7B. 5MHz (t) is Y 5MHz (t)=(7.564E-01)×e -1.565E+0.5t As can be seen from Figures 7A and 7B, the 5MHz received waveform shown in Figure 7B exhibited a more ideal exponential attenuation waveform than the 3MHz received waveform shown in Figure 7A. This result is in good agreement with the trend obtained in the simulation described above.

[0054] Therefore, the frequency of the transverse wave electromagnetic ultrasound is preferably 4 MHz or higher, and more preferably 4.5 MHz or higher or 5 MHz or higher.

[0055] Therefore, in order to obtain a more ideal attenuation waveform and lower the base level of the attenuation constant α, thereby evaluating material changes (changes in Vickers hardness in this embodiment) with higher sensitivity, it is preferable to use high-frequency, axially vibrating, and thickness-propagating ultrasonic waves for the transverse wave electromagnetic ultrasonic waves.

[0056] Next, the relationship between the damping constant α and Vickers hardness will be explained. Several pipes with different hardnesses (cylindrical pipes with an outer diameter of φ57.1 [mm] and a wall thickness of 3.5 [mm]) were prepared. For each pipe, a transverse wave electromagnetic ultrasonic pulse was incident on the EMAT with a frequency of 5 [MHz] and its vibration direction was axial, and the received waveform was obtained by the EMAT. The envelopes of each received waveform for each pipe were determined, and the exponential function that best approximated each envelope was determined, and the damping constant α for each pipe was determined. On the other hand, the Vickers hardness HN [HV] of each pipe was measured. In measuring the Vickers hardness HN, a diamond square pyramidal indenter with a face-to-face angle of 136 [°] was pressed into the pipe, and the pressed state was maintained for a certain period of time under a predetermined test load. The Vickers hardness HN [HV] of the pipe was determined by the average of the diagonal lengths of the permanent indentation formed (average of the lengths of two diagonals). This result is shown in Figure 8. As can be seen from Figure 8, a tendency was observed for the damping constant α[ / μs] to increase as the Vickers hardness HN[HV] decreased, indicating a correlation between the damping constant α and Vickers hardness HN. Note that the correlation coefficient R in the graph of Figure 8 is shown. 2 The value was 0.8421.

[0057] In this embodiment, a correspondence relationship (first correspondence relationship) between the damping constant α and the Vickers hardness HN is determined in advance, and this first correspondence relationship is stored in the storage unit 6 as one of the various predetermined data. Then, the measurement processing unit 22 determines the damping constant α based on the measurement data as described above, and determines the Vickers hardness HN corresponding to the determined damping constant α from the first correspondence relationship stored in the storage unit 6.

[0058] The control unit 21 then outputs the damping constant α and Vickers hardness HN obtained by the measurement processing unit 22 to the output unit 4.

[0059] The control processing unit 2, input unit 3, output unit 4, IF unit 5, and storage unit 6 in such an electromagnetic ultrasonic measuring device 1000 can be configured by, for example, a desktop or notebook computer.

[0060] Next, the operation of this embodiment will be described. Figure 9 is a flowchart showing the operation of the electromagnetic ultrasonic measuring device.

[0061] When the electromagnetic ultrasonic measuring device 1000 with this configuration is powered on, it performs the necessary initialization of each part and starts operating. The control processing unit 2 is functionally configured with a control unit 21 and a measurement processing unit 22 through the execution of its control processing program.

[0062] For measurement, the user (operator) sets EMAT1, as an example of the data acquisition unit 1, on the surface of the object to be measured Ob, such that the vibration direction is axial. The vibration direction may also be circumferential. As described above, EMAT1 uses either a racetrack-type EMAT or a butterfly-type EMAT, and employs electromagnetic ultrasonic waves of transverse vibration in one direction.

[0063] In Figure 9, the electromagnetic ultrasonic measuring device 1000 acquires measurement data with the data acquisition unit 1 via the control unit 21 of the control processing unit 2 and stores it in the storage unit 6 (S1).

[0064] Next, the electromagnetic ultrasonic measuring device 1000, through the measurement processing unit 22 of the control processing unit 2, determines a predetermined physical quantity in the object to be measured Ob, which in this embodiment is the Vickers hardness HN, based on the measurement data acquired by the data acquisition unit 1 in processing S1, and stores it in the storage unit 6 (S2).

[0065] Then, the electromagnetic ultrasonic measuring device 1000 outputs the physical quantity (Vickers hardness HN in this example) obtained by the measurement processing unit 22 in process S2 to the output unit 4 (S3) via the control unit 21 of the control processing unit 2, and the process ends. The control unit 21 may also output the physical quantity to an external device via the IF unit 5 if necessary.

[0066] As described above, the electromagnetic ultrasonic measuring device 1000 and the electromagnetic ultrasonic measuring method implemented therein in the embodiment use ultrasonic data obtained by incidenting a transverse wave electromagnetic ultrasonic wave vibrating in one direction relative to the measurement target Ob onto the measurement target Ob as measurement data. Therefore, the measurement data will have the attenuation characteristics desired by the operator (user), and thus the electromagnetic ultrasonic measuring device 1000 and its measurement method can measure with measurement data having more appropriate attenuation characteristics.

[0067] Since the above-described electromagnetic ultrasonic measuring device 1000 and its measurement method use electromagnetic ultrasonic waves with a frequency of 4 MHz or higher, the measurement data will have the attenuation characteristics desired by the operator (user). Therefore, the above-described electromagnetic ultrasonic measuring device and its measurement method can measure with measurement data having more appropriate attenuation characteristics.

[0068] In the above-described embodiment, the measurement data includes a plurality of measurement data measured using electromagnetic ultrasonic waves of different frequencies, and the electromagnetic ultrasonic measuring device 1000 may functionally further include a frequency processing unit 23 in the control processing unit 2, as shown by the dashed line in Figure 1. The frequency processing unit 23 determines the envelope of each of the plurality of measurement data, determines the exponential function that best fits the determined envelope, determines the error of the determined exponential function of the measurement data with respect to the envelope of the measurement data, selects the smallest error from the plurality of errors determined for each of the plurality of measurement data, and determines the frequency of the measurement data with the selected error. For example, the frequency processing unit 23 determines the mean squared error as the error based on the difference between the envelope and the exponential function determined at each timing corresponding to each peak in the measurement data. Let t(k) be the timing of peak k, PK(k) be the value of peak k, EV(t(k)) be the value of the envelope at timing t(k), and n be the number of peaks k. Then the error ER is given by ER = (√(Σ(PK(t) - EV(t(k)))). 2This becomes )) / n. Note that the operator Σ is an operator that calculates the sum over n k values. With this, we can find the frequency of the measurement data with the smallest error, and thus find the frequency that will yield measurement data with more appropriate attenuation characteristics.

[0069] Furthermore, in the above embodiment, the measurement data includes multiple measurement data taken at predetermined intervals, and each of the multiple measurement data is the same in one direction. As described above, since the attenuation characteristics of ultrasound depend on the vibration direction in transverse ultrasound, when observing the time-dependent changes of the object Ob, if the vibration direction is different for each measurement, the measurement results for each measurement will be different. The electromagnetic ultrasound measuring device 1000 aligns the vibration direction relative to the object Ob for each different measurement, so that each measurement data can be treated equally for each measurement.

[0070] In the above-described embodiment, the electromagnetic ultrasonic measuring device 1000 determined the Vickers hardness HN based on the attenuation constant α. However, as disclosed in Patent Document 1, for example, the creep damage life consumption rate correlates with Vickers hardness, so the electromagnetic ultrasonic measuring device 1000 may also determine the creep damage life consumption rate based on the attenuation constant α. In this case, the correspondence between the attenuation constant α and the creep damage life consumption rate (second correspondence) is determined in advance and stored in the storage unit 6. The measurement processing unit 22 then determines the attenuation constant α in the same manner as described above, selects the creep damage life consumption rate corresponding to the determined attenuation constant α from the second correspondence, and determines the creep damage life consumption rate of the object Ob. Alternatively, the above creep damage life consumption rate may be replaced with the fatigue damage life consumption rate, and the electromagnetic ultrasonic measuring device 1000 may determine the fatigue damage life consumption rate of the object Ob. Furthermore, if we define the lifespan as 100%, the remaining lifespan can be calculated by subtracting the current lifespan consumption rate [%] from the 100% lifespan. Therefore, the electromagnetic ultrasonic measuring device 1000 may also calculate its remaining lifespan ((remaining lifespan) = (lifespan 100%) - (current lifespan consumption rate [%])).

[0071] Furthermore, as disclosed in Reference 1; "Hiroji Ogi et al., "Study on Metal Fatigue by Electromagnetic Ultrasonic Measurement," Transactions of the Japan Society of Mechanical Engineers No. 024-1, March 2002, Kansai Branch 77th Regular General Meeting Lecture," the relationship between the damping constant α, sound velocity v, dislocation density Λ, and dislocation line length L is α∝ΛL 4 、(v0-v) / v0∝ΛL 2 The following relationship exists. Here, v0 is the speed of sound that does not depend on dislocations. When the speed of sound of the object to be measured is determined in advance and the dislocation density Λ is determined, the correspondence between the damping constant α and the dislocation density Λ (third correspondence) is determined in advance and the third correspondence is stored in the storage unit 6 in advance. Then, the measurement processing unit 22 determines the damping constant α in the same manner as described above, selects the dislocation density Λ corresponding to the determined damping constant α from the third correspondence, and determines the dislocation density Λ of the object to be measured Ob. Dislocation density Λ is the number of dislocations contained in a crystal per unit area. When determining the dislocation line length L, the correspondence between the damping constant α and the dislocation line length L (fourth correspondence) is determined in advance and the fourth correspondence is stored in the storage unit 6 in advance. Then, the measurement processing unit 22 determines the damping constant α in the same manner as described above, selects the dislocation line length L corresponding to the determined damping constant α from the fourth correspondence, and determines the dislocation line length L of the object to be measured Ob.

[0072] Furthermore, as disclosed in Reference 2; "Hiroji Ogi et al., 'Non-contact measurement of ultrasonic transmission attenuation and crystal grain size of metallic materials by EMAR method, Journal of the Japan Institute of Metals, Vol. 58, No. 9 (1994), pp. 1021-1028," the attenuation constant α is given by α = a1 × f + a2 × D³f⁴, where f is the frequency, a1 is the absorption constant, a2 is the scattering coefficient, and D is the average crystal grain size. Therefore, the electromagnetic ultrasonic measuring device 1000 may determine the average crystal grain size D based on the attenuation constant α. In this case, the correspondence between the attenuation constant α and the average crystal grain size D (the fifth correspondence) is determined in advance, and the eighth correspondence is stored in the storage unit 6 in advance. The measurement processing unit 22 then determines the attenuation constant α in the same manner as described above, selects the average crystal grain size D corresponding to the determined attenuation constant α from the fifth correspondence, and determines the average crystal grain size D of the object to be measured Ob.

[0073] Thus, the electromagnetic ultrasonic measuring device 1000 in this embodiment may determine at least one of the following: Vickers hardness, creep damage, fatigue, creep life, dislocation density, dislocation line length, and average grain size.

[0074] To illustrate the present invention, the embodiments have been adequately and fully described above with reference to the drawings. However, those skilled in the art should recognize that it is easy to modify and / or improve upon the embodiments described above. Therefore, unless such modifications or improvements implemented by those skilled in the art fall outside the scope of the claims, such modifications or improvements shall be considered to be included within the scope of the claims. [Explanation of Symbols]

[0075] 1000 Electromagnetic Ultrasonic Measuring Device 1. Data Acquisition Unit 2 Control Processing Unit 3. Input section 4 Output section 5. Interface section (IF section) 6 Memory section

Claims

1. A data acquisition unit that acquires measurement data measured using electromagnetic ultrasound, The system includes a measurement processing unit that determines a predetermined physical quantity in the object to be measured based on the measurement data acquired by the data acquisition unit, The object to be measured is a member having a curved surface in which at least one of a predetermined first direction and a second direction intersecting the first direction is a tangential direction. The measurement data is ultrasonic data obtained by incidenting electromagnetic ultrasonic waves of transverse vibration in one direction relative to the measurement target onto the measurement target. A measuring device for electromagnetic ultrasound.

2. The frequency of the electromagnetic ultrasonic wave is 4 MHz or higher. The electromagnetic ultrasonic measuring device according to claim 1.

3. The aforementioned measurement data includes multiple measurement data measured using electromagnetic ultrasound of different frequencies. The system further includes frequency processing to determine the envelope of each of the aforementioned multiple measurement data, find the exponential function that best fits the obtained envelope, determine the error of the obtained exponential function of the measurement data with respect to the envelope of the measurement data, select the smallest error from among the multiple errors obtained for each of the aforementioned multiple measurement data, and determine the frequency of the measurement data with the selected error. The electromagnetic ultrasonic measuring device according to claim 1.

4. The aforementioned measurement data includes multiple measurement data taken at predetermined intervals. The direction in each of the aforementioned multiple measurement data is the same. The electromagnetic ultrasonic measuring device according to claim 1.

5. The aforementioned one direction is the axial direction. The electromagnetic ultrasonic measuring device according to claim 1 or claim 4.

6. The aforementioned one direction is the circumferential direction. The electromagnetic ultrasonic measuring device according to claim 1 or claim 4.

7. The aforementioned physical quantity is at least one of hardness, creep damage degree, fatigue damage degree, remaining life, dislocation density, dislocation line length, and grain size. The electromagnetic ultrasonic measuring device according to claim 1.

8. A data acquisition process for obtaining measurement data measured using electromagnetic ultrasound, The system comprises a measurement processing step that determines a predetermined physical quantity in the object to be measured based on the measurement data acquired in the data acquisition step, The object to be measured is a member having a curved surface in which at least one of a predetermined first direction and a second direction intersecting the first direction is a tangential direction. The measurement data is ultrasonic data obtained by incidenting electromagnetic ultrasonic waves of transverse vibration in one direction relative to the measurement target onto the measurement target. Measurement methods for electromagnetic ultrasound.

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