Sheet for enhancing mechanoluminescence intensity, method for enhancing mechanoluminescence intensity, and method for measuring mechanoluminescence intensity

Abstract

To provide a sheet for enhancing mechanoluminescence intensity, a method for enhancing mechanoluminescence intensity, and a method for measuring mechanoluminescence intensity, which are capable of providing a luminescence intensity comparable to that of an object made of an aluminum-based material, even for an object made of an iron-based material.SOLUTION: A sheet for enhancing mechanoluminescence intensity, comprising an aluminum-containing layer and a mechanoluminescent layer, the mechanoluminescent layer including a coating of a composition containing a mechanoluminescent material.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a sheet for enhancing stress luminescence intensity, and further to a method for enhancing stress luminescence intensity and a method for measuring stress luminescence intensity.

Background Art

[0002] A method of visualizing the strain state of an object by disposing a stress luminescence material that emits light by mechanical stimulation of an externally applied force (tension, compression, displacement, friction, impact, etc.) on the surface of the object is known (Non-Patent Documents 1 to 3). When a load is applied to the object, the stress luminescent body also deforms as the object deforms, and the stress luminescent body emits light. Based on the luminescence intensity of the stress luminescent body, the stress generated in the object can be measured. As a stress luminescence material, a composition containing an oxide of aluminum is known (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Non-Patent Documents

[0004]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] As an application field of the stress luminescence material, visualization of the stress and strain states under a load condition of a metal material can be mentioned. However, in the measurement of stress and strain generated in an object using the stress luminescence material, the luminescence intensity of the stress luminescence body tends to be easily affected by the material of the object. As shown in Fig. 3, when the object is made of an iron-based material, the luminescence intensity tends to be lower than when the object is made of an aluminum-based material. The low luminescence intensity for generally widely used iron-based materials is a problem when considering the wide application of the stress luminescence material. The explanation of Fig. 3 will be described later.

[0006] An object of the present disclosure is to provide a stress luminescence intensity enhancement sheet, a stress luminescence intensity enhancement method, and a stress luminescence intensity measurement method that can obtain a luminescence intensity comparable to that of an object made of an aluminum-based material even in an object made of an iron-based material.

Means for Solving the Problems

[0007] The first aspect of the present disclosure is a stress luminescence intensity enhancement sheet including an aluminum-containing layer and a stress luminescence layer, and the stress luminescence layer includes a coating film of a composition containing a stress luminescence material (hereinafter, also referred to as a composition for forming a stress luminescence layer).

[0008] The second aspect of the present disclosure is a method for enhancing the stress luminescence intensity of a stress luminescence layer formed on a first surface of an object, and is a method for enhancing the stress luminescence intensity by providing an aluminum-containing layer between the first surface of the object and the stress luminescence layer.

Effect of the Invention

[0009] According to the present disclosure, there are provided a stress luminescence intensity enhancing sheet capable of obtaining a luminescence intensity comparable to that of an object made of an aluminum-based material even in an object made of an iron-based material, a method for enhancing stress luminescence intensity, and a method for measuring stress luminescence intensity.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and their description will not be repeated.

[0012] <Configuration of Stress Luminescence Intensity Enhancement Sheet> With reference to FIG. 1, a configuration example of a stress luminescence intensity enhancement sheet according to this embodiment will be described.

[0013] FIG. 1 is a schematic cross-sectional view showing a cross-section in the thickness direction of a stress luminescence intensity enhancement sheet 10 according to this embodiment. The stress luminescence intensity enhancement sheet 10 is attached to an object (not shown) and is used to measure the stress generated in the object when a force (such as a load etc.) is applied to the object.

[0014] As shown in FIG. 1, the stress luminescence intensity enhancement sheet 10 includes an aluminum-containing layer 11 and a stress luminescence layer 12. The stress luminescence layer 12 includes a coating film of a composition for forming a stress luminescence layer.

[0015] As shown in FIG. 2, the stress luminescence layer 12 is joined to the object 100 via the aluminum-containing layer 11. The luminescence intensity of the stress luminescence layer 12 increases in proportion to the magnitude of the applied force. When a force is applied to the object 100, since the object 100, the stress luminescence layer 12, and the aluminum-containing layer 11 will deform equally, the stress generated in the object 100 due to the deformation can be imaged (visualized) by the luminescence of the stress luminescence layer 12.

[0016] The stress luminescent layer 12 may be disposed in direct contact with the aluminum-containing layer 11, or may be disposed on the aluminum-containing layer 11 via, for example, a substrate or an adhesive layer. The aluminum-containing layer 11 may be disposed in direct contact with the object 100, or may be disposed on the aluminum-containing layer 11 via, for example, an adhesive layer. For example, a coating film of a composition containing aluminum particles is directly formed on the object 100 to form the aluminum-containing layer 11, and then a coating film of a composition for forming a stress luminescent layer is directly formed on the aluminum-containing layer 11 to form the stress luminescent layer 12, whereby the stress luminescence intensity enhancement sheet 10 can be formed.

[0017] According to the stress luminescence intensity enhancement sheet of the present disclosure, it is possible to obtain a luminescence intensity comparable to that of an object made of an aluminum-based material even in an object made of an iron-based material.

[0018] FIG. 3 shows the luminescence intensity of a stress luminescent material when a stress luminescent sheet (having a layer structure of a stress luminescent layer / resin substrate / adhesive layer) is attached to an object made of an iron-based material (SUS430) and an object made of an aluminum-based material (A6061), and a uniaxial tensile test is performed under the same conditions (crosshead speed: 2, 5, 10 mm / min, load up to 1.6 kN). As shown in FIG. 3, the aluminum-based material exhibits a luminescence intensity about three times higher than that of the iron-based material. Even considering that the elastic moduli of A6061 and SUS430 are about 70 GPa and 200 GPa, respectively, the above luminescence intensity difference is large. It is presumed that there is a desensitizing effect on the stress luminescent material in the iron-based material or a sensitizing effect in the aluminum-based material. Considering that such a desensitizing effect or sensitizing effect is not shielded by at least the total thickness of the adhesive layer and the resin substrate in view of the fact that the stress luminescent sheet is formed via the adhesive layer and the resin substrate, the present inventor has completed a stress luminescence intensity enhancement sheet including an aluminum-containing layer and a stress luminescent layer for the purpose of shielding the desensitizing effect from the iron-based substrate or obtaining a sensitizing effect due to the material itself. By using aluminum, which is a softer material than the iron-based material, it is also possible to follow the deformation of the iron-based material substrate.

[0019] According to the stress luminescence intensity enhancement sheet of the present disclosure, when used for an object made of an iron-based material, the luminescence intensity of the stress luminescent material can be increased by 2.5 times. At this time, the luminescence intensity of the stress luminescent material increased following the increase in stress-strain within the elastic range of SUS430, and also showed good agreement in repeated tests.

[0020] For the object 100, for example, those defined in Japanese Industrial Standard (JIS) Z-2201 "Tensile test pieces for metallic materials" can be used. The iron-based material may be, for example, high-purity iron, steel, stainless steel, etc. Examples of stainless steel include SUS430, etc. The aluminum-based material may be, for example, pure aluminum, aluminum alloy. Examples of aluminum alloy include A6061, etc.

[0021] The stress luminescent material is one in which an element serving as a luminescence center is dissolved in the skeleton of an inorganic crystal (base material). Typical examples include strontium aluminate (SrAl2O4) doped with europium. In addition, there are zinc sulfide doped with transition metals or rare earths, barium calcium titanate, calcium yttrium aluminate, etc. In the present embodiment, a known stress luminescent material can be used.

[0022] The stress luminescent material is in powder form and may be composed of ceramic particles having a particle diameter on the micron order. In recent years, synthesis of stress luminescent particles having a particle diameter of about 2 to 3 μm has been carried out. By pulverizing the synthesized stress luminescent particles, a stress luminescent material with a small particle diameter can be produced. Particles having a monoclinic crystal structure, even when pulverized, do not change their crystal structure, so the stress luminescence ability is not impaired, and aggregation between the particles after pulverization can be suppressed. For example, by pulverizing stress luminescent particles having a particle diameter of about 2 to 10 μm, a stress luminescent material having a particle diameter of about 1.3 to 4 μm can be produced.

[0023] The pulverization of the stress luminescent material can be carried out using a known pulverizing device. However, the stress luminescent material has low water resistance and may be deteriorated by heating, resulting in a decrease in stress luminescence ability. Therefore, it is preferable to use a pulverizing device capable of pulverizing by causing particles to collide with each other at high speed. The pulverization conditions are not particularly limited and may be set in consideration of the particle size and particle size distribution of the stress luminescent material before pulverization and the like.

[0024] The stress luminescent layer 12 may be a coating film of a composition for forming a stress luminescent layer formed directly in contact with the aluminum-containing layer 11, or may be attached to the aluminum-containing layer 11 via the second bonding layer described later as the stress luminescent sheet described later. The thickness of the stress luminescent layer 12 may be, for example, 10 μm or less, and is preferably 3 μm or more and 7 μm or less from the viewpoints of luminescence intensity and stress change capturing ability.

[0025] The composition for forming a stress luminescent layer can contain a solvent in addition to the stress luminescent material. The solvent can contain a film-forming resin. The solvent may contain additives such as a solvent, a dispersant, a filler, and a thickener as necessary. The stress luminescent material and the solvent can be mixed by pulverizing the stress luminescent material in a slurry state dispersed in the solvent. The pulverization method is not particularly limited, and for example, a roller mill or a ball mill can be used.

[0026] The content of the stress luminescent material in the composition for forming a stress luminescent layer can be adjusted as appropriate. For example, the stress luminescent material can be 150 PHR (150 parts of the stress luminescent material with respect to 100 parts of the solvent) with respect to a solvent mainly composed of a film-forming resin. The content of the stress luminescent material may be, for example, 60% by mass based on the mass of the composition for forming a stress luminescent layer.

[0027] The content of the stress luminescent material in the composition for forming the stress luminescent layer is preferably 20% by mass or more, more preferably 40% by mass or more, still more preferably 50% by mass or more. When the content of the stress luminescent material is less than 20% by mass, the interparticle distance of the particles of the stress luminescent material becomes large, and the stress propagated to the stress luminescent layer escapes into the solvent, so the stress luminescence ability may easily decrease.

[0028] When the stress luminescent layer 12 is formed in direct contact with the aluminum-containing layer 11, examples of the method for forming the stress luminescent layer 12 include a method of printing a paint containing a stress luminescent material on the aluminum-containing layer 11 and drying it. For printing the stress luminescent layer 12, for example, screen printing or inkjet printing can be used.

[0029] The aluminum-containing layer 11 can be, for example, an aluminum foil or a coating film of a composition containing aluminum particles. The thickness of the aluminum foil may be, for example, 1 μm or more and 20 μm or less. The coating film of the composition containing aluminum particles may be, for example, 0.5 μm or more and 10 μm or less. The composition containing aluminum particles may be, for example, an aluminum paint.

[0030] When the aluminum-containing layer 11 is a coating film of a composition containing aluminum particles, the coating film of the composition containing aluminum particles can be formed in direct contact with the object. When the aluminum-containing layer 11 is an aluminum foil, the aluminum foil can be attached to the object via the first bonding layer described below.

[0031] The sheet 10 for enhancing stress luminescence intensity may have a shape in plan view (the shape when viewed from the thickness direction) that is, for example, rectangular, and may be rectangular or square.

[0032] The stress luminescence intensity enhancement sheet 20 shown in Fig. 4 further includes a first bonding layer 13 on the side opposite to the stress luminescence layer 12 of the aluminum-containing layer 11. The stress luminescence intensity enhancement sheet 20 includes the stress luminescence layer 12, the aluminum-containing layer 11, and the first bonding layer 13 in this order. As shown in Fig. 5, the stress luminescence intensity enhancement sheet 20 can be attached to the object 100 through the first bonding layer 13.

[0033] When the stress luminescence intensity enhancement sheet 20 is viewed in the thickness direction, it is preferable that the entire stress luminescence layer 12 overlaps on the first bonding layer 13. By doing so, when the stress luminescence intensity enhancement sheet 20 is attached to the object, the entire stress luminescence layer 12 can be joined to the object using the first bonding layer 13. By propagating the stress generated in the object to the entire stress luminescence layer 12, a luminescence pattern reflecting the distribution of the stress generated on the surface of the object can be made to appear.

[0034] The thickness of the first bonding layer may be, for example, 1 μm or more and 35 μm or less. The smaller the thickness of the first bonding layer 13, the smaller the distance between the object and the stress luminescence layer 12, and even a minute stress generated in the object can be propagated to the stress luminescence layer 12. Therefore, it becomes possible to image the change in the minute stress generated on the surface of the object.

[0035] The first bonding layer 13 may be, for example, an adhesive layer and an adhesive agent layer. The thickness of the adhesive layer may be, for example, 10 μm or more and 35 μm or less, preferably 5 μm or more and 25 μm or less. The adhesive layer can contain, for example, an acrylic-based adhesive or a polyurethane-based adhesive, etc., but does not contain nickel. The adhesive agent layer can contain, for example, a cyanoacrylate-based adhesive agent, etc. The thickness of the adhesive agent layer may be, for example, 1 μm or more and 10 μm or less.

[0036] A release substrate may be provided on the side of the aluminum-containing layer 11 of the first bonding layer 13 opposite thereto. The release substrate has an adhesive force on its surface such that it can be peeled off, and can be a flexible film configured to be peelable from the first bonding layer 13. Examples of the release substrate can include films made of polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyolefin resins such as polypropylene and polyethylene, polycarbonate resins, polystyrene resins, acrylic resins, and the like. The release substrate is peeled off when the stress luminescence intensity enhancing sheet 20 is attached to the object.

[0037] The stress luminescence intensity enhancing sheet 30 shown in FIG. 6 includes a stress luminescence sheet 16 having a stress luminescence layer 12, a base material 14, and a second bonding layer 15. The stress luminescence sheet 16 is attached to the aluminum-containing layer 11 via the second bonding layer 15 and is attached to the object 100 via the first bonding layer 13. The stress luminescence intensity enhancing sheet 30 includes the stress luminescence layer 12, the base material 14, the second bonding layer 15, the aluminum-containing layer 11, and the first bonding layer 13 in this order.

[0038] As shown in FIG. 7, the stress luminescence intensity enhancing sheet 30 can be formed by attaching the aluminum-containing layer 11 to the object 100 via the first bonding layer 13 and then attaching the stress luminescence sheet 16 to the aluminum-containing layer 11 via the second bonding layer 15.

[0039] In the stress luminescence intensity enhancing sheet 30, the aluminum-containing layer 11 may be an aluminum foil or a coating film of a composition containing aluminum particles.

[0040] As shown in FIG. 8, it is also possible to attach the stress luminescence intensity enhancing sheet 30 formed by attaching the stress luminescence sheet 16 to the aluminum-containing layer 11 via the second bonding layer 15 to the object 100 with the aluminum-containing layer 11 via the first bonding layer 13.

[0041] The base material 14 can be, for example, a flexible film. Examples of the flexible film can include films made of polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyolefin resins such as polypropylene and polyethylene, polycarbonate resins, polystyrene resins, acrylic resins, etc.

[0042] The stress luminescence sheet 16 can be formed, for example, by forming a second bonding layer 15 on a release substrate, then forming a stress luminescence layer 12 on the base material 14, and thereafter, attaching the surface of the second bonding layer 15 opposite to the release substrate to the side of the base material 14 opposite to the stress luminescence layer 12.

[0043] As a method for forming the second bonding layer 15, a method such as printing a paint containing an acrylic adhesive or a polyurethane adhesive, etc. on the release substrate can be adopted. For the printing of the second bonding layer 15, for example, screen printing or inkjet printing, etc. can be used.

[0044] As a method for forming the stress luminescence layer 12, a method such as printing a composition for forming a stress luminescence layer on the base material 14 can be adopted. For the printing of the stress luminescence layer 12, for example, screen printing or inkjet printing, etc. can be used.

[0045] <Method for enhancing stress luminescence layer> The method for enhancing the stress luminescence intensity according to this embodiment will be described. The method for enhancing the stress luminescence intensity is a method for enhancing the stress luminescence intensity of a stress luminescence layer formed on a first surface of an object, and includes a step of providing an aluminum-containing layer between the object and the stress luminescence layer.

[0046] According to the method for enhancing the stress luminescence intensity of the present disclosure, according to the stress luminescence intensity enhancing sheet of the present disclosure, it becomes possible to obtain a luminescence intensity comparable to that of an object made of an aluminum-based material even in an object made of an iron-based material. The descriptions of the object, the stress luminescence layer, and the aluminum-containing layer in the above-mentioned stress luminescence intensity enhancing sheet are applicable.

[0047] As a method for providing an aluminum-containing layer between an object and a stress luminescence layer, for example, the following methods can be mentioned. First, it is formed by attaching an aluminum foil to the object via an adhesive layer, or formed by directly applying a composition containing aluminum particles to the object. Next, as shown in FIG. 7, a stress luminescence sheet including a coating film of a composition for forming a stress luminescence layer, a base material, and a second adhesive layer in this order is attached to the aluminum-containing layer via the second adhesive layer on the formed aluminum-containing layer. Or it may be formed by directly printing a coating film of a composition for forming a stress luminescence layer on the formed aluminum-containing layer.

[0048] As another example of a method for providing an aluminum-containing layer between an object and a stress luminescence layer, as shown in FIGS. 5 and 8, a stress luminescence intensity enhancement sheet 30 including a stress luminescence layer 12, an aluminum-containing layer 11, and a first adhesive layer 13 is attached to a first surface of an object 100 via the first adhesive layer 13 such that the aluminum-containing layer 11 faces the object 100 side.

[0049] Next, a method for measuring stress luminescence intensity will be described. The method for measuring stress luminescence intensity includes the above-described method for enhancing stress luminescence intensity. As shown in FIG. 9, the method for measuring stress luminescence intensity can include a stress luminescence intensity enhancement step (S10), an excitation light irradiation step (S20), an extinction step (S30), a load application step (S40), a stress luminescence imaging step (S50), and a stress calculation step (S60). The stress luminescence intensity enhancement step (S10) is performed by the above-described method for enhancing stress luminescence intensity.

[0050] FIG. 10 is a diagram showing a configuration example of a measuring device 200 used for the method for measuring stress luminescence intensity. The measuring device 200 can be used to measure the stress when a tensile load is applied to an object 220. A stress luminescence intensity enhancement sheet is attached to the object 220.

[0051] As shown in FIG. 10, the measuring device 200 includes a tensile testing machine 240, a control device 260, a photographing device 270, a light source 230, a driving device 232, a control device 280, and a storage device 290. At least the tensile testing machine 240, the photographing device 270, and the light source 230 among the measuring devices 200 are installed in a dark room.

[0052] The tensile testing machine 240 is a device for applying a tensile load to the object 220 and measuring mechanical properties such as the tensile strength, yield point, elongation, and constriction of the object 220. For example, as the tensile testing machine 240, a precision universal testing machine (product name: Autograph AG-Xplus, manufactured by Shimadzu Corporation) can be used.

[0053] The tensile testing machine 240 has a table 241, a crosshead 242, a pair of screw rods 244, 246, an upper gripper 248, a lower gripper 250, and a load cell 252. The pair of screw rods 244, 246 are erected on the table 241 so as to be rotatable in a vertical direction. The pair of screw rods 244, 246 are made of ball screws.

[0054] The crosshead 242 is connected to each screw rod 244, 246 via nuts (not shown). The crosshead 242 is configured to be movable in the vertical direction along the pair of screw rods 244, 246. A load mechanism (not shown) for raising and lowering the crosshead 242 is mounted in the table 241.

[0055] The upper gripper 248 is connected to the crosshead 242 and grips the upper end portion of the object 220. The lower gripper 250 is connected to the table 241 and grips the lower end portion of the object 220. The distance L1 between the upper gripper 248 and the lower gripper 250 can be 120 mm. During the tensile test, the tensile testing machine 240 applies a tensile force to the object 220 by raising the crosshead 242 according to the control of the control device 260 while gripping both ends of the object 220 with the upper gripper 248 and the lower gripper 250.

[0056] The load cell 252 is a sensor for detecting a test force, which is a tensile load applied to the object 220. The load cell 252 outputs a signal indicating the detected test force to the control device 260.

[0057] The control device 260 is communicatively connected to the tensile testing machine 240 and controls the tensile operation by the tensile testing machine 240. The control device 260 receives user operations such as setting operations and execution instruction operations of various parameters including test conditions of the tensile test, and controls the load mechanism according to the received user operations. The control device 260 further receives various signals including the output signal of the load cell 252 and the signal indicating the displacement amount of the crosshead 242 from the tensile testing machine 240, and analyzes data such as the detected value of the test force.

[0058] The control device 260 includes a processor such as a CPU (Central Processing Unit), a memory such as a ROM (Read Only Memory) and a RAM (Random Access Memory), an interface circuit for connecting peripheral devices, and a display unit 262. By the processor executing the tensile test program stored in the memory, the above-described various functions are realized.

[0059] The display unit 262 displays various information based on the signal input to the control device 260. For example, during the execution of the tensile test, the display unit 262 displays the test force detected by the load cell 252. The display unit also displays the displacement amount indicating the displacement (stroke) of the crosshead 242.

[0060] The light source 230 is arranged to face the object 220 and is configured to irradiate excitation light to the stress luminescence layer of the stress luminescence intensity enhancement sheet on the object 220. The light source 230 is, for example, a blue LED (Light Emitting Diode). Upon receiving the excitation light irradiated from the light source 230, the stress luminescence layer of the stress luminescence intensity enhancement sheet transitions to an excited state. The number of the light sources 230 is not limited.

[0061] The driving device 232 supplies power for driving the light source 230 and controls the on / off of the light source 230. The driving device 232 can control the amount of excitation light irradiated from the light source 230, the irradiation time of the excitation light, and the like.

[0062] The imaging device 270 is arranged so as to include at least a predetermined region of the object 220 in the imaging field of view. The imaging device 270 includes an optical system such as a lens and an imaging element. The imaging element generates a captured image by converting the light incident from the object 220 through the optical system into an electrical signal.

[0063] The control device 280 controls the imaging operation by the imaging device 270 and the driving of the light source 230 by the driving device 232. The control device 280 is connected to the control device 260 of the tensile testing machine 240 by a communication line 215. The control device 280 can comprehensively control the tensile testing machine 240, the imaging device 270, and the light source 230 by sending and receiving data to and from the control device 260 via the communication line 215. The communication between the control device 280 and the control device 260 may be realized by wireless communication. In this embodiment, the control device 280 for the light source 230 and the imaging device 270 and the control device 260 of the tensile testing machine 240 are provided separately, but the control device 280 and the control device 260 may be integrated.

[0064] The control device 280 includes a processor such as a CPU, a memory such as a ROM and a RAM, an interface circuit for connecting peripheral devices, and a display unit 282. The display unit 282 displays various information based on the signals input to the control device 280. For example, the display unit 282 can display data input from the control device 260 via the communication line 215 (such as the test force detected by the load cell 252 and the displacement amount indicating the displacement (stroke) of the crosshead 242). In addition, the display unit 282 can display an image of the stress-emitting layer (emission image) captured by the imaging device 270. The display unit 282 can display the emission image captured by the imaging device 270 in real time.

[0065] The memory device 290 is a non-volatile memory device that stores a stress measurement program executed by the CPU of the control device 280, data exchanged between the control device 280 and the control device 260, and image data captured by the imaging device 270.

[0066] In the step of irradiating excitation light (S20), the stress-emitting layer is excited by irradiating excitation light from the light source 230 onto the surface of the object 220.

[0067] Next, a step of extinguishing (S30) is performed. In this step (S30), the light source 230 is stopped and the system waits until the emission intensity of the stress-emitting layer after excitation stabilizes.

[0068] Next, a step of applying a load (S40) is performed. In this step (S50), a tensile load is applied to the object 220 by driving the tensile testing machine 240. As the conditions of the tensile test, the tensile speed and the maximum load are set.

[0069] Next, a step of photographing stress emission (S50) is performed. In this step (S50), a predetermined region of the object 220 is photographed by the imaging device 270. That is, the emission of the stress-emitting layer is photographed by the imaging device 270. For the imaging device 270, for example, an industrial camera is used, and the frame rate is set to 1 fps to photograph the stress-emitting layer.

[0070] Next, a step of calculating stress (S60) is performed. In this step (S60), the stress generated in the object 220 is measured using the emission image photographed by the imaging device 270 in the step of photographing stress emission (S50).

[0071] Specifically, the image data (moving image data) captured by the imaging device 270 is cut out in frame units. Then, for the luminescence image of one frame, the luminescence intensity within the ROI (Region Of Interest) is calculated. Using the calculated value of the luminescence intensity within the obtained ROI and the calibration curve data (a function showing the relationship between luminescence intensity and stress) stored in advance in the storage device 290, the stress generated in the ROI is calculated.

[0072] When a plurality of ROIs are set on the surface of the object 220, the stress generated within each ROI is calculated. Then, based on the position information of each ROI and the calculated value of the stress, the stress distribution on the surface of the object 220 is calculated.

[0073] For the luminescence image of one frame, the calculated value of the stress within the ROI is associated and stored in the storage device 290. That is, in the storage device 290, data indicating the stress generated in the object 220 by the tensile load is stored at the timing when the luminescence image of one frame is obtained. By observing the data of each timing in the order in which it is obtained, the temporal change in stress due to the tensile load can be evaluated.

[0074] In the above-described measurement method, a configuration example in which the stress luminescence intensity enhancement sheet is attached to one location of the object 220 has been described, but it is also possible to adopt a configuration in which the stress luminescence intensity enhancement sheet is attached to a plurality of locations of the object 220. In this case, after irradiating the plurality of stress luminescence intensity enhancement sheets with excitation light simultaneously, while applying a load to the object 220, the stress luminescence of the plurality of stress luminescence intensity enhancement sheets is imaged. Based on the luminescence intensity of the stress luminescence layer in the plurality of stress luminescence intensity enhancement sheets, the stress distribution at a plurality of locations on the object 220 can be obtained.

[0075] Hereinafter, the present invention will be described in more detail with reference to examples.

Example

[0076] [Tensile Test] The test system shown in FIG. 10 was installed under darkroom conditions, and test specimens with stress luminescence intensity enhancement sheets prepared in the examples and comparative examples were installed. Next, as an excitation process for accumulating energy in the stress luminescence layer, blue light was irradiated for 60 seconds, and then it was held in the dark for 120 seconds. Thereafter, the luminescence intensity until a load of 1.6 kN (256 MPa) was applied at a crosshead speed of 5 mm / min was recorded. The test results for two test specimens with stress luminescence intensity enhancement sheets are shown in FIGS. 11 and 12.

[0077] [Preparation of Composition 1 for Forming Stress Luminescence Layer] SrAl2O4-based stress luminescence particles (ML-032, Sakai Chemical Industry Co., Ltd., D50 = 3.3 μm, D90 = 5.2 μm, emission wavelength: λ = 520 - 530 nm) were pulverized using a jet mill (D50 = 1.6 μm, D90 = 2.1 μm), and a transparent ink composed of a urethane resin, a curing agent, and a solvent was mixed therewith to prepare Composition 1 for forming a stress luminescence layer.

[0078] [Fabrication of Stress Luminescence Sheet 1] A commercially available polyester sheet having a peelable adhesive layer (t = 59 μm, adhesive strength: 0.25 N / 25 mm: JIS Z 0237) on one side was prepared as a base material. Composition 1 for forming a stress luminescence layer was screen-printed on the surface of the polyester sheet (210 × 297 mm) opposite to the peelable adhesive layer side using a #500 stainless steel mesh, dried, and a stress luminescence layer with a thickness of 5 μm was formed to fabricate a detachable stress luminescence sheet 1.

[0079] [Example 1] An aluminum foil (foil made by UACJ, thickness 11 μm) was adhered to one side of a SUS430 test piece (JIS13B shape, thickness 0.5 mm) via an adhesive layer (instant adhesive, Kyowa Electric Industry, CC-33A). The peelable adhesive layer of the stress luminescence sheet 1 was attached to the aluminum foil, and a test piece with a stress luminescence intensity enhancement sheet having the stress luminescence sheet 1 / aluminum foil / adhesive layer / SUS430 test piece in this order was fabricated. A tensile test was conducted on the fabricated test piece with a stress luminescence intensity enhancement sheet. The measured luminescence intensity is shown in FIG. 11.

[0080] <Example 2> An aluminum paint was applied to one side of a SUS430 test piece (JIS13B shape, thickness 0.5 mm), dried, and an aluminum coating film (thickness 60 to 90 μm) was formed. On this coating film, the peelable adhesive layer of the stress luminescent sheet 1 was pasted, and a test piece with a stress luminescent intensity enhancing sheet having the stress luminescent sheet 1 / aluminum coating film / SUS430 test piece in this order was produced. A tensile test was conducted on the produced test piece with a stress luminescent intensity enhancing sheet. The measured luminescent intensity is shown in FIG. 11.

[0081] <Comparative Example 1> A peelable adhesive layer of the stress luminescent sheet 1 was pasted on one side of a SUS430 test piece (JIS13B shape, thickness 0.5 mm), and a test piece with a stress luminescent intensity enhancing sheet having the stress luminescent sheet 1 / SUS430 test piece in this order was produced. A tensile test was conducted on the produced test piece with a stress luminescent intensity enhancing sheet. The measured luminescent intensity is shown in FIG. 11.

[0082] <Comparative Example 2> A conductive aluminum tape (manufactured by 3M, AL-25BT, thickness 60 μm, aluminum layer thickness 25 μm, containing Ni) having an adhesive layer was pasted on one side of a SUS430 test piece (JIS13B shape, thickness 0.5 mm). On the conductive aluminum tape, the peelable adhesive layer of the stress luminescent sheet 1 was pasted, and a test piece with a stress luminescent intensity enhancing sheet having the stress luminescent sheet 1 / conductive aluminum tape / SUS430 test piece in this order was produced. A tensile test was conducted on the produced test piece with a stress luminescent intensity enhancing sheet. The measured luminescent intensity is shown in FIG. 11.

[0083] As shown in FIG. 11, higher luminescent intensities were obtained in Examples 1 and 2 compared to Comparative Examples 1 and 2.

[0084] <Example 3> On an aluminum foil (aluminum content 99+%, thickness 25 μm, Nilaco, AL-013223), Composition 1 for forming a stress luminescence layer was screen-printed using a #500 stainless steel mesh, dried, and a stress luminescence layer with a thickness of 5 to 8 μm was formed to form a sheet for enhancing luminescence intensity. The aluminum foil side of the sheet for enhancing luminescence intensity was joined to a SUS430 test piece via an adhesive layer (instant adhesive, Kyowa Electric Industry Co., Ltd., CC-33A), and a test piece with a sheet for enhancing stress luminescence intensity having a stress luminescence layer / aluminum foil / adhesive layer / SUS430 test piece in this order was produced. A tensile test was conducted on the produced test piece with a sheet for enhancing stress luminescence intensity.

[0085] <Comparative Example 3> For comparison with Example 4, the results of a tensile test on a specimen prepared in the same manner as in Comparative Example 1 are shown in FIG. 12.

[0086] As shown in FIG. 12, a higher luminescence intensity was obtained in Example 3 than in Comparative Example 3.

[0087] Those skilled in the art will understand that the above-described plurality of exemplary embodiments are specific examples of the following aspects.

[0088] (Item 1) A sheet for enhancing stress luminescence intensity according to one aspect includes an aluminum-containing layer and a stress luminescence layer, and the stress luminescence layer includes a coating film of a composition containing a stress luminescence material.

[0089] (Item 2) In the sheet for enhancing stress luminescence intensity according to Item 1, the aluminum-containing layer is an aluminum foil.

[0090] (Item 3) In the sheet for enhancing stress luminescence intensity according to Item 1, a first bonding layer is further provided on the side of the aluminum-containing layer opposite to the stress luminescence layer.

[0091] (Item 4) In the sheet for enhancing stress luminescence intensity according to Item 1, the aluminum-containing layer is a coating film of a composition containing aluminum particles.

[0092] (Item 5) In the stress luminescence intensity enhancement sheet of Item 1, it includes a stress luminescence sheet including the stress luminescence layer, the base material, and the second bonding layer in this order, and the stress luminescence sheet is attached to the aluminum-containing layer via the second bonding layer.

[0093] (Item 6) In the stress luminescence intensity enhancement sheet of Item 1, in the stress luminescence layer, a coating film of the composition containing the stress luminescence material is formed in direct contact on the aluminum-containing layer.

[0094] (Item 7) In the stress luminescence intensity enhancement sheet of Item 1, the first bonding layer is an adhesive layer or an adhesive agent layer.

[0095] (Item 8) In the stress luminescence intensity enhancement sheet of Item 1, the second bonding layer is an adhesive layer or an adhesive agent layer.

[0096] (Item 9) A method for enhancing the stress luminescence intensity according to another aspect is a method for enhancing the stress luminescence intensity of a stress luminescence layer disposed on an object, including a step of providing an aluminum-containing layer between the object and the stress luminescence layer.

[0097] (Item 10) In the method for enhancing the stress luminescence intensity of Item 9, the object is an iron-based material.

[0098] (Item 11) In the method for enhancing the stress luminescence intensity of Item 9, the aluminum-containing layer is formed by attaching an aluminum foil to the first surface of the object via a bonding layer, or by applying a composition containing aluminum particles to the object.

[0099] (Item 12) In the method for enhancing the stress luminescence intensity of Item 9, the stress luminescence layer is formed by attaching a stress luminescence sheet including a coating film of a composition containing a stress luminescence material, a base material, and a second bonding layer in this order to the aluminum-containing layer via the second bonding layer.

[0100] (Item 13) In the method for enhancing the stress luminescence intensity according to Item 9, the stress luminescence layer is formed by printing a composition containing a stress luminescent material on the aluminum-containing layer.

[0101] (Item 14) In the method for enhancing the stress luminescence intensity according to Item 9, the aluminum-containing layer and the stress luminescence layer are formed by attaching a stress luminescence intensity enhancement sheet including a coating film of a composition containing a stress luminescent material, the aluminum-containing layer, and a first bonding layer to the object via the first bonding layer.

[0102] (Item 15) A method for measuring stress luminescence intensity, including the method for enhancing the stress luminescence intensity according to Items 9 to 14.

Explanation of Reference Numerals

[0103] 10, 20, 30 Stress luminescence intensity enhancement sheet, 11 Aluminum-containing layer, 12 Stress luminescence layer, 13 First bonding layer, 14 Base material, 15 Second bonding layer, 16 Stress luminescence sheet, 100 Object, 200 Measuring device, 215 Communication line, 220 Object, 230 Light source, 232 Driving device, 240 Tensile testing machine, 241 Table, 242 Crosshead, 244, 246 Screw rod, 248 Upper gripper, 250 Lower gripper, 252 Load cell, 260 Control device, 262 Display unit, 270 Imaging device, 280 Control device, 282 Display unit, 290 Storage device, L1 Interval.

Claims

1. comprising an aluminum-containing layer and a stress luminescence layer, The stress luminescence layer is a sheet for enhancing stress luminescence intensity, including a coating film of a composition containing a stress luminescence material.

2. The sheet for enhancing stress luminescence intensity according to Claim 1, wherein the aluminum-containing layer is an aluminum foil.

3. The sheet for enhancing stress luminescence intensity according to Claim 2, further comprising a first bonding layer on the side of the aluminum-containing layer opposite to the stress luminescence layer.

4. The sheet for enhancing stress luminescence intensity according to Claim 1, wherein the aluminum-containing layer is a coating film of a composition containing aluminum particles.

5. comprising a stress luminescence sheet comprising the stress luminescence layer, a substrate, and a second bonding layer in this order, The sheet for enhancing stress luminescence intensity according to any one of Claims 2 to 4, wherein the stress luminescence sheet is attached to the aluminum-containing layer via the second bonding layer.

6. The sheet for enhancing stress luminescence intensity according to any one of Claims 2 to 4, wherein the stress luminescence layer is formed with a coating film of the composition containing the stress luminescence material in direct contact with the aluminum-containing layer.

7. The sheet for enhancing stress luminescence intensity according to Claim 3, wherein the first bonding layer is an adhesive layer or a bonding agent layer.

8. The sheet for enhancing stress luminescence intensity according to Claim 5, wherein the second bonding layer is an adhesive layer or a bonding agent layer.

9. A method for enhancing the stress luminescence intensity of a stress luminescence layer disposed on an object, The method for enhancing stress luminescence intensity, including a step of providing an aluminum-containing layer between the object and the stress luminescence layer.

10. The method for enhancing stress luminescence intensity according to Claim 9, wherein the object is an iron-based material.

11. The method for enhancing stress luminescence intensity according to claim 9, wherein the aluminum-containing layer is formed by attaching an aluminum foil to the object via an adhesive layer, or by applying a composition containing aluminum particles to the object.

12. The method for enhancing stress luminescence intensity according to claim 11, wherein the stress luminescence layer is formed by attaching a stress luminescence sheet including a coating film of a composition containing a stress luminescence material, a base material, and a second adhesive layer in this order to the aluminum-containing layer via the second adhesive layer.

13. The method for enhancing stress luminescence intensity according to claim 11, wherein the stress luminescence layer is formed by printing a composition containing a stress luminescence material on the aluminum-containing layer.

14. The method for enhancing stress luminescence intensity according to claim 9, wherein the aluminum-containing layer and the stress luminescence layer are formed by attaching a stress luminescence intensity enhancement sheet including a coating film of a composition containing a stress luminescence material, the aluminum-containing layer, and a first adhesive layer to the object via the first adhesive layer.

15. A method for measuring stress luminescence intensity, comprising the method for enhancing stress luminescence intensity according to any one of claims 9 to 14.

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