JP2012068209A - Material diagnostic method and apparatus using ultrasonic wave - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic diagnostic method and apparatus which nondestructively detects and images an abnormal part, a minute defect, a dislocation, or the like existing inside a thin plate shaped object to be measured by a water immersion resonance method.SOLUTION: A focusing ultrasonic wave probe 4 transmits large amplitude burst waves having a high repeating number at a constant frequency f to a thin plate shaped object to be measured 8 horizontally placed in a water tank, so as to excite resonance in thickness direction. High order harmonic waves leaked in water due to the resonance are sampled through a high-pass filter 5, so as to perform mapping of the maximum amplitude thereof and the time difference between a resonance start time and a time to reach a threshold. Abnormal structures such as an inclusion, a microvoid, a microcrack, or a dislocation in the thin plate shaped object to be measured are thus detected and imaged.

Description

  The present invention relates to a method and apparatus for nondestructively detecting and imaging a heterogeneous part and an unhealthy part in a thin plate material using water immersion or local water immersion ultrasonic method.

  For multi-layer laminated substrates and clad steel plates that use dissimilar material bonding, it is necessary to non-destructively evaluate and inspect that there is no incompletely bonded portion in the bonded portion. Further, non-destructive evaluation of a high dislocation density portion contained in a power IC substrate such as SiC or GaN is also required. Furthermore, it is desired to nondestructively evaluate the deterioration and damage of a small impact test piece for monitoring irradiation embrittlement of a nuclear power plant pressure vessel.

  As described in Non-Patent Document 1, when a normal pulse reflection method (ultrasonic flaw detection test) is used, a reflected wave is generated even in a healthy joint due to an acoustic impedance difference between different material joint interfaces. It is impossible to detect a minute incompletely joined part (unhealthy part). Further, it is impossible to detect abnormally textured parts (heterogeneous parts) such as dislocation accumulation parts, precipitates, and segregation in a metal having no gap.

  In order to solve the above problem, an integer multiple of the incident frequency excited when a large amplitude burst ultrasonic wave is incident on the material and the imperfect junction or abnormal tissue is shaken using the fluctuating stress excited thereby. There is a technique for detecting a harmonic having a frequency and imaging its amplitude (Patent Document 1).

  However, when trying to detect the incomplete joints and abnormal tissue parts of thin plate-like materials / parts nondestructively using the above technology, dead zones are generated by surface multiple reflected waves at high amplification, and detection / imaging is not possible. The problem becomes difficult.

In order to solve this problem, a resonance method using an electromagnetic ultrasonic probe has been proposed (Patent Document 2). However, since the probe size used in this method is about 1 cm ² at a minimum, it is impossible to detect a minute incomplete joint. In addition, this method cannot be applied to non-metallic materials such as semiconductor substrates.

  In addition, a fine defect detection method has been proposed in which separate probes are used for transmission and reception, and the secondary resonance frequency amplitude is measured by the water penetration method (Patent Document 3). However, in this method, it is necessary to arrange the transmitting and receiving ultrasonic probes on both sides of the measurement specimen perpendicularly to the specimen surface, and the resonance frequency having a ratio of an integer multiple by sweeping the frequency in advance. It is necessary to determine the incident frequency by selecting a pair. Furthermore, it lacks a means for imaging imperfect joints that are important in inspection. For this reason, it is thought that industrial application is difficult.

  There has been proposed a method in which a secondary resonance amplitude is measured by a water immersion resonance method using a single probe, and a plastic strain of a steel plate and piping subjected to plastic deformation is detected (Patent Document 4). However, this method uses only the amplitude at a frequency twice the incident resonance frequency.

  On the other hand, as described in Non-Patent Document 2, in the case where an adhesion crack, fine damage, or the normal line of an inclusion obliquely intersects the incident ultrasonic beam, an odd number such as the third or fifth order It is known that the next higher harmonic is excited.

Japanese Patent No. 4244334 Japanese Patent Laid-Open No. 9-257760 JP-A-2005-114376 JP 2008-107101 A

JIS Handbook 43 Nondestructive Inspection, Japanese Standards Association, 2005 I. Solodov, 11th Non-destructive Evaluation Symposium on New Materials and Products, 67, 2009

  The water immersion resonance method also detects fine incomplete joints in abnormal tissue and foreign material joints within thin plate materials by detecting not only the second order but also the third and higher order resonance frequencies. It is thought that it can be made. However, there is no technique for detecting and imaging them using higher-order resonance frequencies.

  In addition, in the case of burst wave incidence with a large number of repetitions, it is considered that the time to reach the resonance state changes depending on the material characteristics, but there is no technique for imaging the time to reach the higher-order resonance state.

  In view of the above circumstances, the present invention transmits a large-amplitude burst wave from one side of a thin plate-like object to be measured by one focal ultrasonic probe mainly using water immersion or local water immersion ultrasonic method. By receiving the higher-order resonance waveform excited by the same probe with the same probe and imaging the difference between the higher-order resonance amplitude and the higher-order resonance reception time, abnormal parts, inclusions, and dissimilar materials present in the thin plate-like measurement object An object of the present invention is to provide an ultrasonic diagnostic method and apparatus for nondestructively detecting minute defects and the like present at a bonding interface.

  An ultrasonic signal generator that receives a trigger signal from a personal computer and generates an electrical signal for burst wave ultrasonic excitation with variable frequency, and electrically amplifies and transmits the ultrasonic signal generated by the ultrasonic signal generator An ultrasonic signal amplifying unit for converting the ultrasonic signal transmitted from the ultrasonic signal amplifying unit into ultrasonic vibration, and applying ultrasonic vibration to a thin plate-like object to be measured placed in water An ultrasonic probe for receiving an ultrasonic signal leaked into water when an object is resonated, an analog filter for extracting a third-order or higher harmonic analog signal from a signal detected by the ultrasonic probe, Received signal amplification unit that amplifies high-order harmonic analog signal extracted by analog filter, high-order harmonic analog signal amplified by the received signal amplification unit, and digitally converts the waveform of the digital signal Waveform storage unit for recording, waveform processing unit for calculating received wave arrival time difference and maximum amplitude with respect to the surface reflection waveform set by applying digital waveform processing to the waveform stored in the waveform storage unit, at an arbitrary position of the object to be measured An image display unit that displays the received wave arrival time difference and the resonance waveform amplitude of the higher-order resonance waveform calculated by the waveform processing unit on a computer screen by converting them into black and white shades or colors, and the ultrasonic probe Ultrasonic diagnostic apparatus equipped with a scanning mechanism capable of moving along the surface of the thin plate-shaped object to be measured, equipped with a mechanism for changing the distance to the thin plate-shaped object to be measured, or ultrasonic diagnosis using the ultrasonic diagnostic apparatus A method for burst wave ultrasonic excitation corresponding to a thickness resonance frequency of the thin plate-like object to be measured generated by the ultrasonic signal generator based on a command from the personal computer The electrical signal is amplified by the ultrasonic signal amplifying unit, and ultrasonic vibrations are incident on the thin plate-like object to be measured through the water from the ultrasonic probe to resonate the object to be measured. A leaked ultrasonic signal is received by the ultrasonic probe, a high-order resonance reception signal is extracted from the ultrasonic signal received via the analog filter, amplified by the reception signal amplification unit, and then amplified. The analog signal thus obtained is converted into a digital signal waveform at a high speed A / D, and the digital waveform is recorded in the waveform storage unit. The waveform processing unit generates a high-order resonance waveform at an arbitrary position of the thin plate-like object to be measured. The received wave arrival time difference and resonance waveform amplitude are calculated, and the received wave arrival time difference and resonance waveform amplitude of the calculated higher-order resonance waveform are converted into black and white shading or color tone on the computer screen by the image display unit. Characterized by imaging the minute defect or abnormality of the internal DUT by imaging.

  In the ultrasonic diagnostic apparatus, when the transmission / reception ultrasonic probe is of a focus type, a fine abnormal portion can be detected and imaged.

  In the ultrasonic diagnostic apparatus, the entire measured object is placed in water, or a part of the measured object is locally submerged, or ultrasonic waves are transmitted / received through a water column to convert a small measured object from a large plant. Can be applied up to.

  According to the present invention, means has been established for detecting minute defects or abnormal portions, plastic deformation degree, etc. existing inside a thin plate-like object to be measured that cannot be detected by a conventional nondestructive inspection method.

  In addition, the transmission and reception ultrasonic probes are scanned along the surface of the object to be measured, and the time difference of the higher-order resonance reception signal from the surface reflection signal at that position and the higher-order resonance amplitude are converted into light or shade and displayed. As a result, a means for nondestructively imaging defects or abnormal portions inside the object to be measured has been established.

  In the conventional contact-type resonance ultrasonic measurement, only the resonance in which the object to be measured, the ultrasonic probe, and the grease-like catalyst material between them can be excited, but in this resonance measurement, measurement is performed through water. A resonance frequency close to the resonance frequency calculated from the measured object thickness and the longitudinal wave propagation velocity can be set as an initial value.

  In many conventional resonance ultrasonic measurements, since the ultrasonic amplitude having the same frequency as the incident resonance frequency is received, the spatial resolution is determined by the wavelength of the input frequency. On the other hand, since the high-order resonance frequency extracted using the analog high-pass or band-pass filter is detected in the present invention, the spatial resolution is remarkably improved by using the high-order harmonic wavelength.

  In immersion harmonic measurement, harmonics are excited when ultrasonic waves propagate through an underwater path, but by using a measurement configuration with a constant underwater propagation distance, the harmonics are stationary noise that does not depend on the measurement position. Can be considered.

Silicon, SiC, used in semiconductors
The present invention can be applied to nondestructive detection of defects such as dislocations generated in the process of growing a single crystal such as GaN and cutting and polishing a wafer.

  It can also be used for nondestructive evaluation of local plastic deformation caused by extremely low cycle fatigue in thin plates or thin cylindrical steel structures during large earthquakes.

1 is an overall configuration explanatory diagram of a water immersion ultrasonic resonance diagnostic apparatus according to an embodiment. It is the figure which imaged the high-order harmonic amplitude of the band board with a plastic deformation. It is a figure which shows the high order harmonic receiving waveform of the position from which a plastic deformation degree differs. It is the figure which imaged the high-order harmonic amplitude of the band board with a plastic deformation. It is a figure which shows the high order harmonic receiving waveform of the position from which a plastic deformation degree differs. It is a high-order harmonic reception waveform time difference image of the position where plastic deformation degree differs. It is the figure which imaged the higher order harmonic amplitude of the fatigue crack tip plastic region grown from the V-groove. It is the figure which imaged the higher harmonic amplitude of the nonmetallic inclusion surrounding plastic zone in a thin steel plate.

  The best mode for nondestructively detecting minute defects, abnormal parts, plastic deformation, etc. existing in a thin plate-like object to be measured using the ultrasonic diagnostic apparatus according to the present invention based on the embodiment. This will be described below with reference.

  FIG. 1 is a diagram for explaining an ultrasonic diagnostic apparatus using water immersion higher-order resonance according to the present invention. The ultrasonic diagnostic apparatus 1 generates a burst wave electric signal (ultrasound signal) having a variable frequency in response to a trigger signal from the personal computer 15 in synchronization with a synchronous scanning control unit 10 built in the personal computer 15. An ultrasonic signal generator 2, an ultrasonic signal amplifier 3 for electrically amplifying and transmitting the ultrasonic signal generated by the ultrasonic signal generator 2, and an ultrasonic signal transmitted from the ultrasonic signal amplifier 3 Is converted into ultrasonic vibration, and ultrasonic vibration is incident on the thin plate-like object 8 placed in the water of the water tank 9 to resonate the thin plate-like object 8 and receive the ultrasonic signal leaked into the water. An ultrasonic probe 4, an analog filter 5 that extracts a higher-order higher-order harmonic analog signal from the ultrasonic signal received by the ultrasonic probe 4, and a higher-order harmonic extracted by the analog filter 5 analog Received signal amplification unit 6 for amplifying the signal, waveform storage unit 11 for high-speed A / D conversion of the higher-order harmonic analog signal amplified by the received signal amplification unit 6 and digitally recording the waveform of the digital signal, and the waveform storage A waveform processing unit 12 for calculating a received wave arrival time difference and a maximum amplitude with respect to a set surface reflection waveform by performing digital waveform processing on the waveform stored in the unit 11; and the waveform processing at an arbitrary position of the thin plate-like object 8 The image display unit 13 that converts the received wave arrival time difference and the resonance waveform amplitude of the higher-order resonance waveform calculated by the unit 12 into a black and white shade or color tone and displays them on the computer screen, and the ultrasonic probe 4 described above. A mechanism for changing the distance to the thin plate-like object to be measured 8 is mounted, and the scanning mechanism 7 is movable along the surface of the thin plate-like object to be measured 8. Note that the ultrasonic probe 4 and the thin plate-like object 8 are immersed in a water tank 9 filled with water. The synchronous scanning unit 10, the waveform storage unit 11, the waveform processing unit 12, and the image display unit 13 are built in the personal computer 15, and the ultrasonic signal generation unit 2, the reception signal amplification unit 6, and the scanning mechanism 7 are A personal computer 15 is connected. The waveform storage unit 11 includes a high-speed A / D conversion board in order to perform high-speed A / D conversion on the high-order harmonic analog signal amplified by the reception signal amplification unit 6.

Based on the thickness of the thin plate-like object 8 and the longitudinal sound velocity of the material, the thickness resonance frequency is calculated by the following equation.
fn = 2V / (h.n) .. [Formula 1]
Here, fn: n-th resonance frequency, V: longitudinal wave sound velocity, h: thickness of object to be measured, n: integer (1, 2,...).
Due to the presence of water in contact with the thin plate-shaped object to be measured 8, the actual resonance frequency changes somewhat from the value calculated by [Equation 1].

In consideration of the spatial resolution proportional to the wavelength given by Equation 2, a candidate for an incident resonance frequency is selected.
λn = V / fn ·· [Formula 2]
Here, λn is a longitudinal wave wavelength corresponding to the n-th resonance frequency.

  An ultrasonic probe 4 having a center frequency close to the selected incident resonance frequency fn and having a desired focal length is selected.

  The incident frequency is varied in the vicinity of the selected incident resonance frequency fn, and the frequency that maximizes the reception amplitude is selected.

  In order to image the time difference until the harmonic amplitude or the maximum amplitude is reached, an imaging gate is set at a portion of the received waveform that is most sensitive to a material defect or abnormal portion. In many cases, the imaging gate position is set near the end of the received burst wave as shown by the rectangular dotted frame in FIG. 3, and the burst wave is applied to the thin plate-like object 8 while scanning the ultrasonic probe 4. The high-order harmonic component of the ultrasonic wave that is transmitted and leaked from the thin plate-like object 8 to the water via the analog filter 5 is extracted, the amplitude is mapped, and the abnormal part is imaged. Commercially available ultrasound imaging software is used for imaging. In this ultrasonic imaging software, the maximum amplitude within the set imaging gate range is detected, and the amplitude value is converted into black and white density or pseudo color and plotted against the position of the ultrasonic probe.

  In order to image the time difference until the maximum amplitude is reached, the origin of time measurement is set at the rising portion of the received burst wave indicated by the arrow in FIG. 3, the imaging gate is set as indicated by the broken line in FIG. The acoustic probe 4 is scanned to transmit a burst wave to the thin plate-like object to be measured 8, and high-order harmonic components of the ultrasonic waves leaked from the thin plate-like object to be measured 8 into the water via the analog filter 5 are extracted. The time difference until the maximum amplitude value is reached after exceeding the threshold value of the imaging gate from the burst wave rising part is mapped, and the abnormal part is imaged. Here, the threshold value is set to a value larger than the electrical noise signal and as small as possible from the harmonic amplitude to be detected. Commercially available ultrasound imaging software is used for imaging. This ultrasound imaging software detects the time from the rising edge of the received burst wave to the maximum amplitude within the imaging gate range, and converts that time to black and white density or pseudo color to convert the position of the ultrasound probe. Plot against.

As a first embodiment, a high-order harmonic amplitude image of a stainless steel strip with a hole having a different degree of plastic deformation is shown in FIG. After processing a circular hole in the center of the band plate, after giving a plastic strain of about 30% in the longitudinal direction, a test piece processed to a plate thickness of 5.05 mm was used. By RITEC RPR-4000, the frequency is 7.97 MHz, the burst wave of 80 cycles has a nominal center frequency of 10 MHz,
It was transmitted to a focal ultrasound probe having a diameter of 12 mm and an underwater focal length of 76 mm, a high-order harmonic was extracted using a high-pass filter 18 MHz (-60 dB) as an analog filter, and its amplitude was imaged.

  In FIG. 2, the amplitude of the upper part and the lower part adjacent to the hole with the most plastic deformation is the maximum, and the amplitudes of the left and right parts of the hole that are hardly plastically deformed are the minimum. The amplitude decreases from the upper and lower portions of the hole toward the end of the strip, and physically represents the density of dislocations that caused plastic deformation.

  FIG. 3 shows received waveforms from the region a having a low degree of plastic deformation to the region d having the highest degree of deformation in FIG. The amplitude of the imaging gate position indicated by the broken line increases from a to d.

  FIG. 4 shows an amplitude image obtained when the incident frequency is 6.91 MHz, at which the resonance high-order harmonic amplitude is maximized in a region where the plastic deformation is small. The high-order harmonic amplitudes in the left and right regions A and B of the hole are maximum, and the amplitudes of the regions C and D are minimum. However, FIG. 2 accurately represents the region with the strongest plastic deformation. However, in order to perform the imaging of FIG. 2, it is necessary to search for an unknown region having the highest degree of plastic deformation by trial and error and obtain a resonance frequency at which the high-order harmonic amplitude is maximum at each point. As a previous step, if the high-order harmonic amplitude is imaged in a region where the resonance frequency is almost constant and plastic deformation is small, and the minimum position shown in regions C and D shown in FIG. Can be reduced.

  FIG. 5 shows high-order harmonic reception waveforms in regions A to D of FIG. In the regions A and B, the maximum amplitude state continues from the start to the end of the resonance, but in the regions C and D, the amplitude significantly decreases during the resonance continuation time. Therefore, the imaging gate position for FIG. 4 is set in the broken line portion of FIG. By this gate setting, the plastic deformation region and the non-plastic deformation region can be clearly distinguished. In regions C and D, the cause of the significant drop in amplitude during the resonance continuation time is that the ultrasonic interference is physically caused by ultrasonic attenuation and propagation time delay due to dislocation in the plastic deformation region. This is thought to have occurred.

  FIG. 6 shows a time difference image corresponding to the harmonic amplitude image shown in FIG. 2 until reaching the maximum amplitude in the gate position from the top of the resonance waveform. When damage such as dislocations or voids occurs inside the material, the ultrasonic wave propagation speed in the thickness direction of the object to be measured is slower than that of a sound material. By using a time difference image, what is the amplitude image corresponding to the attenuation in the material? Different physical quantities can be displayed. As described above, by imaging and using both the harmonic amplitude image shown in FIG. 2 and the time difference image shown in FIG. 6, a slight difference in material properties of the thin plate-like object to be measured can be imaged. The degree of deformation can be accurately evaluated nondestructively.

  As a second embodiment, FIG. 7 shows a high-order harmonic amplitude image and a high-order resonance time difference image of a plastic region in front of a fatigue crack grown from a V-groove notch of an aluminum alloy plate having a thickness of 10 mm. . The top row is a sketch of a V-groove notch and a fatigue crack, the middle row is a high-order harmonic amplitude image, and the bottom row is a high-order harmonic time difference image. In the amplitude image, the contrast of the crack tip plastic zone is low, but in the time difference image, the crack tip plastic zone imaging is clearly displayed. Thus, by using the time difference image together with the amplitude image, a slight difference in material characteristics can be imaged.

  As a third embodiment, FIG. 8 shows a resonance high-order harmonic amplitude image of an inclusion surrounding plastic region in a 5 mm thick steel sheet. An annular portion having a large amplitude is a plastic deformation region, and inclusions are displayed with two black lines having a lower amplitude inside a rectangular region having a lower amplitude surrounded by the annular portion. In the conventional harmonic measurement using the backscattered wave described in Patent Document 1, only the black line can be imaged. By using the resonance high-order harmonic image, the plastic deformation region around the inclusion can be identified. Although not shown in the drawings, when the time difference image according to the third embodiment is imaged, it is understood that a slight difference in material properties can be imaged as in the first embodiment and the second embodiment. It was.

  Although the focus type probe is used in the measurement form shown in FIG. 1, a planar probe can be used instead. Moreover, it can replace with the system which submerses the whole non-measurement object shown in FIG. 1, and can also transmit / receive an ultrasonic wave by the system which covers a part of to-be-measured object with water, or a water column system. Furthermore, a high-pass filter or a band-pass filter can be selected as an analog filter for extracting high-order harmonics.

1 Ultrasonic diagnostic device 2 Ultrasonic signal generator
DESCRIPTION OF SYMBOLS 3 Ultrasonic signal amplification part 4 Ultrasonic probe 5 Analog filter 6 Reception signal amplification part 7 Scanning mechanism 8 Thin plate-shaped to-be-measured object 9 Water tank 10 Synchronous scanning part 11 Waveform memory | storage part 12 Waveform process part 13 Image display part 15 Personal computer

Ultrasonic signal generator for generating a burst wave ultrasonic excitation electrical signal of several tens of cycles of the variable frequency receiving a trigger signal from the personal computer, the ultrasonic signal generated by ultrasonic signal generator electrically An ultrasonic signal amplifying unit that amplifies and transmits, converts an ultrasonic signal transmitted from the ultrasonic signal amplifying unit into ultrasonic vibration, and makes ultrasonic vibration enter a thin plate-like object to be measured placed in water An ultrasonic probe that receives an ultrasonic signal leaked into water when a thin plate-like object is resonated, and a third-order or higher harmonic analog signal is extracted from the signal detected by the ultrasonic probe. An analog filter, a reception signal amplification unit that amplifies the higher-order harmonic analog signal extracted by the analog filter, a high-order harmonic analog signal amplified by the reception signal amplification unit, and high-speed A / D-converts the digital signal Waveform storage unit for digital recording of waveforms, waveform processing unit for calculating received wave arrival time difference and maximum amplitude with respect to the surface reflection waveform set by applying digital waveform processing to the waveform stored in the waveform storage unit, arbitrary of measured object An image display unit for converting the received wave arrival time difference and the resonance waveform amplitude of the higher order resonance waveform calculated by the waveform processing unit at the position of the image into a black and white gradation or color tone on a computer screen, and the ultrasonic probe An ultrasonic diagnostic apparatus equipped with a scanning mechanism capable of moving along the surface of the thin plate-like object to be measured, equipped with a mechanism for changing the distance of the child to the thin-plate-like object to be measured, or using the ultrasonic diagnostic apparatus an ultrasound diagnostic method, dozens service corresponding to the thickness resonance frequency of the said thin plate measured object is generated by the ultrasonic signal generator based on a command from the personal computer The burst wave ultrasonic excitation electrical signal cycle, said amplified by ultrasonic signal amplifier, through said water from the ultrasound probe incident ultrasonic vibration to the thin plate measured object, the object to be measured The ultrasonic signal leaked into the water at that time is received by the ultrasonic probe, and a high-order resonance reception signal is extracted from the ultrasonic signal received through the analog filter to amplify the received signal. The amplified analog signal is converted into a digital signal waveform at high speed A / D, the digital waveform is recorded in the waveform storage unit, and the waveform is measured at an arbitrary position of the thin plate-like object to be measured. The processing unit calculates the received wave arrival time difference and the resonance waveform amplitude of the high-order resonance waveform, and the image display unit displays the received wave arrival time difference and the resonance waveform amplitude of the higher-order resonance waveform on the computer screen. Characterized by imaging the minute defect or abnormality of the internal DUT by imaging is converted into the gray or color tone.

Claims (5)

An ultrasonic signal generator that receives a trigger signal from a personal computer and generates an electrical signal for burst wave ultrasonic excitation with variable frequency, and electrically amplifies and transmits the ultrasonic signal generated by the ultrasonic signal generator An ultrasonic signal amplifying unit for converting the ultrasonic signal transmitted from the ultrasonic signal amplifying unit into ultrasonic vibration, and applying ultrasonic vibration to a thin plate-like object to be measured placed in water An ultrasonic probe for receiving an ultrasonic signal leaked into water when an object is resonated, an analog filter for extracting a third-order or higher harmonic analog signal from a signal detected by the ultrasonic probe, Received signal amplification unit that amplifies high-order harmonic analog signal extracted by analog filter, high-order harmonic analog signal amplified by the received signal amplification unit, and digitally converts the waveform of the digital signal Waveform storage unit for recording, waveform processing unit for calculating received wave arrival time difference and maximum amplitude with respect to the surface reflection waveform set by applying digital waveform processing to the waveform stored in the waveform storage unit, at an arbitrary position of the object to be measured An image display unit that displays the received wave arrival time difference and the resonance waveform amplitude of the higher-order resonance waveform calculated by the waveform processing unit on a computer screen by converting them into black and white shades or colors, and the ultrasonic probe An ultrasonic diagnostic method using an ultrasonic diagnostic apparatus equipped with a scanning mechanism capable of moving along a surface of the thin plate-like object to be measured, which is equipped with a mechanism for changing the distance to the thin plate-like object to be measured,
The ultrasonic signal amplifying unit amplifies the burst wave ultrasonic excitation electric signal corresponding to the thickness resonance frequency of the thin plate-like object to be measured generated by the ultrasonic signal generating unit based on a command from the personal computer. Then, an ultrasonic vibration is incident on the thin plate-like object to be measured through water from the ultrasonic probe, the object to be measured is resonated, and an ultrasonic signal leaked into water at that time is sent to the ultrasonic probe. The high-order resonance reception signal is extracted from the ultrasonic signal received through the analog filter and amplified by the reception signal amplification unit, and then the amplified analog signal is converted into a digital signal waveform at a high-speed A / D-converted, the digital waveform is recorded in the waveform storage unit, and the received wave arrival time difference and the resonance waveform amplitude of the higher-order resonance waveform are measured by the waveform processing unit at an arbitrary position of the thin plate-like object to be measured. The calculated high-order resonance waveform reception wave arrival time difference and resonance waveform amplitude are converted into black and white shading or color tone on the computer screen by the image display unit, and imaged to form a micro defect inside the object to be measured. Alternatively, an ultrasonic diagnostic method comprising imaging an abnormal part. An ultrasonic signal generator that receives a trigger signal from a personal computer and generates an electrical signal for burst wave ultrasonic excitation with variable frequency, and electrically amplifies and transmits the ultrasonic signal generated by the ultrasonic signal generator An ultrasonic signal amplifying unit for converting the ultrasonic signal transmitted from the ultrasonic signal amplifying unit into ultrasonic vibration, and applying ultrasonic vibration to a thin plate-like object to be measured placed in water An ultrasonic probe for receiving an ultrasonic signal leaked into water when an object is resonated, an analog filter for extracting a third-order or higher harmonic analog signal from a signal detected by the ultrasonic probe, Received signal amplification unit that amplifies high-order harmonic analog signal extracted by analog filter, high-order harmonic analog signal amplified by the received signal amplification unit, and digitally converts the waveform of the digital signal Waveform storage unit for recording, waveform processing unit for calculating received wave arrival time difference and maximum amplitude with respect to the surface reflection waveform set by applying digital waveform processing to the waveform stored in the waveform storage unit, at an arbitrary position of the object to be measured An image display unit that displays the received wave arrival time difference and the resonance waveform amplitude of the higher-order resonance waveform calculated by the waveform processing unit on a computer screen by converting them into black and white shades or colors, and the ultrasonic probe Equipped with a mechanism for changing the distance to the thin plate-like object to be measured and capable of moving along the surface of the thin plate-like object to be measured,
The ultrasonic signal amplifying unit amplifies the burst wave ultrasonic excitation electric signal corresponding to the thickness resonance frequency of the thin plate-like object to be measured generated by the ultrasonic signal generating unit based on a command from the personal computer. Then, an ultrasonic vibration is incident on the thin plate-like object to be measured through water from the ultrasonic probe, the object to be measured is resonated, and an ultrasonic signal leaked into water at that time is sent to the ultrasonic probe. The high-order resonance reception signal is extracted from the ultrasonic signal received through the analog filter and amplified by the reception signal amplification unit, and then the amplified analog signal is converted into a digital signal waveform at a high-speed A / D-converted, the digital waveform is recorded in the waveform storage unit, and the received wave arrival time difference and the resonance waveform amplitude of the higher-order resonance waveform are measured by the waveform processing unit at an arbitrary position of the thin plate-like object to be measured. The calculated high-order resonance waveform reception wave arrival time difference and resonance waveform amplitude are converted into black and white shading or color tone on the computer screen by the image display unit, and imaged to form a micro defect inside the object to be measured. Alternatively, an ultrasonic diagnostic apparatus characterized by imaging an abnormal part.   The ultrasonic diagnostic apparatus according to claim 2, wherein the ultrasonic probe is either a focal type or a planar type.   An ultrasonic wave is transmitted and received by the ultrasonic probe in a state where the whole or a part of the object to be measured is immersed in a water tank filled with water or through a water column. The ultrasonic diagnostic apparatus according to claim 3.   The ultrasonic diagnostic apparatus according to claim 2, wherein the analog filter is a high-pass filter or a band-pass filter.

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