JP7585169B2 - Ultrasonic measurement method and ultrasonic measurement device - Google Patents

Description

The present invention relates to an ultrasonic measurement method and ultrasonic measurement device that use an ultrasonic sensor to evaluate the interface condition.

Friction and wear play an important role in the mechanical properties of industrial products, and the state of the interface between the two surfaces is deeply involved. Microscopic phenomena that occur at the interface between the two surfaces are expressed on a macroscopic level as mechanical properties. For this reason, there is a high demand for the direct observation of the interface state.

However, components involved in friction and wear are often opaque, making it difficult to directly observe the interface state.

Therefore, the interface state is evaluated indirectly using non-destructive measurement. JP 2010-60412 A (Patent Document 1) is a background technology in this technical field.

This patent document 1 describes a contact area ratio evaluation method that measures the intensity of a first reflected wave reflected from the tip of the first electrode tip when the first electrode tip is separated from the workpiece W1, measures the intensity of a second reflected wave reflected from the tip of the first electrode tip when the first electrode tip is in contact with the workpiece W1, and calculates the intensity ratio (reflected wave rate) and the proportion of ultrasonic waves incident on the workpiece W1 (incident wave rate) based on the intensities of the first and second reflected waves, and calculates the ratio of the total area of the part to the contact area in contact with the workpiece W1 at the part (contact area ratio) from the correlation between the contact area of the part to which ultrasonic waves can be incident and the incident wave rate that has been determined in advance (see the summary of patent document 1).

JP 2010-60412 A

For dynamic interfaces that repeatedly go into and out of contact, it is sufficient to obtain reference ultrasonic measurement results when the interface is out of contact, and then evaluate the interface when it is in contact, which is what you want to evaluate.

However, because fittings in turbines, pumps, etc. are static interfaces, it is not possible to obtain standard ultrasonic measurement results. Furthermore, when ultrasonic waves are propagated from the outer surface of an industrial product into its interior to evaluate the interface condition, the contact condition between the ultrasonic sensor and the outer surface of the industrial product is affected by paint or unevenness on the outer surface of the industrial product, making it impossible to obtain a stable standard echo intensity.

Patent Document 1 describes a contact area ratio evaluation method that uses an ultrasonic sensor to evaluate the interface condition of a workpiece. However, the contact area ratio evaluation method described in Patent Document 1 determines in advance the correlation between the contact area of a portion to which ultrasonic waves can be incident and the incident wave rate, and does not evaluate the interface condition at a static interface such as a mating portion of a turbine or pump, where it is not possible to obtain standard ultrasonic measurement results.

The present invention provides an ultrasonic measurement method and ultrasonic measurement device that can evaluate the interface state even at a static interface where it is not possible to obtain reference ultrasonic measurement results.

In order to solve the above-mentioned problems, the ultrasonic measurement method of the present invention is an ultrasonic measurement method for evaluating the interface state of a structure having N- 1 static interfaces composed of N (N is a natural number of 2 or more) , comprising the steps of transmitting and receiving ultrasonic waves from an outer surface of the structure, and extracting the echo intensity of the reflected wave from each of the N-1 interfaces _{and the} echo intensity of the reflected wave from a bottom surface of the Nth layer based on the acquired waveform data _{, and} The control/processing unit executes the steps of: expressing _k by Equation 1-3 described later; dividing the echo intensity of the reflected wave from each interface and the echo intensity of the reflected wave from the bottom surface by a diffusion attenuation term; formulating N equations showing the relationship between the divided echo intensity and an interface state index which is directly proportional to the true contact area; dividing the divided echo intensity of the lower side which is the (k+1)th layer by the divided echo intensity of the upper side which is the kth layer ; eliminating the common term I·C2 ^· U ; formulating N-1 equations showing the relationship between the echo intensity and the interface state index; solving the N-1 equations ; expressing the interface state index in terms of echo intensity; and evaluating the interface state of each interface based on the calculated interface state index of each interface.

The ultrasonic measurement device of the present invention is an ultrasonic measurement device for evaluating the interface state of a structure having N- 1 static interfaces composed of N (N is a natural number of 2 or more) , and includes a transmitting/receiving unit for transmitting and receiving ultrasonic waves from an outer surface of the structure , and extracts the echo intensity of the reflected wave from each of the N-1 interfaces and the echo intensity of the reflected wave from a bottom surface of the Nth layer based on waveform data acquired from the transmitting/receiving unit, where 1≦k≦N is the transmitted wave intensity I, the contact factor C, the device factor U, the reflectance at the interface between the kth layer and the k+1th layer Xk _, the transmittance 1−Xk _, the thickness of the kth layer zk _, the effect of the diffusion attenuation term depending on the propagation distance of the ultrasonic waves d(z), and the shape factor of the reflectance at each interface and the bottom surface Srk _, and the echo intensity E of the reflected wave is the interface state index is calculated by a control/processing unit which expresses _k by Equation 1-3 described later, divides the echo intensity of the reflected wave from each interface and the echo intensity of the reflected wave from the bottom surface by a diffusion attenuation term, formulates N equations showing the relationship between the divided echo intensity and an interface state index which is directly proportional to the true contact area, divides the divided echo intensity of the lower side which is the (k+1)th layer by the divided echo intensity of the upper side which is the kth layer , eliminates the common term I·C ² ·U , formulates N-1 equations showing the relationship between the echo intensity and the interface state index, solves the N-1 equations, expresses the interface state index as echo intensity, calculates the interface state index of each interface, and evaluates the interface state of each interface based on the calculated interface state index of each interface , and has a display unit which displays the evaluation result of the interface state index of each evaluated interface .

The present invention provides an ultrasonic measurement method and ultrasonic measurement device that can evaluate the interface state even at a static interface where it is not possible to obtain reference ultrasonic measurement results.

Note that issues, configurations and effects other than those mentioned above will become clearer in the explanation of the examples below.

1A and 1B are explanatory diagrams illustrating the structure of a fitting portion between a shaft and a disk described in this embodiment, where FIG. 1A shows a case where the shaft is hollow, and FIG. 4 is an explanatory diagram for explaining ultrasonic wave propagation in a fitting portion between a shaft and a disk described in the present embodiment. FIG. 1A and 1B are explanatory diagrams illustrating ultrasonic wave propagation in a fitting portion between a shaft and a disk described in this embodiment, where FIG. 1A shows a case where the shaft is hollow, and FIG. FIG. 2 is an explanatory diagram for explaining ultrasonic measurement in the case of three layers described in the present embodiment. 4 is an explanatory diagram for explaining the relationship between the near-field sound field limit distance d _N (path length z) and the propagation attenuation term d(z) of the ultrasonic sensor described in the present embodiment. FIG. FIG. 11 is an explanatory diagram illustrating acquired waveforms in the case of three layers described in this embodiment. 1 is an explanatory diagram for explaining a measurement evaluation flow in the ultrasonic measurement method described in the present embodiment. FIG. 2 is an explanatory diagram illustrating the relationship between the interface state index and mechanical properties described in the present embodiment. FIG. 11 is an explanatory diagram illustrating the relationship between time and an interface state index described in this embodiment. FIG. 2 is an explanatory diagram for explaining an ultrasonic measuring device described in the present embodiment.

The following describes an embodiment of the present invention with reference to the drawings. In each drawing, substantially the same or similar components are given the same reference numerals, and where explanations overlap, they may be omitted.

First, we will explain the structure of the fitting portion between the shaft and the disk described in this embodiment.

Figure 1 is an explanatory diagram explaining the structure of the fitting part between the shaft and the disk described in this embodiment, where (a) shows the case where the shaft is hollow and (b) shows the case where the shaft is solid, and shows a static interface (measurement object) such as the fitting part of a turbine or pump.

In both (a) and (b), the shaft is fitted to the disk to form an integrated structure (industrial product), for example, that transmits power as a rotating body via the fitting surface (interface).

At this time, depending on the surface roughness of the outer surface of the shaft and the inner surface of the disk, there are some areas where the interface fits together without any gaps, and other areas where there is a space filled with air or liquids such as oil or water.

In this example, the interface condition between the shaft and the disk is evaluated using non-destructive ultrasonic measurement.

The shaft and disk may be made of the same or different materials, but in the case of dissimilar materials, reflection occurs due to the difference in acoustic impedance between the materials, so correction is made using the known material density and sound speed (acoustic impedance). In this example, this correction is easy, so the case of homogeneous materials will be explained.

Next, we will explain the ultrasonic wave propagation in the fitting portion between the shaft and the disk described in this embodiment.

Figure 2 is a schematic diagram illustrating ultrasonic wave propagation at the fitting portion between the shaft and the disk described in this embodiment.

As shown in Figure 2, ultrasonic waves pass through the interface between the shaft and disk if they are tightly fitted together. On the other hand, as shown in Figure 2, in areas where there is space at the interface between the shaft and disk, if nonlinear phenomena are not taken into account, ultrasonic waves are almost completely reflected if air is present, and more than 90% are reflected if liquid is present, with almost no transmission.

In other words, in a mating part, the larger the area of the part that fits without gaps (the part that fits completely), also known as the true contact surface, the easier it is for ultrasonic waves to pass through, and the smaller the area of the mating part, the harder it is for ultrasonic waves to pass through.

Next, we will explain ultrasonic propagation in the fitting area between the shaft and disk described in this embodiment.

Figure 3 is an explanatory diagram that explains ultrasonic wave propagation at the fitting portion between the shaft and the disk described in this embodiment, where (a) shows the case where the shaft is hollow, and (b) shows the case where the shaft is solid.

At static interfaces where it is not possible to obtain standard ultrasonic measurement results, the interface condition is evaluated using ultrasonic measurements.

As shown in Figure 3(a), even if there are two media, a shaft and a disk, if it is hollow, the ultrasound propagates through two layers between the shaft and the disk (two-layer system) and one interface 1 (fitting portion) between the shaft and the disk. On the other hand, as shown in Figure 3(b), even if there are two media, a shaft and a disk, if it is solid, the ultrasound propagates through three layers between the shaft and the disk (three-layer system) and two interfaces 1 (fitting portion) and interface 2 (fitting portion) between the shaft and the disk.

In addition, in the case of a three-media mating area, if the shaft is hollow, the ultrasonic waves will propagate through three layers and two interfaces, and if the shaft is solid, five layers and four interfaces. Therefore, when evaluating the interface condition using ultrasonic measurements, it is important to consider a multi-layer system.

Here, we consider a simple evaluation of the interface condition of N-1 directly below the ultrasonic sensor by irradiating ultrasonic waves from the outer surface of the first layer into the fitting portion, which is the Nth layer (N is a natural number equal to or greater than 2) in ultrasonic measurement, and acquiring a received waveform (acquired waveform) corresponding to the distance to the bottom surface of the Nth layer.

The echo intensity of the wave reflected from the interface between the first and second layers is defined as _E1 , the echo intensity of the wave reflected from the interface between the second and third layers as _E2 , and where 1≦k≦N, the echo intensity of the wave reflected from the interface between the kth and k+1th layers as _Ek , and the echo intensity of the wave reflected from the bottom surface of the Nth layer as _EN , and these are formulated.

_E1 , _E2 , _Ek , and _EN can be expressed as equations 1-1, 1-2, 1-3, and 1-4, respectively.

....

....

Here, the transmitted wave intensity is I, the contact factor is C, the device factor is U, the reflectance at the interface between the kth layer and the (k+1)th layer is _Xk , the transmittance is 1- _Xk , the thickness of the kth layer is _zk , the effect of diffusion attenuation (diffusion attenuation term) due to the propagation distance is d(z), and the shape factor of the reflectance at the interface and the bottom surface is _Srk .

Note that various losses, such as scattering losses and viscous losses, that occur when ultrasonic waves pass through an interface, as well as scattering attenuation that occurs when ultrasonic waves propagate through a material, are ignored.

In addition, d(z) can be selected to be a frequency that is free of scattering attenuation due to the material, and can be theoretically determined at distances sufficiently farther than the near-field limit distance of the ultrasonic sensor being used.

Furthermore, when the shape factor _Sr due to the shape of each layer is a cylinder that is sufficiently large compared to the aperture circle of the ultrasonic sensor and can be regarded as equivalent to a plane, _Sr = 1. Furthermore, even when there is an effect of curvature, it can be theoretically found because the mating portion has a simple shape such as a cylinder or a sphere.

Moreover, the common term K (K=IC ² U) can be eliminated by dividing each equation by the other, that is, by calculating E _k /E _k+1 .

In other words, if the echo intensities E ₁ to E _N can be obtained, then an equation for N-1 E _k /E _k+1 , which is the same as the number of unknowns, N-1, can be obtained. Therefore, X _k and 1-X _k, which are closely related to each interface state, can be obtained.

Of course, since _Xk is defined as reflectance and 1- _Xk is defined as transmittance, the obtained value is mainly determined by the true contact area ratio (real contact area ratio), and includes the influence of air or liquid filling the space at the interface.

The various losses mentioned above are small and can be ignored, and the prerequisite is to select a frequency that does not cause scattering attenuation.

Hereinafter, 1-X _k, which is directly proportional to the true contact area, will be referred to as the interface condition index. The interface condition index is a value close to the true contact area ratio at the interface directly below the installation position of the ultrasonic sensor. Therefore, it is closely related to external forces such as torque and tension, and can be used for quality control and monitoring of mating parts.

Next, we will explain the ultrasonic measurement for the three layers described in this example.

Figure 4 is an explanatory diagram that illustrates the ultrasonic measurement for the three layers described in this embodiment.

Here, we will specifically show a case where an ultrasonic sensor is brought into contact with a structure containing a measurement target, as shown in Figure 4, to measure the interface state of three parallel plates.

Since the sensor is made up of three parallel plate layers, all shape factors _Sr are _Srk = 1 (k = 1, 2, 3). The ultrasonic sensor is an ultrasonic sensor in a frequency band where there is no scattering attenuation due to the material. The thickness of the first layer is _z1 , the thickness of the second layer is _z2 , and the thickness of the third layer is _z3 . The reflectance at the interface between the first and second layers is _X1 , the transmittance is 1- _X1 , and the reflectance at the interface between the second and third layers is _X2 , and the transmittance is 1- _X2 .

Next, the relationship between the near field limit distance d _N (path length z) and the propagation attenuation term d(z) of the ultrasonic sensor described in this embodiment will be described.

FIG. 5 is an explanatory diagram for explaining the relationship between the near field limit distance d _N (path length z) and the propagation attenuation term d(z) of the ultrasonic sensor described in this embodiment.

The horizontal axis of FIG. 5 is the path length (time × ultrasonic velocity) z (e.g., mm) indicating the near-field sound field limit distance _dN of the ultrasonic sensor, and the vertical axis of FIG. 5 is the propagation attenuation term d(z) (e.g., V) indicating the influence of the diffusion attenuation term d(z) due to the propagation distance.

As shown in Fig. 5, an ultrasonic sensor is selected whose near-field sound field limit distance ( _dN = ^A2 /(4λ)), which can be calculated from the wavelength (λ) of the ultrasonic sensor and the area (A) of the circular aperture of the ultrasonic sensor, is equal to or less than half the thickness of the first layer. As shown in Fig. 5, the transmission and reception strength of the ultrasonic sensor tends to be halved according to the path length. For this reason, for example, d( _z1 ) = 1 can be standardized and each d( _zk ) can be calculated by Equation 2.

Then, if the values obtained by correcting each echo intensity with the diffusion attenuation term d(z) are defined as E1', E2', and E3', respectively, E1', E2', and E3' can be expressed as Equation 3-1, Equation 3-2, and Equation 3-3, respectively.
E ₁ '= E ₁ /d(z ₁ ) = K・X ₁ ...Formula 3-1
E ₂ '= E ₂ /d(z ₁ +z ₂ ) = K・(1-X ₁ ) ²・X ₂ ...Formula 3-2
E ₃ '= E ₃ /d(z ₁ +z ₂ +z ₃ )・Sr = K・(1-X ₁ ) ²・(1-X ₂ ) ² ...Formula 3-3
From this equation, two expressions are selected and divided by each other to eliminate the common term K.

And, if we define E ₁₂ '=E ₂ '/E ₁ ' and E ₂₃ '=E ₃ '/E ₂ ', we get equations with unknowns 1-X ₁ and 1-X _2. When we solve these equations, we get Equation 4-1 and Equation 4-2.
(1-X ₁ ) = -E ₁₂ '/(2X ₂ )+(4X ₂・E ₁₂ '+E ₁₂ ' ² ) ^1/2 /(2X ₂ )...Formula 4-1
(1- _X2 ) = 1-1/2・(2+ _E23 '-( _E23 '・(4+ _E23 ')) ^1/2 )・・・Equation 4-2
Based on equations 4-1 and 4-2, the unknowns 1- _X1 and 1- _X2 are found. Specifically, first, 1- _X2 is expressed as the value of _E23 based on equation 4-2. Next, using _X2 expressed as the value of _E23 , 1- _X1 is expressed as the values of _E12 and _E23 based on equation 4-1.

That is, by measuring the echo intensity _E1 from the interface between the first and second layers, the echo intensity _E2 from the interface between the second and third layers, and the echo intensity _E3 from the bottom surface of the third layer, it is possible to obtain the interface state index 1- _X1 at the interface between the first and second layers and the interface state index 1- _X2 at the interface between the second and third layers.

And even if there are four or more layers, as in the case of three layers, the interface state index between the layers closest to the bottom surface is first calculated, and this value is then substituted in turn to calculate the interface state index between each layer in turn. This is because, for the layers closest to the bottom surface, the index is divided by the bottom surface strength, and the effect of penetration through layers other than the layer closest to the bottom surface is cancelled out.

In this way, according to this embodiment, it is possible to evaluate the interface condition even at a static interface where it is not possible to obtain reference ultrasonic measurement results.

Next, we will explain the waveforms obtained in the three-layer case described in this example.

Figure 6 is an explanatory diagram illustrating the waveforms obtained in the case of three layers described in this embodiment.

In other words, FIG. 6 shows the waveform obtained when measuring with an ultrasonic sensor. Note that the horizontal axis in FIG. 6 is the path length z (e.g., mm), and the vertical axis in FIG. 5 is the reception intensity E (e.g., V).

As shown in FIG. 6, the echo intensity from the interface between the first and second layers is obtained as _E1 , the echo intensity from the interface between the second and third layers is obtained as _E2 , and the echo intensity from the bottom surface of the third layer is obtained as _E3 .

Although multiple echoes are also acquired, the multiple echo intensities are much smaller than the echo intensities E ₁ , E ₂ , and E ₃ when determining the interface state index, and therefore may basically be ignored.

Specifically, to correct each echo intensity with the diffusion attenuation term d(z), the thickness of the first layer is set to 100 mm, the thickness of the second layer to 80 mm, and the thickness of the third layer to 110 mm, and the interface condition is evaluated by ultrasonic measurement at four different positions (measurement points) No. 1 to No. 4 on the outer surface.

The interface state is evaluated based on the ultrasonic measurement results (echo intensity _E1 , echo intensity _E2 , echo intensity _E3 ) by using Equations 3-1, 3-2, 3-3, 4-1, and 4-2. The evaluation results of the interface state based on the ultrasonic measurement results (interface state index 1- _X1 , interface state index 1- _X2 ) are shown in Table 1. In Table 1 (obtained interface state index results for three layers), echo intensity _E1 , echo intensity _E2 , and echo intensity _E3 are shown as percentages.

As shown in No. 1 of Table 1, when the echo intensity of _E3 is not acquired, the interface state index 1- _X2 between the second and third layers is 0 (non-contact).

Also, as shown in No. 2 of Table 1, even when the echo intensity of _E3 is acquired as small as 1%, the interface state index 1- _X2 between the second and third layers is acquired as 0.39.

Furthermore, as shown in No. 3 and No. 4 in Table 1, when the ratios of echo intensity E ₁ , echo intensity E ₂ , and echo intensity E ₃ are the same, interface state index 1-X ₁ and interface state index 1-X ₂ are the same.

That is, in both cases of No. 3 and No. 4 in Table 1, the echo intensity E ₁ : echo intensity E ₂ : echo intensity E ₃ is 5:4:2, and the interface state index 1-X ₁ is 0.86 and the interface state index 1-X ₂ is 0.77, which are the same.

As such, according to this embodiment, it can be seen that the influence of factors such as the settings of the flaw detector, the gain of the device, and unstable contact properties does not affect the interface condition index.

In this embodiment, unless E _k (1≦k≦N−1) is 0%, division by zero does not occur, so that the interface state index 1−X _k can always be obtained.

Moreover, according to this embodiment, even in a structure having a static fitting portion such as a shrink fit in which loading and unloading are difficult, the interface state index 1-X _k can be obtained by using the echo intensity that can be stably obtained, without obtaining a reference ultrasonic measurement result.

Moreover, according to this embodiment, the variation in the range of values obtained between the layers is small, and the interface state index 1-X _k is expressed in the range of 0 to 1, so that the interface state between the layers can be evaluated uniformly.

In addition, according to this embodiment, even if the surface condition with which the ultrasonic sensor comes into contact is not constant, there is no need to repeatedly transmit and receive ultrasonic waves, and the time required to evaluate the interface condition can be shortened.

In this way, in this embodiment, by formulating equations for the echo intensity from each interface (between each layer) and the echo intensity from the bottom surface, and canceling the factors of the flaw detector settings, the device gain, and unstable contact, and solving the equations, it is possible to estimate an interface condition index that is closely related to the interface condition without obtaining a reference echo intensity.

In other words, in this embodiment, in the case of an N-layer structure (a structure having (N-1) interfaces), ultrasonic waves are transmitted and received from one surface (one of the faces), and N equations are established that show the relationship between the echo intensity corrected by the diffusion attenuation term d(z) and the interface condition index, using the echo intensity from the (N-1) interface and the echo intensity from the bottom surface after passing through the N layers.

Then, for the two adjacent layers, the echo intensity on the lower side (closer to the bottom) is divided by the echo intensity on the upper side (farther from the bottom), the common term K is eliminated (cancelling the flaw detector setting factors, device gain, and unstable contact factors), and N-1 equations are established.

First, the interface state index is calculated for the interface between the N layer and the N-1 layer, and based on the calculated interface state index, the interface state index is calculated for the interface between the N-1 layer and the N-2 layer, and then the interface state index is calculated for the interface between the N-2 layer and the N-3 layer, the interface between the N-3 layer and the N-4 layer, and so on.

This allows the interface condition index at each interface to be determined, and the interface condition at each interface to be evaluated.

In structures with static mating parts, the interface condition of the mating part affects mechanical properties (physical quantities) such as maximum torque and slippage. However, since the interface condition of this mating part cannot be measured (observed) directly, it must be indirectly evaluated (estimated) using ultrasonic measurements.

For dynamic interfaces that repeatedly go in and out of contact, the ultrasonic reflected wave intensity is obtained when the reference interface is not in contact, and the ultrasonic reflected wave intensity is obtained when the interface to be evaluated is in contact, and the interface condition can be evaluated by comparing these. However, this method cannot be used for structures that have static mating parts.

In this embodiment, ultrasonic waves are transmitted and received from the outer surface, and based on the acquired waveform data (acquired waveform), the echo intensity of the reflected wave from each interface and the echo intensity of the reflected wave from the bottom surface are corrected according to the propagation distance and shape factor, and the interface condition index can be calculated by solving the equation.

By monitoring the interface condition index, it is possible to evaluate the integrity of the structure during operation, correlate the interface condition index with mechanical properties, and manage the quality of the structure during manufacturing.

Next, we will explain the measurement evaluation flow for the ultrasonic measurement method described in this embodiment.

Figure 7 is an explanatory diagram illustrating the measurement evaluation flow in the ultrasonic measurement method described in this embodiment.

The ultrasonic measurement method described in this embodiment has the following steps (procedures):

At S001, evaluation of the interface condition begins using ultrasonic measurements.

In S002, multiple measurement points (total X points) are set on the outer surface of the structure.

In S003, an ultrasonic sensor is placed at the set measurement point i (i≦X) and measurement begins.

In S004, first, transmission and reception of the ultrasonic sensor is started. Note that, when receiving ultrasonic waves and acquiring waveform data, it is preferable to adjust the contact of the ultrasonic sensor so that the echo intensity of the bottom surface of the structure is maximized.

Next, in a control/processing unit (computer) of the ultrasonic measuring device described later, echo intensities (peak values) E _k (1≦k≦N) of the respective interfaces and bottom surfaces are extracted from the acquired waveform data.

Next, in a control/processing unit of the ultrasonic measuring device described later, each _Ek is corrected based on the thickness _zk of each layer, the shape factor _Srk of each layer, and the material density and sound speed (acoustic impedance) of each layer.

Next, in a control/processing unit of the ultrasonic measuring device described later, an equation for the acquired N echo intensities E _k is solved. When solving the equation, the above-mentioned formulas 1-1, 1-2, 1-3, and 1-4 are used to set up N equations, E _k-1 /E _k is calculated, the common term K is eliminated, and the N-1 equations are solved to obtain the interface state index 1-X _k-1 .

Then, the obtained interface state index 1-X _k-1 (1≦k≦N) is output.

At S005, measurement of measurement point i ends.

In S006, it is determined whether or not measurements have been completed (i=X) at all the set measurement points. If measurements have been completed at all measurement points, proceed to S007, and if measurements have not been completed at all measurement points, return to S003 and repeat S004 and S005.

In S007, since only a very limited interface state directly below the ultrasonic sensor can be evaluated, it is preferable to take a large number of measurement points and calculate the average and deviation, if necessary.

In S008, for example, as shown in FIG. 8 described later, the interface condition index may be associated with the mechanical properties to manage the quality of the structure during manufacturing. In addition, for example, as shown in FIG. 9 described later, the change over time of the interface condition index may be monitored to evaluate the soundness of the structure during operation.

In S009, the evaluation of the interface condition using ultrasonic measurements is completed.

In other words, the ultrasonic measurement method described in this embodiment evaluates the interface state of a structure that has N-1 static interfaces consisting of N layers.

This ultrasonic measurement method includes the steps of transmitting and receiving ultrasonic waves from the outer surface of the structure, extracting the echo intensity of the reflected wave in a path length corresponding to from each of the N-1 interfaces to the outer surface of the structure and the echo intensity of the reflected wave in a path length corresponding to from the bottom surface of the N layers after passing through the N layers to the outer surface of the structure based on the acquired waveform data, dividing the echo intensity of the reflected wave from each of the interfaces and the echo intensity of the reflected wave from the bottom surface by a diffusion attenuation term that depends on the propagation distance of the ultrasonic waves, formulating N equations that show the relationship between the divided echo intensity and the interface condition index that is directly proportional to the true contact area, dividing the divided echo intensity on the lower side by the divided echo intensity on the upper side, eliminating the common term, solving the N-1 equations that show the relationship between the echo intensity and the interface condition index, expressing the interface condition index in terms of echo intensity, and calculating the interface condition index at each interface, and evaluating the interface condition at each interface based on the calculated interface condition index at each interface.

This makes it possible to evaluate the interface condition even at static interfaces where it is not possible to obtain standard ultrasonic measurement results.

Next, the relationship between the interface state index and the mechanical properties described in this embodiment will be described. FIG. 8 is an explanatory diagram for explaining the relationship between the interface state index and the mechanical properties described in this embodiment. As shown in FIG. 8, based on the relationship between the interface state index and the mechanical properties of the structure obtained in advance, the obtained interface state index can be associated with the mechanical properties of the structure, and this can be used for the quality of the structure during manufacturing. In other words, in this embodiment, the obtained interface state index of each interface is associated with the mechanical properties of the structure, and the obtained interface state index of each interface is used for quality control of the structure during manufacturing.

Next, the relationship between time and the interface state index described in this embodiment will be explained. Figure 9 is an explanatory diagram explaining the relationship between time and the interface state index described in this embodiment. As shown in Figure 9, the change over time in the interface state index in the structural part can be monitored, and this can be used to evaluate the soundness of the structure during operation. In other words, in this embodiment, the obtained interface state index of each interface is monitored based on the change over time (measurement date and time), and the obtained interface state index of each interface is used to evaluate the soundness of the structure during operation.

Next, we will explain the ultrasonic measurement device described in this embodiment.

Figure 10 is an explanatory diagram illustrating the ultrasonic measurement device described in this embodiment.

The ultrasonic measurement device described in this embodiment has a measurement unit 1 having an ultrasonic sensor 2 that transmits and receives ultrasonic waves to and from a structure (subject) 3, a transmission/reception unit (pulsar/receiver) 4 that transmits and receives signals generated by the ultrasonic sensor 2 and processes the signals generated by the ultrasonic sensor 2 and the reflected wave signals, a control/processing unit (computer) 5, a display unit 6, and an input device 7.

The measurement unit 1 includes an ultrasonic sensor 2 and a gripping mechanism (not shown) that grips the ultrasonic sensor 2.

The transmitter/receiver 4 transmits and receives ultrasonic waves based on the values of the measurement conditions (shape of the transmission pulse, voltage, repetition frequency, amplification value, etc.) stored in the memory device 51 of the control/processing device 5. These may also be input from the input device 7.

The received waves in the transmitter/receiver unit 4 are amplified and A/D converted, and are acquired as waveform data, which is then stored in the storage device 51 of the processing/control unit 5.

The control/processing unit 5 has a storage device 51, a processing device 52, and a transmission/reception control device 53.

The storage device 51 has a database (DB) for measurement evaluation and a database (DB) for status management.

The database for measurement evaluation stores information such as measurement points, measurement conditions, the number of layers and their thicknesses, shape factors required to correct echo intensity, correction items, waveform data, and an algorithm for adjusting the equation that calculates the interface condition index according to the number of layers that has been set.

The interface condition index calculated based on the measurement results is stored in the condition management database in association with the measurement date and time, measurement point, and mechanical characteristics.

The processing device 52 extracts the echo intensity from the received waveform and calculates the interface state index from the extracted echo intensity using the stored algorithm. In correcting the diffusion attenuation term d(z), the layer thickness may be input in advance as shape information of the structure 3, or the position of the received wave may be evaluated from the received waveform as necessary, and the layer thickness may be evaluated and input.

The transmission/reception control device 53 controls the shape, voltage, pulse width, repetition frequency, amplification value, sampling frequency, data storage timing, etc. of the transmission pulse.

The display unit 6 displays the control values for transmitting and receiving ultrasonic waves, values required for the evaluation conditions, the measured raw waveform, the calculation results of the interface state index, the relationship (graph) between the interface state index and the mechanical properties as shown in Figures 8 and 9, and the relationship (graph) between time (measurement date and time) and the interface state index. The display unit 6 also displays the evaluation results (table) of the interface state based on the ultrasonic measurement results as shown in Table 1.

The input device 7 is a general input means (input device) such as a keyboard, mouse, or touch panel.

The ultrasonic measurement device may have a scanner 8 for scanning the ultrasonic sensor 2, although this is not essential. The control and processing unit 5 also has a scanner control device 54 that controls the scanner 8.

The scanner 8 fixes, scans, and moves the ultrasonic sensor 2. The scanner control device 54 scans and moves the ultrasonic sensor 2 and the structure 3 at the set timing and range based on the scanning conditions stored in the processing and control unit 5, and changes the relative positional relationship between the ultrasonic sensor 2 and the structure 3.

The present invention is not limited to the examples described below, and includes various modified examples. For example, the examples described below are specifically described in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all of the configurations described.

It is also possible to replace part of the configuration of one embodiment with part of the configuration of another embodiment. It is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to delete part of the configuration of each embodiment, add part of another configuration, and replace it with part of another configuration.

1: Measurement unit, 2: Ultrasonic sensor, 3: Structure, 4: Transmitter/receiver unit, 5: Control/processing unit, 6: Display unit, 7: Input device, 8: Scanner, 51: Storage device, 52: Processing device, 53: Transmission/reception control device, 54: Scanner control device.

Claims (10)

An ultrasonic measurement method for evaluating an interface state of a structure having N- 1 static interfaces composed of N layers (N is a natural number equal to or greater than 2) , comprising:
transmitting and receiving ultrasonic waves from an outer surface of the structure, and extracting, based on the acquired waveform data, the echo intensity of the reflected wave from each of the N-1 interfaces and the echo intensity of the reflected wave from the bottom surface of the Nth layer;
With 1≦k≦N, the transmitted wave intensity is I, the contact factor is C, the device factor is U, the reflectance at the interface between the kth layer and the (k+1)th layer is Xk _, the transmittance is 1−Xk _, the thickness of the kth layer is zk _, the influence of the diffusion attenuation term depending on the propagation distance of the ultrasonic wave is d(z), and the shape factor of the reflectance at each of the interfaces and the bottom surface is Srk, the echo intensity Ek of the reflected wave _{is expressed} by the following formula:

a step of dividing the echo intensity of the reflected wave from each of the interfaces and the echo intensity of the reflected wave from the bottom surface by the diffusion attenuation term, formulating N equations showing the relationship between the divided echo intensity and an interface state index that is directly proportional to a true contact area, dividing the divided echo intensity of the lower side , which is the (k+1)th layer, by the divided echo intensity of the upper side , which is the kth layer , eliminating the common term I·C ² ·U , formulating N−1 equations showing the relationship between the echo intensity and the interface state index, solving the N−1 equations, expressing the interface state index in terms of echo intensity, and calculating the interface state index of each interface;
evaluating an interface state of each interface based on the calculated interface state index of each interface;
The ultrasonic measuring method is characterized in that the control and processing unit executes the above steps . 2. The ultrasonic measurement method according to claim 1,
An ultrasonic measurement method characterized by correcting the echo intensity of the reflected wave from each of the extracted N-1 interfaces and the echo intensity of the reflected wave from the bottom surface of the Nth layer based on shape factors of the reflectivity at each of the interfaces and the bottom surface, and formulating the N equations. 2. The ultrasonic measurement method according to claim 1,
An ultrasonic measurement method characterized in that the calculated interface condition index of each interface is associated with the mechanical properties of the structure, and the calculated interface condition index of each interface is used for quality control of the structure during manufacturing. 2. The ultrasonic measurement method according to claim 1,
An ultrasonic measurement method comprising the steps of: monitoring the calculated interface condition index of each interface; and using the calculated interface condition index of each interface for evaluating the soundness of a structure during operation. An ultrasonic measurement device for evaluating an interface state of a structure having N- 1 static interfaces composed of N layers (N is a natural number equal to or greater than 2) ,
A transceiver unit that transmits and receives ultrasonic waves from an outer surface of the structure;
Extracting echo intensities of the reflected waves from each of the N-1 interfaces and the reflected wave from the bottom surface of the Nth layer based on the waveform data acquired from the transmitting/receiving unit ;
With 1≦k≦N, the transmitted wave intensity is I, the contact factor is C, the device factor is U, the reflectance at the interface between the kth layer and the (k+1)th layer is Xk _, the transmittance is 1−Xk _, the thickness of the kth layer is zk _, the influence of the diffusion attenuation term depending on the propagation distance of the ultrasonic wave is d(z), and the shape factor of the reflectance at each of the interfaces and the bottom surface is Srk, the echo intensity Ek of the reflected wave _{is expressed} by the following formula:

Dividing the echo intensity of the reflected wave from each of the interfaces and the echo intensity of the reflected wave from the bottom surface by the diffusion attenuation term, formulating N equations showing the relationship between the divided echo intensity and an interface state index that is directly proportional to the true contact area, dividing the divided echo intensity of the lower side, which is the (k+1)th layer, by the divided echo intensity of the upper side , which is the kth layer , eliminating the common term I·C ² ·U , formulating N−1 equations showing the relationship between the echo intensity and the interface state index, solving the N−1 equations, expressing the interface state index in terms of echo intensity, and calculating the interface state index of each interface,
a control and processing unit that evaluates an interface state of each interface based on the calculated interface state index of each interface ;
a display unit that displays an evaluation result of an interface state index of each evaluated interface;
An ultrasonic measuring device comprising: 6. The ultrasonic measuring device according to claim 5,
The control/processing unit is characterized in having a memory device that stores an algorithm for adjusting an equation for calculating an interface state index according to the set number of layers and layer thicknesses, a shape factor required for correcting echo intensity, and the set number of layers. 7. The ultrasonic measuring device according to claim 6,
The ultrasonic measuring device according to claim 1, wherein the memory device stores the interface condition index calculated based on the measurement result in association with a mechanical property. 7. The ultrasonic measuring device according to claim 6,
The ultrasonic measuring device according to claim 1, wherein the storage device stores the interface state index calculated based on the measurement result in association with the measurement date and time. The ultrasonic measuring device according to claim 7,
The ultrasonic measuring device according to claim 1, wherein the display unit displays a relationship between the interface condition index and the mechanical property. 9. The ultrasonic measuring device according to claim 8,
The ultrasonic measuring device according to claim 1, wherein the display unit displays a relationship between the interface condition index and the measurement date and time.

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