KR20200011835A - Pulse-echo nonlinear nondestructive inspection device using array type ultrasonic transducers - Google Patents

Abstract

An inspection apparatus of the present invention comprises: a first irradiation unit for applying a first ultrasonic wave to a first surface of a subject; a second irradiation unit for applying a second ultrasonic wave to the first surface; a reception unit configured to receive a reflection signal which has passed through the subject; and a processing unit analyzing the reflection signal to analyze defects or properties of the subject. The first irradiation unit and the second irradiation unit may generate the first ultrasonic wave and the second ultrasonic wave having different phases.

Description

Pulse echo type nonlinear inspection device using array ultrasonic sensor {PULSE-ECHO NONLINEAR NONDESTRUCTIVE INSPECTION DEVICE USING ARRAY TYPE ULTRASONIC TRANSDUCERS}

The present invention relates to an ultrasonic non-destructive inspection device for inspecting defects of a subject under examination using ultrasonic waves.

Among non-destructive inspection techniques, ultrasonic inspection test is a representative technique for detecting defects and evaluating reliability of industrial equipment. In ultrasonic testing, nonlinear defects such as cracks are the most difficult to inspect. In the case of fine cracks, it is common practice to identify defects by identifying the diffraction wave at the tip of the crack or the reflected wave at the crack face.

However, in the case of closed cracks or partially closed cracks, detection of defects is very difficult because the diffraction signal of the crack tip is very weak or the reflection signal of the crack surface does not appear.

Phased array ultrasound has been developed that focuses beams on defects and thus enhances detection signals. However, it is difficult to expect an improvement in the detection of cracks, which are nonlinear defects.

In addition, a method of radiating a strong incident wave and detecting a nonlinear component generated when the crack plane is opened and closed by the incident wave may be considered. The component output is so weak that successful testing is difficult.

Korean Patent Publication No. 1414520 discloses a technique of determining whether a structure is present by vibrating the structure by applying signals of different frequencies.

Korean Patent Publication No. 1414520

An object of the present invention is to provide an ultrasonic nondestructive testing apparatus capable of performing nondestructive testing normally regardless of the type of test subject and the position of a receiver.

The inspection apparatus of the present invention includes a first irradiation unit for applying a first ultrasonic wave to the first surface of the inspected object; A second irradiator for applying a second ultrasonic wave to the first surface; A receiver configured to receive a reflected signal passing through the test object; And a processor configured to analyze the reflected signal to analyze defects or properties of the object under test, wherein the first irradiator and the second irradiator may generate the first and second ultrasound waves having different phases. have.

According to the present invention, the non-destructive inspection is possible by using only one surface of the object under application of the pulse echo method. Therefore, the field applicability is very high, and it is possible to generate the second harmonic component which is always optimized according to the material and shape of a given object under test.

Applying the array probe based on the second harmonic component, the receiver's calibration, diffraction and attenuation correction can be performed accurately, so that the absolute nonlinear parameter value of the object under test can be measured.

It is inexpensive in terms of cost by constructing a nonlinear ultrasonic diagnostic apparatus using an array transducer of up to 3-4 channels.

1 is a schematic view showing an ultrasonic inspection apparatus of the present invention.
2 is a schematic view showing an ultrasonic diagnostic means of a comparative example.
3 is a graph showing a received wave spectrum of a comparative example.
4 is a block diagram showing an inspection device of the present invention.
5 is a schematic view showing another irradiation part of the present invention.
6 is a schematic diagram illustrating an ultrasonic beam focusing process by the time reversal treatment of the present invention.
Figure 7 is a schematic diagram showing the ultrasonic diagnostic method of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this process, the size or shape of the components shown in the drawings may be exaggerated for clarity and convenience of description. In addition, terms that are specifically defined in consideration of the configuration and operation of the present invention may vary depending on the intention or custom of the user or operator. Definitions of these terms should be made based on the contents throughout the specification.

1 is a schematic diagram showing an ultrasonic examination apparatus of the present invention, Figure 2 is a schematic diagram showing the ultrasonic diagnostic means of a comparative example. 3 is a graph showing a received wave spectrum of a comparative example.

When a single frequency ultrasonic wave of intense intensity propagates inside the object 10, harmonics due to nonlinearity of the material of the object or damage to the object are further generated. Nondestructive testing, which detects and examines material properties or damage by observing additionally generated harmonic changes, is called nonlinear ultrasound.

Basically, the nonlinear ultrasonic wave method for observing the second harmonic wave by using the longitudinal wave, the surface wave, the lamb wave, and the like is used. In the case of the longitudinal wave, a transmission method requiring both sides of the subject is used. However, the longitudinal transmission method introduces many limitations in practical applications.

In the conventional nonlinear ultrasonic method, as shown in Fig. 2, a vibrator 91 for injecting ultrasonic vi of a single intensity ω1 of strong intensity into a damaged material having a plastic deformation, fatigue, creep, or the like (hereinafter, the object under test 10) is used.

For example, the first surface 11 and the second surface 12 of the object 10 may be provided. The second side 12 may be the opposite side of the first side 11. When the vibrator 91 is disposed on the first surface 11, the ultrasonic wave vi propagates toward the second surface 12, and a second harmonic v2 is generated during the propagation process of the ultrasonic vi. The second harmonic v2, originally generated in the pulse echo nonlinear ultrasonic test, can be reflected at the stress free interface. In this case, the stress free interface may correspond to the second surface 12. The stress free interface is a surface in which the medium changes rapidly, and may correspond to the end face of the object under test with another object (including the atmosphere).

After the second harmonic v2 is reflected at the stress free interface, the second reflected harmonic r2 may be newly generated. At this time, the second harmonic v2 and the second reflected harmonic r2 cancel each other at the stress free interface, and become almost zero at the receiver 93 of the first face 11. Therefore, a transmission method in which the receiver 93 is arranged on the opposite side of the vibrator 91 during the ultrasonic inspection is used. However, the permeation method in which the vibrator 91 and the receiver 93 are respectively disposed on opposite surfaces of the inspected object 10 causes many limitations in practical application.

It is necessary to develop a pulse echo method in order to remove the limitation by the transmission method and to significantly improve the field applicability of nonlinear ultrasonic inspection. However, in the case of the pulse echo type nonlinear ultrasound, a stress free interface is included, and the amplitude of the received signal related to the second harmonic is very weak as shown in FIG. 3 due to the destructive interference of the second harmonic reflected therefrom.

Referring to FIG. 3, in the case of a comparative embodiment in which the destructive interference between the second harmonic v2 and the second reflected harmonic r2 is performed, the magnitude of the second harmonic component (Spectrum of 2nd harmonics) is set to the spectrum of fundamental frequency. It can have a value that converges to almost zero as a reference. Therefore, it is practically impossible to calculate the nonlinear parameter value for the defect 20 inside the inspected object 10 at the actual site where the noise exists.

Accordingly, there is a need for a method of increasing the generation of the second harmonic component and easily applying the nonlinear ultrasonic inspection method.

The inspection apparatus of the present invention applies the principles of array sensor, phase shift, and wave mixing to increase the magnitude (amplitude) of the second harmonic in pulse echo nonlinear ultrasonic inspection. Can be. The inspection apparatus of the present invention can accurately inspect the properties and degree of damage of various inspected objects by using the second harmonic of increased size.

The inspection apparatus of the present invention may include a first irradiator 111, a second irradiator 112, a receiver 130, and a processor 150.

The first irradiation unit 111 may apply the first ultrasound vi1 to the first surface of the object under test.

The second harmonic component v21 may be generated by the first ultrasound vi1 inside the object.

The second irradiator 112 may apply the second ultrasound vi2 to the first surface of the object.

The second harmonic component v22 may be generated inside the test object by the second ultrasound vi2.

The first and second ultrasounds have a set phase difference such that the second harmonic component v21 generated due to the first ultrasound vi1 and the second harmonic component v22 generated due to the second ultrasound vi2 are constructively interfered with each other when reflected from the stress free interface. The first ultrasound and the second ultrasound can be applied simultaneously to the first surface of the object under test.

When the first ultrasound and the second ultrasound having different phases are simultaneously applied to the first surface of the object under test, the second harmonic component v21 generated by the first ultrasound and the second harmonic component v22 generated by the second ultrasound are Constructive interference instead of destructive interference at the stress free interface. Due to the two second harmonic components v21 and v22 that are constructively interfered, the magnitude of the second harmonic received by the receiver can be significantly increased.

일 수 있다. 본 실시예에 따르면, 도 1의 (c)의 수신파 스펙트럼과 같이 각 초음파의 기본 진동수 ω1, 제2 고조파의 진동수 2ω1 모두 보강 간섭으로 인해 크기(진폭)가 획기적으로 증가할 수 있다.If the third irradiator 113 for generating the third ultrasound vi3 having the set phase difference is added based on the first ultrasound and the second ultrasound, the second harmonic received by the receiver is generated by the third ultrasound vi3. The second harmonic component v23 may further be constructively interfered. Therefore, as the third irradiator 113, the fourth irradiator, ..., etc. are added, the magnitude (amplitude) of the second harmonic received by the receiver may increase. Like the first irradiating unit and the second irradiating unit, the third irradiating unit 113 and the like may simultaneously apply ultrasonic waves to the first surface of the object under test. The phase difference between the first ultrasonic wave, the second ultrasonic wave, and the third ultrasonic wave is as shown in FIG.

Can be. According to the present exemplary embodiment, the magnitude (amplitude) of both the fundamental frequency ω1 of each ultrasonic wave and the frequency 2ω1 of the second harmonic, as shown in FIG.

When the first irradiator and the second irradiator apply the ultrasonic waves vi1 and vi2 to the first surface of the object under test, the receiver 130 may receive the second harmonic on the first surface.

The receiver 130 may be disposed in the middle of the first irradiator and the second irradiator. For example, the first irradiator may apply the first ultrasound vi1 to the first point of the first surface. The second irradiator may apply the second ultrasound vi2 to a second point surrounding the first irradiator. The third irradiator may apply the third ultrasound vi3 to a third point surrounding the second irradiator. In this case, the receiver 130 may be installed at the first point. In this case, the receiver may be integrally formed with the first irradiation unit.

Alternatively, the receiver 130 may be disposed in plural on the first surface. In this case, each receiver may be integrally formed with each irradiator.

Each radiator must be able to withstand high voltages, and each receiver can receive both fundamental waves (first ultrasound, second ultrasound, ..., etc.) and second harmonic components (v21, v22, ..., etc.). It can have a wide bandwidth frequency bandwidth.

According to the present invention, unlike phased array trasducers for linear ultrasonic waves, which generally use dozens of vibrators and receivers, only three or four elements are used for nonlinear ultrasonic waves, and different phase differences are applied between the elements. To optimize the generation of the second harmonic in pulse-echo mode.

According to the present invention, piezoelectric materials for sensors can be diversified in connection with array sensors for pulse-eco nonlinear ultrasonic waves. In addition, the material, number of elements, geometrical shape, frequency, applied phase difference, and reception method of the sensor are optimized to optimize the generation of the second harmonic and the measurement of the nonlinear parameter according to the thickness and shape of the object under test based on the theoretical analysis. There is an advantage to this. In addition, the non-destructive inspection can be applied not only to the planar subject but also to a tubular subject having a curved surface.

In order to improve the magnitude of the second harmonic component, the initial setting of the first irradiator, the second irradiator, and the receiver is very important.

There is a need for the selection of piezoelectric materials suitable for array ultrasonic sensors for the generation and reception of nonlinear ultrasonic waves, and the fabrication of array ultrasonic sensors. The piezoelectric material may include both a piezoelectric ceramic and a piezoelectric polymer.

The technique which can measure the pulse echo mode of a 1st irradiation part and a 2nd irradiation part, and evaluates a characteristic is calculated | required.

In the application of the relative phase difference for optimal generation of the second harmonic at the stress free interface of the pulse echo mode, a technique for determining the optimal input signal characteristics is required. There is a need for a technique that can measure the shape of the signal, the number of cycles, the frequency, etc. and determine the optimal value.

There is a need for optimization techniques for non-linear ultrasonic array sensors for pulse echo. For example, a number, size, geometric shape, frequency, single element reception or partial element reception or all element reception, fabrication and evaluation methods are required.

The determination of the optimum transmission phase difference required for each element and the application technique of the phase difference are required. In addition, a technique of applying an input wave to each element is required.

Sound field analysis technology of linear and nonlinear waves generated / received by various excitations of the arrayed ultrasonic sensors in the pulse-echo mode to which the phase difference is applied is required, which can be processed by the processing unit 150 of the present invention.

The processor 150 may signal-process the received wave received through the receiver, extract and analyze various frequency components.

The processor 150 may measure and evaluate the nonlinear parameters in consideration of correction due to attenuation of the inspected object and diffraction effects of the array type sensor.

The irradiator may excite the ultrasound in a contact or non-contact manner with respect to the subject.

In order to carry out a diagnosis such as identifying a damage location of a test subject in an actual site, measurement of an absolute nonlinear parameter value through calibration of a receiver that receives a signal passing through the test subject is required. The calibration operation of the receiver is performed using the second harmonic component included in the signal, but in the case of the known nonlinear ultrasound method, the second harmonic component measured is almost zero. Therefore, the existing nonlinear ultrasonic inspection method is not used in the actual field where various kinds of noises that make it difficult to detect the second harmonics are applied, and is applied only in a laboratory where noise can be excluded.

4 is a block diagram showing an inspection device of the present invention. 5 is a schematic view showing another irradiation part of the present invention. 6 is a schematic diagram illustrating an ultrasonic beam focusing process by the time reversal treatment of the present invention. Figure 7 is a schematic diagram showing the ultrasonic diagnostic method of the present invention.

The inspection apparatus of the present invention may include a first irradiator 111, a second irradiator 112, a receiver 130, and a processor 150 to generate a second harmonic that is robust to noise, that is, has a strong intensity. have.

The first irradiator 111 may generate first ultrasonic waves propagating from the first surface 11 to the second surface (bottom surface) 12 of the inspected object 10. The first surface 11 and the second surface 12 may be different surfaces, for example, the first surface 11 is an upper surface of the object 10, and the second surface 12 is an object 10. It may be the bottom of.

위상차를 가질 수 있다.The second irradiator 111 may generate second ultrasonic waves propagating from the first surface 11 to the second surface 12 of the object under test. In this case, the second ultrasound is based on the first ultrasound.

It may have a phase difference.

The receiver 130 may be mounted on the first surface 11 of the inspected object 10 and receive the first reflection signal and the second reflection signal.

One or more receivers may be provided. The receiver may be integrally formed with each irradiation unit.

As another example, as illustrated in FIG. 5, the first irradiator 111 and the second irradiator 112 may include a laser irradiator for irradiating a laser toward the first surface 11 at a position spaced apart from the object 10. . Excitation of the laser irradiated to the first surface 11 may generate the first ultrasound and the second ultrasound passing through the inspected object 10, or a composite waveform of the first ultrasound and the second ultrasound may be generated. have.

The first reflection signal may be a signal in which ultrasound waves propagated from the first surface 11 to the second surface (bottom surface) 12 of the object 10 are reflected.

The second reflection signal may be a signal in which a time reversal signal propagated from the first surface 11 to the second surface 12 is reflected. In this case, the time reversal signal may be generated using the first reflection signal.

The irradiating portion in contact with or spaced from the first surface may generate ultrasonic waves and radiate toward the second surface 12. In order to improve spatial resolution, the plurality of receivers 130 may be disposed at point symmetrical positions based on the point of the object to which the ultrasound is input.

The plurality of receivers 130 disposed on the first surface 11 may receive the first reflection signal reflected by the ultrasonic wave on the second surface 12.

The plurality of receivers 130 may emit the time reversal signal again. The time reversal signal propagates from the first face 11 toward the second face 12, and the second reflected signal may be received in the plurality of receivers.

When the first reflection signal is reflected from a specific position P on the second surface 12, the time reversal signal radiated from the plurality of receivers 130 may be focused at the specific position P. FIG. Since a plurality of beams emitted from the plurality of receivers 130 are focused at a specific position P, the resolution of the second reflected signal corresponding to the beam reflected at the specific position P may be improved.

The receiver 130 may receive the second reflection signal in which the time reversal signal of the first reflection signal is reflected from the second surface 12.

The processor 150 may calculate the non-linear parameter value of the object 10 by using the second reflected signal.

Ultrasound may be reflected at the P position on the second surface 12 of the object 10. Since the second surface 12 is a portion which is bordered with other media such as air and a support plate, the first reflection signal or the second reflection signal reflected by the second surface 12 is subjected to minute cracks inside the test object 10. A second harmonic component having a very large magnitude compared to the reflected signal may be included. Since the second harmonic component included in the signal reflected on the second surface 12 may be distinguished from noise, it may be easily recognized even in a real field where noise is mixed.

In order to obtain a second harmonic component that is more robust to noise, the plurality of receivers 130 disposed on the first surface 11 of the object 10 may generate a focused beam focused at a P position.

In order to ensure the beam focusing, the array receiving unit 130 of three channels or more may be in close contact with the first surface 11 of the object 10, and a time reversal method may be applied for beam focusing. The time reversal signal to which the time reversal method is applied may be accurately focused at the P position of the second surface 12.

Since the signal emitted from each receiver 130 to the object 10 is time-reversed, the ultrasonic beam can be accurately focused at the P position where the nonlinear defect exists even without prior information including the characteristics of the object 10. .

The receiving unit 130 or the processing unit 150 is a particular element of interest among the nonlinear component signals caused by the interface, the multiple modes of the Lamb wave, or the nonlinear component signals caused by the reflected waves of various modes in the flat object 10. Extract the mode signal and time-reverse it.

In the drawings, a time reversal method for an array transducer in which N receivers 130 are arranged is shown. However, the embodiment of the present invention is not limited to the array transducer, but may be provided by the receivers 130 that are individually installed. Can be implemented.

Referring to the first picture of FIG. 6, one of the N receivers 130 provided in the array transducer is excited. The excited incident wave propagates to the inspected object 10.

Referring to the second picture of FIG. 6, the scattering signal (first reflection signal) reflected at the P position of the second surface 12 corresponding to the boundary surface of the object 10 is received by each receiver 130. The difference in the media properties of the inspected object 10, the surface geometry of the inspected object 10, and the distance from each receiver 130 disposed on the first face 11 to the second face 12 is different for each receiver 130. It is expressed as a physical quantity such as a time delay amount difference of an echo signal or a waveform difference of each receiver 130.

According to the time reversal method of the present invention, it requires data on time delay difference or waveform difference, but does not require any knowledge of prior information.

Since the distance to the P position divided by the speed of the ultrasonic wave is the propagation time, the difference between the time delay amount and the waveform difference for each receiver 130 is determined by the surface geometry of the object 10 or the distance from the receiver 130 to the P position. Dictionary information such as differences is already included. Therefore, by calculating the time delay amount from the signal emitted and received by the receiver 130 and using the time reversal process, it is possible to detect the P position without knowing advance information such as surface geometry and medium characteristics.

Even if you do not know any prior information about the array transducer or the object under test 10, the signal returned by propagating the inside of the object 10 is returned so that the information on the geometrical shape and physical properties of the object 10 is returned. It is reflected in. In the time reversal method, the propagation time of the ultrasonic wave is based on an invariant characteristic of the array transducer or the inspected object 10 even if no prior information on the array transducer or the inspected object 10 is input. Furthermore, according to the present invention, the size of the second harmonic can be greatly increased due to the first ultrasound and the second ultrasound.

Referring to the third picture of FIG. 6, the time reversal is performed based on the difference in the time delay amount of each receiver 130 obtained by the N receivers 130 without having to acquire prior information. Process. Each receiver 130 injects a new waveform (time reversal signal) subjected to time reversal processing into the test subject 10. The time-reversed ultrasonic beam (time reversal signal) is correctly focused at the P position.

In the time reversal processing of the received signal, the received original signal may be used as it is, or a nonlinear signal of a specific mode of interest may be selectively extracted and time reversal processed, and an accurate analysis of the P position may be performed.

Referring to the fourth picture of FIG. 6, the ultrasonic beam (time reversal signal) concentrated at the P position is obtained again (second reflection signal) by each receiver 130. The obtained waveform is an improved signal-to-noise ratio and contains accurate information (including coordinates and magnitude) about the P position.

That is, when each receiver 130 is excited in the state of time reversal processing reflecting the amount of time delay calculated by the time reversal method, the excited ultrasonic waves are focused on the P position. Focusing the ultrasound at the P position improves the signal-to-noise ratio, resulting in clear defect images.

In order to improve inspection accuracy of nonlinear defects, the signal reception time of the receiver 130 is preferably longer than the signal transmission time. As the reception time of the first reflection signal is longer, the peak amplitude of the harmonic component is increased, so that pure harmonic components can be extracted without noise.

The first reflection signal may be input to the processor 150. When the frequency spectrum is obtained by Fourier transforming the first reflection signal of the received time domain, the processor 150 may extract a harmonic spectrum using a window function in the frequency domain. The processor 150 may generate a time reversal signal by converting the extracted harmonic spectrum into a time domain after time reversal processing. The processor 150 may amplify the time reversal signal and then provide the received signal to the receiver 130.

The receiver 130 may re-radiate the time reversal signal provided from the processor 150 toward the object 10.

The first reflected signal contains information about nonlinear defects such as the interface. Therefore, the time reversal signal obtained by time reversal processing of the first reflection signal can be accurately focused at the P position having the nonlinear characteristic according to the time reversal processing without any prior information. The time reversal signal propagated to the P position may be reflected back to the P position and obtained by each receiver 130.

The processor 150 may process the first reflected signal or the second reflected signal received by each receiver 130. The processor 150 may extract the fundamental frequency component and the second harmonic component by analyzing the second reflected signal, and calculate the nonlinear parameter value using the second harmonic component. In this case, the second harmonic component may be in a state in which the size of the second harmonic component is dramatically increased by the first ultrasound and the second ultrasound provided by the first and second radiators.

The processor 150 may convert the fundamental frequency component or the second harmonic component to the absolute displacement by multiplying the transfer function of the receiver 130. The processor 150 may apply a time delay to the receiver 130 to synthesize the second reflected signal to calculate a nonlinear parameter value. The processor 150 may calculate the nonlinear parameter value by correcting the rotation or attenuation of the second reflected signal.

The processor 150 includes an oscilloscope 151, a processing module 153, a multi channel function generator 155, a multi channel amplifier 157, and an impedance matcher 159. matching may be provided.

The oscilloscope 151 may monitor the first reflection signal or the second reflection signal received from the receiver 130 and provide the processing module 153.

The processing module 153 may process the first reflection signal and provide it to the multi-channel function generator, or calculate the nonlinear parameter value of the object under test 10 using the second reflection signal.

The processing module 153 may be provided with a receiver calibration module, a time reversal signal processing module, a reception signal processing module, an absolute displacement calculation module, a nonlinear parameter value calculation module, a diffraction and attenuation correction module.

The receiver calibration module may calibrate the reception frequency of the receiver 130 to determine the absolute displacement of the second harmonic component.

The time reversal signal processing module may apply the time reversal method to the first reflection signals received by each receiver 130.

The received signal processing module may process the first reflected signal or the second reflected signal. For example, the reception signal processing module may apply a time delay to the plurality of second reflection signals obtained from the plurality of receivers 130 and then synthesize the received signals.

The absolute displacement calculation module may calculate an absolute displacement of the second harmonic component or the like by multiplying the fundamental frequency component or the second harmonic component by the transfer function of the receiver 130.

The nonlinear parameter value calculation module may calculate the nonlinear parameter value β as shown in Equation 1 using the calculated absolute displacement.

The diffraction and attenuation correction module may correct the diffraction element and the attenuation element included in the second reflected signal or the like.

The detailed behavior and mathematical models of the receiver calibration module, the received signal processing module, the absolute displacement calculation module, the nonlinear parameter value calculation module, the diffraction and attenuation correction module are described in the article 'Review of Second Harmonic Generation Measurement Techniques for Material State Determination in Metals' (J Nondestruct Eval DOI 10.1007 / s10921-014-0273-5).

The multi-channel function generator may generate each time reversal signal allocated to the plurality of receivers 130 installed on the first surface 11 by using the result of processing the first reflection signal.

The multi-channel amplifier may amplify the time reversal signal allocated to each receiver 130.

The impedance matcher prevents the time reversal signal from being reflected from the first surface 11 and returned to the processor 150.

The ultrasound diagnostic method of the present invention is as follows.

First, ultrasonic waves may be radiated onto the first surface 11 of the object 10 by the excitation of the first irradiating unit 111 and the second irradiating unit 112. In this case, the first ultrasound and the second ultrasound may have different phases.

The first and second ultrasound waves passing through the inside of the object 10 are reflected by the second surface 12 (first reflection signal) and received by the plurality of receivers 130 disposed on the first surface 11. Can be. The transducer from which the first reflected signal is received may also include a transducer that generates ultrasonic waves.

When the first reflection signal received by each receiver 130 is reversed and retransmitted, a beam (time reversal signal) may be focused at the reflection position P of the second surface 12.

Each of the receivers 130 receives the second reflected signal reflected by the time reversal signal at the position P, and after processing the signal, obtains a fundamental frequency component and a second harmonic component.

Multiply the transfer function of each receiver 130 to convert it to absolute displacement, and apply a time delay to the receiver 130 to synthesize the received wave.

The nonlinear parameter value before diffraction / damping correction can be obtained, and the final nonlinear parameter value can be obtained by correcting the diffraction and attenuation.

The ultrasonic diagnostic apparatus of the present invention uses the first ultrasonic wave and the second ultrasonic wave, and uses only one surface of the inspected object 10 through the application of a non-contact excitation and reflection method, so that the field applicability is very high. Since the signal propagated inside the object under test 10 is used for beam focusing, it is not necessary to know the specifications of the array receiver 130 and the geometric shape and physical properties of the object under test 10 in advance. The calibration of the receiver 130 may measure an absolute nonlinear parameter value of the object 10 and may provide a more accurate nonlinear parameter value by applying diffraction and attenuation correction. Since the nonlinear ultrasound diagnostic apparatus is configured by using the array receiver 130 of at least three channels, there is an advantage of high productivity.

Although embodiments according to the present invention have been described above, these are merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent embodiments of the present invention are possible therefrom. Therefore, the true technical protection scope of the present invention will be defined by the following claims.

10 Test Subject 11 ... First Page
12 ... 2nd side 20 ... defect
111 ... First Irradiation Unit 112 ... Second Irradiation Unit
130 ... receiver
150 ... Processor 151 ... Oscilloscope
153 Processing Modules 155 Multi-Channel Function Generators
157 ... multi-channel amplifier 159 ... impedance matcher

Claims (4)

A first irradiation unit configured to apply first ultrasonic waves to the first surface of the test object;
A second irradiator for applying a second ultrasonic wave to the first surface;
A receiver configured to receive a reflected signal passing through the test object;
And a processor configured to analyze the reflected signal to analyze defects or properties of the object under test.
And the first irradiator and the second irradiator generate the first and second ultrasound waves having different phases.
The method of claim 1,
And the first irradiating unit and the second irradiating unit simultaneously apply the first ultrasonic wave and the second ultrasonic wave to the first surface.
The method of claim 1,
The receiver is disposed on the first surface,
And the first signal receiving the reflected signal reflected from the stress free interface of the object under test.
The method of claim 1,
The first irradiation unit and the second irradiation unit

The inspection apparatus for generating the first ultrasound and the second ultrasound so as to have a phase difference of.

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