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JP2014051811

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This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
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DESCRIPTION JP2014051811
Abstract: PROBLEM TO BE SOLVED: To provide a method for easily and reliably determining
breakage of a finger joint. SOLUTION: A sound pressure signal of a sound generated when a face
plate of a finger joint installed on a road bridge is vibrating is collected using a sound collecting
means provided with a plurality of microphones, Among the pressure signals, the sound source
direction of the sound pressure signal in which the attenuation time of the sound in the damage
determination band, which is a preset frequency band, is equal to or longer than the reference
attenuation time is estimated. It combines the direction data and the image data of the face plate
to create a damage determination image in which a figure indicating the sound source direction
is drawn, and identifies the damaged part of the finger joint from the created damage
determination image I made it. [Selected figure] Figure 9
Failure judgment method of finger joint
[0001]
The present invention relates to a method of determining whether a finger joint installed on a
bridge such as an expressway is broken.
[0002]
Conventionally, in bridges such as expressways, in order to absorb expansion and contraction in
the longitudinal direction of the bridge girder due to heat, a comb-type expansion and
contraction device called finger joint 50 as shown in FIG. 10 is installed between the bridge
girders. (See, for example, Patent Document 1).
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1
Each of the finger joints 50 supports the face plate 51 on which the comb teeth 51 a are formed,
the web plate 52 supported from the side opposite to the side on which the comb teeth 51 a of
the face plate 51 are formed, and the bridge girder 60 from the web plate 52. A pair of joint
members 50A and 50B including a plurality of rib plates 53 protruding to the side, and the comb
teeth 51a of the face plate 51 constituting each joint member 50A and 50B are engaged with a
gap By installing it on the bridge, it absorbs the expansion and contraction in the longitudinal
direction of the bridge girder 60 due to the temperature difference. The face plate 51, the web
plate 52 and the rib plate 53 are made of steel and are assembled by welding. Moreover, the
bridge girder 60 side of each joint member 50A, 50B is integrated with the concrete of the
bridge girder 60.
[0003]
JP 2003-64613 A
[0004]
Since the finger joint 50 directly receives the repeated action of the wheel load due to the
traveling of the vehicle, the face plate 51 may break.
It is considered that this is because the surface side portion of the concrete of the bridge girder
60 integrated with the face plate 51 is scraped off and the face plate 51 easily vibrates, and as a
result, a fatigue crack occurs in the face plate 51. If the fatigue cracks of the face plate 51 can be
grasped at the initial stage, the finger joints 50 can be replaced before the face plate 51 breaks,
so the traveling safety of the expressway can be improved, but at the initial stage, Under the
present circumstances, the fatigue crack of the face plate 51 can not be grasped only by visual
observation of the surface. Then, although the method of inspecting the existence of the fatigue
crack of face plate 51 using an ultrasonic sensor, AE sensor, etc. which are used for investigation
of flaws, such as piping, can be considered, finger joint 50 has a large area compared with piping
etc. Therefore, the inspection takes time, and the face plate 51 is thick, making it difficult to
detect a crack generated between the web plate and the web plate.
[0005]
The inventors of the present invention have found that when a face plate of a finger joint in
which a crack is present between a face plate and a web plate is vibrated and vibrated with a
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2
hammer or the like, sound in a frequency band higher than the natural vibration frequency of the
finger joint And vibrating sound), it was found that the location of the crack between the face
plate and the web plate can be identified by vibrating the face plate to estimate the position of
the sound source of the vibrating sound. .
[0006]
By the way, when the finger joint where the above-mentioned excitation sound was generated
was removed and the damage condition of the position of the sound source of the excitation
sound estimated by the magnetic powder flaw detector was confirmed, the part where the
damage could be confirmed and the damage could be confirmed. It turned out that there was a
part that did not exist.
Even in the part where the damage was confirmed, the damage is a size that can only be
confirmed with the magnetic powder flaw detector, so even if there is a part where the excitation
sound is generated, there is only a minute damage that can not be confirmed with the magnetic
powder flaw detector The finger joints are fully usable. Since the magnitude of the excitation
sound from the portion where the damage has been confirmed is larger than the magnitude of
the excitation sound from the unidentified portion, it is also possible to judge the finger joint
breakage in consideration of the magnitude of the excitation sound. Although it is conceivable
that the damage judgment is performed with the finger joint installed on the bridge, the
magnitude of the excitation noise varies depending on the installation location and use condition
of the finger joint, and as a result, the finger that can be used sufficiently There is a risk that it is
determined that the joint is a damaged product.
[0007]
The present invention has been made in view of the conventional problems, and it is an object of
the present invention to provide a method for easily and reliably determining breakage of a
finger joint.
[0008]
As a result of intensive investigations, the inventor of the present invention found that the
vibration noise generated in the portion where damage was confirmed and the vibration noise
generated in the portion where damage could not be confirmed not only the magnitude of sound
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but also the degree of attenuation. In the present invention, it has been found that, by examining
the degree of attenuation of the excitation sound used to estimate the position of the sound
source, it is possible to reliably determine the breakage of the finger joint.
That is, the invention according to claim 1 of the present invention is a method of judging
breakage of a finger joint installed in a road bridge, which finger joint is in a vibrating state using
sound collecting means provided with a plurality of microphones. Collecting the sound pressure
signal of the sound generated by the sound pressure signal, and calculating the attenuation time
of the judgment band sound in the damage judgment band which is a frequency band higher
than the natural vibration frequency of the finger joint set in advance from the sound pressure
signal. Step of estimating the sound source direction of the sound pressure signal whose
attenuation time of the determination band sound of the sound pressure signal is equal to or
greater than a preset reference attenuation time, and capturing an image of the faceplate of the
finger joint Combining the data of the estimated sound source direction and the image data of
the captured face plate. Creating a damage determination image in which a figure indicating the
estimated sound source direction is drawn; and determining whether the finger joint is damaged
or not from the created damage determination image; And the like. This makes it possible to
reliably determine whether or not the generation location of the excitation sound is a damage
that can be confirmed by the magnetic powder flaw detector, so that the damage determination
accuracy of the finger joint can be improved.
[0009]
The invention according to claim 2 is the method for judging breakage of a finger joint according
to claim 1, wherein the vibration of the finger joint is generated when a vehicle traveling on a
road bridge passes over the finger joint. It is characterized in that it is a generated vibration.
Thereby, since the condition of the finger joint can be constantly monitored, breakage of the
finger joint can be detected early. The invention according to claim 3 is the method for judging
breakage of a finger joint according to claim 1, wherein the vibration of the finger joint strikes
the face plate of the finger joint from the road surface side to excite. Vibration that occurs when
the Thereby, since the finger joints can be vibrated under the same condition, breakage of the
finger joints can be reliably determined.
[0010]
The invention according to claim 4 is the method for judging breakage of a finger joint according
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to any one of claims 1 to 3, wherein the attenuation time corresponds to several wavelengths to
several tens of wavelengths of the judgment band sound. The present invention is characterized
in that it is calculated from a time change waveform (level waveform) of the magnitude of the
sound pressure signal obtained by filtering with a filter having a time constant of a minute
length. Thus, the length of the decay time can be determined accurately. The invention according
to claim 5 is the method for judging breakage of a finger joint according to any one of claims 1 to
4, wherein the damage judgment zone has a large change in generated sound due to breakage. It
is characterized in that it is in a 2000 Hz to 5000 Hz band. As a result, the damage determination
accuracy of the finger joints can be improved, and since the figure indicating the estimated sound
source direction is only the figure indicating the direction of the sound source in the damage
determination band, the estimation accuracy of the sound source position is improved.
[0011]
The invention according to claim 6 is the method for judging breakage of a finger joint according
to any one of claims 1 to 5, wherein the sound collecting means are respectively specified on two
straight lines intersecting each other. Between the two microphones constituting the first
microphone pair, comprising: first and second microphone pairs arranged at intervals; and a fifth
microphone not on a plane made by the first and second microphone pairs. Arrival time
difference of sounds, arrival time difference of sounds between two microphones constituting the
second microphone pair, and four microphones constituting the fifth microphone and the first
and second microphone pairs, respectively. To estimate the sound source direction using an
arrival time difference between the microphones constituting the four microphone pairs
composed of To. By using such sound collecting means, it is possible to accurately estimate the
sound source direction with a small number of microphones, so it is possible to efficiently and
accurately estimate the location of occurrence of a crack.
[0012]
The summary of the invention does not enumerate all necessary features of the present
invention, and a subcombination of these feature groups can also be an invention.
[0013]
It is a figure which shows the structure of the damage determination apparatus of the finger joint
which concerns on embodiment of this invention.
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It is a figure which shows an example of the installation position of a sound * imaging | video
extraction unit and an excitation means. It is a figure which shows arrangement | positioning of a
microphone. It is a figure which shows an example of the image for damage determination. It is a
figure which shows the striking point of a finger joint, and a damaged part. It is a figure which
shows the frequency spectrum of excitation sound. It is a figure which shows the time-sequential
waveform of excitation sound. It is a figure which shows the attenuation characteristic of
excitation sound. It is a flowchart which shows the damage determination method of a finger
joint. It is a figure which shows an example of a finger joint.
[0014]
Hereinafter, the present invention will be described in detail through the embodiments, but the
following embodiments do not limit the invention according to the claims, and all combinations
of the features described in the embodiments are not limited. It is not necessarily essential to the
solution of the invention.
[0015]
FIG. 1 is a view showing the configuration of a finger joint breakage determination apparatus 1;
the finger joint breakage determination apparatus 1 includes an excitation unit 1D, an audio /
video sampling unit 10, a data processing unit 20, and storage / calculation. A unit 30 and a
display means 40 are provided.
As shown in FIG. 2, the vibration means 1D includes a hammer 1a as a vibration member for
striking the face plate 51 of the joint member 50A (or the joint member 50B), and a hammer
driving portion 1b for moving the hammer 1a up and down. A base 1c supporting the drive unit
11b, a signal generation unit 1d for outputting an impact signal for each impact, and a traveling
means (not shown), and self-propelled to strike a predetermined position on the face plate 51
with the hammer 1a. In addition, the joint member 50A (or the joint member 50B) is vibrated,
and an impact signal indicating an impact point is generated and output to the data processing
unit 20. In FIG. 2, the data processing unit 20, the storage / calculation unit 30, and the display
means 40 are omitted. In this example, the striking point of the face plate 51 is a point on the
opposite side of the comb teeth from the comb teeth.
[0016]
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As shown in FIG. 1, the sound / image collecting unit 10 includes a sound collecting unit 11, a
CCD camera (hereinafter referred to as a camera) 12 as a photographing unit, a microphone
fixing unit 13, a camera support 14 and a support 15. And a support leg 16. The sound collecting
means 11 comprises a plurality of microphones M1 to M5. In the arrangement of the
microphones M1 to M5, as shown in FIG. 3, the four microphones M1 to M4 are arranged at
predetermined intervals L on two straight lines (here, x and y axes) orthogonal to each other. A
second microphone pair (M1, M3) and a microphone pair (M2, M4) are arranged to constitute a
fifth microphone M5 at a position not on the plane made by the microphones M1 to M4 (here, Z
On the axis). In this example, the microphone M5 is disposed at the top of a quadrangular
pyramid whose bottom is a square formed by the microphones M1 to M4. Thus, four microphone
pairs (M5, M1) to (M5, M4) are further configured.
[0017]
The shooting direction of the camera 12 passes through the intersection of two orthogonal
straight lines in which two pairs of microphone pairs (M1, M3) and microphone pairs (M2, M4)
are disposed, as indicated by the hollow arrow D in FIG. It is set in a direction that makes an
angle of about 45 ° with the two straight lines. In this example, since the finger joint 50 in a
state of being installed on a highway bridge is photographed, as shown in FIG. 2, the sound /
image collecting unit 10 is installed on the shoulder side of the bridge girder 60 and gives a
strike. The sound / image collecting unit 10 is installed so that the camera 12 is positioned at a
position looking down on the surface of the face plate 51 of the side joint member 50A. In
addition, the imaging | photography range of the camera 12 was taken as the range of +/- 60
degrees by horizontal angle (theta), and -20 degrees--60 degrees by elevation angle (phi).
[0018]
Microphones M1 to M5 are installed on the microphone fixing unit 13, the camera 12 is installed
on the camera support 14, and the microphone fixing unit 13 and the camera support 14 are
connected by three columns 15. That is, the sound collection means 11 and the camera 12 are
integrated. The microphones M1 to M5 are disposed above the camera 12. The support leg 16 is
a so-called tripod, and supports the sound collecting means 11 and the camera 12 at the
measurement point. The microphones M1 to M5 each measure a sound pressure level which is a
magnitude of a sound pressure signal of a sound transmitted from the finger joint 50 which is a
sound source.
03-05-2019
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[0019]
The data processing unit 20 includes a data acquisition unit 21, an amplifier 22, an A / D
converter 23, and an image input / output unit 24. When the impact signal sent from the signal
generation unit 1d of the excitation unit 1D is input, the data acquisition unit 21 acquires the
sound pressure signal of the sound collected by the microphones M1 to M5 into the amplifier 22,
and It has the function of a measurement start switch that permits the capture of the video signal
to the output means 24. The acquisition of the sound pressure signal and the video signal takes a
preset acquisition time (for example, 2 sec. Only) and resume data capture when the next strike
signal comes. The amplifier 22 includes a low pass filter, removes high frequency noise
components from the sound pressure signal of the sound sampled by the microphones M1 to
M5, amplifies the sound pressure signal, and outputs the amplified signal to the A / D converter
23. The A / D converter 23 sends sound pressure waveform data obtained by A / D converting a
sound pressure signal to the data storage means 31 of the storage / calculation unit 30. The
video input / output means 24 inputs a video signal photographed by the camera 12 and sends
image data obtained by A / D converting this video signal to the data storage means 31.
[0020]
The storage and operation unit 30 includes a data storage unit 31, a sound source direction
estimation unit 32, an attenuation time calculation unit 33, a damage determination image
creation unit 34, and a damage determination unit 35. Each means which comprises the memory
| storage and calculating part 30 is comprised by the software and memory of a personal
computer, for example. The data storage means 31 stores sound pressure waveform data and
image data for each impact location Fk (k = 1 to n). The sound source direction estimation means
32 uses the sound pressure waveform data stored in the data storage means 31 to calculate the
horizontal angle θ and the elevation angle φ, which are sound source directions, and measures
the sound pressure level.
[0021]
The horizontal angle θ and the elevation angle φ determine the respective phase differences
between the microphones M1 to M5, and are estimated from the determined phase differences,
but in this example, instead of the phase differences, they are physical quantities proportional to
the phase differences. The horizontal angle θ and the elevation angle φ are determined using a
03-05-2019
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certain arrival time difference Dij. Specifically, from the time delay Dij of each microphone pair
(Mi, Mj), the sound source direction viewed from the observation point is estimated (i, j = 1 to 5).
The horizontal angle θ and the elevation angle φ can be expressed by the following equations
(1) and (2). Here, the time delay Dij is a time difference between the sound pressure signal
arriving at the microphone Mi and the sound pressure signal arriving at the microphone Mj to be
paired with the microphone Mi, and the two microphones Mi The cross spectrum P ij (f) of the
signal input to M j is obtained, and further, it is calculated by the following equation (3) using
phase angle information 算出 (rad) of the target frequency f. The sound source direction and the
sound pressure level are measured for each frequency, but in this example, the measurement is
performed only for a damage determination band (a frequency band of 2000 Hz to 5000 Hz)
described later. Further, the magnitude of the signal input to the microphone M5 is the
magnitude of the sound pressure signal of the observed sound.
[0022]
The attenuation time calculation means 33 includes a band pass filter 33a and an attenuation
time calculation unit 33b. The band pass filter 33a has a time constant of 10 msec. The sound
pressure waveform data of the excitation sound A / D converted by the A / D converter 23 is a
frequency band set in advance to determine the breakage of the finger joint 50. Sound pressure
waveform data, which is data of a sound pressure signal in the damage determination band, is
extracted and sent to the attenuation time calculation unit 33b. The attenuation time calculation
unit 33b calculates the attenuation time of the excitation sound from the level waveform, while
obtaining the level waveform which is a time change waveform of the sound size of the damage
determination band from the sound pressure waveform data of the excitation sound. The method
of setting the damage determination band and the method of obtaining the level waveform will
be described later.
[0023]
The damage determination image creation unit 34 includes data (horizontal angle θ and
elevation angle φ) and sound pressure of the sound source direction of the excitation sound
calculated by the sound source direction estimation unit 32 for each impact location Fk (k = 1 to
n). The level and the image data stored in the data storage means 31 are combined, and a graphic
(for example, a circle) indicating the direction of the sound source is drawn in the image, as
shown in FIGS. 4 (a) to 4 (c). The created image for damage determination Gk (k = 1 to n) is
created and output to the display means 40. The horizontal axis of the damage determination
image Gk is the horizontal angle θ, and the vertical axis is the elevation angle φ. The frequency
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range is a damage determination band (2000 Hz to 5000 Hz) and the sound pressure level is a
predetermined value (for example, 70 dBSPL) or higher Only the figure indicating the sound
source direction is depicted. When the figure is a circle, the radius of the circle represents the
magnitude of the sound pressure signal of the excitation sound.
[0024]
The damage determination means 35 determines whether there is a damage determination
image in which a figure indicating the direction of the sound source is displayed among the n
damage determination images Gk (k = 1 to n) created for each impact location. It is determined
whether or not the finger joint 50 is broken by determining whether or not the finger joint 50 is
broken, and, for example, barycentric coordinates of a plurality of figures indicating the sound
source direction are determined. Identify the place where the crack has occurred (broken place).
In addition, since the image for damage determination is created for every impact location, there
is no problem even if the damage location is the root of the comb teeth opposing the impact
location Fk. At this time, if the figure showing the direction of the sound source of the excitation
sound at a location where the attenuation time calculated by the attenuation time calculation
means 33 is shorter than the preset reference attenuation time is deleted, the finger joint is
broken. It is possible to obtain the damage determination image G in which the graphic indicating
the direction of the sound source is displayed only at the place determined to be, so that the
place (broken place) where the finger joint 50 is broken can be identified with certainty. . The
display means 40 includes a display screen 40M such as a liquid crystal display, and displays the
image for damage determination created by the image creation means for damage determination
34 on the display screen 40M.
[0025]
Here, how to set the damage determination band and how to obtain the level waveform will be
described. As for a plurality of finger joints in use at a bridge part of a highway, as shown in FIG.
5, a plurality of places (hit places F1 to F11) of the face plate 51 of the joint member 50A are hit
one by one with a hammer to excite Then, the sound pressure signal of the sound generated by
the joint member 50A is collected by the sound collecting means, and the vicinity of the hitting
points F1 to F11 is photographed by the camera 12, respectively, and the damage determination
image Gk (k = 1 to 11). After making the finger), the finger joint where the excitation sound was
generated was removed, and the damage of the joint member 50A was examined with a magnetic
particle flaw detector. Hereinafter, the method of setting the damage determination band will be
described by taking the finger joint in which the excitation sound is generated at the striking
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portion F4 and the striking portion F6 of the joint member 50A as an example. It goes without
saying that the joint members 50A and 50B of the plurality of finger joints in which the
excitation sound is generated are investigated.
[0026]
As a result of the inspection by the magnetic particle flaw detector, as shown in FIG. 5, it was
confirmed that there is a crack K between the face plate 51 and the web plate 52 in the vicinity
of the striking location F6, but in the vicinity of the striking location F4 No damage was observed
despite the occurrence of tremors. Hereinafter, the impact point where the excitation sound is
generated is referred to as a change part, and the impact point where the excitation sound is not
generated is referred to as a sound part. The damage determination images G1, G4 and G6 shown
in FIGS. 4 (a) to 4 (c) described above are damage determination images when the healthy
portion F1 and the change portions F4 and F6 are respectively vibrated. (A)-(c) is a figure which
shows an example of the frequency spectrum obtained by FFT-analyzing the sound which
generate | occur | produced when each of the sound part F1 and the change parts F4 and F6 is
vibrated. The horizontal axis of the frequency spectrum is the frequency [Hz], and the vertical
axis is the sound pressure level [dB], which corresponds to a sound pressure level of 70 dBSPL
indicated by an alternate long and short dash line. As can be seen by comparing FIG. 6 (a) with
FIGS. 6 (b) and 6 (c), there is a frequency band where the sound pressure level is larger in the
change part F4 and the change part F6 compared to the sound part F1. I understand that.
Although FIG. 6 shows the frequency spectrum of the finger joint in which this frequency band is
between 2000 Hz and 2500 Hz, a frequency band in which there is a clear difference in sound
pressure level with the sound part F1 at finger joints with different specifications was examined.
By the way, it was found that the above frequency band was between 2000 Hz and 5000 Hz.
Therefore, in this example, the 2000 Hz to 5000 Hz band, which is a frequency band having a
clear difference from the sound pressure level with the sound part F1, is set as the damage
determination band.
[0027]
Next, how to obtain the level waveform will be described. FIGS. 7 (a) to 7 (c) are time-varying
waveforms of the sound pressure signal obtained by filtering and extracting the sound pressure
signal in the set damage determination band, and the attenuation time of the excitation sound is
the change portion F4. Then, it was found to be small but long at the change part F6. In the
sound part F1, the damping time of the excitation sound is the shortest. Therefore, the RMS value
of the damage determination band sound pressure signal which is the sound pressure signal
03-05-2019
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extracted by the filtering is calculated, and the level waveform which is the time change
waveform of the RMS value is determined. An example of the level waveform is shown in FIG.
The thick solid line in the figure is the level waveform of the change part F6, the thin solid line is
the level waveform of the change part F4, and the thick dashed-dotted line is the level waveform
of the sound part F1. Here, assuming that the attenuation time is the time from when the sound
pressure level reaches the maximum value to decrease by 50 dB with respect to the maximum
value, as is clear from the figure, the attenuation of the excitation sound in the change portion F6
It can be seen that the time is clearly longer than the decay time of the excitation sound of the
change part F4. Therefore, by comparing the attenuation time of the excitation sound with the
threshold value (predetermined reference attenuation time), it can be determined whether or not
the generation location of the excitation sound is a damage that can be confirmed by the
magnetic powder flaw detector. . In this example, the time constant for obtaining the RMS value
is 10 msec. To 50 msec. とした。 This is because when the time constant is too large, the
influence from the entire finger joint becomes large, and individual phenomena are hidden. In
addition, if the time constant is too small, the influence of fine flaws and the like will be reflected,
so that the measurement accuracy of the decay time will decrease. Therefore, as a time constant
for obtaining the level waveform, it is preferable to set a length of 10 msec. To 50 msec., That is,
several wavelengths to several tens of wavelengths of the damage determination band sound.
[0028]
Next, a method of judging breakage of a finger joint according to the present invention will be
described with reference to the flowchart of FIG. First, the sound / image collecting unit 10 was
set at the measurement point, and the shooting direction of the camera 12 was directed to the
hitting point F1 on the face plate 51 of the joint member 50A constituting the finger joint 50
installed on the bridge of the expressway. Thereafter, the striking point F1 is struck to excite the
finger joint 50 (step S10). Then, the sound pressure signal of the excitation sound generated by
the finger joint 50 and the image in the vicinity of the hitting point F1 are collected by the
microphones M1 to M5 (step S11). Next, sound pressure waveform data obtained by amplifying
and A / D converting sound pressure signals which are output signals of the microphones M1 to
M5 are stored in the data storage means 31, and the video signal of the camera 12 is A / D. The
image data obtained by D conversion is stored in the data storage means 31 (step S12). Next,
using the sound pressure waveform data stored in the data storage unit 31, the horizontal angle
θ and the elevation angle φ, which are the sound source direction of the excitation sound, are
estimated, and the sound pressure level is calculated (step S13). Also, in parallel with the
estimation of the sound source direction, the sound pressure signal of the damage determination
band is extracted from the sound pressure waveform data stored in the data storage unit 31, and
the level waveform is determined using the data of the sound pressure signal. Attenuation time of
vibration sound is calculated (step S14).
03-05-2019
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[0029]
Next, as shown in FIGS. 4A to 4C, on the map in which the horizontal axis is the horizontal angle
θ and the vertical axis is the elevation angle φ, the sound source direction (θ, φ) and the
frequency and magnitude of the sound pressure signal An image for damage determination in
which a circle displaying Sato is displayed is created (step S15). The diameter of the circle
represents the sound pressure level. Only the band component of the sound pressure signal of
2000 Hz to 5000 Hz which is the damage determination band (a circle with a slanting line falling
to the left) is displayed in the damage determination image G1. Next, it is determined whether or
not the damage determination images Gk (k = 1 to n) of all the impact locations Fk (k = 1 to n)
have been created (step S16). In the case where the damage determination image for all impact
points is not created, the vibration means 1D is made to self-run and self-propelled to the next
impact point, and then the hammer 1a strikes a predetermined position on the face plate 51. In
addition, after striking the next striking point Fk + 1 to excite the finger joint 50, the operation
from step S11 to step S16 is performed to generate the sound pressure signal of the sound
generated by the finger joint 50 and the vicinity of the striking point Fk + 1. Images are taken,
and damage determination images Gk (k = 1 to n) of all the striking points Fk (k = 1 to n) are
created.
[0030]
When the creation of the damage determination images for all impact points is completed, the
process proceeds to step S17, and the excitation sound used to estimate the sound source
direction for each of the n damage determination images Gk (k = 1 to n) It is determined whether
or not the decay time of the vibration damping time is equal to or more than a preset reference
decay time, and a damage determination image in which the decay time of the excitation sound is
greater than or equal to the reference decay time is selected. It is set as a damaged part
identification image (step S17). Finally, the damaged portion of the joint member 50A
constituting the finger joint 50 is specified by using the selected failure portion specifying image
(step S18). Specifically, as in the damage determination image G6 shown in FIG. 4C, a large
number of circles indicating the sound source position are displayed in the vicinity of the
damaged portion of the damage location identification image. Therefore, the position of the crack
K can be specified from the size, density, and the like of the circle displayed in the damaged
portion specifying image. Note that, as described above, the position of the crack K may be a root
of a comb that opposes the hitting point F6. When the damage determination of the joint
member 50A constituting the finger joint 50 is completed, the process returns to step S10, and
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the operation from step S10 to step S19 is performed to perform the damage determination of
the joint member 50B.
[0031]
In the above embodiment, the estimation of the sound source direction and the attenuation time
are performed in parallel, but the attenuation time is calculated first, and the calculated
attenuation time is only for excitation sound that is longer than the reference attenuation time.
The estimation of the sound source direction may be performed. In this case, the damage
determination image Gk may be created only for the excitation sound for which the calculated
decay time is equal to or more than the reference decay time, and there is no need to select the
damage location identification image, so the work process can be simplified. . Alternatively, the
estimation of the sound source direction may be performed in parallel with the calculation of the
attenuation time, and the damage determination image may be created only for the excitation
sound whose attenuation time is calculated more than the reference attenuation time. On the
other hand, in the method of the present embodiment, since the damage determination image is
created for all the impact points, there is an advantage that the damage determination image can
be left as data even if the damage can not be confirmed by the magnetic powder flaw detector. .
In the above example, the attenuation time is calculated by obtaining the level waveform, but the
attenuation time is calculated from the envelope of the time series waveform of the sound
pressure signal in the damage determination band as shown in FIGS. 7 (a) to 7 (c). You may do it.
[0032]
Further, in the above-described example, although the striking point Fk of the face plate 51 is 11
places on the opposite side to the comb teeth of the place having the comb teeth, the present
invention is not limited to this. It may be between the comb teeth and the comb teeth. Also, the
number of hitting points may be set independently of the number of comb teeth. The number of
hitting points may be at least one. In addition, a plurality of hitting points Fk may be hit one by
one in order, or a plurality of points may be hit simultaneously. The vibration means 1D is not an
essential item of the present invention, and the sound pressure signal of the sound generated
when the finger joint 50 is vibrated and in the vibration state and the image of the face plate 51
at that time are taken If the damage determination image is created, the damage of the finger
joint 50 can be determined. Specifically, the worker may vibrate the finger joint 50 by striking
the face plate 51 with the hammer 1a. Alternatively, when a vehicle traveling on an expressway
passes the finger joint 50, the load of the tire excites the finger joint 50. Therefore, the sound
and the image at the time of passing the vehicle are collected to create a damage determination
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14
image. For example, the failure of the finger joint 50 can be determined without artificially
vibrating the finger joint 50, and the state of the finger joint can be constantly monitored, so that
the failure of the finger joint can be detected early. .
[0033]
As described above, according to the present invention, breakage of the finger joint 50 in a state
of being installed on a bridge such as an expressway can be determined reliably and in a short
time, so maintenance and management of the expressway can be performed efficiently. It can be
carried out.
[0034]
DESCRIPTION OF SYMBOLS 1 Damage determination apparatus for finger joints, 10 sound /
image collecting units, 11 sound collecting means, 12 cameras, 13 microphone fixing parts, 14
camera supports, 15 posts, 16 supporting legs, 20 data processing parts, 21 data taking means ,
22 amplifier, 23 A / D converter, 24 image input / output means, 30 memory / calculation unit,
31 data storage means, 32 sound source direction estimation means, 33 attenuation time
calculation means, 33a band filter, 33b attenuation time calculation part, 34 image forming
means for damage judgment, 35 damage judging means, 40 display means, 40M display screen,
50 finger joints, 50A, 50B joint members, 51 face plates, 51a comb teeth, 52 web plates, 53 rib
plates, 60 bridge girder, M1 to M5 Microphones.
03-05-2019
15
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