JP7319626B2 - Method for measuring vibration characteristics of structures and apparatus for measuring vibration characteristics of structures - Google Patents

Description

The present invention relates to a method for measuring vibration characteristics of a structure and a measuring device for measuring vibration characteristics of a structure.

Tiles are sometimes provided on the outer surface of a structure for purposes such as decoration and reinforcement. The tiles are provided in a state of being adhered to the base via mortar, elastic adhesive, or the like. However, exposure to rain and wind causes deterioration of the structure over time, and the tiles may float or peel off from the foundation. As the deterioration of the structure progresses, the tiles will peel off from the foundation, fall, and be damaged.

Therefore, it is necessary to periodically inspect the presence or absence of deterioration of the structure provided with the tiles and the degree of progress thereof. Inspection methods include visual inspection, hammering inspection, and infrared inspection. Visually, the deterioration appearing outside the structure is visually recognized, but the deterioration of the structure inside the tiles is difficult to be visually recognized.

For example, Patent Literatures 1 to 4 disclose methods for inspecting deterioration of a structure due to hammering sound. In the hammering sound inspection, the structure is hit with an instrument such as a hammer, and the presence or absence of deterioration and the qualitative degree of deterioration are determined by the hammering sound generated at that time. However, in the inspection using the hammering sound described in Patent Document 1, for example, there is a possibility that the determination results may vary depending on the inspector, and the inspector may have to work at a high place and may need to set up a scaffold. be. In addition, for example, in the inspection by hammering described in Patent Documents 2 to 4, a sensor or the like that detects and analyzes the hammering sound is introduced, and the variation in the judgment result by the inspector is suppressed, but the instrument that hits the structure A moving mechanism is required to move to a predetermined position.

For example, Patent Literature 5 discloses a method of inspecting deterioration of a structure using infrared rays. However, the inspection using infrared rays has limitations on the use conditions of infrared rays, and is somewhat lacking in accuracy.

In view of the circumstances of each inspection method described above, for example, Patent Document 6 discloses a method of measuring vibration characteristics of a structure by irradiating the structure with laser pulse light and applying an impulse input to the structure. . In the measurement method described in Patent Document 6, the impulse input is obtained from the relationship between the intensity of the laser pulse light and the impulse input by the rigid body pendulum method, and the complex Fourier spectrum obtained from the response output from the structure and the impulse Analyze the structure based on the input. Since the measurement method described in Patent Document 6 can be performed without contacting the structure, it can be applied to high places and structures that are difficult for a person to directly contact.

JP-A-8-201353 JP-A-10-170482 JP 2018-87765 A Japanese Patent Application Laid-Open No. 2007-132720 JP-A-2000-81403 Japanese Patent No. 5750788

However, in the method of measuring the vibration characteristics of a structure described in Patent Document 6 and the conventional method of measuring the vibration characteristics of a structure from the response obtained by irradiating the structure with laser pulse light, based on the measurement results However, there is a problem that it is difficult to quantitatively determine how the tiles are lifted from the base in consideration of the characteristics of the tiles. In other words, there is a problem that it is difficult to quantitatively determine how the building materials such as tiles are lifted from the foundation in the structure where the building materials such as tiles are provided on the foundation via an adhesive.

The present invention provides a structure vibration characteristic measuring method and a structure vibration characteristic measuring apparatus capable of quantitatively determining how a building material is lifted from a foundation.

The method for measuring the vibration characteristics of a structure according to the present invention includes a laser irradiation step of irradiating a laser pulse beam onto the outer surface of a building material in a structure having a foundation and a building material attached to the surface of the foundation via an adhesive. a vibration characteristic acquiring step of acquiring a vibration characteristic to be measured including a power spectrum due to impulse excitation of emissions emitted from the outer surface of the building material by irradiation with the laser pulse light; and Based on the reference Mahalanobis distance calculated by the Recognition Taguchi Method (hereinafter referred to as the RT method) based on the reference vibration characteristics obtained in the reference state normally stretched on the base via the agent and the vibration characteristics to be measured and a ratio calculation step of calculating a ratio to the Mahalanobis distance to be measured calculated from the RT method.
According to the above-mentioned method for measuring the vibration characteristics of structures, the power spectrum of the impulse excitation of the emission emitted from the outer surface of the building material contains information on the state of adhesion between the building material and the substrate via the adhesive. reflected as Therefore, in the ratio calculation process, the reference Mahalanobis distance calculated by the RT method based on the reference vibration characteristics and the Mahalanobis to be measured calculated by the RT method based on the vibration characteristics of the measurement object including information on the adhesion state between the building material and the foundation By calculating the ratio to the distance, the state of adhesion between the building material and the substrate can be quantitatively calculated and evaluated quantitatively with respect to the reference state. Therefore, it is possible to quantitatively determine how the building material is lifted from the foundation.

The method for measuring the vibration characteristics of a structure according to the present invention may further include a determination step of determining a state of adhesion between the building material and the foundation based on the ratio.
According to the method for measuring the vibration characteristics of a structure described above, in the determination step, the measured bonding state between the building material and the foundation is quantitatively determined with respect to the reference state, and the building material and the foundation are originally bonded to each other. It is possible to acquire information such as the ratio of the normally adhered area or the ratio of the peeled area with respect to the total area.

In the method for measuring vibration properties of a structure according to the invention, the adhesive may be an elastic adhesive.
Further, the state of adhesion between the building material and the base may be determined based on the ratio in a frequency band lower than a predetermined frequency of the power spectrum.
According to the method for measuring the vibration characteristics of a structure described above, the stress relaxation of the adhesive against vibration and impact causes the power spectrum of the building material to fall in a frequency band lower than a predetermined frequency due to the characteristics of the material of the building material in the power spectrum due to impulse excitation. It is possible to reflect information about the state of adhesion between the substrate and the substrate.

The apparatus for measuring the vibration characteristics of a structure according to the present invention comprises a pulsed laser for irradiating the outer surface of the building material in a structure having a foundation and a building material attached to the surface of the foundation via an adhesive. , a vibration measuring instrument for acquiring vibration characteristics to be measured including a power spectrum due to impulse excitation of emissions emitted from the outer surface of the building material by irradiation with the laser pulse light; The reference Mahalanobis distance calculated by the RT method based on the reference vibration characteristics obtained in the reference state normally stretched on the base through the reference Mahalanobis distance and the Mahalanobis distance to be measured calculated by the RT method based on the vibration characteristics to be measured and an analysis unit that calculates a ratio of .
According to the method for measuring the vibration characteristics of a structure described above, in the same way as the method for measuring a structure of the present invention, the power spectrum of the emission emitted from the outer surface of the building material due to impulse excitation is obtained through an adhesive. Information about the state of adhesion between the building material and the base is reflected as a frequency distribution. Therefore, the analysis unit can quantitatively determine how the building material is lifted from the foundation based on the ratio between the reference Mahalanobis distance and the Mahalanobis distance to be measured.

According to the method for measuring the vibration characteristics of a structure and the apparatus for measuring the vibration characteristics of a structure according to the present invention, it is possible to quantitatively determine how the building material is lifted from the foundation of the structure.

1 is a schematic diagram of an apparatus for measuring vibration characteristics of a structure according to one embodiment of the present invention; FIG. 1 is a schematic diagram of a measurement device for vibration characteristics of a structure in Example 1. FIG. 1 is a plan view of a structure in Example 1. FIG. FIG. 2 is a cross-sectional view along the Y direction of the main part of the structure in Example 1; 4 is a graph showing measurement results of a power spectrum of impulse excitation caused by emissions from a structure in Example 1. FIG. FIG. 10 is another graph showing the measurement results of the power spectrum of the impulse excitation due to the emission from the structure in Example 1. FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the method for measuring the vibration characteristics of a structure and the apparatus for measuring the vibration characteristics of a structure according to the present invention will be described below with reference to the drawings.

[Equipment for measuring vibration characteristics of structures]
As shown in FIG. 1, an apparatus 10 for measuring vibration characteristics of a structure according to one embodiment of the present invention (hereinafter simply referred to as the measuring apparatus 10) is a portion of a building 100 on which tiles (building materials) 130 are laid, that is, a structure. A device for measuring vibration characteristics of an object 150 .

The tiles 130 are applied to the base 110 of the building 100 via an adhesive 120 and are adhered to the base 110 . The construction method of the tiles 130 may be adhesive application or mortar application. Adhesive application is a construction method in which an elastic adhesive is used as the adhesive 120 to apply the tiles 130 to the base 110 . Mortaring is a construction method in which mortar is used as the adhesive 120 to attach the tiles 130 to the base 110 . In the following, unless otherwise specified, the tiles 130 are assumed to be installed with an adhesive.

The foundation 110 is made of concrete, for example. The tiles 130 are, for example, porcelain tiles, earthenware tiles, or the like. Materials for the base 110 and the tiles 130 are not particularly limited as long as they can be adhered to each other with the adhesive 120 . However, as will be described later in the method for measuring vibration characteristics of a structure of this embodiment, when the tile 130 is irradiated with the laser pulse light 201, the emission 136 is emitted.

The adhesive 120 is appropriately selected according to the materials of the substrate 110 and the tiles 130 described above, the construction method for applying the tiles 130 to the substrate 110, and the like.

The measuring device 10 includes a pulse laser 20 , a light collecting element 22 , a vibration measuring meter 30 , and a control analysis section (analysis section) 50 . The pulse laser 20 emits laser pulse light 201 that irradiates the tile 130 . In this embodiment, the laser pulse light 201 is a short pulse. The respective conditions of the laser pulse light 201, such as the wavelength spectrum width, the time width, and the pulse energy, are appropriately set so as to exceed a threshold value for generating laser-induced plasma by irradiating the tile 130 with the laser pulse light 201. It is set and adjusted by parameters. Examples of the pulse laser 20 having the parameters described above include a Q-switched YAG laser and a Ti sapphire laser.

The condensing element 22 converges the laser pulsed light 201 emitted from the pulsed laser 20 onto the tile 130 . The condensing element 22 is, for example, a biconvex lens, but is not particularly limited as long as it has a condensing function as described above. If the condensing element 22 is a biconvex lens, the conditions such as the numerical aperture, focal length, and refractive index of the condensing element 22 are appropriately set so that irradiation of the tile 130 with the laser pulse light 201 generates laser-induced plasma. be.

The vibration measurement meter 30 acquires vibration measurement data of the entire structure 150 that is impulse-excited by the laser pulse light 201 . The vibration measurement data includes vibration characteristics that reflect information about the state of adhesion between the tile 130 and the substrate 110 . The vibration measuring instrument 30 is, for example, a laser Doppler vibrometer, but is not particularly limited as long as it can acquire the vibration characteristics as described in the method for measuring the vibration characteristics of the structure 150, which will be described later.

The control analysis unit 50 analyzes vibration measurement data measured by the vibration meter 30 to obtain vibration characteristics of the structure 150 . For example, an FFT analyzer or a frequency analyzer is used as the control analysis unit 50 . The frequency analyzer consists of a vibration measurement data collection board, a computer and an analysis program.

[Method for measuring vibration characteristics of structures]
The method for measuring the vibration characteristics of a structure according to this embodiment is a method for measuring the vibration characteristics of the structure 150, and includes a laser irradiation process, a vibration characteristic acquisition process, and a ratio calculation process. In this embodiment, in the structure 150, the portion where the entire inner surface 131 of the tile 130 is adhered to the base 110 via the adhesive 120 is defined as a "healthy portion", and even a part of the inner surface 131 of the tile 130 A portion that is not adhered to the base 110 is defined as an "abnormal portion".

In advance, the outer surface 132 of the tile 130 of the healthy portion is irradiated with the laser pulsed light 201 emitted from the pulsed laser 20, and the power spectrum (reference vibration characteristic) is obtained as reference data at a predetermined measurement frequency and the number of sampling points, Save in the control analysis unit 50 . Specifically, when the laser pulse light 201 is irradiated, plasma is generated on the outer surface 132 , and emitted substances 136 such as atoms, molecules, and ions of the tile 130 are emitted from the tile 130 . If Δp is the mass of ejected matter 136 and v is the rate of ejection, then the momentum of ejected matter 136 is Δpv. A change in the momentum Δpv is an impulse, and an excitation force acts in the normal direction of the tile 130 . Such excitation is ideal impulse excitation. In the healthy portion, the tiles 130 are in close contact with the base 110 . The frequency characteristics of the healthy portion are reflected in the power spectrum measured by impulse excitation by the emission 136 emitted from the tile 130 .

Subsequently, as shown in FIG. 1 , in the laser irradiation step, the laser pulse light 201 emitted from the pulse laser 20 is condensed onto the tile 130 by the condensing element 22 . For example, the condensing position of the laser pulsed light 201 is close to the position moved from the center of the long side of the tile 130 to one end, and the pulsed laser 20 is sufficiently close to generate plasma on the outer surface 132. This is the narrowed down position. The position of the condensing element 22 is not particularly limited as long as the condensing position of the laser pulse light 201 is sufficiently focused as described above.

Next, in the vibration measurement data acquisition step, the vibration measurement meter 30 acquires the power spectrum of a predetermined position of the structure 150 at the same predetermined measurement frequency and sampling points as when the reference data of the sound portion is obtained. The acquired power spectrum is stored in the control analysis unit 50 as measurement data. Also in the abnormal portion, plasma is generated on the outer surface 132 by irradiating the outer surface 132 with the laser pulse light 201 as in the normal portion, and the emission 136 of the tile 130 is emitted from the tile 130 . However, in the abnormal portion, the power spectrum of the emission 136 due to the impulse excitation reflects the state of adhesion between the tile 130 and the base 110 , that is, how the tile 130 is lifted from the base 110 .

Next, in the ratio calculation step, k items ( Vibration characteristic data) X ₁ , X ₂ , . . . , X _k are members. The aforementioned n and k are arbitrary natural numbers.

Here, the principle of calculating the Mahalanobis distance based on the RT method for each of the reference data of the healthy portion and the measurement data of the abnormal portion will be described. _{The average m j of} each item X ₁ , X ₂ , . The aforementioned j is from 1 to k.

The sensitivity β _i of the i-th member of the unit space is obtained from the equation (4) using the linear expression L _i expressed by the following equations (2) and (3) and the sum of the mean squares r.

The total variation S _Ti and the variation S _βi of the proportional term are obtained from the following equations (5) and (6).

Using the parameters obtained as described above, the error variation S _ei , the error variance V _ei and the standard signal-to-noise ratio η _i are obtained by the following equations (7), (8) and (9). .

Here, parameters Y _i1 and Y _i2 expressed by equations (10) and (11) are introduced. The parameters Y _i1 , Y _i2 are the i-th values of the items Y ₁ , Y ₂ .

From the following equations (12) to (16), the variance V ₁₁ of Y ₁ , the covariance V ₁₂ of Y ₁ and Y ₂ , the variance V ₂₂ of Y ₂ , the variance/covariance matrix V, and the cofactor Find the matrix A. It should be noted that Y ₁ and Y ₂ with a bar above the letter Y in the equations (12) to (14) respectively mean the average values of Y ₁ and Y ₂ .

The Mahalanobis distance D _i ² is calculated for each member by the following equation (17).

The Mahalanobis distance D(-) from the zero point of each data in the unit space is obtained from the following equation (18). The Mahalanobis distance D(-) is the same as the bar above D in equation (18).

In the ratio calculation step, based on the above- _described principle, the reference Mahalanobis distance D (− ₎ calculated using the items X ₁ , X ₂ , _. Calculate Subsequently, the Mahalanobis distance D(− ₎ calculated using the measurement data of the abnormal portion as items X _{1 ,} X ₂ , _. Subsequently, the ratio (D _M /D _S ) is calculated. It can be seen that the closer the ratio (D _M /D _S ) is to 1, the smaller the area where the tile 130 is separated from the base 110 and the poor contact or the area where the adhesive is peeled off in the abnormal portion. Conversely, the more the ratio (D _M /D _S ) is farther from 1, the larger the area where the tile 130 is separated from the base 110 and the poor contact or the area where the adhesive is peeled off in the abnormal portion. . That is, by calculating the ratio (D _M /D _S ), the area where the tile 130 is separated from the base 110 in the abnormal portion resulting in poor contact, or the area where the adhesive is peeled off, and the vibration of the abnormal portion Characteristics can be determined quantitatively.

The method for measuring vibration characteristics of a structure according to this embodiment further includes a determination step. In the determination step, the state of adhesion between the tile 130 and the substrate 110 is determined based on a predetermined standard according to the ratio (D _M /D _S ) calculated in the ratio calculation step. The predetermined criteria differ depending on the material of the substrate 110, the tiles 130 and the adhesive 120. FIG.

For example, the predetermined criterion is to prepare samples in which the bonding state between the tiles 130 and the substrate 110 is appropriately changed in advance from a sound state to a state just before peeling off from each other at a place away from the site. Calculate the ratio (D _M /D _S ) for the sample. How far from 1 the ratio (D _M /D _S ) should be determined to indicate that the state of adhesion between the tile 130 and the substrate 110 is “abnormal” based on the ratio (D _M /D _S ) calculated for each sample; It is possible to quantitatively know how far the ratio (D _M /D _S ), which should be determined to require immediate response/treatment, deviates from 1. As a result, the threshold of the ratio (D _M /D _S ) for judging the state of adhesion between the tile 130 and the substrate 110 can be set quantitatively and finely as necessary.

According to the method and apparatus 10 for measuring the vibration characteristics of a structure according to the present embodiment described above, the power spectrum of the emission 136 emitted from the outer surface 132 of the tile 130 due to the impulse excitation includes the Information about the state of adhesion between the tile 130 and the base 110 is reflected. Therefore, in the ratio calculation step, the ratio (D _M /D _S ) between the reference Mahalanobis distance D _S and the Mahalanobis distance D _M to be measured based on the vibration characteristics to be measured including information on the bonding state of the tile 130 and the substrate 110 is calculated. Accordingly, the state of adhesion between the tile 130 and the substrate 110 can be quantitatively calculated and evaluated quantitatively with respect to the reference state. Therefore, it is possible to quantitatively determine how the tile 130 is lifted from the base 110 .

Further, according to the method of measuring the vibration characteristics of the structure of the present embodiment, in the determination step, the measured bonding state between the tile 130 and the substrate 110 can be quantitatively determined with respect to the reference state. In addition, information such as the ratio of the normally adhered area or peeled area to the total area where the tile 130 and the base 110 should be adhered is quantitatively obtained, and is determined according to a predetermined standard. Therefore, the adhesion state can be judged more accurately than the conventional method for measuring the vibration characteristics of a structure. In addition, it is possible to suppress variations in determination results among inspectors.

Further, according to the method of measuring the vibration characteristics of a structure according to the present embodiment, if the adhesive 120 is an elastic adhesive, the stress relaxation properties of the adhesive 120 against vibration and impact will cause the tile to be tiled in the power spectrum due to impulse excitation. Information about the state of adhesion between the tile 130 and the base 110 is likely to be reflected in a frequency band lower than a predetermined frequency due to the characteristics of the material of the 130 . Therefore, it is possible to quantitatively and clearly measure how the tile 130 is lifted from the base 110 .

Further, according to the method for measuring the vibration characteristics of a structure according to the present embodiment, the stress relaxation property of the adhesive 120 against vibration and shock can provide a predetermined power spectrum due to, for example, impulse excitation of the emission 136 of the tile 130 in the abnormal portion. Since the ratio (D _M /D _S ) in the frequency band lower than the frequency of 1 is proportional to the degree of poor contact between the tile 130 and the substrate 110, it is easy and clear to see how the tile 130 is lifted from the substrate 110. can be measured to

Although preferred embodiments of the invention have been described in detail above, the invention is not limited to any particular embodiment. The invention can be modified within the scope of the invention described in the claims.

For example, in the above-described embodiment, the portion where the entire inner surface 131 of the tile 130 is adhered to the base 110 via the adhesive 120 is defined as the "healthy portion", and the reference state of adhesion between the tile 130 and the adhesive 120 is and However, the "reference state" in the method for measuring the vibration characteristics of a structure according to the present invention is not limited to the state of the sound portion described above. For example, 80% of the inner surface 131 of tile 130 may adhere to substrate 110 via adhesive 120 . In other words, the "reference state" may be any state that serves as a reference when measuring the vibration characteristics of the structure of the present invention.

Further, the building material in the method for measuring the vibration characteristics of a structure of the present invention is not limited to the tiles 130, and is not particularly limited as long as it can be adhered to the base 110 via the adhesive 120. Examples of building materials other than the tiles 130 include ornaments for decoration. Also, the number of building materials may be plural or singular.

Examples of the present invention will be described below. It should be noted that the method and apparatus for measuring the vibration characteristics of structures according to the present invention are not limited to the contents of the following examples.

As an example, a concrete (base) 160 having a length of 300 mm, a width of 600 mm, and a thickness of 60 mm in a plan view is prepared, and as shown in FIG. 4 tiles 130 vertically and 5 tiles 130 horizontally. An elastic adhesive (product name: Tile Ace Pro, manufacturer or distributor: Cemedine Co., Ltd.) was used as the adhesive 120 . As the tile 130, a tile (product name/model number: Mino Koguchidaira 060-745-1P, manufacturer: Shino Tosai) having a length of 108 mm, a width of 60 mm, and a thickness of 9 mm was used. Hereinafter, the vertical direction is the X direction, the horizontal direction is the Y direction, and the thickness direction is the Z direction. A total of 20 tiles 130 are numbered from 1 to 20 from lower left to upper right as shown in FIG. In plan view, the joints between the tiles 130 were not filled with anything, and the dried adhesive 120 after the tiles 130 were attached was exposed to form the structure 105 shown in FIG.

Of the 20 tiles 130 of the structure 105 , the tiles 130 with tile numbers 7, 9, 13, and 15 were formed with portions floating from the adhesive 120 (ie, “floats”). Hereinafter, the tile 130 with tile number N may be referred to as tile 130-N. N is any natural number from 1 to 20. In the tile 130-7, as shown in FIGS. 3 and 4, the central portion excluding the outer peripheral portion and the portion having an area ratio of 90% with respect to the inner surface 131 in a plan view was defined as "floating". That is, as shown in FIG. 4, in the Z direction, between the central portion of the tile 130-7 and the inner surface 131 having an area ratio of 90% and the surface of the adhesive 120 contacting the concrete 160 and the surface 122 on the opposite side. , a gap is provided, and an adhesive tape 138 is arranged in this embodiment. As the adhesive tape 138, a commercially available Kraft adhesive tape was used.

A gap was provided between the inner surface 131 of the central portion of the tile 130-9 and having an area ratio of 50% and the surface 122 of the adhesive 120, and an adhesive tape 138 was placed. A gap was provided between the outer peripheral portion of the tile 130-13 and the inner surface 131 having an area ratio of 90% and the surface 122 of the adhesive 120, and an adhesive tape 138 was placed. A gap was provided between the inner surface 131 of the outer peripheral portion of the tile 130-15 and having an area ratio of 50% and the surface 122 of the adhesive 120, and an adhesive tape 138 was placed. In the tiles 130 other than tile numbers 7, 9, 13, and 15, the inner surface 131 with an area ratio of 100% was closely attached to the surface 122 of the adhesive 120 without gaps. In the structure 105, portions having tiles 130 other than tile numbers 7, 9, 13, and 15 correspond to healthy portions, and portions having tiles 130-7, 130-9, 130-13, and 130-15 are abnormal portions. correspond to

As a device for measuring the vibration characteristics of the structure 105, the measuring device 15 shown in FIG. 2 was configured. As shown in FIG. 2, the measuring device 15 further includes reflecting mirrors 26-1, 26-2, and 26-3 in addition to the constituent parts of the measuring device 10. As shown in FIG. As the pulse laser 20, a compact Q-switch pulse YAG laser (product name: Surelite III-10, manufacturer: Continuum, Ltd.) was used. As the reflecting mirrors 26-1, 26-2, and 26-3, prism mirrors having reflecting surfaces capable of specularly reflecting the laser pulsed light 201 emitted from the pulsed laser 20 are used. A biconvex lens with a focal length of 100 mm and a refractive index of 1.519 was used as the condensing element 22 . A compact laser Doppler vibrometer (model number: NLV-2500, manufacturer: Polytec Japan Co., Ltd.) was used as the vibrometer 30 . As the control analysis unit 50, a spectrum analyzer (product name/model number: NI PXI1042Q, NI4472B, manufacturer/Japan National Instruments Co., Ltd.) equipped with CAT-system (manufacturer: Catec) was used.

The laser pulse light 201 emitted from the pulse laser 20 along the XY plane including the X direction and the Y direction is appropriately folded back in the Z direction by the reflecting mirrors 26-1 and 26-2, and the irradiation position of the tile 130 to be measured for the vibration characteristics is measured. It was propagated up to 141 above. In this embodiment, the irradiation position 141 of each tile 130 is set to a position that is 35 mm away from the center in the Y direction toward the front side. A reflecting mirror 26-3 is placed above the irradiation position 141, and a condensing element 22 is placed between the reflecting mirror 26-3 and the tile 130 to be measured in the Z direction. The laser pulsed light 201 was lowered by the reflecting mirror 26 - 3 , and the laser pulsed light 201 was condensed on the irradiation position 141 by the condensing element 22 .

A vibration meter 30 was arranged above the measurement position 142 . In this embodiment, the measurement position 142 of each tile 130 is a position that is 35 mm away from the center in the Y direction. That is, the distance in the Y direction between the irradiation position 141 and the measurement position 142 was 70 mm. The output from vibrometer 30 was input to spectrum analyzer 28, which calculated the power spectrum of emission 136 (not shown in FIG. 2) from tile 130 to be measured.

The calculated power spectrum was output to a computer as the control analysis section 50 . Based on the principle described in the method for measuring the vibration characteristics of a structure, the reference Mahalanobis distance D for the portion of the structure 105 having the tiles 130 other than the tile numbers 7, 9, 13, and 15 is determined by the computer's built-in program. _S and the measured Mahalanobis distances D _M and ratios (D _M /D _S ) of the portions having tiles 130-7, 130-9, 130-13, and 130-15 were calculated.

First, using the measuring device 15, the outer surface 132 of each of the tiles 130-7, 130-8, 130-9, and 130-10 is irradiated with the laser pulse light 201, and the power spectrum of the emission 136 due to impulse excitation is obtained. was measured. As conditions for power spectrum measurement, the measurement frequency was set to 0 to 10000 [Hz] and the number of sampling points was set to 16384. FIG. 5 shows the measurement results of the power spectrum of the emission 136 from each of the tiles 130-7, 130-8, 130-9 and 130-10 with impulse excitation. Hereinafter, the portion of the structure 105 having the tiles 130-N may be referred to as the structure 105-N. As shown in FIG. 5, the magnitude (intensity) [dB] of the power spectrum of the structure 105-7 is about 2500 to 7000 [dB] compared to the power spectra of the structures 105-8 and 105-10. Hz] frequency band. Also, the intensity [dB] of the power spectrum of the structure 105-9 is about 4000 to 6000 [Hz] compared to the power spectrum of the structure 105 having the tiles 130-8 and 130-10. increased in bandwidth.

Next, using the measuring device 15, the outer surface 132 of each of the tiles 130-12, 130-13, 130-14, and 130-15 is irradiated with the laser pulse light 201, and the power generated by the impulse excitation of the emission 136 is Spectra were measured. The conditions for the power spectrum measurement were the same as those described above, with the measurement frequency set to 0 to 10000 [Hz] and the number of sampling points set to 16,384. FIG. 6 shows the measurement results of the power spectrum of the emission 136 from each of the tiles 130-12, 130-13, 130-14 and 130-15 with impulse excitation. As shown in FIG. 6, the strengths [dB] of the power spectra of structures 105-13 and 105-15 are both about 1500 to 1500 compared to the power spectra of structures 105-12 and 105-14. It increased in the frequency band of 5000 [Hz].

As can be seen from the measurement results shown in FIGS. 5 and 6, structures 105-8, 105-10, 105-12, and 105-14 in which the inner surface 131 with an area ratio of 100% is in close contact with the surface 122 without gaps. , have substantially the same tendency in the frequency band from 0 to 10000 [Hz] without any significant change. On the other hand, the power spectra of structures 105-7, 105-9, 105-13, and 105-15 in which "floats" are formed are A change occurred in a predetermined frequency band compared to each power spectrum.

In this embodiment, the intensity [dB] of each power spectrum of the structures 105-7 and 105-9 having the “float” formed in the center of the inner surface 131 like the tiles 130-7 and 130-9 is , increased in the frequency band below about 7000 [Hz] with respect to the power spectra of structures 105-8 and 105-10 in which no "float" was formed. Further, in the power spectrum of structure 105-7 having a larger area ratio of "float" than structure 105-9, the frequency band in which the strength [dB] is increased compared to the power spectra of structures 105-8 and 105-10. is wider than the frequency band in which the strength [dB] is increased in the structure 105-9 compared to the power spectra of the structures 105-8 and 105-10. As a result, when the “float” is formed in the central portion of the inner surface 131, the power spectrum of the structure 105 in which the “float” is not formed increases as the area ratio of the “float” increases. It is considered that the frequency band in which the strength [dB] increases is widened. However, as described above, the change in the frequency band in which the strength [dB] increases compared to the power spectrum of the structure 105 in which the "float" is not formed, the power spectrum of the structure 105-7 , the irradiation position 141 and the measurement position 142 are overlapped with the adhesive tape 138 in plan view, and the irradiation position 141 and the measurement position 142 are overlapped with the adhesive tape 138 as in the measurement of the power spectrum of the structure 105-9. The difference from the portion where the measurement position 142 is "floated" in plan view, that is, the state where it does not overlap with the adhesive tape 138 may also have had an effect.

Further, in this embodiment, the strength of each power spectrum [dB ] increased in the frequency band below about 5000 [Hz] with respect to the power spectra of the structures 105-12 and 105-14 in which no "float" was formed. In the power spectrum of structure 105-13, where the area ratio of the "float" is larger than that of structure 105-15, the frequency band in which the strength [dB] is increased compared to the power spectra of structures 105-12 and 105-14 is It is substantially the same as the frequency band in which the strength [dB] of the structure 105-15 is increased compared to the power spectra of the structures 105-12 and 105-14. Furthermore, in the frequency band of about 5000 [Hz] or less, the increased strength [dB] in the power spectrum of the structure 105-13 compared to the power spectra of the structures 105-12 and 105-14 is 15 is higher than the increased intensity [dB] compared to the power spectra of structures 105-12 and 105-14. In addition, when the power spectra of the structures 105-13 and 105-15 were measured, the irradiation position 141 and the measurement position 142 overlapped with the adhesive tape 138 in plan view. As a result, when the "float" is formed at least on the outer periphery of the inner surface 131, the power spectrum of the structure 105 in which the "float" is not formed increases as the area ratio of the "float" increases. It is thought that the strength [dB] that increases with increasing

Subsequently, the RT method was applied to the measured power spectrum of the structure 105 during impulse excitation, and the ratio (D _M /D _S ) was calculated. First, the power spectra of the structures 105-8, 105-10, 105-12, and 105-14, which are sound portions, during impulse excitation were measured twice each. It was created. That is, in this embodiment, n=8 in the standard state. In addition, power spectrum items X ₁ , X _{2 ,} . , 5000 to 7500 [Hz], and 7500 to 10000 [Hz], the intensity [dB] of the power spectrum at each frequency of 100 [Hz]. That is, in this embodiment, k=25. For example, the item _X1 of the divided band of 0 to 2500 [Hz] is the average value [dB] of the power spectrum in 0 to 100 [Hz] of the power spectrum. The item _X2 of the same division band is the average value [dB] of the power spectrum at 100 to 200 [Hz] of the power spectrum. The item X ₂₅ of the same subband is the average value [dB] of the power spectrum at 2400 to 2500 [Hz] of the power spectrum.

Using _the items X ₁ , X ₂ , . The Mahalanobis distance D(−) of the structure 105 in the sound portion, that is, the reference Mahalanobis distance D _s was calculated by the above-mentioned formulas (1) to (18).

Subsequently, the power spectra of structures 105-7, 105-8, 105-9, 105-10, 105-12, 105-13, 105-14, and 105-15 at the time of measurement for each one time are measured in the reference state As with the calculation of the power spectrum at frequencies every 100 [Hz] in each sub-band of 0 to 2500 [Hz], 2500 to 5000 [Hz], 5000 to 7500 [Hz], 7500 to 10000 [Hz] Intensity [dB] was newly set as items X ₁ , X ₂ , . . . , X ₂₅ . In other words, in this embodiment, n=1 and k=25 for the measurement object. Using the newly calculated items X _{1 ,} X ₂ , . Each Mahalanobis distance D(-) of -12, 105-13, 105-14, and 105-15, that is, the Mahalanobis distance D _M to be measured was calculated.

Table 2 shows the structures 105-7, 105-8, 105-9 _, 105-10, 105-12, 105-13, _105- 14, 105-15 ratio (D _M /D _S ).

The threshold value of the ratio (D _M /D _S ) for judging whether or not the bonding state between the tiles 130 and the base 110 is abnormal, that is, whether or not "floating" is formed was set to 10.0. In that case, the ratio (D _M /D _S ) of the structures 105-7, 105-9, 105-13, and 105-15 in which the "float" is formed in the divided band with a frequency of 2500 to 5000 [Hz] is , were all greater than the threshold of 10.0, or even all greater than 20.0. On the other hand, in the same subband, the ratios (D _M /D _S ) of structures 105-8, 105-10, 105-12, and 105-14 in which "floats" are not formed are all at least greater than the threshold value of 10.0. smaller, or even all smaller than 2.0. Therefore, in this embodiment, if the ratio (D _M /D _S ) is smaller than 10.0 in the divided band of frequencies of 2500 to 5000 [Hz], the contact state between the tile 130 and the base 110 is good and sound. Conversely, if the ratio (D _M /D _S ) is greater than 10.0, it can be determined that the contact state between the tile 130 and the base 110 is defective.

As described above, also in this embodiment, it was confirmed that the power spectrum of the emission 136 due to the impulse excitation reflected the information on the state of adhesion between the tile 130 and the substrate 110 as a frequency distribution. Further, it was confirmed that by calculating the ratio (D _M /D _S ), the state of adhesion between the tile 130 and the substrate 110 can be expressed quantitatively, and the state of "floating" can be quantitatively determined.

10 measuring device (measurement device for vibration characteristics of structures)
110 base 120 adhesive 130 tile (building material)
105, 150 structure 132 outer surface 160 concrete (substrate)
201 laser pulse light D _S reference Mahalanobis distance D _M Mahalanobis distance to be measured

Claims (5)

A laser irradiation step of irradiating the outer surface of the building material in a structure having a base and a building material attached to the surface of the base with an adhesive;
a vibration characteristic acquiring step of acquiring a vibration characteristic to be measured including a power spectrum due to impulse excitation of emissions emitted from the outer surface of the building material by being irradiated with the laser pulse light;
Recognition Taguchi based on the reference Mahalanobis distance calculated by the Recognition Taguchi Method based on the reference vibration characteristics acquired in the reference state in which the building material is normally attached to the base via the adhesive, and the vibration characteristics to be measured. A ratio calculation step of calculating the ratio with the Mahalanobis distance to be measured calculated from Method;
with
A method for measuring the vibration characteristics of structures. Further comprising a determination step of determining the state of adhesion between the building material and the substrate based on the ratio,
A method for measuring vibration characteristics of a structure according to claim 1. the adhesive is an elastic adhesive;
3. A method for measuring vibration characteristics of a structure according to claim 1 or 2. Determining the adhesion state between the building material and the base based on the ratio in a frequency band lower than a predetermined frequency of the power spectrum;
A method for measuring vibration characteristics of a structure according to claim 3. a pulsed laser for irradiating laser pulsed light onto the outer surface of a building material in a structure having a base and a building material attached to the surface of the base via an adhesive;
a vibration measuring instrument for acquiring vibration characteristics of a measurement target including a power spectrum due to impulse vibration of emissions emitted from the outer surface of the building material by being irradiated with the laser pulse light;
Recognition Taguchi based on the reference Mahalanobis distance calculated by the Recognition Taguchi Method based on the reference vibration characteristics acquired in the reference state in which the building material is normally attached to the base via the adhesive, and the vibration characteristics to be measured. an analysis unit that calculates the ratio of the Mahalanobis distance to be measured calculated from the method;
with
A device for measuring the vibration characteristics of structures.

Images