JP6933686B2 - Detection system, information processing device, and detection method - Google Patents

Description

Embodiments of the present invention relate to detection systems, information processing devices, and detection methods.

For example, it is known that fatigue cracks occur in welded portions of structures such as bridges due to long-term sharing of the structures.
Here, various detection methods for detecting the deterioration of the structure have been proposed so far. However, these detection methods have various restrictions on the installation height and state of the structure, and there are cases where cracks generated in the structure cannot be easily detected.

JP-A-2010-54497

Mitsuaki Uchima, 5 others, "U-rib water retention diagnosis of steel deck by thermal infrared measurement method", JSCE 64th Annual Academic Lecture Material IV-340, September 2009, p. 679-680

An object to be solved by the present invention is to provide a detection system, an information processing apparatus, and a detection method capable of easily detecting a crack generated in a structure.

The detection system of the embodiment includes a first member that supports a traveling surface on which the vehicle travels from below, a second member that is a traffrib provided on the side opposite to the traveling surface with respect to the first member, and the above. A detection system provided along an end of a second member facing the first member and detecting the state of a structure composed of a welded portion in which the first member and the second member are fixed. It has a first sensor group, a second sensor group, and a control unit. The first sensor group is arranged so as to be separated from each other in the extending direction of the welded portion, and is attached to the second member to detect elastic waves transmitted to the second member, respectively. Includes sensors. The second sensor group includes a plurality of AE sensors attached to the first member and detecting elastic waves transmitted to the first member. The standardizing unit handles the detection results of the plurality of AE sensors included in the first sensor group and the detection results of the plurality of AE sensors included in the second sensor group separately from each other, and handles the detection results of the plurality of AE sensors included in the first sensor group separately. The determination of the source position of the elastic wave based on the detection results of the plurality of AE sensors included and the determination of the source position of the elastic wave based on the detection results of the plurality of AE sensors included in the second sensor group are separately performed. conduct. The standardizing portion detects a crack extending from a welded portion of the first member to the first member by using the detection results of a plurality of AE sensors included in the first sensor group.

Sectional drawing which shows the bridge structure of one Embodiment. The cross-sectional perspective view which shows the steel deck slab of the said embodiment. A cross-sectional perspective view of the steel deck of the above embodiment as viewed from another angle. FIG. 3 is a cross-sectional perspective view showing a welded portion of the steel deck of the above embodiment and its surroundings. The block diagram which shows the system configuration of the detection system of the said embodiment. The figure which shows the arrangement example of the AE sensor of the said embodiment. The figure which shows an example of the detection result of the detection system of the said embodiment. The side view which conceptually shows the method of locating a crack position of the said embodiment. The graph which shows the crack growth limit curve of the said embodiment. The figure which shows the relationship between the size of a crack of the said embodiment, and the variation of a locating position. The figure which shows the relationship between the installation parameter θ of the said embodiment, and the variation of a control position. The block diagram which shows the system structure of the signal processing part of the said embodiment. The figure which shows the parameter about the characteristic of the elastic wave of the said embodiment. The block diagram which shows the system structure of the deterioration detection part of the said embodiment. The flowchart which shows an example of the flow of the detection method of the said embodiment.

Hereinafter, the detection device, the detection system, and the detection method of the embodiment will be described with reference to the drawings. In the following description, the same reference numerals are given to configurations having the same or similar functions. Then, the duplicate description of those configurations may be omitted.

One embodiment will be described with reference to FIGS. 1 to 15.
The detection system 1, the detection device 2, and the detection method of the present embodiment detect the state of the structure. The term "structure state" as used in the present application is used in a broad sense including a state of deterioration and a state of cracks. That is, "detecting the state of the structure" referred to in the present application means detecting at least one such as the presence / absence of deterioration, the degree of deterioration, the presence / absence of cracks, the position of cracks, and the degree of cracks. Here, first, an example of the detection system 1, the detection device 2, and the structure to which the detection method is applied will be described.

FIG. 1 is a cross-sectional view showing an example of the bridge structure 10.
The bridge structure 10 is an example of the detection system 1, the detection device 2, and the “structure” to which the detection method of the present embodiment is applied. The term "bridge" as used in the present application is not limited to structures erected on rivers, valleys, etc., but broadly includes various structures (for example, viaducts on highways) provided above the ground. Further, the detection system 1, the detection device 2, and the structure to which the detection method of the present embodiment can be applied are not limited to bridges, and may be structures in which elastic waves are generated as cracks occur or grow. Just do it. That is, the detection system 1, the detection device 2, and the detection method of the present embodiment may be applied to, for example, a structure unrelated to a road.

As shown in FIG. 1, the bridge structure 10 includes a main girder 11 and a steel deck 12.
The main girder 11 is provided on the ground and stands up substantially in the vertical direction.
The steel deck 12 is installed on the main girder 11 to form a traveling surface TS on which the vehicle V travels. The steel deck 12 is supported from below by the main girder 11 and is arranged at a position higher than the ground.

FIG. 2 is a cross-sectional perspective view showing the steel deck 12.
As shown in FIG. 2, the steel deck 12 includes a deck plate 21, a pavement portion 22, a trafrib (vertical rib) 23, and a horizontal rib 24 (see FIG. 3).

The deck plate 21 extends below the traveling surface TS on which the vehicle V travels, and supports the traveling surface TS from below. The deck plate 21 is an example of the “first member”. For example, the deck plate 21 is a metal plate member that extends substantially parallel to the traveling surface TS.

The pavement portion (pavement member) 22 is provided on the upper surface of the deck plate 21. The pavement portion 22 is formed of, for example, asphalt. The upper surface of the pavement portion 22 forms a traveling surface TS on which the vehicle V travels. The phrase "(the first member) supports the traveling surface from below" in the present application includes, for example, the meaning that the first member supports the member (for example, the pavement portion 22) forming the traveling surface TS from below. ..

FIG. 3 is a cross-sectional perspective view of the steel deck 12 as viewed from diagonally below.
As shown in FIG. 3, the trafrib 23 is provided below the deck plate 21. That is, the traffrib 23 is provided on the side opposite to the traveling surface TS with respect to the deck plate 21. The trough rib 23 is an example of the “second member”. The trough rib 23 is a reinforcing member that reinforces the deck plate 21. For example, the traffrib 23 is a metal rib (U rib) having a U-shaped cross section. The trough rib 23 is attached to the lower surface of the deck plate 21 and extends along the bridge axial direction BD. The "bridge axis direction" is a direction in which the bridge structure 10 extends, for example, a direction along the traveling direction of the vehicle V traveling on the bridge structure 10.

More specifically, the trafrib 23 includes upright portions 26A, 26B and a horizontal portion 27.
Each of the pair of standing portions 26A and 26B is a plate portion along a direction intersecting the traveling surface TS, and extends in a direction away from the traveling surface TS. For example, the pair of standing portions 26A and 26B are tilted from each other so that the distance between the standing portions 26A and 26B gradually narrows as the distance from the traveling surface TS increases. For example, the thickness (plate thickness) of each of the standing portions 26A and 26B is thinner than the thickness (plate thickness) of the deck plate 21. Further, the thickness (plate thickness) of each of the standing portions 26A and 26B is substantially constant, for example, in the bridge axial direction BD.

The horizontal portion 27 is a plate portion substantially parallel to the traveling surface TS. The horizontal portion 27 is provided between the lower ends of the pair of standing portions 26A and 26B, and connects the lower ends of the standing portions 26A and 26B to each other. The trough rib 23 is formed in a U shape by connecting the standing portions 26A and 26B and the horizontal portion 27.

On the other hand, the lateral rib 24 is a metal plate member along a direction intersecting (for example, substantially orthogonal to) the bridge axis direction BD. The lateral rib 24 has a notch 24a through which the trafrib 23 is passed. For example, the lateral ribs 24 are fixed to the lower surface of the deck plate 21 and the side surfaces of the upright portions 26A and 26B of the trafrib 23.

Next, the welded portion 28 provided on the steel deck 12 will be described.
As shown in FIG. 3, the steel deck 12 has a welded portion 28 between the deck plate 21 and the trough rib 23. More specifically, each of the upright portions 26A and 26B of the trafrib 23 has an end portion (upper end portion) 26e facing the deck plate 21. The welded portion 28 is provided along the end portions 26a of the upright portions 26A and 26B of the traffrib 23. The welded portion 28 extends in the bridge axial direction BD along the direction in which the traffrib 23 extends. The welded portion 28 fixes (joins) the lower surface of the deck plate 21 and the end portions 26e of the standing portions 26A and 26B of the traffrib 23.

FIG. 4 shows the welded portion 28 of the steel deck 12 and its surroundings. For convenience of explanation, hatching applied to the cross-sectional portion is omitted in FIG.
As shown in FIG. 4, the end portions 26e of the upright portions 26A and 26B of the trafrib 23 include the inclined portion (inclined surface, root surface) 26i. The inclined portion 26i is provided on the outer portion of the pair of standing portions 26A and 26B at the end portions 26e of the standing portions 26A and 26B. The inclined portion 26i is inclined in a direction away from the lower surface of the deck plate 21 as it advances to the outside of the pair of standing portions 26A and 26B. Therefore, a gap into which the welded portion 28 enters is formed between the lower surface of the deck plate 21 and the inclined portion 26i of the standing portions 26A and 26B. At least a part of the welded portion 28 is provided between the lower surface of the deck plate 21 and the inclined portion 26i of the standing portions 26A and 26B.

Here, fatigue cracks C (hereinafter, simply referred to as cracks C) may occur in the welded portion 28 due to long-term sharing of the bridge structure 10. The crack C has two main patterns. As shown in FIG. 4A, the crack C of the first pattern is a crack (bead penetrating crack) extending from the root (root portion) 28a of the welded portion 28 toward the weld bead. On the other hand, as shown in FIG. 4B, the crack C in the second pattern is a crack extending from the root 28a of the welded portion 28 to the deck plate 21 (deck plate penetrating crack). Here, the upper surface of the deck plate 21 is covered with the pavement portion 22. Therefore, it is particularly difficult to visually confirm the crack C extending to the deck plate 21.

Next, the detection system 1 of the present embodiment will be described.
FIG. 5 is a block diagram showing a system configuration of the detection system 1 of the present embodiment.
As shown in FIG. 5, the detection system (deterioration detection system, deterioration diagnosis system) 1 includes a detection device 2, an information aggregation device 3, and an information processing device 4.

First, the detection device 2 will be described.
The detection device 2 is an acoustic emission (AE) type detection device installed in the bridge structure 10 and detecting elastic waves generated in the bridge structure 10. Note that AE is a phenomenon in which elastic waves are generated inside the material due to the occurrence of fatigue cracks in the material or the growth of fatigue cracks. The AE type detection device detects, for example, the occurrence of fatigue cracks in the structure or the elastic waves generated by the growth of the fatigue cracks by a high-sensitivity sensor, and detects the state of the structure based on the detected elastic waves. ..

More specifically, the detection device 2 of the present embodiment includes a first AE sensor group 31, a second AE sensor group 32, a BPF (bandpass filter) 33, an ADC (analog-digital converter) 34, and a signal processing unit. It has 35 and a wireless transmitter 36.

FIG. 6 shows an arrangement example of the first and second AE sensor groups 31 and 32. Note that (a) in FIG. 6 shows a plan view of the steel deck 12. (B) in FIG. 6 shows a side view of the steel deck 12. FIG. 6C in FIG. 6 shows a cross-sectional view of the steel deck 12.

First, the first AE sensor group 31 will be described.
As shown in FIG. 6, the first AE sensor group 31 includes a plurality of AE sensors 41. The first AE sensor group 31 shown by a solid line in FIG. 6 is, for example, a sensor group that detects a crack C in a welded portion 28 provided in one of the standing portions 26A of the trafrib 23. The sensor group for detecting the crack C in the welded portion 28 provided in the other upright portion 26B of the trafrib 23 will be described later. Further, FIG. 6 shows representatives of the two AE sensors 41 included in the first AE sensor group 31. The first AE sensor group 31 may include, for example, three or more AE sensors 41 arranged at predetermined intervals in the bridge axis direction BD.

Here, the AE sensor 41 according to the present embodiment will be described.
The AE sensor 41 has a piezoelectric element, detects an elastic wave (AE wave) transmitted from a crack C generation portion, converts it into a voltage signal (AE signal), and outputs it. The AE signal is detected as a sign before material breakage occurs. Therefore, the frequency of occurrence of the AE signal and the signal intensity are useful as indicators of the soundness of the material. For example, the AE sensor 41 has a piezoelectric element having a sensitivity in the range of 10 kHz to 1 MHz. The AE sensor 41 may be either a resonance type having a resonance peak within the frequency range, a broadband type in which resonance is suppressed, or the like. Further, the AE sensor 41 may be a preamplifier type having a built-in preamplifier, or may be other than these. The detection element itself of the AE sensor 41 may be any of a voltage output type, a resistance change type, and a capacitance type, or may be other than these. The AE sensor 42 included in the second AE sensor group 32, which will be described later, has the same sensor configuration and function as the AE sensor 41 of the first AE sensor group 31.

As shown in FIG. 6, the plurality of AE sensors 41 included in the first AE sensor group 31 are attached to the trafrib 23, respectively. More specifically, each AE sensor 41 is attached to the side surface of the upright portion 26A of the trafrib 23 and comes into contact with the upright portion 26A. As a result, each AE sensor 41 detects an elastic wave transmitted from the crack C to the upright portion 26A of the trough rib 23.

The plurality of AE sensors 41 are arranged apart from each other in the bridge axial direction BD. That is, the plurality of AE sensors 41 are arranged apart from each other in the extending direction of the welded portion 28. As shown in FIG. 6B, the plurality of AE sensors 41 are arranged at the same height, for example. The plurality of AE sensors 41 may be arranged at different heights from each other as shown in FIG. 8 described later. Further, the place where the AE sensor 41 is attached is not limited to the standing portion 26A of the trafrib 23. For example, the AE sensor 41 may be attached to the horizontal portion 27 of the trafrib 23.

Further, the detection device 2 may have a plurality of AE sensors 43 for detecting cracks C in the welded portion 28 provided in the other upright portion 26B of the trough rib 23. The AE sensor 43 is attached to, for example, the side surface of the upright portion 26B of the trough rib 23, as shown by the alternate long and short dash line in FIG. 6 (c).

Next, the second AE sensor group 32 will be described.
As shown in FIG. 6, the second AE sensor group 32 includes a plurality of AE sensors 42. In FIG. 6, four AE sensors 42 included in the second AE sensor group 32 are shown as representatives. The second AE sensor group 32 may include, for example, more AE sensors 42 arranged at predetermined intervals in the bridge axis direction BD.

As shown in FIG. 6, the plurality of AE sensors 42 included in the second AE sensor group 32 are attached to the deck plate 21, respectively. More specifically, each AE sensor 42 is attached to the lower surface of the deck plate 21 and is in contact with the deck plate 21. As a result, each AE sensor 42 detects an elastic wave transmitted from the crack C to the deck plate 21.

The plurality of AE sensors 42 are arranged apart from each other in a direction intersecting (for example, substantially orthogonal to) the bridge axial direction BD and the bridge axial direction BD. That is, some AE sensors 42 included in the second AE sensor group 32 are arranged apart from each other in the extending direction of the welded portion 28. Further, some AE sensors 42 included in the second AE sensor group 32 are separately arranged on both sides of the trafrib 23 in a direction intersecting (for example, substantially orthogonal to) the bridge axis direction BD. In the following, the direction that intersects (for example, substantially orthogonal to) the bridge axis direction BD is simply referred to as the "width direction".

Here, for convenience of explanation, in the AE sensors 41 and 42 shown in FIG. 6, the two AE sensors 41 included in the first AE sensor group 31 are referred to as a first AE sensor 41A and a second AE sensor 41B. Further, the four AE sensors 42 included in the second AE sensor group 32 are referred to as a third AE sensor 42A, a fourth AE sensor 42B, a fifth AE sensor 42C, and a sixth AE sensor 42D.

FIG. 7 shows an example of the actual detection result of the detection system 1. That is, FIG. 7 analyzes the signals detected by the AE sensors 41 and 42 included in the first and second AE sensor groups 31 and 32 in the arrangement example of FIG. 6, and displays the detection result of the AE occurrence frequency. It is a thing. Note that FIG. 7A shows the detection result of the AE occurrence frequency by the second AE sensor group 32 (AE sensor 42 attached to the deck plate 21). In FIG. 7A, the darker the color in the figure, the higher the frequency of AE occurrence. On the other hand, (b) in FIG. 7 shows the detection result of the AE occurrence frequency by the first AE sensor group 31 (AE sensor 41 attached to the trafrib 23). In FIG. 7B, the higher the bar graph in the figure, the higher the frequency of AE occurrence.

As described above, when a crack C is generated in the welded portion 28, an elastic wave is generated. This elastic wave propagates from the crack C to the deck plate 21 and the trough rib 23, respectively. Here, noise may be added to the bridge structure 10 from the vehicle V traveling on the traveling surface TS. Further, the direction in which the elastic wave propagates more strongly may differ depending on the growth direction of the crack C, the penetration state of the weld, and the like.
Here, according to the research by the present inventors, it has been found that even elastic waves that cannot be detected by the AE sensor 42 attached to the deck plate 21 can be detected by installing the AE sensor 41 on the trough rib 23. rice field. That is, as shown in FIG. 7, the AE sensor 41 attached to the trough rib 23 detects the elastic wave associated with the crack C even at a plurality of places where the AE sensor 42 attached to the deck plate 21 does not detect the elastic wave. It turns out that it can be done. That is, it was found that the detection accuracy of the crack C can be improved by installing the AE sensor 41 on the traffrib 23.

Next, a method of defining the position of the crack C will be described.
In the present embodiment, the position of the crack C is defined by using the detection results of two AE sensors 41A and 41B adjacent to each other included in the first AE sensor group 31. The term "positioning" as used in the present application means to obtain (calculate, specify) the position of an object or the like based on, for example, the detection result of the sensor.

FIG. 8 is a side view conceptually showing a method of defining the position of the crack C.
As shown in FIG. 8, in the present embodiment, the source position of the elastic wave (the position of the crack C) is the time difference between the times when the two AE sensors 41A and 41B detect the elastic wave and the elastic wave in the trough rib 23. It is standardized based on the propagation speed and the position of the weld 28.

More specifically, the dashed line curve shown in FIG. 8 is a hyperbola 51 having two AE sensors 41A and 41B as focal points. That is, at each point located on the line of the hyperbola 51, the difference in distance from the two AE sensors 41A and 41B with respect to the hyperbola 51 is constant. In other words, the propagation velocity of the elastic wave in the trafrib 23 is v, and it is between the time when the first AE sensor 41A detects the elastic wave (t ₁ ) and the time when the second AE sensor 41B detects the elastic wave (t ₂ ). Assuming that the time difference (t _{1 − t 2} ) is Δt, the double curve 51 is a line connecting points where v × Δt is constant. The "time when the sensor detects the elastic wave" in the present application may be read as "the time when the elastic wave arrives at the sensor".

Here, the crack C can be regarded as occurring in the welded portion 28. Further, the welded portion 28 is provided in a straight line along the end portion 26e of the traffrib 23. Therefore, as shown in FIG. 8, only one point is determined at the intersection (intersection) 52 between the hyperbola 51 and the welded portion 28. The intersection 52 where the hyperbola 51 and the welded portion 28 intersect can be defined as the source position of the elastic wave (the position of the crack C). As a result, even if the AE sensor 41 is installed at a position away from the welded portion 28, the position of the crack C can be accurately located.

と表すことができる。
また、３次元体の場合は、せん断弾性率をＧとすると、

と表すことができる。
これは、材料中を伝わる弾性波の伝播速度ｖは、その材料固有の物性値で決まることを意味する。このため、材料に対して弾性波の伝播速度ｖを予め計算しておき、ルックアップテーブルを用意しておくことができる。すなわち、亀裂Ｃの位置標定の計算において伝播速度ｖを選択する場合に、上記ルックアップテーブルを参照することで、材料に応じた伝播速度を適切に選択することができる。 Here, the propagation velocity v of elastic waves propagating in a material is such that the bulk modulus of the material (material) is κ (Pa) and the density is ρ ₀ (kg / m ³ ).

It can be expressed as.
In the case of a three-dimensional body, assuming that the shear modulus is G,

It can be expressed as.
This means that the propagation velocity v of the elastic wave propagating in the material is determined by the physical property value peculiar to the material. Therefore, the propagation velocity v of the elastic wave can be calculated in advance for the material, and a look-up table can be prepared. That is, when the propagation velocity v is selected in the calculation of the position orientation of the crack C, the propagation velocity according to the material can be appropriately selected by referring to the above lookup table.

Next, the relationship between the arrangement position of the AE sensor 41 and the detection accuracy of the crack C will be described.
Here, the size of the crack C to be detected in this embodiment is, for example, 3 mm at the minimum. This value of 3 mm can be obtained from the crack growth limit curve. That is, regarding the relationship between crack growth and stress, the crack shape parameter is a [mm], the stress range is Δσ [MPa], the lower limit stress intensity factor range is ΔK _th [MPa / m ^0.5 ], and the correction coefficient determined by the material is F. Then, it can be represented by the following crack growth limit curve.

FIG. 9 shows a crack growth limit curve based on the above equation (3).
As shown in FIG. 9, if the relationship between the size of the crack C and the stress is equal to or less than the above curve, the crack C does not grow. Here, the maximum stress range assumed on the lower surface of the deck plate 21 is 30 MPa. Therefore, a crack C of less than 3 mm can be regarded as not growing. In other words, if a crack C of 3 mm or more can be detected, the state of deterioration of the bridge structure 10 can be detected with high accuracy.

Further, here, the relationship between the size of the crack C and the variation in the orientation position will be described.
FIG. 10 shows the relationship between the size of the crack C and the variation in the localization position of the source of the elastic wave (imposition error). Note that FIG. 10A shows an example of a crack C having a size of 3 mm. (B) in FIG. 10 shows the distribution of variations in the orientation position of the source of elastic waves.

As shown in FIG. 10A, elastic waves generated from the crack C are generated from both ends e1 and e2 of the crack C when the crack C is large to some extent. Here, if the variation in the control position of the source of the elastic wave is larger than 3 mm, the control position varies within the range including both ends e1 and e2 of the crack C, so that the crack C is 3 mm or more or less than 3 mm. It may be difficult to determine whether or not the crack C is. On the other hand, when the variation in the control position of the source of the elastic wave is smaller than 3 mm, the elastic wave emitted from one end e1 of the crack C and the elastic wave emitted from the other end e2 of the crack C. Can be detected separately. Therefore, if the variation in the orientation position of the source of the elastic wave is smaller than 3 mm, the crack C having a size of 3 mm or more can be found more reliably.

Next, the arrangement position of the AE sensor 41 for making the variation of the control position of the source of the elastic wave smaller than 3 mm will be described.
Here, referring to FIG. 8 again, the extension line L1, the reference line L2, and the setting parameter θ are defined. The extension line L1 is a line extending a straight line passing through two adjacent AE sensors 41A and 41B. The reference line L2 is a line along the direction in which the welded portion 28 extends. For example, the reference line L2 is a line that passes through the first AE sensor 41A and is substantially parallel to the welded portion 28 (approximately parallel to the traveling surface TS). The setting parameter θ is an angle between the extension line L1 and the reference line L2. Here, the present inventors have found that the variation in the orientation position of the source of elastic waves changes depending on the difference in the installation parameter θ.

FIG. 11 shows the relationship between the installation parameter θ and the variation in the orientation position. Note that (a) in FIG. 11 conceptually shows the change in the variation in the orientation position due to the change in the installation parameter θ. FIG. 11B is a simulation result of a change in the variation in the orientation position when the installation parameter θ is changed.

As shown in (a) in FIG. 11, when the installation parameter θ changes, the intersection angle of the hyperbola 51 with respect to the welded portion 28 changes. Therefore, when the installation parameter θ changes, the variation in the control position of the source position of the elastic wave changes.

FIG. 11B is a result of performing a Monte Carlo simulation based on the arrangement example of FIG. 6 to obtain the variation in the localization position of the elastic wave generation source with respect to the installation parameter θ. The simulation conditions were x _{1 set} to 400 mm, y _{1 set} to 100 mm, and the number of trials set to 34,000. Moreover, the source position of the elastic wave was calculated for three ways of x = 0, x = 100, and x = 200.

As shown in FIG. 11B, as a result of the above simulation, when the installation parameter θ is smaller than 20 degrees regardless of the position of the source of the elastic wave, the variation of the control position of the source of the elastic wave varies. It was found to be smaller than 3 mm. That is, when the two AE sensors 41A and 41B are arranged so as to satisfy the relationship of −20 degrees <θ <20 degrees, the variation in the control position of the source of the elastic wave can be made smaller than 3 mm.

Summarizing the above, when two AE sensors 41A and 41B are arranged so as to satisfy the relationship of -20 degrees <θ <20 degrees, the variation in the control position of the elastic wave source can be made smaller than 3 mm. can. If the variation in the orientation position of the source of elastic waves can be made smaller than 3 mm, cracks C of 3 mm or more can be detected more reliably. If the crack C of 3 mm or more can be detected more reliably, the state of deterioration of the bridge structure 10 can be detected more accurately.

Next, with reference to FIG. 5 again, the BPF 33, the ADC 34, the signal processing unit 35, and the wireless transmission unit 36 of the detection device 2 will be described.

The BPF (bandpass filter) 33 is provided between the first and second AE sensor groups 31 and 32 and the ADC 34. The voltage signals output from the AE sensors 41 and 42 of the first and second AE sensor groups 31 and 32 are input to the BPF 33, and noise components other than the signal band are removed.

The ADC (analog-to-digital converter) 34 is provided between the BPF 33 and the signal processing unit 35. The signal that has passed through the BPF 33 is input to the ADC 34. The signal input to the ADC 34 is input to the signal processing unit 35 as discretized waveform data.

The signal processing unit (signal processing circuit) 35 is formed by, for example, an FPGA (Field Programmable Gate Array). For example, when the signal processing unit 35 is formed by the non-volatile FPGA, the power consumption during standby can be suppressed. The signal processing unit 35 may be formed by a dedicated LSI.

FIG. 12 is a block diagram showing a system configuration of the signal processing unit 35.
As shown in FIG. 12, the signal processing unit 35 includes a time information generation unit 61, a waveform shaping filter 62, a gate generation circuit 63, a feature amount extraction unit 64, an arrival time determination unit 65, a transmission data generation unit 66, and an internal memory. 67 is provided.

The time information generation unit 61 generates cumulative time information from the time when the power of the detection device 2 is turned on, based on a signal from a clock source such as a crystal oscillator. For example, the time information generation unit 61 includes a counter that counts the edge of the clock, and uses the value of the register of the counter as the time information.

の関係を満たす整数である。
すなわち、ビット長ｂは、時刻分解能ｄｔと、測定継続時間ｙとから決定される。 More specifically, the counter register has a predetermined bit length b. For the predetermined bit length b, where the time resolution is dt and the measurement duration is y,

It is an integer that satisfies the relationship of.
That is, the bit length b is determined from the time resolution dt and the measurement duration y.

の関係から求められる。
すなわち、時刻分解能ｄｔは、弾性波の伝播速度ｖと、位置標定精度ｄｒとから決定される。言い換えると、位置標定精度ｄｒに基づいてビット長ｂを決定することで、位置標定精度ｄｒを任意の範囲で設定することができ、必要かつ十分な位置標定を実現することができる。 Further, the time resolution dt is determined by assuming that the propagation velocity of the elastic wave based on the material of the bridge structure 10 (for example, the material of the trafrib 23) is v and the position positioning accuracy is dr.

It is required from the relationship of.
That is, the time resolution dt is determined from the propagation velocity v of the elastic wave and the position positioning accuracy dr. In other words, by determining the bit length b based on the position orientation accuracy dr, the position orientation accuracy dr can be set in an arbitrary range, and necessary and sufficient position orientation can be realized.

For example, assuming that the target structure is made of iron, the propagation velocity of the elastic wave is v = 5950 [m / s]. Assuming that the accuracy of positioning the source of elastic waves is 3 mm and the number of years of measurement continuation is 100 years,
dt = 0.50 [μsec].
As a result, b ≧ 53 bits.

Here, the transmission packet of a general wireless module is subjected to data transmission in byte units. Therefore, the bit length b is a multiple of 8 that satisfies the above equation (4). That is, by setting the bit length b ≧ 56 bits = 7 bytes, it is possible to use a general-purpose wireless module.

The waveform shaping filter 62 is provided between the ADC 34 and the gate generation circuit 63. The signal (waveform data) input from the ADC 34 to the signal processing unit 35 is passed through the waveform shaping filter 62. The signal passed through the waveform shaping filter 62 is input to the gate generation circuit 63 and the feature amount extraction unit 64.

The gate generation circuit 63 extracts a series of continuous waveforms. The gate generation circuit 63 includes, for example, an envelope detector and a comparator. For example, the gate generation circuit 63 outputs a gate signal of H (High) when the detected envelope is equal to or greater than a predetermined threshold value. On the other hand, the gate generation circuit 63 outputs a gate signal that becomes L (Low) when the detected envelope falls below the threshold value.

The feature amount extraction unit 64 is an example of the “extraction unit”. When the gate signal output from the gate generation circuit 63 is H, the feature amount extraction unit 64 processes the waveform data and extracts the feature amount (parameters that characterize the waveform shape) of the waveform shape of the elastic wave. The feature amount of the waveform shape is an example of "information on the characteristics of elastic waves". The feature amount extraction unit 64 extracts at least one value such as signal amplitude, energy, rise time, duration, frequency, and zero cross count number as the feature amount of the waveform shape in each elastic wave. The "information about a certain content (for example, characteristics of elastic waves)" referred to in the present application may be information that directly includes the content, or the content is extracted by performing a preset arithmetic processing or determination processing. It may be possible information.

FIG. 13 shows a specific example of parameters related to the characteristics of elastic waves.
As shown in FIG. 13, the “signal amplitude” is, for example, the value of the maximum amplitude A in the elastic wave. The "energy" is, for example, a value obtained by time-integrating the square of the amplitude at each time point. The definition of "energy" is not limited to the above example, and may be approximated by using, for example, a waveform envelope. The “rise time” is, for example, the time T1 from the zero value until the elastic wave rises beyond a preset predetermined value. The “duration” is, for example, the time T2 from the start of the rise of the elastic wave until the amplitude becomes smaller than the preset value. "Frequency" is the frequency of elastic waves. The "zero cross count number" is, for example, the number of times an elastic wave crosses a reference line BL passing through a zero value.

The feature amount extraction unit 64 extracts the feature amount of the waveform shape of the elastic wave in each AE sensor 41, 42 based on the detection result of each AE sensor 41, 42. The feature amount extraction unit 64 sends information regarding the feature amount of the waveform shape in each of the extracted AE sensors 41 and 42 to the transmission data generation unit 66.

On the other hand, as shown in FIG. 12, the arrival time determination unit 65 receives the time information from the time information generation unit 61. Further, the arrival time determination unit 65 receives a gate signal indicating the presence or absence of the AE signal from the gate generation circuit 63. Then, the arrival time determination unit 65 generates the arrival time information of the elastic wave based on the time information received from the time information generation unit 61 and the gate signal received from the gate generation circuit 63. For example, the arrival time determination unit 65 uses the time information when the rising edge of the gate signal is generated as the arrival time of the elastic wave.
The arrival time determination unit 65 calculates the arrival time of the elastic wave for each AE sensor 41, 42 based on the detection result of each AE sensor 41, 42. The arrival time determination unit 65 sends the calculated information regarding the arrival time of the elastic wave to each of the AE sensors 41 and 42 to the transmission data generation unit 66.

The transmission data generation unit 66 relates to information regarding the feature amount of the waveform shape in each AE sensor 41, 42 received from the feature amount extraction unit 64, and regarding the arrival time of the elastic wave for each AE sensor 41, 42 received from the arrival time determination unit 65. Generates a set of AE data for transmission by associating (associating) with information. The generated AE data is stored in the internal memory 67. The internal memory 67 is, for example, a dual port RAM. The generated AE data may be directly sent to the wireless transmission unit 36 (see FIG. 5) without being stored in the internal memory 67.

Next, the wireless transmission unit 36 will be described with reference to FIG.
The radio transmission unit (radio transmission circuit) 36 includes, for example, an antenna and a radio module that generates a high frequency signal. The wireless transmission unit 36 wirelessly transmits AE data at a predetermined timing set in advance. The wireless transmission unit 36 is an example of each of the “output unit” and the “transmission unit”. The wireless transmission unit 36 outputs information obtained from the outputs of the AE sensors 41 and 42 to the outside. The "information obtained from the output of the AE sensor" may be the voltage signal itself output from the AE sensor, or the voltage signal may be subjected to preset noise processing, arithmetic processing, determination processing, or the like. It may be the one. Further, when the deterioration detection unit 72 described later is provided in the detection device 2, the “information obtained from the output of the AE sensor” output by the wireless transmission unit 36 is the presence or absence of deterioration or the degree of deterioration of the bridge structure 10. May include information about.

In the present embodiment, the wireless transmission unit 36 receives information on the feature amount of the waveform shape of the elastic wave in each AE sensor 41, 42 and information on each AE sensor 41, 42 as information obtained from the output of the AE sensors 41, 42. It is transmitted in association with information on the arrival time of elastic waves.

Next, the information aggregation device 3 and the information processing device 4 will be described.
As shown in FIG. 5, the information aggregation device 3 has a wireless receiving unit (radio receiving circuit) 71. The radio receiver 71 includes, for example, an antenna and a radio module that processes high frequency signals. For example, one information aggregation device 3 is provided in one bridge structure 10. Further, the wireless receiving unit 71 has a storage DB (not shown). The wireless reception unit 71 receives the AE data from one or more detection devices 2 installed in the bridge structure 10, and stores the received AE data in the storage DB.

The information processing device 4 is, for example, an electronic device (for example, a server) installed in a management office of an organization that manages the bridge structure 10. The information processing device 4 has a deterioration detection unit 72. All or part of each functional unit of the deterioration detection unit 72 is realized, for example, by executing a program by a processor (for example, a CPU (Central Processing Unit)) of the information processing device 4. Instead of this, all or a part of each functional unit of the deterioration detection unit 72 may be formed by hardware (for example, LSI (Large Scale Integration)) included in the information processing device 4.

FIG. 14 is a block diagram showing a system configuration of the deterioration detection unit 72.
As shown in FIG. 14, the deterioration detection unit 72 includes a position setting unit 81, a threshold value setting unit 82, and a deterioration diagnosis unit 83.

The position positioning unit 81 is an example of a “positioning unit” and determines the position of the source of elastic waves. More specifically, the position setting unit 81 reads the AE data group in the storage DB of the wireless receiving unit 71 at a predetermined timing set in advance. The position determining unit 81 determines whether or not the elastic waves detected by the AE sensors 41 and 42 are the same as each other by comparing the information regarding the feature amount of the waveform shape of the elastic waves in the AE sensors 41 and 42. do. That is, the position setting unit 81 has at least one of the amplitude, energy, rise time, duration, frequency, zero cross count number, etc. of the elastic wave signal detected by each AE sensor 41, 42 (for example, AE sensors 41A, 41B). By comparing one (for example, two or more), it is determined whether or not the elastic waves detected by each AE sensor 41, 42 (for example, AE sensor 41A, 41B) are the same.

When the degree of similarity (similarity of the waveform shape) of the feature amount of the waveform shape of the elastic wave in the plurality of AE sensors 41 (or the plurality of AE sensors 42) is within a predetermined range set in advance in the position setting unit 81. In addition, it is determined that the elastic waves detected by the plurality of AE sensors 41 (or the plurality of AE sensors 42) are the same elastic waves, and the position of the source of the elastic waves is defined. The determination of the similarity of elastic waves is performed separately for the AE sensor 41 attached to the trough rib 23 and the AE sensor 42 attached to the deck plate 21. This is because the thickness of the trough rib 23 and the thickness of the deck plate 21 are different, so that the waveform shape of the elastic wave input to the AE sensor 41 is different from the waveform shape input to the AE sensor 42.

Specifically, as described above with reference to FIG. 8, the position setting unit 81 has, for example, the time difference between the times when the two AE sensors 41A and 41B detect the elastic wave, and the propagation speed of the elastic wave in the trough rib 23. , The position of the source of the elastic wave is determined based on the position of the welded portion 28. That is, the position positioning portion 81 positions the intersection 52 between the hyperbola 51 and the welded portion 28 in FIG. 8 as the source position of the elastic wave.

Further, the position locating unit 81 performs noise processing associated with the position locating. The position setting unit 81 is an example of a noise removing unit that removes noise based on a predetermined algorithm set in advance. For example, the position setting unit 81 receives a threshold value as a determination standard for noise processing from the threshold value setting unit 82. The threshold value stored in the threshold value setting unit 82 can be changed by the user. The position locating unit 81 regards an elastic wave determined to be generated from outside the predetermined threshold range as noise based on the position locating result. In this way, in noise removal, it is determined whether the signal is noise or a meaningful signal based on a predetermined threshold value. Therefore, the threshold condition can be flexibly changed by performing noise processing on the server side. That is, it is possible to flexibly set the threshold value in consideration of many conditions such as the installation condition, the condition of the object to be measured, and the climatic condition. This makes it possible to remove noise more effectively.

The deterioration diagnosis unit 83 determines the deterioration status of the bridge structure 10 based on the information that has passed the noise processing in the position determination unit 81. The deterioration diagnosis unit 83 is an example of a “determination unit”. The deterioration diagnosis unit 83 detects the presence or absence of deterioration or the degree of deterioration of the bridge structure 10 based on the information regarding the position of the source of the elastic wave. For example, the deterioration diagnosis unit 83 deteriorates the bridge structure 10 based on the information on the density of the source position of the elastic wave obtained by accumulating the information on the source position of the elastic wave defined by the position setting unit 81. Judge the presence or absence of or the degree of deterioration. For example, the deterioration diagnosis unit 83 determines that deterioration exists (or the degree of deterioration is a certain level, etc.) when the spatial density of the source of elastic waves becomes equal to or higher than a preset predetermined value. .. The deterioration diagnosis unit 83 is not limited to the above example. For example, the deterioration diagnosis unit 83 may determine the presence or absence of deterioration and the degree of deterioration of the bridge structure 10 based on the frequency of occurrence of elastic waves and the intensity of elastic waves (for example, amplitude and energy).

Next, a detection method (deterioration detection method, deterioration diagnosis method) using the detection system 1 of the present embodiment will be described.
FIG. 15 is a flowchart showing an example of the flow of the detection method of the present embodiment.
As shown in FIG. 15, first, AE sensors 41 and 42 provided in the bridge structure 10 are used to detect elastic waves accompanying the generation of cracks C or the growth of cracks C (step S11). In the present embodiment, for example, an AE sensor 41 attached to the trafrib 23 detects an elastic wave transmitted from the crack C to the trafrib 23.

Next, based on the detection results of the AE sensors 41 and 42, the feature amount (parameter that characterizes the waveform shape) that characterizes the waveform shape of the elastic wave detected by the AE sensors 41 and 42 is extracted (step S12). Further, based on the detection results of the respective AE sensors 41 and 42, the arrival time of the elastic wave for each of the AE sensors 41 and 42 is calculated (step S13). The order in which the steps S12 and S13 are performed may be reversed, or they may be performed at the same time.

Next, the position of the source of the elastic wave is determined (step S14). Specifically, the similarity of elastic waves detected by, for example, AE sensors 41A and 41B is compared based on the information on the feature amount of the waveform shape of the elastic wave. Then, when the similarity of the elastic waves detected by the AE sensors 41A and 41B is within a predetermined range, it is determined that the elastic waves are the same elastic wave, and the position of the source of the elastic wave is determined. It is said. For example, the position of the source of the elastic wave is determined based on the time difference between the times when the two AE sensors 41A and 41B detect the elastic wave, the propagation speed of the elastic wave in the trough rib 23, and the position of the welded portion 28. ..

Next, noise processing associated with position localization is performed (step S15). Specifically, based on the position orientation result, it is determined whether or not the elastic wave is generated within a predetermined threshold range. When it is determined that the elastic wave is generated from within the range within a predetermined threshold value (step S15: YES), the process proceeds to the determination of the deterioration status. On the other hand, when it is determined that the elastic wave is generated from outside the range within a predetermined threshold value (step S15: NO), the signals detected by the AE sensors 41A and 41B are regarded as noise, and the degree of deterioration is determined. No judgment is made.

Next, the state of deterioration of the bridge structure 10 is determined (step S16). For example, the state of deterioration is determined based on information regarding the density of the source position of elastic waves. As a result, the presence or absence of deterioration or the degree of deterioration of the bridge structure 10 is detected.
The details of the operation of each of the above steps are as described in the description of the detection system 1.

According to the above configuration, it is possible to provide a detection system 1, a detection device 2, and a detection method capable of easily detecting a crack C generated in a structure.
That is, for example, in a steel deck, fatigue cracks may occur in the welded portion between the deck plate and the trough rib. If fatigue cracks occur in the welded part, it may lead to the collapse of the road. Therefore, detecting fatigue cracks is important for the maintenance of infrastructure structures.

Here, as Comparative Example 1, a detection method for detecting a crack generated in a structure by an ultrasonic flaw detection method will be considered. In such a detection method, it is necessary to actually bring the flaw detector into contact with the surface of the structure and scan it, so that the operator needs to approach the structure. Therefore, it is necessary to build a scaffold for a structure such as a bridge. For this reason, it may be difficult to investigate a wide area of the structure.

Further, as Comparative Example 2, a detection method for indirectly detecting a crack by detecting the stagnant water that has invaded the crack and accumulated inside the structure with infrared rays will be considered. In such a detection method, since the stagnant water is directly detected, the crack may not be detected if there is no intrusion of rainwater or the like from the crack.

On the other hand, the detection device 2 of the present embodiment includes a deck plate 21 that supports the traveling surface TS on which the vehicle V travels from below, and a traffrib 23 provided on the side opposite to the traveling surface TS with respect to the deck plate 21. , A plurality of detection devices provided along the end portion 26e of the trafrib 23 facing the deck plate 21, and installed on the bridge structure 10 including the welded portion 28 to which the deck plate 21 and the trafrib 23 are fixed. The AE sensor 41 and the wireless transmission unit 36 are provided. The plurality of AE sensors 41 are arranged apart from each other in the extending direction of the welded portion 28, and are attached to the trafrib 23 to detect elastic waves transmitted to the trafrib 23. The wireless transmission unit 36 outputs information obtained from the outputs of the plurality of AE sensors 41 to the outside.
According to such a configuration, by detecting the elastic wave transmitted from the crack C to the traffrib 23 by the AE sensor 41, the crack C can be detected even if the crack is difficult to visually confirm, for example. Further, according to the above configuration, the crack C can be detected without being restricted by the installation height and state of the structure (such as the presence of water retention).

Here, in the present embodiment, the plurality of AE sensors 41 are attached to the trafrib 23 instead of the deck plate 21. Further, as described above with reference to FIG. 7, by attaching the AE sensor 41 to the traffrib 23, it is possible to detect the crack C which cannot be detected by the AE sensor 42 attached to the deck plate 21. As a result, the crack C can be detected more accurately by attaching the AE sensor 41 to the traffrib 23.

It is considered that one of the reasons why the crack C that cannot be detected by the AE sensor 42 attached to the deck plate 21 can be detected by attaching the AE sensor 41 to the traffrib 23 is as follows. That is, the deck plate 21 is relatively close to the traveling surface TS on which the vehicle V travels. Therefore, various vibrations are likely to be input to the deck plate 21 from the traveling surface TS. Further, since the AE sensors 41 and 42 generally have high sensitivity, it is easy to detect the vibration input from the traveling surface TS. Therefore, in the output signal from the AE sensor 42, a signal for detecting an elastic wave and a signal for detecting a vibration input from the traveling surface TS are mixed. As a result, in the process of noise removal, the signal in which the elastic wave is detected may be removed together with the noise.

On the other hand, the traffrib 23 is arranged farther from the running surface TS than the deck plate 21. Therefore, the vibration input from the traveling surface TS to the traffrib 23 is limited. As a result, it is considered that when the AE sensor 41 is attached to the traffrib 23, the crack C can be detected with high accuracy.

Further, in the present embodiment, the trafrib 23 includes an upright portion 26A along the direction away from the traveling surface TS. The plurality of AE sensors 41 are attached to the standing portion 26A of the trafrib 23 and detect elastic waves transmitted to the standing portion 26A.
According to such a configuration, the AE sensor 41 is arranged farther from the traveling surface TS than the end portion 26e of the trafrib 23 among the trafribs 23. Therefore, the noise input from the traveling surface TS to the AE sensor 41 is further reduced. As a result, the detection accuracy of the crack C can be further improved.

In the present embodiment, the angle between the extension line L1 of the straight line connecting the two adjacent AE sensors 41A and 41B included in the plurality of AE sensors 41 and the reference line L2 along the extending direction of the welded portion 28 is θ. Then, the relationship of −20 degrees <θ <20 degrees is satisfied.
Here, the traffrib 23 of the bridge structure 10 may partially have holes, protrusions, or the like. Further, another sensor may be attached to the traffrib 23. Therefore, it may not be possible to arrange the plurality of AE sensors 41A and 41B at the same height.
However, by arranging a plurality of AE sensors 41A and 41B so as to satisfy the above relationship, the crack C can be defined with higher accuracy. As a result, the state of deterioration of the bridge structure 10 can be detected more accurately.

In the present embodiment, the welded portions 28 are arranged apart from each other in the extending direction, and each further includes a plurality of AE sensors 42 attached to the deck plate 21 and detecting elastic waves transmitted to the deck plate 21. The radio transmission unit 36 outputs information obtained from the outputs of the plurality of AE sensors 41 attached to the trafrib 23 and the plurality of AE sensors 42 attached to the deck plate 21 to the outside.
According to such a configuration, in addition to the plurality of AE sensors 41 attached to the traffrib 23, the plurality of AE sensors 42 attached to the deck plate 21 can be used in combination to further improve the detection accuracy of the crack C. can. Further, as shown in FIG. 6A, the position of the crack C in the two-dimensional plane is detected by arranging a plurality of AE sensors 42 divided on both sides of the traffrib 23 in the width direction of the bridge structure 10. can do.

In the present embodiment, the detection device 2 further includes a feature amount extraction unit 64. The feature amount extraction unit 64 extracts information on the characteristics of elastic waves in the AE sensors 41A and 41B, for example, based on the detection results of the AE sensors 41A and 41B. The radio transmission unit 36 outputs information on the characteristics of the elastic waves in the AE sensors 41A and 41B extracted by the feature amount extraction unit 64 in association with information on the arrival time of the elastic waves in the AE sensors 41A and 41B.
According to such a configuration, it is possible to determine with high accuracy whether or not the elastic waves detected by the AE sensors 41A and 41B are the same elastic waves based on the information regarding the characteristics of the elastic waves. Thereby, the accuracy of detecting the crack C can be further improved.

The detection system 1 of the present embodiment is a detection system that detects the state of the bridge structure 10, and includes a plurality of AE sensors 41 and a position positioning unit 81. The position determination unit 81 determines the position of the source of the elastic wave based on the information obtained from the outputs of the plurality of AE sensors 41.
According to such a configuration, as described above, by detecting the elastic wave transmitted from the crack C to the traffrib 23 by the AE sensor 41, for example, even if the crack is difficult to visually confirm, the structure can be installed. The crack C can be detected without being restricted by the height and the state.

In the present embodiment, the plurality of AE sensors 41 include a first AE sensor 41A and a second AE sensor 41B. The positioning unit 81 is a source of elastic waves based on the time difference between the arrival times of elastic waves with respect to the first AE sensor 41A and the second AE sensor 41B, the propagation speed of elastic waves in the trough rib 23, and the position of the welded portion 28. Position the position.
According to such a configuration, the position of the crack C can be detected accurately even by the AE sensors 41A and 41B arranged apart from the actual position of the crack C.

In the present embodiment, the position determination unit 81 is the first AE sensor when the similarity between the elastic wave characteristics of the first AE sensor 41A and the elastic wave characteristics of the second AE sensor 41B is within a preset range. It is determined that the elastic wave detected by 41A and the elastic wave detected by the second AE sensor 41B are the same elastic wave, and the source position of the elastic wave is defined.
According to such a configuration, it is possible to more accurately determine whether or not the elastic wave detected by the first AE sensor 41A and the elastic wave detected by the second AE sensor 41B are the same elastic wave. Thereby, the detection accuracy of the crack C can be further improved.

In the present embodiment, the detection system 1 further includes a deterioration diagnosis unit 83. The deterioration diagnosis unit 83 deteriorates the bridge structure 10 based on, for example, information on the density of the source position of the elastic wave obtained by accumulating the information on the source position of the elastic wave defined by the position setting unit 81. Judge the situation of. The term "determining the state of deterioration" as used in the present application includes determining at least one of the presence or absence of deterioration and the degree of deterioration.
According to such a configuration, the state of deterioration of the bridge structure 10 can be easily detected with relatively high accuracy based on the density of the source position of the elastic wave.

The detection method of the present embodiment is a detection method for detecting the state of the bridge structure 10, and is a detection result of detecting elastic waves transmitted to the trough rib 23 at a plurality of positions separated from each other in the extending direction of the welded portion 28. Based on, the position of the source of elastic waves is determined. The "detection result" referred to in the present application may be the voltage signal itself output from the AE sensor, or may be a voltage signal subjected to preset noise processing, arithmetic processing, determination processing, or the like. ..
According to such a configuration, as described above, by detecting the elastic wave transmitted from the crack C to the traffrib 23 by the AE sensor 41, for example, even if the crack is difficult to visually confirm, the structure can be installed. The crack C can be detected without being restricted by the height and the state.

The detection system 1, the detection device 2, and the detection method according to one embodiment have been described above. However, the configuration of the detection system 1, the detection device 2, and the detection method is not limited to the above embodiment. For example, the detection device 2 may have only the AE sensor 41 attached to the trough rib 23 and may not have the AE sensor 42 attached to the deck plate 21. Each of the position setting unit 81, the threshold value setting unit 82, and the deterioration diagnosis unit 83 of the deterioration detection unit 72 may be a software function unit realized by executing a program by the processor (for example, CPU) of the information processing device 4. , It may be a hardware functional unit such as an LSI. Further, in the detection device 2, the BPF 33 and the ADC 34 may be formed as a part of the signal processing unit 35.

According to at least one embodiment described above, the detection device is provided with a first member that supports the traveling surface on which the vehicle travels from below, and a side opposite to the traveling surface with respect to the first member. Detection installed in a structure composed of a second member and a welded portion provided along the end of the second member facing the first member and fixing the first member and the second member. It is a device and has a plurality of AE sensors and an output unit. The plurality of AE sensors are arranged apart from each other in the extending direction of the welded portion, and are attached to the second member and detect elastic waves transmitted to the second member. The output unit outputs information obtained from the outputs of the plurality of AE sensors. With such a configuration, cracks generated in the structure can be easily detected.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, as well as in the scope of the invention described in the claims and the equivalent scope thereof.

1 ... Detection system, 2 ... Detection device, 10 ... Bridge structure (structure), 21 ... Deck plate (first member), 23 ... Trafrib (second member), 26A, 26B ... Standing part (plate part), 28 ... Welded part, 36 ... Radio transmission part (output part), 41, 42 ... AE sensor, 41A ... 1st AE sensor, 41B ... 2nd AE sensor, 64 ... Feature quantity extraction part (extraction part), 81 ... Positioning part (Positioning unit), 83 ... Deterioration diagnosis unit (judgment unit), V ... Vehicle, TS ... Running surface, L1 ... Extension line, L2 ... Reference line.

Claims (7)

A first member that supports a traveling surface on which the vehicle travels from below, a second member that is a traffrib provided on the side opposite to the traveling surface with respect to the first member, and the first member of the second member. A detection system that detects the state of a structure that is provided along an end facing a member and is composed of a welded portion that fixes the first member and the second member.
A first sensor group including a plurality of acoustic emission (AE) sensors in which the welded portions are arranged apart from each other in the extending direction and attached to the second member to detect elastic waves transmitted to the second member. When,
A second sensor group including a plurality of AE sensors attached to the first member and detecting elastic waves transmitted to the first member, respectively.
The detection results of the plurality of AE sensors included in the first sensor group and the detection results of the plurality of AE sensors included in the second sensor group are treated separately from each other, and the plurality of AEs included in the first sensor group are handled separately. A locating unit that separately determines the source position of the elastic wave based on the detection result of the sensor and the source position of the elastic wave based on the detection result of a plurality of AE sensors included in the second sensor group.
With
The control unit
A detection system that detects cracks extending from a welded portion of the first member to the first member by using the detection results of a plurality of AE sensors included in the first sensor group. The control unit
Based on the similarity between the elastic waves detected by the plurality of AE sensors included in the first sensor group, the elastic waves detected by the plurality of AE sensors included in the first sensor group are the same elastic wave. Determine if there is,
Based on the similarity between the elastic waves detected by the plurality of AE sensors included in the second sensor group, the elastic waves detected by the plurality of AE sensors included in the second sensor group are the same elastic wave. Determine if there is,
The detection system according to claim 1. The first member is a deck plate.
The detection system according to claim 1 or 2. A first member that supports a traveling surface on which the vehicle travels from below, a second member that is a traffrib provided on the side opposite to the traveling surface with respect to the first member, and the first member of the second member. An information processing device provided along an end facing a member and detecting the state of a structure including a welded portion in which the first member and the second member are fixed.
A group of first sensors including a plurality of acoustic emission (AE) sensors that are arranged apart from each other in the extending direction and attached to the second member to detect elastic waves transmitted to the second member. Determining the source position of elastic waves based on the detection results,
Determining the source position of elastic waves based on the detection results of a second sensor group including a plurality of AE sensors attached to the first member and detecting elastic waves transmitted to the first member, respectively.
Equipped with a locating section that performs
The control unit
An information processing device that detects a crack extending from a welded portion of the first member to the first member by using the detection result of the first sensor group. A first member that supports a traveling surface on which the vehicle travels from below, a second member that is a traffrib provided on the side opposite to the traveling surface with respect to the first member, and the first member of the second member. It is a detection method for detecting the state of a structure provided along an end portion facing a member and composed of a welded portion in which the first member and the second member are fixed.
A group of first sensors including a plurality of acoustic emission (AE) sensors that are arranged apart from each other in the extending direction and attached to the second member to detect elastic waves transmitted to the second member. Determining the source position of elastic waves based on the detection results,
Determining the source position of elastic waves based on the detection results of a second sensor group including a plurality of AE sensors attached to the first member and detecting elastic waves transmitted to the first member, respectively.
Do separately,
A detection method for detecting a crack extending from a welded portion of the first member to the first member by using the detection result of the first sensor group. A first member that supports a traveling surface on which the vehicle travels from below, a second member that is a traffrib provided on the side opposite to the traveling surface with respect to the first member, and the first member of the second member. A detection system that detects the state of a structure that is provided along an end facing a member and is composed of a welded portion that fixes the first member and the second member.
A first sensor group including a plurality of acoustic emission (AE) sensors in which the welded portions are arranged apart from each other in the extending direction and attached to the second member to detect elastic waves transmitted to the second member. When,
A second sensor group including a plurality of AE sensors attached to the first member and detecting elastic waves transmitted to the first member, respectively.
The detection results of the plurality of AE sensors included in the first sensor group and the detection results of the plurality of AE sensors included in the second sensor group are treated separately from each other, and the plurality of AEs included in the first sensor group are handled separately. A locating unit that separately determines the source position of the elastic wave based on the detection result of the sensor and the source position of the elastic wave based on the detection result of a plurality of AE sensors included in the second sensor group.
With
The target tough is,
Based on the result of any of the above-mentioned orientations, a crack extending from the root portion of the welded portion of the first member and the second member toward the weld bead is detected.
Detection system. The target tough is,
The waveform shape of the elastic wave detected by the first sensor group and the second sensor group is determined in accordance with the plate thicknesses of the first member and the second member, respectively.
The detection system according to claim 1.

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