JPH11190724A - Layer inspecting apparatus for laminar composite material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a layer inspecting apparatus for accurately deciding number of layers of a laminar composite material or the like irrespective of a slight roughness of a surface. SOLUTION: The layer inspecting apparatus for a laminar composite material comprises an ultrasonic probe for receiving an ultrasonic wave by the laminar composite material to receive a reflected wave, a probe moving means for moving a probe along a surface of the material at least in one direction, a gate means for obtaining a time exceeding a threshold S of a received signal via the probe in a firs gate Gt as surface wave or the like receiving times T1, T1', and a gate function generator for obtaining a mean value of surface wave or the like receiving times by a single unit scanning of the probe. The gate means decides a range of the received signal for inspecting the layer of a test piece at respective positions of the probe with a mean value of the surface wave or the like receiving time as a reference via a second gate Gf for timingly selecting the range. To decide the gate Gf instead of the mean value of the receiving times, a function obtained by low-pass filter processing the receiving times may be used or a scanning range is divided, and the mean value of the sections may be used in the adjacent division.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a plurality of layers of different kinds of materials, such as a multi-layer of different metals and non-metals or a fiber-reinforced plastic having a plurality of layers of a fiber layer and a resin layer. The present invention relates to a layer inspection device for determining the number of layers of a layered composite material formed as described above.

[0002]

2. Description of the Related Art As for the above-mentioned layered composite material, it is necessary to secure a certain number of layers or more in order to obtain predetermined performance and strength. In order to non-destructively check the number of layers and the properties of the interface after manufacturing a product or a structure, it is desirable to perform an internal inspection using, for example, ultrasonic waves. However, not only layered composite materials but also structural materials often have rough and uneven surface states, and it is difficult to accurately capture surface reflected waves. Therefore, for example, even if an attempt is made to perform tomographic display (so-called B-scope) using ultrasonic waves based on surface reflected waves, it is difficult to determine the number of layers and the interface state of the composite material because the image is disturbed. , The inventors faced.

[0003]

SUMMARY OF THE INVENTION In view of the above-mentioned conventional situation, an object of the present invention is to provide a layer inspection capable of more accurately determining the number of layers of a layered composite material regardless of the surface roughness. It is to provide a device.

[0004]

In order to achieve the above object, a first feature of a layer inspection apparatus according to the present invention is that an ultrasonic probe which makes an ultrasonic wave incident on a layered composite material and receives a reflected wave. Probe moving means for moving the probe in at least one direction along the surface of the layered composite material, and a value of a signal received by the probe within a first gate exceeding a threshold value And a gate function generator for calculating an average value of the reception time such as the surface wave in one unit scan of the probe.
The gate means sets a second gate that temporally selects a range of a reception signal for performing a layer inspection of the layered composite material at each position of the probe based on an average value of reception time such as the surface wave. Is to determine.

On the other hand, a second feature of the layer inspection apparatus according to the present invention is that an ultrasonic probe which irradiates an ultrasonic wave to the layered composite material and receives a reflected wave, and along the surface of the layered composite material, A probe moving means for moving the probe in at least one direction, and a gate for obtaining a time when a value of a signal received by the probe exceeds a threshold in a first gate as a reception time such as a surface wave. Means, by performing low-pass filter processing on a function representing the relationship between each position of the probe and the reception time such as the surface wave in one unit scan of the probe, to make each position of the probe a variable. A gate function generator for obtaining another function, wherein the gate means temporally selects a range of a reception signal for performing a layer inspection of the layered composite material at each position of the probe. Is determined based on the other functions. Lies in the fact.

[0006] A third feature of the layer inspection apparatus according to the present invention is that an ultrasonic probe which irradiates an ultrasonic wave to the layered composite material and receives a reflected wave, and along the surface of the layered composite material. A probe moving means for moving the probe in at least one direction, and a gate for obtaining a time when a value of a signal received by the probe exceeds a threshold in a first gate as a reception time such as a surface wave. Means, and a gate function generator for dividing one unit scan of the probe for each fixed scanning length and obtaining a section average value of the reception time of the surface wave or the like in each section. A second gate for temporally selecting a range of a received signal for performing a layer inspection of the layered composite material at each position of the tentacle is determined based on the section average of sections sequentially adjacent to each section to which the section belongs. It is in.

When the start of the second gate is corrected by the first to third features, the value of the received signal in the second gate is averaged every time in the one unit scan. The function of the received signal in the second gate is normalized, and a first average value of the normalized function is obtained, and a second average value that is a threshold value for determining the number of layers of the layered composite material is calculated. It is preferable that the apparatus further comprises processing means for obtaining the average of the normalized functions in the portion equal to or larger than the first average value.

In addition, the processing means includes a terminal time of the function for obtaining the first and second average values based on a reception time of the reception signal obtained from a thickness expected from the number of layers of the layered composite material. It is desirable that this is determined.

[0009]

Next, an embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, a layer inspection apparatus 1 according to the present invention includes a sensor unit 20 for scanning a two-dimensional plane on a specimen 100 and a driving unit 3.
0, a personal computer 40, and a CRT device 50. The personal computer 40
It is a general-purpose product that incorporates software for implementing specific functions. By operating the personal computer 40, the sensor unit 20 is controlled via the drive unit 30 to transmit and receive ultrasonic waves. Then, the received waveform is processed by the personal computer 40, and the processing result is displayed on the CRT device 50.

The driving unit 30 transmits ultrasonic waves from the probe 21 and drives a pulsar / receiver 31 for receiving ultrasonic waves received from the probe 21 and two driving motors 22. And a motor driver 32 for driving the motor. These pulsers / receivers 3
1 and the motor driver 32 are controlled by a personal computer 40. The trigger 41 and the motor controller 42 in the personal computer 40 are:
It is activated by an input from the control means 43 such as a keyboard. The trigger 41 transmits an ultrasonic wave from the pulser / receiver 31 and activates a first gate of a gate means 44 described later. The motor controller 42
The drive motor 22 is driven via the motor driver 32, and the coordinate signals are sent to the memory 45.

The signal received by the pulsar / receiver 31 is digitized by the A / D converter 33 and then stored in the memory 45, and together with the coordinate information of the probe 21,
The processing result is displayed on the CRT device 50 via the processing means 47. The received wave stored together with the coordinate information in the memory 45 is subjected to signal processing via the processing means 47, and the analysis result is displayed on the CRT device 50 by a B scope display or the like.

As shown in FIG. 2, a sensor unit 20 according to the present invention generally includes a probe 21, a water tank 23 for storing water W, and a device for moving (scanning) the probe 21. A probe moving mechanism 24 is provided. Also,
The test body 100 used in the present embodiment is entirely planar, and is made of a layered composite material 101 made of a resin reinforced with a plurality of layers of a fibrous material. Is covered. This layered composite material 1
01 is in a rough state.

The water tank section 23 has a case 23a having an open lower surface and a rubber film 23 which transmits ultrasonic waves and does not allow water to pass through.
b. The probe moving mechanism 24 has reference numerals 25 to
Slider and guide shown in 27 and two motors 2 ahead
By 2, the surface of the test object 100 is scanned by moving the probe 21 in the X and Y axis directions orthogonal to each other along the surface of the test object 100.

Two Y-axis end guides 26a are attached to the left and right sides of the case 23a in FIG. 2 along the Y-axis direction, and the Y-axis slider 25 is slidable on each of the left and right Y-axis end guides 26a. It is plugged in. As shown in the figure, two X-axis guides 26b are arranged to overlap between the left and right Y-axis sliders 25, 25 in the direction of the paper surface. The two Y-axis guides 26c, 26c also extend between two similar X-axis guides (not shown). The center slider 27 that supports the probe 21 is slidably inserted into both the X-axis guide 26b and the Y-axis guide 26c. Then, the probe 21 is moved along the surface of the test object 100 by moving the X-axis slider and the Y-axis slider 25 by the drive motor 22.

P (t) shown in FIG.
1 is obtained by detecting a signal received in a portion having a smooth surface, only on the minus side. Such detection is performed by the gate unit 44. The processing of the first and second gates in the gate means 44, which will be described later, can be performed with either the Rf waveform before detection or the waveform after detection, but the following description will be made using the waveform after detection.

The first gate Gt realized by the gate means 44 is set to a threshold value S and is set to a time Ta to Tb during which a surface reflected wave from the surface of the layered composite material 101 can be captured. I have. This time Ta, T
b can be determined based on the distance between the probe 21 and the surface of the layered composite material 101 or the like. A time when the function P (t) of the received signal first exceeds the threshold value S within the function P (t) of the received signal is defined as a reception time such as a surface wave T1, and a minute time dT from this time T1. The second gate Gf for storing a signal in the memory 45 corresponding to each coordinate position of the probe 21 up to the end time T3 based on the traced time T2 is operated.

The function P (t) of the received signal shown in FIG. 4 shows a case where a projection is present on the surface of the layered composite material 101. In this case, the time T1 'at which the function P (t) of the received signal exceeds the threshold value S within the first gate Gt is shifted by the minute time dTs, and the second gate Gf is also shifted by the minute time dTs. In such signal processing, since there is almost no displacement inside the layered composite material 101, the second gate G is set based on the times T2 and T2 '.
When the signal in f is displayed on the B scope, the situation shown in FIG. 9A is obtained, and it is difficult to determine the number of layers of the layered composite material 101.

Therefore, first, the first scan is performed, and as shown in FIG. 6, the surface echo moving time f0 (X) is averaged over one scanning unit, so that the gate function generator 46
, A surface echo moving time f1 (X), which is a constant value, is obtained. Next, in the second scanning, the second gate Gf is applied based on the surface echo moving time f1 (X) averaged over the entire surface to thereby obtain the layered composite material 10.
1 has been eliminated. This processing method is hereinafter referred to as “overall averaging method”.

FIG. 9B shows the second gate G set based on the surface echo movement time f1 (X) averaged over the entirety.
This is a function P (t) of the received signal in f. It can be understood that the shading indicating the signal intensity is continuous in the horizontal direction, and the number of layers is easily determined.

Here, the number of layers of the layered composite material 101 determined by the processing means 47 will be described with reference to FIG. As shown in the figure, the second gate Gf at each position of the probe 21 obtained by the overall averaging method
The processing means 47 averages the function P (t) of the received signal in the processing unit 47 for each time in one scanning unit, and obtains the function Q (t) of the normalized received signal. And the normalized function Q
A first average value S1 of (t) is obtained. However, since noise due to local surface disturbance or the like may exceed the first average value S1, determination using only the first average value S1 is not sufficient. Therefore, a second average value S2 is obtained by averaging the normalized function Qt in the portion equal to or greater than the first average value S1, and this second average value S2 is calculated as
It is used as a threshold for determining the number of layers of 1.
In the figure, there are four remarkable peaks, and since this peak exceeds the second average value S2 four times, it can be determined that there are four fiber layers. Since the fiber layer has a remarkable peak as compared with the resin layer and the noise, it is meaningful to obtain the second average value S2.

By the way, the number of fiber layers in the layered composite material 101 is already known from the construction specifications, and it is a problem when the number of layers is smaller than the specified number, but not when the number is larger. . The base member 102
Epoxy resin is thickly applied to the interface with the interface, and the interface can be easily identified. Therefore, the processing means 47 sets the first and second average values S based on the reception time of the reception signal obtained from the thickness expected from the number of layers of the layered composite material 101.
It is preferable to determine the end time Te2 of the normalized function Q (t) for obtaining 1, S2. In FIG. 5, the peak near the end time Te1 of the second gate Gf is attributable to the base member 102, and is not desirably used for calculating the first and second average values S1 and S2. Therefore, it is desirable to use the normalized function Q (t) between the gate start time T0 and the end time Te2 to calculate the first and second average values S1 and S2. Note that, instead of the second gate Gf, a second gate Gh whose termination time is limited to Te2 may be used.

Next, second and third embodiments will be described with reference to FIGS. In these embodiments, the processing in the gate means 44 and the gate function generator 46 is different from that in the first embodiment.

In the second embodiment shown in FIG. 7, the surface echo movement time f2 (X) obtained by subjecting the surface echo movement time f0 (X) to low-pass filtering is used as the basis of the second gate Gf. That is, in the first scan, the gate function generator 46 sets X in the surface echo moving time f0 (X) as a time and passes the signal through a desired low-pass filter, so that the gate function generating section 46 makes the time smaller than the surface echo moving time f0 (X). The surface echo movement time f2 (X) that has been subjected to the low-pass filter processing that changes gradually is obtained. Since the disturbance of the surface echo due to the surface roughness of the layered composite material 101 appears locally at the probe position X, it can be considered as a high-frequency component. Therefore, by passing through a low-pass filter, the disturbance caused by the surface of the layered composite material 101 can be removed. When applying the second gate Gf in the second scan, the gate means 44 uses the surface echo movement time f2 (X) subjected to the low-pass filter processing in correspondence with each probe position X. This processing method is hereinafter referred to as a “filter method”.

On the other hand, the third embodiment shown in FIG. 8 differs from the first and second embodiments in that the correction of the second gate Gf is performed by one scan. The previous gate function generator 4
In step 6, one unit scan of the probe 21 is divided into dt for each constant scan length, and a section average value f3 (x) of the reception time such as a surface wave in each section dt is obtained. The gate means 44 sets the second gate Gf at each position X of the probe based on the section average f3 (x) of the sections sequentially adjacent to the sections to which the second gate Gf belongs. That is, as a reference for correcting the second gate Gf in a certain section A2, the value of the surface echo moving time f3 (X) subjected to the moving average processing in the section A1 adjacent thereto is used. However, since the correction of the second gate Gf cannot be performed in the section on the start side end in one scanning unit,
This division may be excluded from the normalization target of P (t). This processing method is hereinafter referred to as “moving average method”. This processing method is excellent in that the B-scope display and the number of layers can be determined by correcting the second gate in one scan in real time even if the memory capacity is limited.

Finally, the possibility of another embodiment of the present invention will be enumerated. In each of the above embodiments, scanning was performed by moving the probe 21 in parallel with respect to the planar test object. However, the flat surface of the test object 100 may be a curved surface, and becomes parallel to the curved surface. Thus, it is desirable that the probe is also moved in a curved shape. However, the filter method according to the second embodiment and the moving average method according to the third embodiment can be applied to some curved surfaces.
In the first and second embodiments, the second scan is separately performed after obtaining the average value of the reception time such as a surface wave in the first scan. However, all the processes may be performed by a single scan by taking in the signal memory with a gate wider than the second gate and applying the second gate to the memory signal. Also, in the case of using such a wide gate, when using the section in the moving average method of the third embodiment, unlike the third embodiment, even if the average of each section is used in each section, Good. For example, the section average value of section A1 may be used for correcting the second gate Gf in this section.

In the above embodiment, a two-axis scanner for moving the probe 21 along the XY plane is used, but a single-axis scanner for moving the probe 21 in only one direction may be used.

In each of the above embodiments, the specimen 100 having the FRP as the layered composite material 101 was used, but the layered composite material is not limited to the FRP. For example, it is also possible to determine the number of layers of a composite material in which a plurality of different metal layers are formed, or a composite material in which a metal layer and a resin layer are formed. Also,
The test object to be inspected includes FRP manufactured at a factory etc.
In addition to structural products, FRP reinforcing materials for on-site structures are also included.

[0028]

As described above, according to the first to third features of the layer inspection apparatus according to the present invention, the function of the time when the threshold value is first exceeded at the first gate is calculated by the overall average and the low-pass filter. By correcting by processing or moving average, the start time of the second gate at each position of the probe is corrected,
This makes it possible to remove noise due to roughness of the surface of the layered composite material. As a result, the number of layers of the layered composite material can be more accurately determined using an ultrasonic reflection signal capable of accurately grasping the internal state of the layered composite material regardless of the surface roughness.

Further, the number of layers of the layered composite material can be objectively and more accurately determined by using the first and second average values as described above. As described above, by further determining the terminal time of the function normalized from the expected thickness of the layered composite material, it is possible to further improve the accuracy of the determination.

It should be noted that the reference numerals written in the claims are merely for convenience of comparison with the drawings, and the present invention is not limited to the configuration of the attached drawings by the description. .

[Brief description of the drawings]

FIG. 1 is an ethical block diagram of a layer inspection apparatus according to the present invention.

FIG. 2 is a longitudinal sectional view schematically showing a sensor head.

FIG. 3 is a graph showing the relationship between the time of a detected reception signal and the reception intensity at a gentle portion on the surface of the layered composite material.

FIG. 4 shows a rough portion of the surface of the layered composite material in FIG.
FIG.

FIG. 5 is a graph showing a relationship between a time of a received signal normalized and a reception intensity.

FIG. 6 is a graph showing a relationship between a function f0 (X) indicating a surface echo moving time and a surface echo moving time function f1 (X) obtained based on the function f0 (X).

FIG. 7 is a graph showing a relationship between a function f0 (X) indicating a surface echo movement time and a surface echo movement time function f2 (X) obtained based on the function f0 (X).

FIG. 8 is a graph showing a relationship between a function f0 (X) indicating a surface echo moving time and a surface echo moving time function f3 (X) obtained based on the function f0 (X).

FIG. 9 is a so-called B-scope display using the reception signal selected by the second gate Gf, where the horizontal axis represents the probe X, the vertical axis represents the reception time, and the density represents the function P (t) of the reception signal. FIG. 6A shows the case where no correction is applied to the second gate Gf, and FIG. 6B shows the case where the start time of the second gate Gf is corrected using the overall average of FIG. .

[Explanation of symbols]

 1 layer inspection apparatus 20 sensor unit 21 probe 22 drive motor 23 water tank 23a case 23b rubber film 24 probe moving means (scanning means) 25 Y-axis slider 26a Y-axis end guide 26b X-axis guide 26c Y-axis guide 27 Central slider 30 Drive unit 31 Pulser / receiver 32 Motor driver 33 A / D converter 40 Personal computer 41 Trigger 42 Motor controller 43 Control means 44 Gate means 45 Memory 46 Gate function generation unit 47 Processing means 50 CRT device 100 Specimen 101 Layered composite Material 102 Base material W Water Gt First gate Gf Second gate P (t) Function of received signal Q (t) Function of normalized received signal S Threshold f0 (X) Surface echo movement time f1 (X ) Overall averaged surface echo transfer Moving time f2 (X) Moving time of surface echo processed with low-pass filter f3 (X) Moving time of surface echo processed with moving average X Probe position

Claims (5)

[Claims] An ultrasonic probe (21) for irradiating an ultrasonic wave to a layered composite material (101) and receiving a reflected wave, and the probe (21) along a surface of the layered composite material (101). A probe moving means (24) for moving the probe (21) in at least one direction, and the probe (2) in the first gate (Gt).
Gate means (44) for obtaining the time when the value of the received signal according to 1) exceeds the threshold value (S) as reception time (T1, T1 ') such as a surface wave, and one unit scan of the probe (21) And a gate function generator (46) for obtaining an average value (f1 (x)) of the reception time of the surface wave or the like at the position of the probe (21). The second gate (Gf) for temporally selecting the range of the reception signal for performing the layer inspection of the composite material (101) is determined based on the average value (f1 (x)) of the reception time such as the surface wave. Characteristic layer inspection equipment for layered composite materials. 2. An ultrasonic probe (21) for irradiating an ultrasonic wave to a layer composite material (101) and receiving a reflected wave, and the probe (21) along a surface of the layer composite material (101). A probe moving means (24) for moving the probe (21) in at least one direction, and the probe (2) in the first gate (Gt).
Gate means (44) for obtaining the time when the value of the received signal according to 1) exceeds the threshold value (S) as reception time (T1, T1 ') such as a surface wave, and one unit scan of the probe (21) , A function (f0 (x)) representing the relationship between each position (X) of the probe (21) and the reception time of the surface wave or the like is subjected to a low-pass filter processing to thereby obtain a position A gate function generator (46) for obtaining another function (f2 (x)) having (X) as a variable, wherein the gate means (44) is provided for each position (X) of the probe (21). Wherein a second gate (Gf) for temporally selecting a range of a received signal for performing a layer inspection of the layered composite material (101) is determined based on the other function (f2 (x)). Inspection equipment for layered composite materials. 3. An ultrasonic probe (21) for irradiating an ultrasonic wave to a layered composite material (101) and receiving a reflected wave, and said probe (21) along a surface of said layered composite material (101). A probe moving means (24) for moving the probe (21) in at least one direction, and the probe (2) in the first gate (Gt).
Gate means (44) for obtaining the time when the value of the received signal according to 1) exceeds the threshold value (S) as reception time (T1, T1 ') such as a surface wave, and one unit scan of the probe (21) Are divided for each fixed scanning length (dt) and each section (dt)
(F3)
(X)) and a gate function generator (46) for determining
The gate means (44) temporally selects a range of a reception signal for performing a layer inspection of the layered composite material (101) at each position (X) of the probe (21). A layer inspection apparatus for a layered composite material, wherein Gf) is determined based on the section average (f3 (x)) of sections sequentially adjacent to each section to which the section belongs. 4. The function (Pt) of the received signal in the second gate (Gf) is normalized by averaging the value of the received signal in the second gate (Gf) every time in the one unit scan. , The first average value of the normalized function (Qt) (S
1) and a second average value (S2) which is a threshold value for determining the number of layers of the layered composite material (101).
Processing means (47) for determining the average of the normalized function (Qt) in the portion equal to or greater than the first average value (S1).
The layer inspection apparatus for a layered composite material according to any one of claims 1 to 3, further comprising: 5. The processing means (47) is configured to determine the first and second average values (S1 and S2) based on a reception time of the reception signal obtained from a thickness expected from the number of layers of the layered composite material (101). , S2), the normalized function (Q
The layer inspection apparatus for a layered composite material according to claim 4, wherein an end time (Te2) of t) is determined.