JP6470863B1 - Stress luminescence measuring apparatus and stress luminescence measuring method - Google Patents

Abstract

The present invention provides a stress luminescence measuring apparatus and a stress luminescence measuring method capable of measuring stress luminescence continuously generated at irregular time intervals separately from spontaneous emission light including fluorescence and phosphorescence.
An excitation light irradiating unit for continuously irradiating a stress luminescent coating material including a stress luminescent material with excitation light L0, and a stress luminescence amount for obtaining in advance a stress luminescence amount corresponding to a reference stress applied to the stress luminescent material. An acquisition unit 14, a relationship acquisition unit 15 that acquires in advance the relationship between the amount of fluorescent light and the amount of excitation light that excites the stress illuminant, and the amount of excitation light that causes the ratio of the amount of stress luminescence to the amount of fluorescent light to be a predetermined value or more. An excitation light amount determination unit 16 and an irradiation control unit 17 that continuously irradiates the excitation light irradiation unit 20 with excitation light of the excitation light amount determined by the excitation light amount determination unit 16 are provided.
[Selection] Figure 1

Description

  The present invention relates to a stress luminescence measuring apparatus and a stress luminescence measuring method capable of measuring stress luminescence continuously generated at indefinite time intervals separately from spontaneous emission light including fluorescence and phosphorescence.

  Conventionally, a stress distribution is often measured in order to detect or predict a failure due to a residual stress or stress concentration to be measured. In general, as a stress distribution measurement method, (1) a method A in which a strain gauge is attached to a measurement target to electrically detect a strain amount, and (2) a heat generation action on vibration of the measurement target using an infrared camera or There are known a method B for obtaining a stress distribution by measuring an endothermic effect, and (3) a digital image correlation method C for obtaining a stress variation by applying a random pattern to a surface to be measured and imaging with a plurality of cameras.

  However, the above-mentioned method A has a problem that the strain gauge is troublesome for attaching and the measurement site is limited. In addition, the above method B has a problem that the infrared camera has a limited measurement range and requires repeated excitation. Further, the digital image correlation method C has a problem that it is necessary to prepare a surface pattern in advance.

  For this reason, in order to measure stress in a wide area in a non-contact manner, attention has been paid to a technique for measuring the stress distribution of the measurement object in a non-contact manner by imaging the stress emission from the measurement object with a stress illuminant applied to the surface. Has been. For example, Patent Document 1 stores the excitation light irradiation time until the excitation state of the stress luminescent material is saturated, and the excitation state of the stress luminescent material is determined by irradiating the excitation light for this excitation light irradiation time. An apparatus that saturates and emits light under certain conditions is disclosed. In addition, in order to make the stress luminescent paint emit stress, the stress luminescent material in the stress luminescent paint needs to be in an excited state, and the excitation of the stress luminescent paint needs to irradiate the stress luminescent paint with excitation light. .

Japanese Patent Laid-Open No. 2006-180637

  However, when the stress energy luminescent paint has a low excitation energy filling rate, even if stress is applied to the stress luminescent paint, the luminescence sensitivity of stress luminescence due to the stress decreases, so time-dependent stress measurement It becomes impossible to do. Therefore, in order to maintain a sufficient excitation state of the stress-stimulated luminescent paint, it is only necessary to continuously irradiate the stress-stimulated luminescent paint with excitation light. Fluorescence and phosphorescence are emitted as spontaneous emission light, and stress emission due to stress is buried in the spontaneous emission light, which causes a problem that it becomes difficult to detect the stress emission separately from the spontaneous emission light.

  The present invention has been made in order to solve the above-described problem, and stress luminescence measurement capable of separately measuring stress luminescence continuously generated at indefinite time intervals from spontaneous emission light including fluorescence and phosphorescence. An object is to provide an apparatus and a stress luminescence measurement method.

  In order to solve the above-mentioned problems and achieve the object, the present invention irradiates a stress-stimulated luminescent material including a stress-stimulated luminescent material with excitation light to bring the stress-stimulated luminescent material into an excited state, and the stress-stimulated luminescent material is indefinitely spaced. A stress luminescence measuring device for measuring stress luminescence according to stress applied to the excitation light irradiating unit for continuously irradiating the stress luminescent paint with excitation light, and stress according to a reference stress applied to the stress luminescent material A stress emission amount acquisition unit for acquiring the emission amount in advance, a relationship acquisition unit for acquiring in advance a relationship of the spontaneous emission amount with respect to the excitation amount for exciting the stress illuminant, and a ratio of the stress emission amount with respect to the spontaneous emission amount is predetermined. An excitation light amount determination unit that determines an excitation light amount that is equal to or greater than a value, and an irradiation control unit that continuously irradiates the excitation light with the excitation light amount determined by the excitation light amount determination unit to the excitation light irradiation unit Features To.

  Further, the present invention is the above invention, wherein the excitation light amount determining unit is configured to perform the above-described measurement with respect to the spontaneous emission light amount when the stress light emission amount is equal to or greater than a predetermined stress light emission amount exceeding a stress light emission amount corresponding to the reference stress. The ratio of the stress light emission amount is equal to or greater than a predetermined value, and the excitation light amount that enables the stress light emission of the predetermined stress light emission amount is determined.

  Moreover, the present invention is characterized in that, in the above-described invention, an image pickup unit for picking up light emitted from the stress-stimulated luminescent paint is provided.

  Further, the present invention irradiates a stress-stimulated luminescent material including a stress-stimulated luminescent material with excitation light to bring the stress-stimulated luminescent material into an excited state, and measures stress luminescence according to the stress applied to the stress-stimulated luminescent material at indefinite time intervals. A stress luminescence measuring method for obtaining a stress luminescence amount in accordance with a reference stress applied to the stress luminescence body, and a relationship between a spontaneous emission amount and an excitation light amount for exciting the stress luminescence body The relationship acquisition step of acquiring the excitation light amount, the excitation light amount determination step for determining the excitation light amount for which the ratio of the stress light emission amount to the spontaneous emission light amount is a predetermined value or more, and the excitation light of the excitation light amount determined by the excitation light amount determination step And an irradiation control step of continuously irradiating the light.

  Further, the present invention is the above invention, wherein the excitation light amount determination step is configured to perform the step for determining the amount of spontaneous emission when the stress light emission amount is equal to or greater than a predetermined stress light emission amount exceeding a stress light emission amount corresponding to the reference stress. The ratio of the stress light emission amount is equal to or greater than a predetermined value, and the excitation light amount that enables the stress light emission of the predetermined stress light emission amount is determined.

  Moreover, the present invention is characterized in that, in the above-mentioned invention, an imaging step of imaging the light emission of the stress-stimulated luminescent paint is included.

  According to the present invention, it is possible to measure stress luminescence continuously generated at indefinite time intervals separately from spontaneous emission light including fluorescence and phosphorescence.

FIG. 1 is a diagram showing a configuration of a stress luminescence measuring apparatus according to the present embodiment. FIG. 2 is a diagram showing a temporal transition of the spontaneous emission light amount when the excitation light irradiation is turned off. FIG. 3 is a diagram illustrating the relationship of the amount of stress luminescence to the generated stress. FIG. 4 is a diagram showing a stress light emission profile when a reference stress is applied. FIG. 5 is a diagram showing the relationship of the spontaneous emission light quantity with respect to the excitation light quantity. FIG. 6 is a diagram comparing a light emission state by conventional continuous excitation and a light emission state by continuous excitation of the present embodiment. FIG. 7 is a flowchart showing a stress luminescence measurement processing procedure by the control unit.

  Hereinafter, a stress luminescence measurement apparatus and a stress luminescence measurement method according to the present embodiment will be described with reference to the accompanying drawings.

<Device configuration>
FIG. 1 is a diagram showing a configuration of a stress luminescence measuring apparatus 1 according to the present embodiment. In the stress luminescence measuring apparatus 1 shown in FIG. 1, for example, a stress luminescent paint 2 including a stress luminescent material is formed on the surface of a measurement target member 101 in which metal fatigue occurs due to a stress S generated by applying an external force P. It has been applied.

  The stress S generated in the measurement target member 101 is continuously generated at indefinite time intervals. The stress luminescence measuring apparatus 1 continuously irradiates the stress luminescent paint 2 including the stress luminescent material with the excitation light L0 to bring the stress luminescent material into an excited state, and measures the stress luminescence L2 corresponding to the stress S generated in the stress luminescent material. . When the stress luminescent material is in an excited state, spontaneous emission light L1 that spontaneously emits as fluorescence and phosphorescence is emitted regardless of the stress emission L2.

  The stress-stimulated luminescent material is a luminescent material that emits light by external mechanical stimulation. Types of mechanical stimulation include friction, impact, compression, tension, torsion, and the like, and stress is generated in the stress light emitter by such mechanical stimulation. The stress-stimulated luminescent material is, for example, powdery ceramic fine particles whose particle diameter can be controlled, strontium aluminate doped with europium (SrAl2O4: Eu), zinc sulfide doped with transition metal or rare earth (ZnS: Mn), barium-calcium titanate ((Ba, Ca) TiO3: Pr), calcium aluminate-yttrium (CaYAl3O7: Ce), and the like. The stress-stimulated luminescent material emits visible light using ultraviolet light as excitation light, but may emit ultraviolet light or near infrared light.

  The stress luminescence measuring apparatus 1 shown in FIG. 1 includes an excitation light irradiating unit 20 that continuously irradiates the stress luminescent paint 2 with ultraviolet light that is excitation light L0, an imaging unit 30 that images the luminescence of the stress luminescent paint 2, and an apparatus main body. 10 and.

  The apparatus main body 10 includes an input / output unit 11, a storage unit 12, and a control unit 13, and is connected to the excitation light irradiation unit 20 and the imaging unit 30. The input / output unit 11 is an input / output interface such as a touch panel display for performing various operation inputs and display outputs.

  The storage unit 12 is a storage device composed of a non-volatile memory such as a flash memory or a secondary storage medium such as a hard disk device, etc., and the stress luminescence amount data D1 including the stress luminescence amount LMS and the excitation light amount dependency of the fluorescence light amount. The relationship data D2 including the relationship f2, the excitation light amount data D3 including the excitation light amount L0a, and the measurement image data D4 including the measurement image D are stored.

  The control unit 13 is a control unit that totally controls the stress luminescence measurement apparatus 1, and includes a stress luminescence amount acquisition unit 14, a relationship acquisition unit 15, an excitation light amount determination unit 16, an irradiation control unit 17, and a measurement image acquisition control unit 18. . In practice, programs corresponding to these functional units are stored in a ROM or non-volatile memory (not shown), and these programs are loaded into a CPU (Central Processing Unit) and executed, thereby obtaining a stress emission amount acquisition unit. 14, the relationship acquisition unit 15, the excitation light amount determination unit 16, the irradiation control unit 17, and the measurement image acquisition control unit 18 execute corresponding processes.

  The stress light emission amount acquisition unit 14 acquires in advance the stress light emission amount LMS corresponding to the reference stress SS applied to the stress light emitter. The stress light emission amount LMS is included in the stress light emission amount data D1.

  The relationship acquisition unit 15 acquires in advance a relationship f2 of the fluorescence light amount with respect to the excitation light amount that excites the stress illuminant. This relationship f2 is included in the relationship data D2.

  The excitation light amount determination unit 16 determines the excitation light amount L0a at which the ratio of the stress light emission amount LMS to the fluorescence light amount is equal to or greater than a predetermined value. The determined excitation light amount L0a is included in the excitation light amount data D3.

  The irradiation control unit 17 continuously irradiates the stress luminescent paint 2 with the excitation light of the excitation light amount L0a determined by the excitation light amount determination unit 16 via the excitation light irradiation unit 20.

  The measurement image acquisition control unit 18 acquires the measurement image D of the stress-stimulated luminescent paint 2 imaged by the imaging unit 30 and stores it as measurement image data D4 in the storage unit 12.

<Determination processing of excitation light quantity L0a>
Next, the determination process of the excitation light amount L0a by the excitation light amount determination unit 16 will be described.

First, as described above, the spontaneous emission light L1 spontaneously emits fluorescence and phosphorescence regardless of the stress emission L2 when the stress luminescent material is in an excited state. Fluorescence emits a part of the excited state energy absorbed from the excitation light L0 as heat, and emits the remaining excited state energy as light. Light that is shifted to a longer wavelength side than the excitation light, for example, It is emitted as green visible light. On the other hand, phosphorescence causes an intersystem crossing between different energy levels, does not immediately return to the ground state, and continues to emit light more slowly than fluorescence. For example, fluorescence is emitted in 10 ⁻⁶ to 10 ⁻³ seconds, and phosphorescence is emitted in 10 ⁻³ to 10 seconds. On the other hand, the stress luminescence L2 caused by the stress S emits a part of the energy of the excited state as heat, is close to the energy levels of fluorescence and phosphorescence, and transitions to different specific energy levels. When S is generated, light is emitted as, for example, green visible light by transitioning from the transitioned specific energy level to the ground state.

  Therefore, as shown in FIG. 2, the spontaneous emission light quantity LM1 is formed with a fluorescence region E1 in which the fluorescence is mostly occupied while the first excitation light L01 or the second excitation light L02 is irradiated, and the first excitation light L01 is formed. From the time t1 when the irradiation of the light L01 is turned off, only phosphorescence is obtained, and a time transition is formed in which a phosphorescent region E2 in which the amount of phosphorescence decreases with the passage of time is formed. For example, when the spontaneous emission light amount LM1 (maximum light amount Lmax) in the maximum excitation state is normalized as 100%, the light amount decreases to 30%, 20%, and 10% as time elapses at time points t2, t3, and t4, respectively. .

  On the other hand, when the stress S is generated, the stress light emission amount LM2 of the stress light emission L2 emitted from the stress light emitter is determined by the product of the strain amount and the strain rate, and when the strain rate is constant, FIG. As shown, there is a linear relationship f1 with respect to the magnitude of the generated stress S. However, when the stress S is generated, if the energy filling rate in the energy level of the stress luminescence in the stress luminescent material is low, the stress luminescence quantity LM2 corresponding to the stress S cannot be emitted. If stress emission that does not maintain this relationship f1 occurs, highly accurate stress distribution and stress change cannot be obtained, and stress emission may be buried in phosphorescence.

  Therefore, in the present embodiment, the irradiation controller 17 continuously irradiates the stress luminescent paint 2 with the excitation light L0 via the excitation light irradiator 20, and the stress luminescence LMS corresponding to the generated stress S. The energy filling amount is obtained. However, when the stress light emitter is irradiated with the excitation light L0, the above-described spontaneous emission light L1, particularly fluorescence, is generated, and the stress emission light amount LM2 is spontaneously emitted even when excited with a sufficient energy filling amount. The light amount LM1 is buried, and the stress emission L2 and the spontaneous emission light L1 are separated and cannot be measured.

  Therefore, as illustrated in FIGS. 3 and 4, the stress light emission amount acquisition unit 14 acquires the stress light emission amount LMS with respect to the reference stress SS. Then, in order to be able to measure the stress light emission amount LMS as the signal component separately from the spontaneous emission amount LM1 as the noise component, the excitation light amount LM1 during the continuous irradiation of the excitation light L0 is reduced to reduce the spontaneous emission amount LM1. Reduce the light quantity LM0.

  As shown in FIG. 5, in the relationship f2 of the spontaneous emission light quantity LM1 with respect to the excitation light quantity LM0, the spontaneous emission light quantity LM1 increases as the excitation light quantity LM0 increases. The relationship acquisition unit 15 acquires this relationship f2 in advance. The spontaneous emission light quantity LM1 is almost a fluorescent light quantity because the excitation light L0 is continuously irradiated. The spontaneous emission light amount LM1 and the stress light emission amount LM2 are light amounts that pass per unit time.

  Then, the excitation light amount determination unit 16 determines the excitation light amount L0a at which the ratio of the stress light emission amount LMS to the spontaneous emission light amount (fluorescence light amount) LM1 is equal to or greater than a predetermined value. The excitation light amount L0a is a value at which the ratio of the stress light emission amount LMS to the spontaneous emission light amount La when the excitation light amount L0a is a predetermined value, for example, 25 dB or more. In addition, when exciting with the excitation light quantity L0a, the energy filling rate with which the stress light emitter is filled with the excitation light quantity L0a is not saturated, and the energy filling quantity is low. For this reason, the excitation light amount L0a needs to be equal to or more than the energy filling amount capable of emitting the stress light emission amount LMS corresponding to the generated stress S (reference stress SS).

  As shown in FIG. 6A, conventionally, the spontaneous emission light quantity LM1 has a maximum energy filling rate of 100% (saturated) due to continuous irradiation of the excitation light L0, and the spontaneous emission light quantity LM1 is the maximum. The amount of light Lmax. When the stress light emission amount LMS is equal to or less than the maximum light amount Lmax, the stress light emission L2 is completely buried in the spontaneous emission light L1.

  On the other hand, in the present embodiment, as shown in FIG. 6B, the excitation light amount LM0 is reduced to the excitation light amount L0a so that the spontaneous emission light amount LM1 is smaller than the maximum light amount Lmax and is smaller than the stress light emission amount LMS. Since the spontaneous emission amount La is used, the stress emission L2 is not buried in the spontaneous emission light L1. That is, a large light amount difference ΔL occurs between the stress light emission amount LMS and the spontaneous emission light amount La, and the stress light emission L2 and the spontaneous emission light L1 can be measured separately. That is, even when the excitation light L0 is continuously irradiated, the ratio (S / N ratio) of the stress emission amount LMS as the signal component to the spontaneous emission amount La as the noise component is not less than a predetermined value, for example, not less than 25 dB. The stress emission L2 and the spontaneous emission light L1 can be separated and measured.

  In particular, even when the stress luminescence L2 is continuously generated at an indefinite time interval, since the excitation light L0 is continuously irradiated, the stress luminescence L2 can be measured separately from the spontaneous emission light L1.

<Stress luminescence measurement processing>
Next, the stress light emission measurement processing procedure by the control unit 13 will be described. FIG. 7 is a flowchart showing a stress luminescence measurement processing procedure by the control unit 13. As shown in FIG. 7, first, the stress light emission amount acquisition unit 14 acquires the stress light emission amount LMS corresponding to the reference stress SS (step S101). Thereafter, the relationship acquisition unit 15 acquires the relationship f2 of the spontaneous emission light amount (fluorescence light amount) LM1 with respect to the excitation light amount LM0 (step S102). Thereafter, the excitation light amount determination unit 16 determines the excitation light amount L0a at which the ratio of the stress light emission amount LMS to the spontaneous emission light amount LM1 is equal to or greater than a predetermined value (step S103).

  Thereafter, the control unit 13 determines whether or not the stress luminescence measurement is started (step S104). If the stress luminescence measurement is not started (step S104; No), the determination process of step S104 is repeated. On the other hand, if the stress luminescence measurement is started (step S104; Yes), the excitation light irradiation with the excitation light L0 of the excitation light amount L0a determined by the excitation light amount determination unit 16 under the control of the irradiation control unit 17 is performed. The measurement image D of the stress-stimulated luminescent paint 2 is imaged through the imaging unit 30 and stored as measurement image data D4 under the control of the measurement image acquisition control unit 18 while being continuously irradiated through the unit 20 (step S1). S105).

  Thereafter, it is determined whether or not the stress luminescence measurement is finished (step S106). If it is not the end of the stress luminescence measurement (step S106; No), the process proceeds to step S105, and the above irradiation process and imaging process are repeated. On the other hand, if it is the end of the stress luminescence measurement (step S106; Yes), this process is ended.

  The excitation light quantity determination unit 16 determines that the ratio of the stress light emission quantity LM2 to the spontaneous emission light quantity LM1 is a predetermined value when the stress light emission quantity LM2 is equal to or greater than the predetermined stress light emission quantity LMS exceeding the stress light emission quantity LMS corresponding to the reference stress SS. In this way, adjustment may be made to determine the excitation light amount that enables stress light emission of a predetermined stress light emission amount. That is, when the stress light emission amount LM2 increases and the energy consumption amount per unit time increases, the excitation light amount LM0 may be increased so as to constantly maintain a high energy filling rate. In this case, since the reference stress SS is increased and this is equivalent to an increase in the stress emission amount LMS with respect to the reference stress SS, the stress emission amount LMS may be changed.

  Furthermore, in the above embodiment, a measurement image using the imaging unit 30 is obtained. However, the measurement image is not limited to this, and visual measurement may be performed.

  Note that each configuration illustrated in the above embodiment is functionally schematic, and does not necessarily need to be physically configured as illustrated. That is, the form of distribution / integration of each device is not limited to that shown in the figure, and all or a part thereof may be functionally or physically distributed / integrated in an arbitrary unit according to various loads or usage conditions. Can be configured.

  The stress luminescence measuring apparatus and the stress luminescence measuring method of the present invention are a method in which a stress luminescent coating material including a stress luminescent material is irradiated with excitation light to bring the stress luminescent material into an excited state, and a stress corresponding to the stress applied to the stress luminescent material. This is useful when measuring luminescence, and particularly useful when measuring stress luminescence continuously generated at indefinite time intervals separately from spontaneous emission light including fluorescence and phosphorescence.

DESCRIPTION OF SYMBOLS 1 Stress luminescence measuring device 2 Stress luminescent paint 10 Apparatus main body 11 Input / output part 12 Storage part 13 Control part 14 Stress luminescence amount acquisition part 15 Relation acquisition part 16 Excitation light quantity determination part 17 Irradiation control part 18 Measurement image acquisition control part 20 Excitation light Irradiation unit 30 Imaging unit 101 Measurement target member D Measurement image D1 Stress emission amount data D2 Relationship data D3 Excitation light amount data D4 Measurement image data E1 Fluorescence region E2 Phosphorescence region f1, f2 Relationship L0 Excitation light L0a Excitation amount L1 Spontaneous emission light L2 Stress Light emission La Spontaneous emission light LM0 Excitation light quantity LM1 Spontaneous emission light quantity LM2 Stress light emission quantity Lmax Maximum light quantity LMS Stress light emission quantity P force S Stress SS Reference stress t1, t2, t3, t4 Time ΔL Light quantity difference

Claims (6)

A stress luminescence measuring apparatus that irradiates a stress luminescent coating material including a stress luminescent material with excitation light to bring the stress luminescent material into an excited state and measures stress luminescence according to the stress applied to the stress luminescent material at indefinite time intervals. There,
An excitation light irradiating unit for continuously irradiating the stress luminescent paint with excitation light;
A stress light emission amount acquisition unit for acquiring in advance a stress light emission amount corresponding to a reference stress applied to the stress light emitter;
A relationship acquisition unit that acquires in advance the relationship of the amount of spontaneous emission with respect to the amount of excitation light that excites the stress illuminant;
An excitation light amount determination unit for determining an excitation light amount at which a ratio of the stress light emission amount to the spontaneous emission light amount is a predetermined value or more;
An irradiation control unit that continuously irradiates the excitation light with the excitation light amount determined by the excitation light amount determination unit to the excitation light irradiation unit;
A stress luminescence measuring apparatus comprising:   The excitation light amount determination unit determines that a ratio of the stress light emission amount to the spontaneous emission light amount is equal to or greater than a predetermined value when the stress light emission amount is equal to or greater than a predetermined stress light emission amount exceeding a stress light emission amount corresponding to the reference stress. The stress light emission measuring device according to claim 1, wherein an excitation light amount that enables stress light emission of the predetermined stress light emission amount is determined.   The stress luminescence measuring apparatus according to claim 1, further comprising an imaging unit that images the luminescence of the stress luminescent paint. A stress luminescence measuring method that irradiates a stress luminescent coating material including a stress luminescent material with excitation light to bring the stress luminescent material into an excited state and measures stress luminescence according to the stress applied to the stress luminescent material at indefinite time intervals. There,
A stress light emission amount obtaining step for obtaining in advance a stress light emission amount corresponding to a reference stress applied to the stress light emitter;
A relationship acquisition step of acquiring in advance the relationship of the spontaneous emission light amount to the excitation light amount for exciting the stress illuminant;
An excitation light amount determination step for determining an excitation light amount at which a ratio of the stress light emission amount to the spontaneous emission light amount is a predetermined value or more;
An irradiation control step of continuously irradiating excitation light of the excitation light amount determined by the excitation light amount determination step;
A stress luminescence measuring method comprising:   In the excitation light amount determination step, when the stress light emission amount is equal to or greater than a predetermined stress light emission amount exceeding the stress light emission amount according to the reference stress, a ratio of the stress light emission amount to the spontaneous emission light amount is equal to or greater than a predetermined value. The stress light emission measuring method according to claim 4, wherein an excitation light amount that enables stress light emission of the predetermined stress light emission amount is determined.   The stress luminescence measurement method according to claim 4, further comprising an imaging step of imaging luminescence of the stress luminescent paint.

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