Deterioration detection method, and deterioration detection system

Abstract

To provide a technology that improves detectability of deterioration of a structure.SOLUTION: A deterioration detection method, which detects deterioration of a structure, is configured to: irradiate colloidal crystal sheet adhered to a structure with colored light; and detects a place where a color of the colloidal crystal sheet changes as an occurrence portion of the deterioration of the structure. If the deterioration such as a crack occurs in the structure having the colloidal crystal sheet adhered, the colloidal crystal sheet distorts accompanied by the deterioration, and fine displacement occurs, for example, a distance between particles changes and a wavelength of diffraction light shortens. That is, in the colloidal crystal sheet, a non-displacement occurring place and a displacement occurring place cause a difference in color development wavelengths. Thus, according to the deterioration detection method, the method is configured to use a color change in the colloidal crystal sheet to visualize the distortion or crack being difficult to check by an ordinary visual observation, which in turn can easily detect the distortion or crack.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an impairment detection method. [Background technology]

[0002] In recent years, the problem of deterioration of infrastructure, which is the foundation of human activity, has become apparent, and the importance of domestic infrastructure maintenance is increasing. For example, in the field of infrastructure construction, maintenance that takes into account the life cycle cost (LCC) of concrete structures is required, and technological development is becoming important to prevent cracks from occurring and detect them early to halt their progression and increase the long-term durability of structures.

[0003] Conventionally, various techniques for detecting cracks on the surface of cement / concrete have been proposed (see, for example, Patent Documents 1 to 4 and Non-Patent Documents 2 and 3). Patent Document 1 proposes a technique in which a detection sheet including a surface protection layer, a retention layer containing glass spheres, a focus forming layer, and a specular reflection layer is attached to the surface of a hardened cement / concrete body, and the reflective structure of the detection sheet surface in the area along the crack is destroyed and no longer able to reflect, making it possible to easily visually observe the presence of the crack.

[0004] Patent Document 2 proposes a technology in which a first layer containing a polymer and a fluorescent whitening agent and a second layer containing a polymer and an ultraviolet absorber are laminated in that order on a base made of concrete; when a crack occurs in the base, the luminescence intensity increases in the crack-covering portion of the first layer that covers the surface side of the crack, making it possible to easily identify the location of the crack.

[0005] Patent Document 3 discloses a crack detection label having a resin substrate and a rupture layer of a different color from the resin substrate. It states that the rupture layer of this crack detection label ruptures before the resin substrate due to tensile force generated in the surface direction of the resin substrate, and therefore when a crack occurs in an object to which the crack detection label is attached, the rupture layer ruptures and the color of the resin substrate is visible through the crack, making it easy to check the crack.

[0006] Patent Document 4 discloses a concrete microcrack sensor that contains a fiber-containing plastic sheet. It states that when a crack occurs in concrete to which the sensor is attached, a discolored area appears in the fiber-containing plastic sheet, making it possible to detect the crack.

[0007] Non-Patent Documents 2 to 5 propose technologies for detecting cracks using RGB monochromatic light. Non-Patent Documents 2 and 3 consider early diagnosis of deterioration of structures by image measurement using lighting devices and digital cameras or video cameras.

[0008] Incidentally, resin sheets onto which colloidal crystals (three-dimensional regular structures of monodispersed colloidal fine particles) have been fixed have been proposed (see, for example, Patent Documents 5 to 9 and Non-Patent Document 1). [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2016-218049 A [Patent Document 2] JP 2013-88405 A [Patent Document 3] Patent No. 5567057 [Patent Document 4] Patent Publication No. 2022-62207 [Patent Document 5] JP 2006-208453 A [Patent Document 6] JP 2008-303261 A [Patent Document 7] JP 2010-132771 A [Patent Document 8] JP 2012-201755 A [Patent Document 9] JP 2007-51944 A [Non-patent literature]

[0010] [Non-Patent Document 1] Ishii et al., “Large-Domain Colloidal Crystal Films Fabricated Using a Fluidic Cell”, Langmuir, American Chemical Society, 2005, 21, 5367-5371 [Non-Patent Document 2] Masato Shiozaki et al., "Research on a method for detecting abnormalities using RGB monochromatic light", Sumitomo Mitsui Construction Technology Development Center Report, 2013, No. 11, pp. 69-72 [Non-Patent Document 3] Tatsunori Sada et al., "Study on Crack Detection in Tunnel Concrete Walls Using RGB Monochromatic Light and Shadows", Journal of the Japan Society of Civil Engineers, F3, 2013, vol.69, No.2, I_82-I_89 [Non-Patent Document 4] Akiyuki Ishimori et al., "Research on crack detection in existing tunnel concrete walls using RGB monochromatic light", Proceedings of the Civil Engineering Information Symposium, 2013, vol. 38, p35-38 [Non-Patent Document 5] Maekawa, Ryoji, et al., "Study on Crack Detection in Concrete Structures Using RGB Monochromatic Light," 67th Annual Conference of the Japan Society of Civil Engineers, September 2012, cs08-0011 Summary of the Invention [Problem to be solved by the invention]

[0011] However, even when the techniques of the above Patent Documents 1 to 4 and Non-Patent Documents 2 to 5 are used, there is a possibility that deterioration of a structure cannot be detected depending on the position of the worker detecting the deterioration, etc.

[0012] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a technique for improving the ability to detect deterioration of a structure. [Means for solving the problem]

[0013] The present disclosure has been made to solve at least a part of the above-mentioned problems, and can be realized in the following forms.

[0014] (1) According to one aspect of the present disclosure, there is provided a degradation detection method for detecting degradation of a structure, which comprises irradiating a colloidal crystal sheet affixed to the structure with specific colored light and detecting any change in color of the colloidal crystal sheet as the location of degradation of the structure.

[0015] Here, colored light does not include white light. A structure is a structure that is composed of multiple materials and members, such as roads, buildings, dams, and embankments, and is constructed with a structure that supports its weight by foundations, etc. The concept includes various structures, such as concrete structures made of concrete, such as airports, highways, high-rise buildings, stations, and ports, steel structures whose main members are steel, such as steel bridges, factories, and other steel-framed buildings, and earth structures that use earth, such as embankments, embankments, and banks.

[0016] If a structure to which a colloidal crystal sheet is affixed experiences deterioration such as cracks, and the colloidal crystal sheet distorts and undergoes minute displacement as a result of this deterioration, the distance between the fine particles will change, for example, and the wavelength of the diffracted light will become shorter. That is, in the colloidal crystal sheet, there will be a difference in the color wavelength between areas where there is no displacement and areas where there has been displacement. Therefore, according to this deterioration detection method, the color change in the colloidal crystal sheet can be used to visualize and easily detect distortions and cracks that are difficult to see with the naked eye.

[0017] Furthermore, in normal ambient light (white light), the light that hits the colloidal crystal sheet is scattered, making the original color of the colloidal crystals less visible. In contrast, this deterioration detection method uses a specific colored light that matches the colloidal crystals, emphasizing the color contrast of discolored areas caused by cracks, etc., making it easier to visually distinguish differences in color, improving visibility. As a result, deterioration can be detected more easily.

[0018] (2) In the deterioration detection method of the above embodiment, when the displaced portion of the colloidal crystal sheet is defined as the displaced portion and the non-displaced portion as the matrix portion, the specific colored light contains wavelength components that intensify the diffracted light of the structural colors of the displaced portion and the matrix portion of the colloidal crystal sheet at the observation position relative to the colloidal crystal sheet, and may contain no other components. In this way, the color contrast of the discolored portion due to cracks or the like can be more appropriately emphasized, and deterioration can be further detected.

[0019] (3) In the deterioration detection method of the above aspect, the specific colored light may have a hue between H165° and H200°. Colloidal crystal sheets are generally red in ambient light. Therefore, by irradiating the colloidal crystal sheet with colored light having a hue between H165° and H200°, discoloration becomes more visible.

[0020] (4) In the deterioration detection method of the above aspect, the colloidal crystal sheet irradiated with the specific colored light may be imaged and discoloration of the colloidal crystal sheet detected by image analysis, thereby making it possible to easily detect deterioration.

[0021] (5) According to another aspect of the present disclosure, there is provided a deterioration detection system for detecting deterioration of a structure, the deterioration detection system comprising an irradiation section which irradiates a colloidal crystal sheet affixed to the structure with specific colored light, an imaging section which images the colloidal crystal sheet irradiated with the specific colored light, and an analysis section which analyzes the image captured by the imaging section and determines that the structure has deteriorated if discoloration of the colloidal crystal sheet is detected.

[0022] According to this configuration, the color change in the colloidal crystal sheet can be used to visualize distortions and cracks that are difficult to see with the normal naked eye, making them easily detectable.

[0023] The present disclosure can be realized in various aspects, for example, in the form of a control method for controlling a deterioration detection system, a computer program for realizing the method, etc. [Brief description of the drawings]

[0024] [Figure 1] FIG. 2 is an explanatory diagram conceptually showing a deterioration detection method according to the present embodiment. [Diagram 2] FIG. 1 is an explanatory diagram conceptually showing the structure of a colloidal crystal sheet 1. [Diagram 3] FIG. 2 is a SEM photograph of colloidal crystal sheet 1. [Figure 4] FIG. 2 is an explanatory diagram showing elongation strain of a colloidal crystal sheet 1. [Diagram 5] FIG. 2 shows changes in the reflection spectrum associated with the stretching of the colloidal crystal sheet 1. [Figure 6] FIG. 13 is a diagram showing a shift in reflection peak wavelength. [Figure 7] FIG. 1 is an explanatory diagram showing a schematic diagram of a colloidal crystal sheet tensile test piece. [Figure 8] FIG. 13 is an explanatory diagram showing the results of color observation in a crack simulation test. [Figure 9] FIG. 1 is a diagram showing an example of the spectrum of ambient light and LED illumination light. [Figure 10]FIG. 1 is a diagram showing reflected light due to ambient light or LED light. [Figure 11] FIG. 1 is a diagram showing the measured spectrum of LED irradiation light by hue. [Figure 12] FIG. 11 is an explanatory diagram conceptually showing a deterioration detection system according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] First Embodiment Fig. 1 is an explanatory diagram conceptually showing the deterioration detection method of this embodiment. In the deterioration detection method of this embodiment, a specific colored light 20L is irradiated onto a colloidal crystal sheet 1 attached to a structure ST, and a change in color of the colloidal crystal sheet 1 is detected as the location of deterioration of the structure. In the example shown in Fig. 1, a bridge is shown as the structure ST, and cracks CR are shown as the deterioration.

[0026] As shown in the figure, when a crack CR occurs in the structure ST, the colloidal crystal sheet 1 attached across the crack CR of the structure ST stretches at the crack CR, forming a displaced portion 1a. As will be described later, the displaced portion 1a of the colloidal crystal sheet 1 develops a color different from that of the non-displaced portion (matrix portion 1b). In FIG. 1, the displaced portion 1a is shown with oblique lines. In the example shown in FIG. 1, a dimmable light 20 is used to irradiate the colloidal crystal sheet 1 with a specific colored light 20L, thereby making it easier to visually recognize the discoloration of the displaced portion 1a. The reason why the discoloration of the displaced portion 1a becomes easier to visually recognize by irradiating the colloidal crystal sheet 1 with the specific colored light 20L will be described in detail later. First, the colloidal crystal sheet used in the deterioration detection method of this embodiment will be described.

[0027] 1. Composition of colloidal crystal sheets: 2 is an explanatory diagram conceptually showing the structure of the colloidal crystal sheet 1. The colloidal crystal sheet 1 is a resin sheet in which colloidal crystals 14, which are three-dimensional regular structures in which monodispersed microparticles 12 are regularly arranged in a three-dimensional manner, are fixed by resin 16. The resin 16 is a matrix resin that fills the spaces between the monodispersed microparticles 12 that make up the colloidal crystals 14.

[0028] The material of the monodispersed particles is not particularly limited, and various materials can be used. In general, when the material of the monodispersed particles (particularly the refractive index) changes, the optical properties of the colloidal crystal sheet 1 change. Therefore, the material of the monodispersed particles is selected to be optimal depending on the application of the colloidal crystal sheet 1, the required properties, etc. Specific examples of the monodisperse fine particles 12 include: (1) Inorganic monodisperse particles such as silica, alumina, titania, and zinc oxide (ceramic particles) (2) Organic monodisperse particles such as styrene-based (e.g., polystyrene), acrylic-based (e.g., polymethyl methacrylate (PMMA)), and melamine-based particles. (3) Core / shell type particles in which the surface of a core made of a ceramic particle, polymer particle, etc. is covered with a shell made of a material different from the core (e.g., metal particles, metal oxide particles such as titania, metal oxide nanosheets such as titania, etc.) (4) Hollow particles obtained by removing the core from the core / shell particles using methods such as calcination and extraction. etc.

[0029] The monodisperse microparticles 12 used have a sufficiently narrow particle size distribution. The average particle size is preferably about 200 nm, since the colloidal crystals that are generated exhibit structural colors in the visible light region. The selection criterion is that the colloidal crystals can be easily formed during the generation of the dispersion liquid for producing the colloidal crystal sheet 1.

[0030] The resin 16 is not particularly limited, and various materials can be used. For example, acrylic resin (polyacrylic acid ester, acrylate, methacrylate), polystyrene, fluororesin, silicone resin, polymer of a compound having a vinyl group, etc. can be used. The resin 16 is preferably transparent (amorphous) and extensible, and easily processed into a sheet shape. Examples of acrylic monomers that are the raw material of acrylic resin include polyethylene glycol (meth)acrylate, polyethylene glycol di(meth)acrylate, polyethylene glycol tri(meth)acrylate, polypropylene glycol (meth)acrylate, polypropylene glycol di(meth)acrylate, polypropylene glycol tri(meth)acrylate, 2-hydroxyethyl (meth)acrylate, acrylamide, methylenebisacrylamide, etc., each having different ethylene glycol chain lengths. Since the colloidal crystal sheet 1 of this embodiment is attached to the structure ST, it is preferable that the resin 16 has adhesive properties. However, if the resin 16 does not have adhesive properties, adhesive properties may be imparted by using an adhesive, adhesive tape, etc.

[0031] Acrylic resin is colorless and transparent, and silica microparticles are also inherently colorless (they appear white due to scattered light). Therefore, when acrylic resin is used as resin 16, which is the matrix material of colloidal crystal sheet 1, and silica microparticles are used as monodispersed microparticles 12, the colloidal crystal sheet 1 does not fade due to light (high light resistance) because it does not contain pigments (components that absorb light in the visible light range), which are normal coloring materials, and is expected to maintain its performance even in outdoor exposure environments. Therefore, as a colloidal crystal sheet to be used in a method for detecting deterioration of a structure, a colloidal crystal sheet 1 using acrylic resin as resin 16 and silica microparticles as monodispersed microparticles 12 is preferred.

[0032] Even though the particles that make up colloidal crystals are not colored, they appear colored due to the Bragg reflection of light caused by the periodic structure. Colors resulting from such geometric structures are generally called structural colors. When colloidal crystal sheet 1 is distorted or deformed, a color change (coloration) is observed. This reflects a change in the interparticle distance (usually called the d value) of colloidal crystals 14 within colloidal crystal sheet 1. In other words, this is caused by macroscopic displacement inducing structural changes at the nanometer level, which causes a change in the wavelength of scattered light (Bragg condition).

[0033] When attaching a colloidal crystal sheet 1 to a structure ST and attempting to detect deterioration of the structure ST, such as distortion or cracks CR, by means of color changes in the colloidal crystal sheet 1, for example, the following problems arise. (1) If the location where colloidal crystal sheet 1 is applied is dark, such as outdoors, the color change is difficult to see. (2) Due to the principle of structural coloration of colloidal crystal sheet 1, the visible color is angularly dependent, and therefore the range in which color changes due to strain can be confirmed (the observable viewing angle) is narrow. Therefore, in the degradation detection method of the present embodiment, the above problem is improved by irradiating a specific colored light 20L instead of detecting using only environmental light (ambient light).

[0034] 2. Colour change of colloidal crystal sheets: The following describes the results of observing (visually or by camera) the color change using colloidal crystal sheet 1 under conditions simulating specific cracks. [Method of manufacturing colloidal crystal sheet 1] Colloidal crystal sheet 1 was produced in accordance with the production methods described in JP 2008-303261 A, JP 2010-132771 A, and JP 2012-201755 A. However, the ratio of monofunctional and polyfunctional monomers constituting the copolymer is preferably in the range of 99.5:0.5 to 90:10 from the viewpoint of imparting flexibility to the sheet, and therefore this point was added. Specifically, it was produced as follows.

[0035] 38 g of powdered monodisperse silica particles (made by Nippon Shokubai, KE-P20 / average particle size 200 nm) were placed in an eggplant-shaped flask, and 62 g of acrylic monomers, a mixture of Shin-Nakamura Chemical's NK Ester, AM-90G and A-600 in a weight ratio of 97:3, were added. The flask was placed in a water bath, and ultrasonic waves were carefully applied (1 minute to 24 hours) to prevent the temperature from rising, to prepare a monomer dispersion (particle concentration 38 wt%) in which colloidal crystals of the particles were formed in a three-dimensional regular arrangement. A cell was prepared by bonding two glass slides (Matsunami Glass Industry S9111) together using a silicone sheet less than 1 mm thick as a spacer. A photopolymerization initiator (DAROCUR 1173, manufactured by Chiba Specialty Chemicals) was added to the acrylic monomer dispersion at about 0.5% of the weight of the dispersion, and a small amount of pigment (about one spoonful of a microspatula) was added, and the mixture was then poured into a glass cell, after which ultraviolet light was irradiated from a high-pressure mercury lamp for one minute on each side of the glass cell. After the acrylic monomer had hardened by photopolymerization, the glass cell was disassembled, and an elastic colloidal crystal sheet 1 was obtained.

[0036] Figure 3 shows a scanning electron microscope (SEM) photograph of colloidal crystal sheet 1. From the SEM photograph of colloidal crystal sheet 1 shown in Figure 3, the center-to-center distance of silica microparticles was obtained to be about 270 nm (measured value at zero displacement). From this value, it can be seen that the lattice spacing of the colloidal crystal, which has an fcc structure (face-centered cubic), is d 111 = approx. 220 nm. Here, the effective refractive index [n eff =(1-φ)·n acryl +φ n SiO2 ] defined in (n eff 1.436) and the silica microparticle diameter of 200 nm leads to a volume fraction (φ) of 0.30.

[0037] Next, the wavelength of the Bragg reflection spectrum was calculated from the following (Equation 1) to be λ(5°)=630 nm. Here, the wavelength of the Bragg reflection spectrum was determined by referring to JP 2012-201755 A, and the angle in brackets λ was the angle of incidence when the vertical direction was 0°. At this time, as will be explained later using FIG. 4, the visible color was red, which was in good agreement with the above calculated value (FIG. 4, observed color when the sheet was vertical and the displacement was 0). In addition, when the viewing angle was oblique, λ(45°)=539 nm was calculated. As will be explained later using FIG. 8, this is consistent with the fact that it is actually observed as "green" at a position where the angle with the sheet surface is small (low angle viewing).

[0038]

number

[0039] It is believed that the change in interparticle distance due to displacement of the colloidal crystal sheet 1 differs between the in-plane direction and the film thickness direction of the colloidal crystal sheet 1. In other words, it is speculated that tensile displacement occurs in the in-plane direction of the colloidal crystal sheet 1, causing localized thinning, which shortens the crystal lattice of the colloidal crystals in the film thickness direction. The stretched portion of the colloidal crystal sheet 1 becomes thinner in the thickness direction, and the above d 111 becomes smaller. When the displaced part is actually viewed vertically, it is observed as "green," and when viewed from a 45° angle, it is observed as "blue." From the same calculation as for the case of 0 displacement, it can be seen that the distance between the particles is shortened by approximately 18%.

[0040] Next, under conditions simulating a specific crack that had occurred in the structure ST, the change in color of the colloidal crystal sheet 1 was observed (visually or photographed). Furthermore, a specific colored light 20L was used to irradiate the colloidal crystal sheet 1 with a dimmable light 20, and observations were also carried out.

[0041] Fig. 4 is an explanatory diagram showing the stretching strain of the colloidal crystal sheet 1. Fig. 4 is a diagram of the colloidal crystal sheet 1 observed from directly above. Fig. 5 is a diagram showing the change in reflection spectrum accompanying the stretching of the colloidal crystal sheet 1. Fig. 6 is a diagram showing the shift in the reflection peak wavelength.

[0042] The above test was carried out under the following conditions. Tensile measuring device: Manual unit (Misumi, PCKUE14-270 linear type, 2 movable boards), micrometer (Mitutoyo) installed (semi-custom jig used) Light irradiation device: Dimmable light (PIXEL G1, LED / RGB full color, 10W, hue range 0-360°, color temperature fixed at 5600K), color gamut range can be set arbitrarily between H0°~359° (360 colors). Colloidal crystal sheet 1: Colloidal crystal sheet 1 produced by the above method Size: 40mm x 70mm x 0.3mm (thickness) Spectral measurement: Spectrophotometric device (Soma Optical S-2650), exposure conditions: 10 ms x 200 times (average photometric value used), working distance (WD) of the receiver: 0.35 to several meters (measured at a specified position, adjusted so that the spectrum would not plateau).

[0043] The photograph on the left in Fig. 4 shows the colloidal crystal sheet 1 attached to the tensile measurement device (displacement 0), and the photograph on the right in Fig. 4 shows the colloidal crystal sheet 1 being pulled by the tensile measurement device (displacement present). Fig. 4 shows that the colloidal crystal sheet 1 is being pulled and deformed by the tensile measurement device. Fig. 4 is a grayscale photograph, but in reality the colloidal crystal sheet 1 in the left photograph (displacement 0) appears red, and the colloidal crystal sheet 1 in the right photograph (pulled) appears green (colloidal crystal sheet 1 observed from directly above).

[0044] 5 shows the results of measuring the reflection spectrum of ambient light each time the total length L of the colloidal crystal sheet 1 is stretched in 1 mm intervals from 40 mm (displacement 0) to 47 mm (displacement 7 mm). As shown in the figure, the reflection spectrum changes according to the stretching of the colloidal crystal sheet 1. FIG. 6 shows the results of FIG. 5 as the reflection peak wavelength versus the stretching strain. The stretching strain is the stretch relative to the total length L of the colloidal crystal sheet 1 at a displacement of 0 (40 mm in this example). As shown in FIGS. 4 to 6, the reflection spectrum of ambient light differs according to the displacement of the colloidal crystal sheet 1, so that when the colloidal crystal sheet 1 is stretched, the displaced portion 1a (FIG. 1) is visually perceived as a different color from the matrix portion 1b (FIG. 1).

[0045] Next, a crack simulation test was carried out using the above colloidal crystal sheet 1. 7 is a schematic diagram of the colloidal crystal sheet tensile test piece 1T used in the crack simulation test. The colloidal crystal sheet tensile test piece 1T is made by butting together two separate manual unit substrates B1 and B2 and attaching and fixing the colloidal crystal sheet 1 to the manual unit substrates B1 and B2 so as to straddle the two.

[0046] Crack simulation test: Displacement in the tensile direction shown in Figure 7 was applied to manual unit boards B1 and B2 of colloidal crystal sheet tensile test piece 1T. The color of the sheet was observed visually under ambient light and under illumination with a dimmable light. At the same time, the width of the opening that actually occurred was measured with a micrometer, and the displacement value was read.

[0047] When viewed from directly above, the colloidal crystal sheet 1 used in this test had a reddish parent body color, but where displacement had occurred (displaced portion), a blue-green line different in color from the parent body color (parent body color) appeared (not shown). The measured crack width (opening width W in Figure 8) was approximately 0.56 mm. By pulling the colloidal crystal sheet tensile test piece 1T horizontally, the thickness of the colloidal crystal sheet 1 became thinner at the opening (the portion where manual unit board B1 and manual unit board B2 are separated), and it is presumed that the interparticle distance (d value) of the internal colloidal crystals 14 became shorter, causing the observed spectrum (Bragg condition) to shift to shorter wavelengths.

[0048] Next, when the visual observation position was shifted from directly above the colloidal crystal sheet 1 (high-angle view) to a position where the angle with the sheet surface was smaller (low-angle view), the color of the matrix changed to blue-green, and no difference in hue was observed with the displaced part caused by pulling the colloidal crystal sheet 1. Since the human eye is less sensitive to blue than other colors, it was found that in the case of the colloidal crystal sheet 1 used in this test, it was difficult to distinguish the color change with a low-angle view. In other words, assuming a situation in which the colloidal crystal sheet 1 is attached to a structure, when an operator inspecting for cracks looks at the colloidal crystal sheet 1 from a direction perpendicular to the sheet surface (high-angle view) under ambient light, the operator can detect (identify) the cracks that have occurred by the color change, but when the observation direction becomes a low-angle view, it is possible that the operator may overlook the cracks even if they have occurred.

[0049] Based on the above results, as a way to increase visibility (improve detectability), we attempted to observe the colloidal crystal sheet 1 by irradiating it with colored light rather than observing it using ambient light.

[0050] Figure 8 is an explanatory diagram showing the results of color observation in a crack simulation test. Figure 8(A) shows an example of ambient light, and Figure 8(B) shows an example of colored light (LED light) irradiation. First, colloidal crystal sheet 1 was observed at a low angle under only ambient light, and it was confirmed that the color difference between the darker parent body (blue-green) and the displaced body (blue) was difficult to distinguish (there was no contrast) (Fig. 8(A)). Next, blue light was irradiated using a dimmable light while maintaining the same observation position. As a result, the blue color of the displaced body was clearly visible, as if it was floating up from the parent body color, making it easier to see the color difference (Fig. 8(B)). Note that Fig. 8 is a grayscale photograph, but while the displaced body is not visible in Fig. 8(A), it can be seen that the displaced body can be seen as a line of a color different from the parent body color in Fig. 8(B).

[0051] As a result, it was found that when using colloidal crystal sheet 1 to visualize cracks, even when sufficient contrast is not obtained under ambient light, making them difficult to see depending on the viewing angle, visibility can be improved by irradiating the sheet with a specific colored light. In other words, it was experimentally demonstrated that irradiating the sheet with colored light makes it possible to detect cracks even when the person performing the detection is in an unfavorable position (angle at which the sheet is viewed).

[0052] 3. Colored light: Fig. 9 is a diagram showing an example of the spectrum of ambient light and LED illumination light. Fig. 9 shows an example of LED illumination light with a hue of H165°. As shown in the figure, ambient light emits light containing various wavelength components from close to 400 nm to over 750 nm. In contrast, LED light with a hue of H165° emits light with wavelength components equivalent to B and G in the RGB space.

[0053] Figure 10 shows the reflected light from the ambient light or LED light shown in Figure 9. As shown in the figure, the light reflected by the colloidal crystal sheet 1, both under ambient light and under light with a hue of H165°, is light (diffracted light) with a strong wavelength component corresponding to G in the RGB space. However, reflected light under ambient light is mixed with a significant amount of wavelength components other than G. Therefore, when this enters the field of view of the inspector as scattered light, the inherent structural color of the colloidal crystal sheet 1 is buried and becomes difficult to see.

[0054] Figure 11 shows the measured spectrum of LED light by hue. As shown in the figure, LED light emits light of a specific wavelength depending on the hue.

[0055] The reason why the discoloration caused by the deformation of the colloidal crystal sheet 1 may be difficult to visually recognize under ambient light is believed to be as follows. The colloidal crystal sheet 1 has the characteristic that its color tone changes depending on the viewing angle. For example, when the sheet is viewed (i) perpendicularly to the surface and (ii) at an angle of about 60° to 30°, the sheet appears red in (i) and green in (ii). The stretched parts are observed as green in (i) and blue in (ii). In (i), the stretched parts are green and the non-stretched parts are red, a combination with a strong color contrast, so it is believed that the color difference can be visually recognized to some extent even when white light (ambient light) is applied. However, in the above case of (ii) (observed at an angle not directly facing the sheet), the combination of the parent color (the color of the non-stretched parts) being "green" and the stretched parts being "blue" is a combination with a weak color contrast, resulting in the result being difficult to visually recognize even when white light is applied.

[0056] When the colloidal crystal sheet 1 is affixed to a structure such as a bridge or a building and observed to detect deterioration, the observer's viewing angle and standing position will often be as in (ii) above, and it is expected that discoloration of the colloidal crystal sheet 1 due to deformation of the structure will be difficult to identify when observed under ambient light. Furthermore, under ambient light, wavelength components other than the structural color are mixed in, and when these enter the field of view as scattered light, the inherent structural color of the colloidal crystal sheet 1 becomes buried and difficult to see. It can be assumed that the difference in color of the displaced area can be observed with high contrast by irradiating the colloidal crystal sheet with light of a hue consisting only of wavelength components that produce strong diffraction intensity from the colloidal crystals.

[0057] The selection of colored light capable of improving the visibility of the color change accompanying the deformation of the colloidal crystal sheet 1 will be described below. As described above, it is believed that the color change in the colloidal crystal sheet 1 is caused by the occurrence of cracks, which causes the colloidal crystal sheet 1 to distort, shortening the interval between colloidal crystal particles (distance on the order of nanometers), and shortening the wavelength of light diffracted under the Bragg condition. As a result, the cracks can be visualized as a color change and detected based on the difference in color between the non-displaced portion (matrix portion) and the displaced portion. However, even if such a change in the interval between colloidal crystal particles occurs, the light that hits the colloidal crystal sheet 1 is scattered when viewed with the naked eye under ambient light (generally white light), and depending on the angle at which the worker views the colloidal crystal sheet 1, the original color of the colloidal crystals may be buried and difficult to see. To address this problem, the deterioration detection method of this embodiment irradiates colored light (LED light) adjusted to match the color tone of the colloidal crystal sheet 1, thereby emphasizing the color contrast of the displaced portion and improving visibility.

[0058] It is desirable to set the colored light according to the combination of the matrix color and the color of the displaced portion of the colloidal crystal sheet 1 as seen from the observation position. For example, in the case of the colloidal crystal sheet 1 used in the above-mentioned experiment, where the structural colors of the colloidal crystal sheet 1 are green and blue (when viewed from an angle of 45 degrees or more from the front toward the colloidal crystal sheet 1, the matrix color appears green and the displaced portion appears blue), colored light containing only G and B components may be irradiated. When expressed in terms of hue parameters, colored light in the range of H165° to 200° is suitable. On the other hand, when the combination of the matrix color and the color of the displaced portion is red and blue (when viewed from almost the front toward the colloidal crystal sheet 1), colored light having R and B components may be irradiated. When expressed in terms of hue parameters, colored light in the range of H290° to 340° is suitable. In either case, when the structural colors of the colloidal crystal sheet 1 are green and blue, or red and blue, it is desirable to select colored light that contains wavelength components that intensify the diffracted light of the structural colors of the displaced and matrix parts of the colloidal crystal sheet at the observation position relative to the colloidal crystal sheet, and that contains as few other components as possible.

[0059] In the above explanation, the HSV system is used as the color space that specifies the hue, and the RGB system is used for the lighting (light-emitting LED), but these two systems can be converted into each other, and for example, the formula for converting from HSV values ​​to RGB is as follows: If H is expressed as an angle that varies from 0.0° to 360.0° along the color wheel on which the hue is placed, and saturation S and brightness V vary between 0.0 and 1.0, and a certain color defined by such (H,S,V) values ​​is given, the (R,G,B) color can be determined as follows (however, conversion from a cylindrical model is assumed: C=V×S).

[0060]

number

[0061] For example, the color at H=180°, S=1.0 (100%), and V=1.0 (100%) is calculated as (R,G,B)=(0,1,1), which is converted to full color (8-bit RGB) gradation as (0,255,255). Similarly, the color at H=165° is determined as (R,G,B)=(0,1,0.75), which is expressed in full color as (0,255,191).

[0062] When inspecting infrastructure, if colored light (LED light) with a hue based on a calculated value is irradiated according to the colloidal crystal sheet 1 used by the observer (worker), the color contrast of the discolored area will be emphasized and visibility will be improved. As a result, it is believed that visualization and detection of cracked areas will become easier. This effect is effective even in situations where it is difficult to approach actual infrastructure structures from any position. In the unlikely event that the color of the base part changes depending on the viewing angle, the color can be adjusted accordingly.

[0063] 4.Effects of this embodiment: For example, the techniques described in the above Non-Patent Documents 2 to 5 are methods for early diagnosis of structural deterioration by image measurement using lighting fixtures and digital or video cameras, but because light is directly irradiated onto the concrete itself to identify cracks, there is a problem that identification is difficult and recognition accuracy cannot be achieved. In response to this problem, the deterioration detection method of the present embodiment makes use of the properties of colloidal crystals to improve the ability to detect cracks by using a colloidal crystal sheet 1 attached to the structure in combination with irradiation of colored light 20L by a dimmable light 20.

[0064] Furthermore, the colloidal crystal sheet 1 of this embodiment is less susceptible to fading over time and can withstand outdoor use. Furthermore, in recent years, the dimmable lights 20 (LED lights) used to irradiate colored light have become more powerful (brighter) and less expensive, and equipment designed for outdoor use has become available on the market. Therefore, the deterioration detection method of this embodiment can be said to be highly useful, as it can improve the ability to detect deterioration without using expensive equipment.

[0065] <Second embodiment> 12 is an explanatory diagram conceptually showing a deterioration detection system 100 of the second embodiment. The deterioration detection system 100 of this embodiment executes the deterioration detection method of the first embodiment. The deterioration detection system 100 irradiates a structure ST to which a colloidal crystal sheet 1 described in the first embodiment is attached with colored light 20L while capturing an image, detects discoloration of the colloidal crystal sheet 1 by image analysis, and if discoloration of the colloidal crystal sheet 1 is detected, judges that the structure ST has deteriorated.

[0066] The deterioration detection system 100 includes a moving body 40. In this embodiment, an unmanned aerial vehicle, a so-called drone, is used as the moving body 40. Alternatively, a vehicle can be used as the moving body 40. The moving body 40 includes a control unit 110 that controls its own operation, a dimming light 20, a camera 30, an analysis unit 120, and an input / output unit 140. The moving body 40 includes a computer, and has a CPU, a ROM, and a RAM (not shown). The CPU deploys a control program prestored in the ROM into the RAM and executes it to realize the functions of the above-mentioned parts. In this embodiment, the dimming light 20 is also called an "illumination unit", and the camera 30 is also called an "imaging unit".

[0067] The control unit 110 controls the operation of the moving object 40, as well as the dimming light 20 and the camera 30. The control unit 110 causes the moving object 40 to fly along a predetermined route, irradiates the colored light 20L at a predetermined timing, and causes the camera 30 to capture an image. The control unit 110 may control the moving object 40, the dimming light 20, and the camera 30 according to instructions input via the input / output unit 140 from a terminal held by an operator of the deterioration detection.

[0068] The dimmable light 20 emits colored light 20L (as explained in the first embodiment above) corresponding to the colloidal crystal sheet 1 attached to the structure ST. In this embodiment, the colored light 20L emitted by the dimmable light 20 is set in advance to correspond to the colloidal crystal sheet 1. The colored light 20L emitted by the dimmable light 20 may be controlled by the control unit 110. For example, the colloidal crystal sheet 1 attached to the structure ST is imaged by the camera 30 under ambient light, and the control unit 110 may determine appropriate colored light 20L according to the color of the matrix portion 1b obtained by image analysis of the captured image by the analysis unit 120, and the control unit 110 may control the dimmable light 20 to emit the determined colored light 20L.

[0069] The control unit 110 causes the mobile object 40 to fly to a predetermined position of the structure ST, and causes the dimmable light 20 to irradiate the colloidal crystal sheet 1 with colored light 20L, while also causing the camera 30 to capture an image of the colloidal crystal sheet 1. The analysis unit 120 processes the captured image IMG and detects discoloration of the colloidal crystal sheet 1. If the analysis unit 120 detects discoloration of the colloidal crystal sheet 1, it determines that the structure ST has deteriorated. On the other hand, if the analysis unit 120 does not detect discoloration of the colloidal crystal sheet 1, it determines that the structure ST has not deteriorated.

[0070] In this embodiment, the control unit 110 outputs the image IMG captured by the camera 30 and the analysis result (presence or absence of deterioration) by the analysis unit 120 to the display unit 200 via the input / output unit 140. In the example shown in FIG. 12, a tablet terminal is illustrated as the display unit 200, but various display devices such as a display screen of a smartphone or a notebook computer, a display, etc. can be used. In the example shown in FIG. 12, an example is shown in which data is transmitted from the deterioration detection system 100 to the display unit 200 by wireless communication, but for example, a configuration in which the mobile body 40 is equipped with a display unit may be used. In the case where the mobile body 40 is equipped with a display unit, the mobile body 40 may return to the worker after detecting deterioration at multiple points of the structure ST, and the worker may check the deterioration of the structure ST using the display unit equipped in the mobile body 40. Furthermore, the mobile body 40 may not be equipped with a display unit, and the display unit may be connected by wire via the input / output unit 140 of the mobile body 40.

[0071] As described above, according to the deterioration detection system 100 of this embodiment, since the deterioration detection system 100 has a dimmable light 20, a camera 30, and an analysis unit 120, deterioration of the structure ST can be easily detected using the colloidal crystal sheet 1.

[0072] Furthermore, according to the deterioration detection system 100 of this embodiment, since it has the mobile body 40, it is possible to easily detect deterioration in places where workers cannot approach, such as bridges and buildings.

[0073] <Modifications of this embodiment> The present disclosure is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit of the present disclosure. For example, the following modifications are also possible.

[0074] In the above second embodiment, an example was given in which the mobile object 40 had the dimmable light 20 and the camera 30, but the mobile object 40 does not have to have the dimmable light 20 and the camera 30. In other words, the deterioration detection system does not have to have a mobile object 40. For example, the dimmable light 20 and the camera 30 may be carried by an operator who detects deterioration of a structure. Furthermore, the dimmable light 20 and the camera 30 may be attached to the structure that is the subject of deterioration detection. The dimmable light 20 may be positioned so that it can irradiate the colloidal crystal sheet 1 with colored light, and the camera 30 may be positioned so that it can capture an image of the colloidal crystal sheet 1.

[0075] In the above second embodiment, an example was shown in which the functions of the analysis unit were realized in the computer of the mobile object 40, but a computer that realizes the functions of the analysis unit may be provided separately. For example, an image captured by the camera 30 of the mobile object may be sent to a separately configured computer, and the image may be analyzed by the separately configured computer to detect deterioration.

[0076] In the above embodiment, cracks were given as an example of deterioration, but the deterioration detection method and deterioration detection system of the above embodiment can be used for various types of deterioration such as peeling, distortion, deformation, etc. By utilizing the change in color caused by changes in the interparticle distance of the colloidal crystals 14 when the colloidal crystal sheet 1 is stretched, compressed, etc., the ability to detect various types of deterioration can be improved.

[0077] In each of the above embodiments, a part of the configuration realized by hardware may be replaced by software, and conversely, a part of the configuration realized by software may be replaced by hardware. In addition, when a part or all of the functions of the present disclosure are realized by software, the software (computer program) may be provided in a form stored in a computer-readable recording medium. The term "computer-readable recording medium" is not limited to portable recording media such as flexible disks and CD-ROMs, but also includes internal storage devices in a computer such as various RAMs and ROMs, and external storage devices fixed to a computer such as a hard disk. In other words, the term "computer-readable recording medium" has a broad meaning including any recording medium to which data packets can be fixed, not temporarily.

[0078] The present disclosure has been described above based on the embodiments and modified examples, but the embodiments of the above-mentioned aspects are intended to facilitate understanding of the present disclosure and do not limit the present disclosure. The present disclosure may be modified or improved without departing from the spirit and scope of the claims, and the present disclosure includes equivalents thereof. Furthermore, if a technical feature is not described as essential in this specification, it may be deleted as appropriate.

[0079] The present disclosure can also be realized in the following application examples. [Application example 1] A deterioration detection method for detecting deterioration of a structure, comprising: Irradiating the colloidal crystal sheet attached to the structure with specific colored light; A change in color of the colloidal crystal sheet is detected as a location where deterioration of the structure has occurred. Degradation detection method. [Application example 2] The deterioration detection method according to Application Example 1, If the displaced portion of the colloidal crystal sheet is defined as a displaced portion and the non-displaced portion is defined as a matrix portion, the specific colored light contains wavelength components that produce intensified diffracted light of the structural colors of the displacement portion and the matrix portion of the colloidal crystal sheet at an observation position relative to the colloidal crystal sheet, and does not contain other components; Degradation detection method. [Application example 3] The deterioration detection method according to the first or second aspect of the present invention, The specific colored light has a hue between H165° and H200°. Degradation detection method. [Application example 4] The deterioration detection method according to any one of Application Examples 1 to 3, an image of the colloidal crystal sheet irradiated with the specific colored light is captured, and discoloration of the colloidal crystal sheet is detected by image analysis; Degradation detection method. [Application example 5] A deterioration detection system for detecting deterioration of a structure, comprising: an irradiation unit that irradiates the colloidal crystal sheet attached to the structure with a specific colored light; an imaging section for imaging the colloidal crystal sheet irradiated with the specific colored light; an analysis unit which analyzes the image captured by said imaging unit, and judges that the structure has deteriorated when discoloration of said colloidal crystal sheet is detected; Equipped with Deterioration detection system. [Explanation of symbols]

[0080] B1, B2...Manual unit board CR…Crack IMG…Image ST…Structure W…Opening width 1…Colloidal crystal sheet 1T: Colloidal crystal sheet tensile test piece 1a…Displacement section 1b…Maternal body part 12...Monodisperse particles 14...Colloidal crystals 16…Resin 20…Dimmable light 20L…Colored light 30…Camera 40...Mobile 100…Deterioration detection system 110...Control unit 120…Analysis department 140…Input / output section 200…Display section

Claims

1. A deterioration detection method for detecting deterioration of a structure, comprising: Irradiating the colloidal crystal sheet attached to the structure with specific colored light; A change in color of the colloidal crystal sheet is detected as a location where deterioration of the structure has occurred. Degradation detection method.

2. 2. The degradation detection method according to claim 1, If the displaced portion of the colloidal crystal sheet is defined as a displaced portion and the non-displaced portion is defined as a matrix portion, the specific colored light contains wavelength components that produce intensified diffracted light of the structural colors of the displacement portion and the matrix portion of the colloidal crystal sheet at an observation position relative to the colloidal crystal sheet, and does not contain other components; Degradation detection method.

3. 2. The degradation detection method according to claim 1, The specific colored light has a hue between H165° and H200°. Degradation detection method.

4. The deterioration detection method according to any one of claims 1 to 3, an image of the colloidal crystal sheet irradiated with the specific colored light is captured, and discoloration of the colloidal crystal sheet is detected by image analysis; Degradation detection method.

5. A deterioration detection system for detecting deterioration of a structure, comprising: an irradiation unit that irradiates the colloidal crystal sheet attached to the structure with a specific colored light; an imaging section for imaging the colloidal crystal sheet irradiated with the specific colored light; an analysis unit which analyzes the image captured by said imaging unit, and judges that the structure has deteriorated when discoloration of said colloidal crystal sheet is detected; Equipped with Deterioration detection system.

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