KR101961267B1 - Device and method for estimating ultrasonic absolute nonlinear parameter by using ultrasonic relative nonlinear parameter and calculation of proportional correction factor - Google Patents

Abstract

More particularly, the present invention relates to an ultrasonic transmitter for transmitting an ultrasonic signal to a reference specimen and an object to be inspected, an ultrasonic transmitter for transmitting the ultrasonic signal to the ultrasonic transmitter, A signal processing unit for measuring relative nonlinear parameters of the reference specimen and the test object using the received ultrasonic signal, a signal processing unit for measuring a relative nonlinear parameter of the test specimen using the received ultrasonic signal, A correcting unit for measuring a waveness correction coefficient and a proportional coefficient of the object and an absolute nonlinear parameter of the object based on the relative nonlinear parameter, the absolute nonlinear parameter of the reference sample, the wavenumber correction coefficient, Absolute nonlinear parameters Wherein the reference specimen and the subject are different materials, and the proportional correction coefficient is calculated from the acoustic impedance ratio of the reference specimen and the subject.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an ultrasonic absolute nonlinear parameter estimating apparatus and a ultrasonic absolute nonlinear parameter estimating apparatus using ultrasonic relative non-

The present invention relates to an apparatus and method for estimating an absolute nonlinear parameter of an ultrasonic wave, and more particularly, to a technique for evaluating the strength characteristics and the degree of deterioration of a material by using ultrasonic waves and evaluating the characteristics of fine materials such as microstructure alteration.

The nonlinear elasticity of solid material is a characteristic that the working stress on the molecular distance between atoms in the material physically appears in nonlinear elastic behavior. In fact, the interatomic energy of solid material does not have harmonic characteristic and shows non-harmonic characteristic.

When a sinusoidal wave having a constant frequency propagates in a solid medium having sufficient amplitude and non-harmonic characteristics, the ultrasonic wave having the fundamental incident frequency is distorted due to the difference in the local phase velocity depending on the nonlinear elastic property of the material So that a higher harmonic component corresponding to an integral multiple of the fundamental frequency is generated.

The damage to the material can be assessed by determining the magnitude of the harmonic component or the magnitude of the absolute nonlinear parameter before and after the material is damaged.

This absolute nonlinear parameter? Can be quantified as shown in Equation (1) below.

[Equation 1]

Where A ₁ is the displacement amplitude of the fundamental wave component, A ₂ is the displacement amplitude of the second harmonic component, k is the wave number, and x is the propagation distance.

This absolute nonlinear parameter can be used to analyze the degree of deterioration of the material and can be used specifically to analyze the collapse of the lattice structure due to the generation and disappearance of precipitates and the change of microstructure due to the heat treatment of the material.

However, as it can be seen from the non-patent documents 'Measurement of nonlinear parameters of Fused Silica and Al2024-T4', since it is necessary to measure A ₁ and A ₂ experimentally in a very complicated manner, many researchers have found that absolute non- The relative nonlinear parameter (beta ') is measured, for example, by observing the voltage change of the received signal using a contact probe without measuring the value.

The relative nonlinear parameter? 'Can be expressed by Equation (2) below.

&Quot; (2) "

Here, A ₁ 'is the amplitude of the fundamental wave component of the received voltage signal, and A ₂ ' is the amplitude of the harmonic component of the received voltage signal.

That is, in order to quantitatively evaluate the deterioration of materials, it is necessary to measure the absolute nonlinear parameters, but it is difficult to quantitatively measure the fine deviations of harmonic components. Therefore, many researchers have measured relative nonlinear parameters that observe the relative change of nonlinear parameters.

However, the relative nonlinear parameter is applied only to the comparison before and after the deterioration using the characteristics showing the correlation with the deterioration of the material, and there is a problem that the deterioration or damage of the material can not be quantitatively measured from the relative nonlinear parameter.

Further, in order to precisely measure relative nonlinear parameters, all the measurement conditions must be the same, which is a very difficult problem in reality.

Nonlinear Parameter Measurement of Fused Silica and Al2024-T4, Journal of the Korean Society for Nondestructive Testing, Vol. 33, No. 1: 14-19, 2013, page 1

In the field of deterioration measurement of conventional materials, the correlation between physically different parameters such as absolute nonlinear parameters and relative nonlinear parameters has been studied only qualitatively, and it has not been quantitatively presented. Since it is difficult to measure absolute nonlinear parameters, In the thesis, only relative nonlinear parameters are measured.

However, in order to overcome the above limitations, the present invention provides an apparatus and method for estimating an absolute nonlinear parameter from a measurement result of a relative nonlinear parameter by securing a correlation between two physical parameters having different dimensions.

In order to achieve the above object, an apparatus for estimating an absolute ultrasonic absolute parameter using ultrasonic relative nonlinear parameters and calculating a proportional correction coefficient of a dissimilar material according to an embodiment of the present invention includes a reference specimen and an ultrasonic signal transmitter An ultrasonic transmission unit, an ultrasonic receiver for receiving ultrasonic signals reflected or transmitted inside the reference specimen and the subject, a signal for measuring relative nonlinear parameters between the reference specimen and the subject using the ultrasonic signal, Based on the relative nonlinear parameter, the absolute nonlinear parameter of the reference specimen, the wave number correction coefficient, and the proportional coefficient of the test specimen based on the correction coefficient and the proportional coefficient of the test specimen, The absolute ratio of estimating the absolute nonlinear parameter Wherein the reference specimen and the subject are different materials, and the proportional correction coefficient is calculated from the acoustic impedance ratio of the reference specimen and the subject.

Further, the acoustic impedance ratio of the reference specimen and the test object according to an embodiment of the present invention has the relationship expressed by Equation (1).

[Equation 1]

Here, α 'is the proportional correction coefficient, ρ ₀ is the density of the reference specimen, v ₀ is the ultrasonic velocity of the reference specimen, z _o is the acoustic impedance of the reference specimen, and z is the acoustic impedance of the subject.

The absolute nonlinear parameter estimator according to an embodiment of the present invention can measure the relative nonlinear parameter by calculating a ratio of a relative nonlinear parameter of the reference specimen to the measured object.

In addition, the displacement amplitudes A ₁ and A ₁ 'measured to obtain the absolute nonlinear parameter according to an embodiment of the present invention have a relation as shown in Equation 2 below, and the received voltage measured to obtain the relative nonlinear parameter The amplitudes A ₂ and A ₂ 'of the signal are characterized by having the relationship expressed by the following equation (3).

[Equation 2]

[Equation 3]

Wherein A ₁ is the displacement amplitude of the fundamental wave component, A ₂ is the displacement amplitude of the _second harmonic component, A ₁ 'is the amplitude of the fundamental wave component of the received voltage signal, A ₂ ' And α ₁ and α ₂ are proportional correction coefficients indicating the relationship between the displacement and the received voltage signal.

Further, the relative nonlinear parameter ratio r _? According to an embodiment of the present invention is calculated by applying the following equation (4).

[Equation 4]

Here, β 'is a relative nonlinear parameter of the object and β ₀ ' is a relative nonlinear parameter of the reference sample.

Also, the relative nonlinear parameter according to an embodiment of the present invention is measured through the following equation (5).

[Equation 5]

Here, l is an arbitrary constant.

Further, the absolute nonlinear parameter? Of the subject according to the embodiment of the present invention is estimated by applying Equation (6) below.

[Equation 6]

Here, β ₀ is a relative nonlinear parameter of the reference specimen, r _β is a ratio of a relative nonlinear parameter, k 'is a wavenumber correction coefficient, and α' is a proportional correction coefficient.

The waveness correction coefficient k 'according to an embodiment of the present invention has a relationship expressed by Equation (7) below, and the proportional correction coefficient (?') Has a relationship as expressed by Equation (8) do.

[Equation 7]

[Equation 8]

Here, k is the wave number of the object, k ₀ is the wave number of the reference specimen, and α _1,0 and α _2,0 are proportional correction coefficients indicating the relationship between the displacement of the reference specimen and the received voltage signal.

Also, the reference specimen according to an embodiment of the present invention is a reference specimen in which the absolute nonlinear parameter value is already known or the absolute nonlinear parameter is measured in advance.

The signal processing unit according to an embodiment of the present invention is characterized in that the relative nonlinear parameters of the reference specimen and the subject are measured by separating each of the received ultrasonic signals into a fundamental frequency component and a harmonic component .

In addition, the signal processing unit according to an embodiment of the present invention separates the received ultrasound signals into a fundamental frequency component and a second harmonic component using a band pass filter.

The signal processing unit may further include a fundamental frequency waveform extraction unit for separating the fundamental frequency components from the received ultrasound signals using a first band pass filter, And a second harmonic waveform extractor for separating the second harmonic components from the received ultrasound signals using a second band pass filter having a different band.

In order to achieve the above object, a method for calculating a proportional correction coefficient of a dissimilar material and an ultrasonic absolute nonlinear parameter estimation method using ultrasonic relative nonlinear parameters according to an embodiment of the present invention includes transmitting an ultrasonic signal to a reference specimen and a subject, Receiving the ultrasonic signal reflected or transmitted inside the reference specimen and the object to be inspected, measuring a relative nonlinear parameter between the reference specimen and the specimen using the received ultrasonic signal, And estimating an absolute nonlinear parameter of the subject based on the absolute nonlinear parameter of the reference specimen, the relative nonlinear parameter, the wavenumber correction coefficient, and the proportional coefficient of the subject specimen, Wherein the reference specimen and phase The inspection object is a dissimilar materials, the proportional correction factor, characterized in that the acoustic impedance is calculated from the ratio of the reference sample and the inspection object.

Quantitative evaluation of material deterioration requires quantitative measurement of nonlinear parameters, but it is difficult to quantitatively measure the fine displacement of about 1 nm of harmonic components. Many researchers have measured relative nonlinear parameters to observe relative changes in nonlinear parameters However, the measurement of the relative nonlinear parameter has a disadvantage in that it can not quantify the damage of the material.

According to an embodiment of the present invention, there is provided a method of estimating an absolute nonlinear parameter through comparison of a relative nonlinear parameter between a reference specimen that knows an absolute nonlinear parameter value and a subject in an absolute nonlinear parameter measurement, The time and cost can be greatly reduced.

In addition, according to an embodiment of the present invention, even when the material of the reference specimen and the test subject differ, the absolute nonlinear parameter of the test subject can be measured by introducing the wave number correction coefficient and the proportional correction coefficient. There is an advantage that the absolute nonlinear parameter of the object to be measured can be measured using the reference specimen whose value is known or the absolute nonlinear parameter is measured in advance.

Further, according to an embodiment of the present invention, the proportional correction coefficient between dissimilar materials can be arithmetically calculated through the impedance ratio of the dissimilar materials. Using the thus calculated proportional correction coefficient and relative nonlinear parameter measurement results, There is an advantage that the ratio of the nonlinear parameters can be easily obtained.

FIG. 1 is a diagram illustrating a method of measuring harmonics.
Fig. 2 is a view for explaining a calibration measurement method.
FIG. 3 is a block diagram illustrating an apparatus for estimating an absolute ultrasonic absolute nonlinear parameter using an ultrasonic relative nonlinear parameter by calculating a proportional correction coefficient according to an embodiment of the present invention. Referring to FIG.
4 is a block diagram showing a detailed configuration of the signal processing unit of FIG.
5 is a flowchart illustrating an ultrasonic absolute nonlinear parameter estimation method using an ultrasonic relative nonlinear parameter through calculation of a proportional correction coefficient according to an embodiment of the present invention.
6 is a flowchart illustrating a method of measuring relative nonlinear parameters of a reference specimen and an object according to an exemplary embodiment of the present invention.
7 is a flowchart illustrating a method of estimating an absolute nonlinear parameter of an object according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving it will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings.

The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Before describing an embodiment of the present invention, a general method of measuring absolute nonlinear parameters will be described first.

In the absolute nonlinear parameter measurement method, a piezoelectric receiving method is widely used as a method of measuring the displacement of an ultrasonic wave transmitted through an object. In order to compensate for the disadvantage of the method of measuring a relative nonlinear parameter, The displacement of the ultrasonic wave transmitted through the object is measured.

The piezo-electric reception technique is based on a harmonic measurement experiment in which a probe having a fundamental frequency and a double frequency is attached to both sides of the object and a double frequency transducer is attached to compensate the nonlinearity occurring in the couplant and the probe. This is a two-stage experiment in which a calibration is performed to perform an experiment.

H (ω) is obtained through a calibration experiment to obtain I _out (ω) through a harmonic measurement experiment as shown in the following equation (3), and an absolute size of the displacement A ₁ of the fundamental frequency and the displacement A ₂ of the _second harmonic have.

&Quot; (3) "

FIG. 1 is a diagram illustrating a method of measuring harmonics.

Referring to FIG. 1, there is a change efficiency K _R (?) Between input / output electrical energy and mechanical energy.

If the relationship between P _{A , in - trans} (ω ₁ , ω ₂ ) and P _{E , out} (ω ₁ , ω ₂ ) _in FIG. 1 is established by measuring the current received through the subject in the harmonic measurement experiment, It is as shown in equation _4, P _{a, in -} to measure _{a inc (ω 1, ω 2} ) from the _trans (ω _1, ω _2), and is expressed as shown in equation (5).

Therefore, if the primary conversion efficiency K _R (?) Is obtained, the displacement amplitude of the ultrasonic wave transmitted through the subject from the measured electric signal can be obtained. Where A _inc (ω) is the displacement amplitude and I _out (ω) is the measured output current value.

&Quot; (4) "

&Quot; (5) "

Fig. 2 is a view for explaining a calibration measurement method.

In the calibration measurement experiment the electrical signal P is incident on the test subject ^{_{'E, cal - in (ω}} 2) and the echo signal ^P' _{E, cal -} by measuring _out (ω _2), also of the 2 P _{^'E, cal - in} (ω ₂ ), P ^' _{E and cal - out} (ω ₂ ), the following equation (6) is obtained.

&Quot; (6) "

The current and voltage that are transmitted and received during the calibration process are measured, and the calibration parameter H (?) Can be obtained from the following equation (7).

&Quot; (7) "

Where v is the ultrasonic velocity, a is the area of the probe, I ' _in (ω) is the current signal incident on the material in the broadband pulser, V' _in (ω) I ' _out (ω) is a current signal received after the ultrasonic wave incident on the material is reflected on the bottom surface of the material, and V' _out (ω) is the voltage signal of the ultrasonic wave incident on the material after being reflected from the bottom surface of the material It is the received voltage signal.

However, since the absolute nonlinear parameter measurement method described above must be performed in two steps, that is, harmonic measurement and calibration measurement, the measurement is cumbersome and complicated, so that it is very difficult to actually apply it.

Accordingly, in an embodiment of the present invention, an ultrasonic absolute nonlinear parameter is estimated from a relative nonlinear parameter, and an ultrasonic relative nonlinear parameter capable of diagnosing the deterioration of the material in a quantitative and precise manner in a more straightforward manner than the absolute non- An apparatus and method for estimating an absolute nonlinear parameter using ultrasonic waves are provided.

For this purpose, in an embodiment of the present invention, a reference specimen having an absolute nonlinear parameter value already known or having previously measured an absolute nonlinear parameter is prepared, and the relative nonlinear parameter of the reference specimen and the specimen are measured, And an absolute nonlinear parameter of the subject from the ratio of the relative nonlinear parameter values of the reference specimen and the subject. If the material of the reference specimen and the subject differ from each other, an appropriate wavenumber correction factor and a proportional correction coefficient The absolute nonlinear parameter can be estimated.

First, when the displacement amplitudes A ₁ and A ₂ measured to obtain the absolute nonlinear parameter values are proportional to the amplitudes A ₁ 'and A ₂ ' of the received voltage signals measured to obtain the relative nonlinear parameter values, And Equation (9) can be satisfied.

&Quot; (8) "

&Quot; (9) "

Where A ₁ is the displacement amplitude of the fundamental wave component, A ₂ is the displacement amplitude of the second harmonic component, A ₁ 'is the amplitude of the fundamental wave component of the received voltage signal, A ₂ ' is the second harmonic of the received voltage signal Where α ₁ and α ₂ are proportional correction factors that represent the relationship between the displacement and the received voltage signal and are affected by the acoustic impedance of the material.

The relative nonlinear parameter (beta ') can be measured using Equation (10) below and can be specifically transformed from the fundamental frequency component and the second harmonic component.

&Quot; (10) "

Here, l represents an arbitrary constant.

The relationship between the absolute nonlinear parameter and the relative nonlinear parameter of the dissimilar material can be expressed by the following equation (11) from the relationships of the equations (8) to (10).

&Quot; (11) "

Here, k 'is a wavenumber correction coefficient as shown in Equation (12), and?' Is a proportional correction coefficient as shown in Equation (13).

&Quot; (12) "

&Quot; (13) "

Where k is the wave number of the object, k ₀ is the wave number of the reference specimen, and α _1,0 and α _2,0 are the proportional correction coefficients indicating the relationship between the displacement of the reference specimen and the received voltage signal.

As described above, if the reference specimen and the object to be inspected are different materials, correction by the coefficients α 'and k' to the ratio of the relative nonlinear parameters can be equal to the ratio of the absolute nonlinear parameters. At this time, the thickness of the dissimilar materials is preferably the same.

&Quot; (13) "

Equation (13) is a method for obtaining a ratio (r _? ) Of a relative nonlinear parameter value for estimating an absolute nonlinear parameter, wherein the relative nonlinear parameter value (? ₀ ') of the reference sample, The ratio r _? Of the relative nonlinear parameter value can be obtained from the nonlinear parameter value? '.

So between the calculated relative non-linear parameter ratio (r _β) and the target object using the absolute nonlinear parameter value (β ₀₎ and the proportional correction factor (α ') and frequency correction factor (k') of the reference sample known to the existing The absolute nonlinear parameter? Can be estimated.

&Quot; (14) "

Equation (14) is a method for estimating an absolute nonlinear parameter of an object, wherein the ratio (r _? ) Of the relative nonlinear parameter values of the reference specimen and the subject obtained through relative nonlinear parameter measurement and the absolute nonlinear parameter It is possible to estimate the absolute nonlinear parameter? Of the subject from the product of the value? ₀ and the wave-number correction coefficient k 'and the proportional correction coefficient?'.

If the two materials to be compared are of the same kind and determine before and after the deterioration, the correction of the proportional correction coefficient and the wave number can be ignored since the difference between the wave number and the impedance between the two materials is negligibly small. And (14) can be expressed by the following equations (15) and (16), respectively.

&Quot; (15) "

&Quot; (16) "

As described above, although the method of estimating the absolute nonlinear parameter from the relative nonlinear parameter is a method capable of easily estimating the absolute nonlinear parameter, the actual displacement is measured by the piezoelectric measuring method or the laser displacement measuring method, The absolute nonlinear parameter of the dissimilar material can be estimated by easily calculating the proportional correction coefficient? 'From the ratio of the amplitude of the reception voltage measured by the contact probe.

Specifically, the displacement amplitudes A ₁ and A ₂ to be measured to obtain the absolute nonlinear parameter and the amplitudes A ₁ 'and A ₂ ' of the received voltage signal measured to obtain the relative nonlinear parameters are converted into a conversion function H and an electric impedance Z The following equations (17) and (18) can be obtained.

&Quot; (17) "

&Quot; (18) "

Using this relationship, the proportional correction coefficient? 'Can be expressed by the following equation (19).

&Quot; (19) "

Here, α 'is a proportional correction coefficient, α _1.0 is a proportional coefficient of the fundamental frequency component of the reference specimen, α _2,0 is a proportional coefficient of the second harmonic component of the reference specimen, and α ₁ is a proportional coefficient , α ₂ is the proportional coefficient of the second harmonic component of the inspection object, H _1,0 is a reference calibration (calibration) of the sample the fundamental frequency component of the parameter, H _{2, 0} are calibration parameters, H of the second harmonic component of the reference sample ₁ is a calibration parameter of a basic frequency component of the object, H ₂ is a calibration parameter of a second harmonic component of the object, and Z is an electrical impedance. At this time, Z can preferably be kept constant at 50? During the experiment.

The equation (19) can be summarized by the following equation (20).

&Quot; (20) "

는 캘리브레이션 과정에서 탐촉자에 인가하는 소스 신호의 전압으로 실험셋업을 일정하게 유지하면 그 값이 동일한바, 분모들이 약분되어 하기 수학식 21처럼 정리될 수 있다.Here, the denominator of each term

Is the voltage of the source signal applied to the probe during the calibration process. If the experimental set-up is kept constant, the denominators can be approximated as shown in Equation (21).

&Quot; (21) "

Here, ω is the frequency, a is the width of the probe, and the current signal I _out (ω) received after propagating the material is constant when ignoring the attenuation in the material. If we divide the terms by the above constants, we can compute the following equation (22).

&Quot; (22) "

In this case, if the velocity change according to the frequency can be neglected, Equation (22) can be summarized as an acoustic impedance z which is a product of density and velocity as shown in Equation (23).

&Quot; (23) "

Here, α 'is the proportional correction coefficient, ρ ₀ is the density of the reference specimen, v ₀ is the ultrasonic velocity of the reference specimen, z _o is the acoustic impedance of the reference specimen, and z is the acoustic impedance of the subject.

That is, the proportional correction coefficient can be calculated from the acoustic impedance ratio of the reference specimen and the subject.

As a result, if the ratio of the acoustic impedance of the dissimilar materials is known, the proportional correction coefficient between the dissimilar materials can be calculated arithmetically, and the ratio of the absolute nonlinear parameters between the dissimilar materials can be easily .

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a block diagram illustrating an apparatus for estimating an ultrasound absolute non-linear parameter using ultrasonic relative nonlinear parameters of dissimilar materials according to an embodiment of the present invention.

3, an ultrasonic absolute nonlinear parameter estimating apparatus 100 using ultrasonic relative nonlinear parameters of dissimilar materials according to an embodiment of the present invention includes an ultrasonic transmitter 110, an ultrasonic receiver 120, a signal processor 130, A correction unit 140, an absolute nonlinear parameter estimator 150, and a controller 160, and the reference specimen and the subject are different materials.

The ultrasound transmitting unit 110 transmits ultrasound signals to the reference specimen and the subject, and the ultrasound signals are preferably a single frequency. At this time, the ultrasonic transmission unit 110 may be arranged in a line or an array so that the ultrasonic transmission unit 110 may be attached to one surface of the object or a position where a path of an ultrasonic beam can be converged.

The ultrasound receiving unit 120 receives the ultrasound signals reflected or transmitted through the reference specimen and the subject, and the ultrasound signals are preferably a plurality of frequencies. At this time, the ultrasonic wave receiver 120 may be arranged in a line or array form, like the ultrasonic wave transmitter 110, and may be attached to one surface of the object to be examined or a path where an ultrasonic beam path can be focused.

When there is a defect in the object, the ultrasound signal radiated into the object undergoes reflection at a point where the defect exists. The ultrasound receiving unit 120 reflects the reflected ultrasound signal at the point where the defect exists . At this time, the reflected ultrasound signal includes information on a defect.

The signal processor 130 measures relative nonlinear parameters between the reference specimen and the subject using the received ultrasound signals.

At this time, the signal processor 130 may measure the relative non-linear parameters of the reference specimen and the subject by separating the received ultrasonic signals into a fundamental frequency component and a harmonic component.

That is, the signal processing unit 130 separates the received ultrasound signals into a fundamental frequency component and a second harmonic component using a bandpass filter, and based on the separated fundamental frequency component and the second harmonic component, The relative non-linear parameter of the reference specimen and the subject can be measured.

4, the signal processing unit 130 includes a fundamental frequency waveform extraction unit 131 and a second harmonic waveform extraction unit 132. The basic frequency waveform extraction unit 131 and the second harmonic waveform extraction unit 132 are connected to the signal processing unit 130, .

The fundamental frequency waveform extractor 131 may separate the fundamental frequency components from the received ultrasound signals using a first band pass filter.

The second harmonic wave extractor 132 may separate the second harmonic components from the received ultrasound signals using a second band pass filter having a band different from the first band pass filter.

The signal processing unit 130 receives the fundamental frequency component and the second frequency component with respect to the time axis from the received ultrasound signal through the fundamental frequency waveform extraction unit 131 and the second harmonic waveform extraction unit 132, It is possible to obtain harmonic components.

The signal processing unit 130 may measure the values of the relative nonlinear parameters of the reference specimen and the subject by applying the basic frequency component and the second harmonic component thus obtained to the following nonlinear parameter equations.

In other words, the signal processor 130 may convert the fundamental frequency component and the second harmonic component into the value of the relative nonlinear parameter using Equation (10).

The correction unit 140 can measure the wave correction coefficient and the proportional correction coefficient of the reference specimen and the subject. At this time, the correcting unit 140 does not operate when the reference specimen and the inspected object are made of the same material, and operates in the case of different materials.

The absolute nonlinear parameter estimator 150 estimates an absolute nonlinear parameter of the subject based on the relative nonlinear parameter, the absolute nonlinear parameter of the reference specimen, the wave number correction coefficient, and the proportional correction coefficient.

Specifically, the absolute nonlinear parameter estimator 150 calculates a ratio of the relative nonlinear parameter of the reference specimen and the relative nonlinear parameter of the object, a ratio of the relative nonlinear parameter measured, an absolute nonlinear parameter of the reference specimen, The absolute nonlinear parameter of the subject can be estimated using the proportional correction coefficient and the wave number correction coefficient.

Here, the ratio of the relative nonlinear parameters may be calculated through an operation of dividing the relative nonlinear parameter of the subject by the relative nonlinear parameter of the reference specimen, and the absolute nonlinear parameter of the subject may be calculated by a ratio of the relative non- Can be estimated by multiplying the absolute nonlinear parameter of the specimen, the proportional correction coefficient calculated from the acoustic impedance ratio of the reference specimen and the wave number correction coefficient, and the wave number correction coefficient.

On the other hand, in the present embodiment, it is preferable that the reference specimen is a reference specimen in which the value of the absolute nonlinear parameter is already known or the absolute nonlinear parameter is measured in advance.

The controller 160 may be configured to estimate the absolute nonlinear parameter of the ultrasonic wave based on the relative nonlinear parameters of the ultrasonic wave according to the embodiment of the present invention, that is, the ultrasonic transmission unit 110, the ultrasonic receiving unit 120, ), The signal processing unit 130, and the absolute nonlinear parameter estimating unit 150, for example.

5 is a flowchart illustrating an ultrasonic absolute non-linear parameter estimation method using an ultrasonic relative non-linear parameter according to an embodiment of the present invention.

Referring to FIG. 5, an ultrasonic signal is first transmitted to the reference specimen and the subject, and the ultrasonic signal is preferably a single frequency.

Next, the ultrasonic signal reflected or transmitted inside the reference specimen and the subject is received (S20), and the ultrasonic signal is preferably a plurality of frequencies.

When a defect exists in the inspection object, the reflected ultrasonic signal inside the inspection object causes reflection at a point where the defect exists, and the reflected ultrasonic signal includes information on the defect.

Next, the relative non-linear parameters of the reference specimen and the subject are measured using the received ultrasonic signal (S30).

In this case, it is possible to measure the relative non-linear parameter between the reference specimen and the subject by separating the received ultrasonic signal into a fundamental frequency component and a harmonic component. Preferably, the harmonic component is a higher harmonic component such as a second harmonic component Do.

Next, a proportional correction coefficient and a waveness correction coefficient of the reference specimen and the subject are measured (S40). However, if the reference specimen and the test object are made of the same material, this step may be omitted and this step may be performed in the case of a different material.

Then, an absolute non-linear parameter of the subject is estimated based on the absolute nonlinear parameter of the reference specimen, the relative nonlinear parameter, the wavenumber correction coefficient, and the proportional correction coefficient.

6 is a flowchart illustrating a method of measuring relative nonlinear parameters of a reference specimen and an object according to an exemplary embodiment of the present invention.

Referring to FIG. 6, a fundamental frequency component can be separated from an ultrasound signal received using a first band-pass filter (S31).

Thereafter, a second harmonic component may be separated from the received ultrasound signal using a second band-pass filter having a different band than the first band-pass filter (S32).

Next, the relative non-linear parameters of the reference specimen and the subject can be measured using the fundamental frequency component and the second harmonic component (S33).

7 is a flowchart illustrating a method of estimating an absolute nonlinear parameter of an object according to an embodiment of the present invention.

Referring to FIG. 7, the ratio of the relative non-linear parameters of the reference specimen and the object is calculated. Then, the absolute non-linear parameter of the subject can be estimated using the ratio of the calculated relative nonlinear parameters, the absolute nonlinear parameter of the reference specimen, the wavenumber correction coefficient, and the proportional correction coefficient.

Specifically, the absolute nonlinear parameter estimator 150 calculates a ratio of the relative nonlinear parameters of the reference specimen and the object, calculates a ratio of the calculated relative nonlinear parameters, an absolute nonlinear parameter of the reference specimen, The absolute nonlinear parameter of the subject can be estimated using the proportional correction coefficient and the wavenesis correction coefficient calculated from the acoustic impedance ratio of the reference specimen and the subject.

Here, the reference specimen is already known in which the value of the absolute nonlinear parameter is already known or the absolute nonlinear parameter is measured in advance. Therefore, in the process of estimating the absolute nonlinear parameter of the subject, it is possible to measure the absolute nonlinear parameter of the reference specimen or to use an already known value immediately.

Embodiments of the present invention include computer readable media including program instructions for performing various computer implemented operations. The computer-readable medium may include program instructions, local data files, local data structures, etc., alone or in combination. The media may be those specially designed and constructed for the present invention or may be those known to those skilled in the computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape, optical recording media such as CD-ROMs and DVDs, magneto-optical media such as floppy disks, and ROMs, And hardware devices specifically configured to store and execute the same program instructions. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like.

As described above, an optimal embodiment has been disclosed in the drawings and specification. Although specific terms have been employed herein, they are used for purposes of illustration only and are not intended to limit the scope of the invention as defined in the claims or the claims. Therefore, those skilled in the art will appreciate that various modifications and equivalent embodiments are possible without departing from the scope of the present invention. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

100: Ultrasonic absolute non-linear parameter estimator
110: Ultrasonic transmitter
120: Ultrasound receiver
130: Signal processor
131: Fundamental frequency waveform extracting unit
132: Second harmonic wave extraction unit
140:
150: Absolute nonlinear parameter estimator
160:

Claims (13)

An ultrasonic transmitter for transmitting an ultrasonic signal to a reference specimen and a subject;
An ultrasound receiver for receiving the ultrasound signals reflected or transmitted inside the reference specimen and the test object;
A signal processing unit for measuring a relative nonlinear parameter between the reference specimen and the subject using the received ultrasonic signal;
A correcting unit for measuring a wave number correction coefficient and a proportional correction coefficient of the reference specimen and the test subject; And
And an absolute nonlinear parameter estimator for estimating an absolute nonlinear parameter of the object based on the relative nonlinear parameter, the absolute nonlinear parameter of the reference specimen, the wave number correction coefficient, and the proportional correction coefficient,
Wherein the reference specimen and the object to be inspected are different materials,
Wherein the proportional correction coefficient is calculated from the acoustic impedance ratio of the reference specimen and the subject,
Wherein the acoustic impedance ratio between the reference specimen and the test subject has a relationship expressed by Equation (1) below. ≪ EMI ID = 1.0 >
[Equation 1]

Here, α 'is the proportional correction coefficient, ρ ₀ is the density of the reference specimen, v ₀ is the ultrasonic velocity of the reference specimen, z _o is the acoustic impedance of the reference specimen, and z is the acoustic impedance of the subject.
delete The method according to claim 1,
Wherein the absolute nonlinear parameter estimator comprises:
Wherein the relative nonlinear parameter is calculated by calculating a ratio of a relative nonlinear parameter between the reference specimen and the object to be measured, and calculating a proportional correction coefficient of the dissimilar material and an ultrasonic absolute nonlinear parameter Estimating device.
The method of claim 3,
The displacement amplitudes A ₁ and A ₁ 'measured to obtain the absolute nonlinear parameter have the relationship as shown in Equation 2, and the amplitudes A ₂ and A ₂ ' of the received voltage signal measured to obtain the relative nonlinear parameter are And calculating the proportional correction coefficient of the dissimilar material and calculating the ultrasonic absolute nonlinear parameter using the relative nonlinear ultrasonic parameter.
[Equation 2]

[Equation 3]

Wherein A ₁ is the displacement amplitude of the fundamental wave component, A ₂ is the displacement amplitude of the _second harmonic component, A ₁ 'is the amplitude of the fundamental wave component of the received voltage signal, A ₂ ' And α ₁ and α ₂ are proportional correction coefficients representing the relationship between the displacement and the received voltage signal.
5. The method of claim 4,
Wherein the relative nonlinear parameter ratio (r _? ) Is calculated by applying the following Equation (4): " (5) "
[Equation 4]

Here, β 'is a relative nonlinear parameter of the object and β ₀ ' is a relative nonlinear parameter of the reference sample.
6. The method of claim 5,
Wherein the relative nonlinear parameter is measured by the following equation (5): " (5) "
[Equation 5]

Here, l is an arbitrary constant.
The method according to claim 6,
Wherein the absolute nonlinear parameter (beta) of the subject is estimated by applying the following equation (6): " (6) "
[Equation 6]

Here, β ₀ is a relative nonlinear parameter of the reference specimen, r _β is a ratio of a relative nonlinear parameter, k 'is a wave number correction coefficient, and α' is a proportional correction coefficient.
8. The method of claim 7,
Wherein the wave correction coefficient k 'has a relation as expressed in Equation (7), and the proportional correction coefficient (?') Has a relationship as expressed by the following Equation (8) An apparatus for estimating ultrasonic absolute nonlinear parameters using relative nonlinear parameters.
[Equation 7]

[Equation 8]

Here, k is the wave number of the object, k ₀ is the wave number of the reference specimen, and α _1,0 and α _2,0 are proportional correction coefficients indicating the relationship between the displacement of the reference specimen and the received voltage signal.
The method according to claim 1,
The reference specimen is a specimen,
Wherein the absolute nonlinear parameter is already known or the reference is an absolute nonlinear parameter measured beforehand. The absolute nonlinear parameter estimating apparatus according to claim 1,
10. The method of claim 9,
The signal processing unit,
Wherein the relative nonlinear parameters of the reference specimen and the subject are measured by separating the received ultrasonic signals into a fundamental frequency component and a harmonic component, and calculating a proportional correction coefficient of the dissimilar material and an ultrasonic wave based on the relative non- Absolute nonlinear parameter estimator.
11. The method of claim 10,
The signal processing unit,
Wherein each of the received ultrasound signals is separated into a fundamental frequency component and a second harmonic component by using a bandpass filter, and the ultrasonic absolute nonlinear parameter estimating apparatus using the ultrasonic relative nonlinear parameters.
12. The method of claim 11,
The signal processing unit,
A fundamental frequency waveform extractor for separating the fundamental frequency components from the received ultrasound signals using a first band pass filter; And
And a second harmonic waveform extractor for separating the second harmonic components from the received ultrasound signals using a second band pass filter having a band different from that of the first band pass filter. Calculation of Proportional Correction Factor and Ultrasonic Absolute Nonlinear Parameter Estimation Using Ultrasonic Relative Nonlinear Parameters.
Transmitting ultrasound signals to the reference specimen and the subject;
Receiving ultrasonic signals reflected or transmitted inside the reference specimen and the object to be inspected;
Measuring relative non-linear parameters of the reference specimen and the test object using the received ultrasonic signal;
Measuring a waveness correction coefficient and a proportional correction coefficient of the reference specimen and the subject;
Estimating an absolute nonlinear parameter of the subject based on the absolute nonlinear parameter of the reference specimen, the relative nonlinear parameter, the wavenumber correction coefficient, and the proportional correction coefficient,
Wherein the reference specimen and the object to be inspected are different materials,
Wherein the proportional correction coefficient is calculated from the acoustic impedance ratio of the reference specimen and the subject,
Wherein the acoustic impedance ratio between the reference specimen and the subject has a relation as expressed by the following Equation (1): < EMI ID = 1.0 >
[Equation 1]

Here, α 'is the proportional correction coefficient, ρ ₀ is the density of the reference specimen, v ₀ is the ultrasonic velocity of the reference specimen, z _o is the acoustic impedance of the reference specimen, and z is the acoustic impedance of the subject.

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