JP6601267B2 - Evaluation method for structures - Google Patents

Description

  The present invention relates to a structure evaluation method.

In recent years, structures built during the period of high economic growth have become obsolete. Many accidents and damage cases due to aging of structures have been reported. In particular, industrial steel structures represented by belt conveyor frames and piping mounts are often directly exposed to the external environment, and often suddenly collapse.
Therefore, in order to minimize the risks associated with corrosion deterioration in industrial steel structures, it is one of the important maintenance issues to correctly grasp the soundness of the structure. .

  As an evaluation method of a structure when the entire structure is an evaluation target part that is an evaluation target, those described in Patent Documents 1 and 2 are known.

JP 2001-215148 A JP 2002-310847 A

  However, the structure evaluation method disclosed in Patent Documents 1 and 2 uses a vibration mode corresponding to a low frequency (frequency) of about 20 Hz (hertz) or less as an object of evaluation. For this reason, when an evaluation object part is a small member compared with the whole structure like a part of member which comprises a structure, there exists a problem that damage etc. of this evaluation object part cannot be evaluated with sufficient sensitivity.

  The present invention has been made in view of such problems, and is a structure that can evaluate the evaluation target portion with high sensitivity even if the evaluation target portion is a small member compared to the entire structure. The purpose is to provide an evaluation method.

In order to solve the above problems, the present invention proposes the following means.
The structure evaluation method of the present invention has a plurality of evaluation object parts, and in the initial state, the plurality of specifications of the plurality of evaluation object parts are equal structures, and in the evaluation state, the plurality of evaluation object parts. Is a structure evaluation method for evaluating what has become an evaluation object change part by reducing the thickness of the evaluation object part, and measuring vibration of the structure in the evaluation state A spectrum acquisition step for acquiring a time waveform of vibration speed, analyzing the frequency waveform of the vibration speed to obtain a frequency-specific spectrum, and specifying a natural frequency and a vibration mode from the frequency-specific spectrum From the difference between the natural frequency at which only the evaluation target part vibrates in the same order of the vibration mode and the natural frequency at which only the evaluation target changing part vibrates, the evaluation target There rows and frequency comparison step, the to evaluate the performance of the unit, in the frequency comparison step, said from the natural frequency and the vibration mode identified in a particular step, the evaluation object change portion or the structure By calculating and analyzing the measurement flexibility matrix that is the flexibility matrix of the evaluation object, the analysis flexibility matrix that is the flexibility matrix of the evaluation object changing part or the structure when the thickness of the evaluation object part is changed is calculated. The thickness of the evaluation object changing portion when the value obtained by dividing the difference between the analytic flexibility matrix and the measurement flexibility matrix by the size of the measurement flexibility matrix is equal to or less than a predetermined allowable value. The thickness is the measured thickness of the evaluation object changing portion .
According to this invention, the natural frequency differs even in the order of the same vibration mode in the evaluation object changing part and the evaluation object part in which at least one of the plurality of specifications of the evaluation object part has changed. By selecting the vibration mode, the evaluation target part and the evaluation target change part can be evaluated with high sensitivity even if the evaluation target part is a small member such as a part of a structure.
Generally, since the evaluation target portion becomes an evaluation target changing portion when the thickness is reduced, the evaluation target portion can be more reliably evaluated.
Moreover, the thickness of the measured evaluation object change part can be obtained quantitatively.

Further, another structure evaluation method of the present invention has a plurality of evaluation target portions, and in the initial state, the plurality of specifications of the plurality of evaluation target portions are equal to each other, and in the evaluation state, a plurality of evaluation target portions. In the evaluation method of a structure, at least one of the evaluation target portions evaluates what has become an evaluation target change portion by changing at least one of the plurality of specifications, and in the evaluation state, A spectrum acquisition step of measuring vibration to obtain a time waveform of vibration speed, analyzing the time waveform of the vibration speed to obtain a frequency-specific spectrum, and a natural frequency and vibration from the frequency-specific spectrum. A specific step of specifying a mode, and the natural frequency at which only the evaluation target part vibrates in the same order of the vibration mode and the natural frequency at which only the evaluation target changing part vibrates. The frequency comparison step for evaluating the performance of the evaluation object changing unit is performed, and the same vibration mode in the frequency comparison step is fixed at both ends of the evaluation object unit and the evaluation object changing unit. In this state, the center part of the evaluation object part and the evaluation object changing part is a vibration mode by lateral vibration that vibrates like a string.
According to this invention, the natural frequency differs even in the order of the same vibration mode in the evaluation object changing part and the evaluation object part in which at least one of the plurality of specifications of the evaluation object part has changed. By selecting the vibration mode, the evaluation target part and the evaluation target change part can be evaluated with high sensitivity even if the evaluation target part is a small member such as a part of a structure.
The state where both ends of the evaluation target part and the evaluation target changing part are fixed here means a state where both end parts of the evaluation target part and the evaluation target changing part are rigidly fixed by welding or the like, bolt joining, etc. Means a semi-rigid fixed state or a pin-coupled state.

In the structure evaluation method described above, the change of at least one of the plurality of specifications may be a reduction in the thickness of the evaluation target portion.
 Generally, an evaluation object part becomes an evaluation object change part because thickness becomes thin. According to this invention, an evaluation object part can be evaluated more reliably.
Further, in the structure evaluation method, in the vibration frequency comparison step, the measurement is a flexible matrix of the evaluation object changing portion or the structure from the natural frequency and the vibration mode specified in the specifying step. By calculating and analyzing a flexibility matrix, an analysis flexibility matrix that is a flexibility matrix of the evaluation object changing portion or the structure when the thickness of the evaluation object portion is changed is calculated, and the analysis flexibility matrix The value obtained by dividing the difference between the measurement flexibility matrix and the measurement flexibility matrix is equal to or less than a predetermined allowable value. It may be the thickness of the evaluation object changing portion.
According to this invention, it is possible to quantitatively determine the thickness of the measured evaluation object changing portion.

Further, another structure evaluation method of the present invention has a plurality of evaluation target portions, and in the initial state, the plurality of specifications of the plurality of evaluation target portions are equal to each other, and in the evaluation state, a plurality of evaluation target portions. In the evaluation method of a structure, at least one of the evaluation target portions evaluates what has become an evaluation target change portion by changing at least one of the plurality of specifications, and in the evaluation state, A spectrum acquisition step of measuring vibration to obtain a time waveform of vibration speed, analyzing the time waveform of the vibration speed to obtain a frequency-specific spectrum, and a natural frequency and vibration from the frequency-specific spectrum. A specific step of specifying a mode, and the natural frequency at which only the evaluation target part vibrates in the same order of the vibration mode and the natural frequency at which only the evaluation target changing part vibrates. Then, a frequency comparison step for evaluating the performance of the evaluation target changing portion is performed, and the evaluation target portion is formed by joining the first plate member and the second plate member extending in the reference direction at a joint portion. The same vibration mode in the frequency comparison step is configured in a state where both ends of the evaluation object part and the evaluation object change part are fixed, respectively, and the joining of the evaluation object part and the evaluation object change part The part other than the joint part of the evaluation object part and the evaluation object change part is a vibration mode in which the part vibrates around the joint part on a reference plane orthogonal to the reference direction without moving the part. .
According to this invention, the natural frequency differs even in the order of the same vibration mode in the evaluation object changing part and the evaluation object part in which at least one of the plurality of specifications of the evaluation object part has changed. By selecting the vibration mode, the evaluation target part and the evaluation target change part can be evaluated with high sensitivity even if the evaluation target part is a small member such as a part of a structure.
In addition, even if the evaluation target part is a small member fixed by a fixing member in the middle part in the longitudinal direction among the shaft-shaped members constituting the structure, a position where the evaluation target part is evaluated and damaged, etc. Can be specified.

In the structure evaluation method described above, the change of at least one of the plurality of specifications may be a reduction in the thickness of the evaluation target portion.
 Generally, an evaluation object part becomes an evaluation object change part because thickness becomes thin. According to this invention, an evaluation object part can be evaluated more reliably.
Further, in the structure evaluation method, in the vibration frequency comparison step, the measurement is a flexible matrix of the evaluation object changing portion or the structure from the natural frequency and the vibration mode specified in the specifying step. By calculating and analyzing a flexibility matrix, an analysis flexibility matrix that is a flexibility matrix of the evaluation object changing portion or the structure when the thickness of the evaluation object portion is changed is calculated, and the analysis flexibility matrix The value obtained by dividing the difference between the measurement flexibility matrix and the measurement flexibility matrix is equal to or less than a predetermined allowable value. It may be the thickness of the evaluation object changing portion.
According to this invention, it is possible to quantitatively determine the thickness of the measured evaluation object changing portion.
In the structure evaluation method described above, the same vibration mode in the frequency comparison step may be such that the central portion of the first plate rotates to one side around the joint and the second plate A state in which the central portion rotates to the other side around the joint portion, a central portion of the first plate member rotates to the other side around the joint portion, and a central portion of the second plate member rotates around the joint portion. Alternatively, the vibration mode may alternately repeat the state rotated to the one side.

In the structure evaluation method described above, in the spectrum acquisition step, the structure may be vibrated by applying an impact force to the structure.
In the structure evaluation method, in the spectrum acquisition step, the vibration of the structure may be measured using a non-contact velocimeter.
According to the present invention, the time waveform of the vibration speed can be acquired without directly contacting the structure.

Further, in the structure evaluation method, in the spectrum acquisition step, the evaluation object part or the evaluation object change part using a first non-contact velocimeter and one or more second non-contact velocimeters. Measuring the time waveform of the vibration speed of the structure at a predetermined position of the evaluation object section measured by one or more second non-contact speedometers and the vibration speed of the evaluation object changing section. The speed spectrum response value obtained by frequency analysis of the time waveform is divided by the speed spectrum response value obtained by frequency analysis of the time waveform of the vibration speed measured using the first non-contact speedometer. The velocity spectrum response value set obtained by combining the velocity spectrum response values measured by the second non-contact velocimeter and normalized. Process, Fine said frequency comparison step may be performed.
According to the present invention, it is possible to perform processing of a plurality of velocity spectrum response values and the like by normalizing even vibrations given impact forces of different magnitudes without measuring the magnitude of the impact force. it can.
In the structure evaluation method, in the spectrum acquisition step, the magnitude of the applied impact force is measured, the time waveform of the vibration speed is measured, and the time waveform of the vibration speed is measured. The velocity spectrum response value is divided by the magnitude of the impact force and normalized to perform a plurality of times as a set, and the specified velocity spectrum response value set obtained by combining the normalized velocity spectrum response values is identified. You may perform a process and the said frequency comparison process.
According to the present invention, even if impact forces having different magnitudes are applied, a plurality of speed spectrum response values can be processed by normalization.

Further, another structure evaluation method of the present invention has a plurality of evaluation target portions, and in the initial state, the plurality of specifications of the plurality of evaluation target portions are equal to each other, and in the evaluation state, a plurality of evaluation target portions. In the evaluation method of a structure, at least one of the evaluation target portions evaluates what has become an evaluation target change portion by changing at least one of the plurality of specifications, and in the evaluation state, A spectrum acquisition step of measuring vibration to obtain a time waveform of vibration speed, analyzing the time waveform of the vibration speed to obtain a frequency-specific spectrum, and a natural frequency and vibration from the frequency-specific spectrum. A specific step of specifying a mode, and the natural frequency at which only the evaluation target part vibrates in the same order of the vibration mode and the natural frequency at which only the evaluation target changing part vibrates. And a frequency comparison step for evaluating the performance of the evaluation object changing portion. In the spectrum acquisition step, an impact force is applied to the structure to vibrate the structure, and in the spectrum acquisition step, Measure the magnitude of the impact force, measure the time waveform of the vibration speed, and normalize the speed spectrum response value of the time waveform of the vibration speed divided by the magnitude of the impact force. This is performed a plurality of times, and the specifying step and the frequency comparison step are performed on the velocity spectrum response value aggregate obtained by combining the normalized velocity spectrum response values.
According to this invention, the natural frequency differs even in the order of the same vibration mode in the evaluation object changing part and the evaluation object part in which at least one of the plurality of specifications of the evaluation object part has changed. By selecting the vibration mode, the evaluation target part and the evaluation target change part can be evaluated with high sensitivity even if the evaluation target part is a small member such as a part of a structure.
Even if impact forces having different magnitudes are applied, a plurality of speed spectrum response values can be processed by normalization.

Further, another structure evaluation method of the present invention has a plurality of evaluation target portions, and in the initial state, the plurality of specifications of the plurality of evaluation target portions are equal to each other, and in the evaluation state, a plurality of evaluation target portions. In the evaluation method of a structure, at least one of the evaluation target portions evaluates what has become an evaluation target change portion by changing at least one of the plurality of specifications, and in the evaluation state, A spectrum acquisition step of measuring vibration to obtain a time waveform of vibration speed, analyzing the time waveform of the vibration speed to obtain a frequency-specific spectrum, and a natural frequency and vibration from the frequency-specific spectrum. A specific step of specifying a mode, and the natural frequency at which only the evaluation target part vibrates in the same order of the vibration mode and the natural frequency at which only the evaluation target changing part vibrates. And a frequency comparison step for evaluating the performance of the evaluation object changing portion, and in the spectrum acquisition step, a first non-contact speedometer and one or more second non-contact speed meters are used. Measuring the time waveform of the vibration speed of the structure at a predetermined position of the evaluation object part or the evaluation object changing part; and the evaluation object part measured by one or more second non-contact speedometers; The frequency spectrum response value obtained by frequency analysis of the time waveform of the vibration speed in the evaluation object changing portion is measured using the first non-contact speedometer and the frequency waveform of the vibration speed is analyzed. The velocity spectrum obtained by dividing the velocity spectrum response value obtained by normalization and performing normalization a plurality of times and combining the velocity spectrum response value measured and normalized by the second non-contact velocimeter Response value Against coalescence, it is characterized by performing the specific process, and the frequency comparison step.
According to this invention, the natural frequency differs even in the order of the same vibration mode in the evaluation object changing part and the evaluation object part in which at least one of the plurality of specifications of the evaluation object part has changed. By selecting the vibration mode, the evaluation target part and the evaluation target change part can be evaluated with high sensitivity even if the evaluation target part is a small member such as a part of a structure.
Moreover, even if it is the vibration which gave the impact force from which a magnitude | size differs without measuring the magnitude | size of an impact force, a process of several speed spectrum response values etc. can be performed by normalizing.

In the structure evaluation method described above, in the spectrum acquisition step, the structure may be vibrated by applying an impact force to the structure.
In the structure evaluation method, in the spectrum acquisition step, the vibration of the structure may be measured using a non-contact velocimeter.
According to the present invention, the time waveform of the vibration speed can be acquired without directly contacting the structure.
In the structure evaluation method described above, the change of at least one of the plurality of specifications may be a reduction in the thickness of the evaluation target portion.
 Generally, an evaluation object part becomes an evaluation object change part because thickness becomes thin. According to this invention, an evaluation object part can be evaluated more reliably.

  According to the structure evaluation method of the present invention, the evaluation object part can be evaluated with high sensitivity even if the evaluation object part is a smaller member than the whole structure.

It is a figure which shows the outline | summary of the evaluation apparatus used for the evaluation method of the belt conveyor of 1st Embodiment of this invention. It is a perspective view of the belt conveyor. It is a side view of the belt conveyor. It is a perspective view of the beam material of the belt conveyor. It is a flowchart which shows the evaluation method of the belt conveyor of 1st Embodiment of this invention. It is a perspective view explaining one of the vibration modes of cross-sectional vibration. It is a perspective view explaining another one of the vibration modes of cross-sectional vibration. It is a front view explaining another one of the vibration modes of cross-sectional vibration. It is a figure which shows an example of the time waveform of the vibration speed acquired with the evaluation method of the same belt conveyor. It is a figure which shows an example of the spectrum according to frequency acquired at the spectrum acquisition process of the evaluation method of the same belt conveyor. It is a figure which shows an example of the normalized speed spectrum response value acquired at the spectrum acquisition process of the evaluation method of the same belt conveyor. It is a figure which shows the eigenvalue analysis result of the same belt conveyor when the beam piece vibrates with the natural frequency which vibrates. It is a figure which shows the eigenvalue analysis result of the same belt conveyor when the thin beam piece vibrates with the natural frequency which vibrates. It is a figure which shows an example of the normalized speed spectrum response value acquired with the evaluation method of the same belt conveyor. It is a flowchart which shows the frequency comparison process of the evaluation method of the same belt conveyor. It is a figure which shows the change of the value of NE by the thickness of the thin plate material assumed in the frequency comparison process of the evaluation method of the same belt conveyor. It is a figure which shows an example of the state which the beam piece vibrates in the vibration mode by lateral vibration. It is a figure which shows the outline | summary of the evaluation apparatus used for the evaluation method of the belt conveyor of 2nd Embodiment of this invention. It is a front view of the modification of the beam piece. It is a front view of the modification of the beam piece.

(First embodiment)
Hereinafter, a first embodiment of a structure evaluation method (hereinafter also referred to as an evaluation method) according to the present invention will be described with reference to FIGS. 1 to 17 in the case where the structure is a belt conveyor (belt conveyor frame). While explaining.
In FIG. 1, the evaluation apparatus 1 used suitably for this evaluation method is shown. This evaluation apparatus 1 evaluates the performance of the belt conveyor 50, for example. The performance mentioned here means damage or the like.

As shown in FIGS. 2 and 3, the belt conveyor (structure) 50 is disposed with a main body 51 extending in a longitudinal direction (reference direction) X parallel to the horizontal plane, and a predetermined interval in the longitudinal direction X. The leg part 52 which supports this from below is provided.
The main body 51 includes a beam member 54 that is four shaft-like members extending in the longitudinal direction X and a vertical connection member (connection member) 55 that connects a pair of beam members 54 that are spaced apart in the vertical direction Z. It has an oblique member (oblique member) 56, a left and right connecting member (connecting member) 57 that connects a pair of beam members 54 that are spaced apart in the left-right direction Y, and a right and left oblique member (oblique member) 58. .
Hereinafter, when the upper and lower connecting members 55 or the left and right connecting members 57, the upper and lower diagonal members 56 or the left and right diagonal members 58 are used singly, they will be described with the upper and lower or left and right members. In this case, it is described as a connecting member, and when both the upper and lower diagonal members 56 and the left and right diagonal members 58 are referred to, it is unified to be described as diagonal members.

  In the present embodiment, as shown in FIG. 4, the beam member 54 is formed of a steel material or the like so that the cross section in the longitudinal direction X is L-shaped. When the belt conveyor 50 is viewed in the longitudinal direction X, the four beam members 54 are respectively disposed at positions that are rectangular corners. The length of each beam member 54 is about the pitch of the leg portions 52 adjacent in the longitudinal direction X.

Although not shown, the connecting members 55 and 57 and the diagonal members 56 and 58 are also formed in an L-shaped cross section in the longitudinal direction by a steel material or the like.
As shown in FIGS. 2 and 3, the vertical connection member 55 extends in the vertical direction Z and is disposed at equal intervals in the longitudinal direction X. The upper and lower connecting member 55 is fixed to the beam member 54 by a welding portion, a bolt, or the like (not shown). The upper and lower diagonal members 56 include a portion in which the upper end portion of one upper and lower connecting member 55 is fixed to the beam member 54, and the lower end portion of another upper and lower connecting member 55 adjacent to the upper and lower connecting member 55 in the longitudinal direction X. It is being fixed to the part currently fixed to the material 54, respectively.

The left and right connecting members 57 and the left and right diagonal members 58 are configured in the same manner as the upper and lower connecting members 55 and the upper and lower diagonal members 56. In other words, the left and right connecting members 57 are arranged in the left-right direction Y and at equal intervals in the longitudinal direction X. The left and right connection member 57 is fixed to the beam member 54 by a welded portion, a bolt, or the like (not shown). The left and right connection members 57 are disposed at the same position as the upper and lower connection members 55 in the longitudinal direction X.
The left and right diagonal members 58 include a portion in which one end portion of one left and right connecting member 57 in the left and right direction Y is fixed to the beam member 54 and another left and right connecting member adjacent to the left and right connecting member 57 in the longitudinal direction X. 57 and the other end in the left-right direction Y are fixed to the beam member 54, respectively.

Here, as shown in FIG. 3, the beam member 54 that is partitioned in the longitudinal direction X by the ends of the connection members 55 and 57 is referred to as a beam piece 60. Since the intermediate portion in the longitudinal direction of the beam member 54 is fixed by the connecting members 55, 57, etc., the beam piece 60 is defined between the fixed portions of the beam member 54.
Each beam member 54 has both ends fixed to connecting members 55 and 57, and an intermediate portion in the longitudinal direction X is fixed to connecting members 55 and 57 and diagonal members 56 and 58. The 54 specifications are equal to each other. Specifically, the dimensions (cross-sectional shape, length, etc.), the material (iron or wood, etc.) of the four beam members 54, and the constraint conditions (boundary conditions) such as the ends are equal to each other. Since the materials are equal to each other, the elastic coefficients and densities of the four beam members 54 are equal to each other.
Both ends of the beam piece 60 are fixed to the connecting members 55 and 57 and the diagonal members 56 and 58.

As will be described later, in this example, an example in which the beam piece 60 is an evaluation target portion will be described. Here, the configuration of the beam piece 60 will be described with reference to FIG. 4.
The beam piece 60 has a configuration in which, for example, a plate member is bent and an end portion of the first plate member 60a extending in the longitudinal direction X and an end portion of the second plate member 60b are joined by the joint portion 60c. The beam piece 60 is a so-called angle member, and the thickness of the first plate member 60a is equal to the thickness of the second plate member 60b. The joint portion 60c extends in the longitudinal direction X. The beam piece 60 is a part of the belt conveyor 50 and is a small member compared to the entire belt conveyor 50.

The specifications of the upper and lower connecting members 55 are equal to each other. Similarly, the specifications of the upper and lower diagonal members 56, the left and right connecting members 57, and the left and right diagonal members 58 are equal to each other.
The structure of the leg part 52 is not specifically limited. In this example, as shown in FIG. 2, the leg portion 52 is a ramen structure reinforced with diagonal materials. In addition, in FIG. 1, the leg part 52 is simplified and shown.

In the initial state immediately after the belt conveyor 50 is manufactured, the plurality of specifications of the plurality of beam pieces 60 included in the belt conveyor 50 are equal to each other. Specifically, the lengths of the beam pieces 60 in the longitudinal direction X are equal to each other. The thickness of the first plate member 60a of each beam piece 60 is equal to each other, and the thickness of the second plate member 60b of each beam piece 60 is equal to each other.
It is assumed that a certain period has elapsed from the initial state in a state where the belt conveyor 50 is directly exposed to the external environment. In the evaluation state to which this evaluation method is applied, the thickness of the first plate member 60a and the second plate member 60b shown in FIG. Assume that one thin plate member 60aA and the second thin plate member 60bA are obtained. At this time, it is assumed that the beam piece 60 becomes a thin-walled beam piece (evaluation target changing portion) 60A.
The thin beam piece 60A, which is the evaluation object changing portion, is obtained by reducing the thickness of the beam piece 60. However, the evaluation object changing portion is obtained when the beam piece 60 is cracked or a hole is opened in the beam piece 60. It may be. However, when the thickness of the beam piece 60 is reduced to become a thin-walled beam piece 60A, the natural frequency described later changes more clearly, so that the evaluation is easier.

As shown in FIG. 1, the evaluation apparatus 1 includes a hammer 10 having an impact force meter 11 that measures the magnitude of impact force, and a laser Doppler velocimeter (non-contact velocimeter, first measurer) that measures vibration of the belt conveyor 50. A second non-contact speedometer) 12 and a control unit 13 for processing a time waveform of the vibration speed obtained by measuring the vibration of the belt conveyor 50. The member that measures vibration with the laser Doppler velocimeter 12 and the member that gives an impact with the hammer 10 having the impact force meter 11 are the same member.
Note that the impact force is not limited to the hammer 10, and the impact force may be applied by a laser wave or a sound wave.
The impact force meter 11 is connected to the control unit 13. The impact force meter 11 transmits the measurement result of the magnitude of the impact force to the control unit 13.
As the laser Doppler velocimeter 12, a known configuration capable of measuring a time waveform of the vibration velocity at one point can be used. The laser Doppler velocimeter 12 is connected to the control unit 13. The laser Doppler velocimeter 12 transmits a time waveform of the detected vibration speed to the control unit 13.
The number of laser Doppler velocimeters 12 provided in the evaluation device 1 is not particularly limited. Further, it is preferable to use a laser Doppler velocimeter that can measure the time waveform of the vibration velocity in the linear range at one time and that that can measure the time waveform of the vibration velocity in the planar range at one time.

The control unit 13 includes an arithmetic element, a memory, and the like (not shown). A control program or the like is stored in the memory. The control program is a program for causing an arithmetic element or the like to perform a spectrum acquisition step S1, a specifying step S3, and a frequency comparison step S5 described later.
An input unit 15 such as a keyboard for issuing an instruction to the control unit 13 and a display unit 16 such as a liquid crystal display for displaying the results processed by the control unit 13 are connected to the control unit 13. The control unit 13, the input unit 15, and the display unit 16 can be configured by a personal computer 17 or the like.

Next, the evaluation method of this embodiment for evaluating the belt conveyor 50 in the evaluation state will be described. FIG. 5 is a flowchart showing the evaluation method of this embodiment. In the following example, it is assumed that one of the plurality of beam pieces 60 is a thin-walled beam piece 60A in the evaluation state.
The vibration modes of the beam piece 60 and the thin beam piece 60A include longitudinal vibration that vibrates in the direction along the longitudinal direction of each member, lateral vibration that vibrates in a direction orthogonal to the longitudinal direction, and the like. In the following description, the inventors focus on the vibration mode named cross-sectional vibration.
It is preferable to obtain, as a database (a database obtained in advance), changes in the natural frequency and vibration mode depending on the size and material of the angle member by performing analysis or the like in advance.

As shown in FIG. 6, the vibration mode of the cross-sectional vibration is such that the joint portion 60c between the beam piece 60 and the thin beam piece 60A does not move, and the portion other than the joint portion 60c between the beam piece 60 and the thin beam piece 60A is in the longitudinal direction. This is a vibration mode that vibrates around the joint portion 60c on the reference plane T orthogonal to X. At this time, both ends of the beam piece 60 and the thin-walled beam piece 60A are fixed.
Note that the vibration mode shown in FIG. 6 is one of cross-sectional vibrations, and a state P1 in which the center part in the longitudinal direction X of the first plate member 60a and the second plate member 60b is rotated to one side D1 around the joint 60c. This is a vibration mode having the same phase, in which the central portion of the first plate member 60a and the second plate member 60b is rotated alternately to the state P2 rotated to the other side D2 around the joint portion 60c.

  On the other hand, as shown in FIGS. 7 and 8, the other vibration mode of the cross-sectional vibration is that the central portion of the first plate member 60a rotates to the one side D1 around the joint portion 60c and the second plate member. The state P3 in which the central portion of 60b is rotated around the joint portion 60c to the other side D2, and the center portion of the first plate member 60a is rotated around the joint portion 60c to the other side D2 and the center of the second plate member 60b. This is an anti-phase vibration mode that alternately repeats the state in which the portion rotates around the joint portion 60c to the one side D1.

Hereinafter, this evaluation method will be described.
First, in the spectrum acquisition step (step S1 shown in FIG. 5), an experiment is performed to measure the vibration of the belt conveyor 50 and acquire a time waveform of the vibration speed in the evaluation state. Specifically, as shown in FIGS. 1 and 4, the laser beam L irradiated by the laser Doppler velocimeter 12 is irradiated to the position P <b> 6 of the belt conveyor 50. An operator strikes the belt conveyor 50 with the hammer 10 to give an impact force to the belt conveyor 50 to vibrate the belt conveyor 50. The part where the operator hits the belt conveyor 50 is not particularly limited, and may be the beam piece 60, or the vertical connection member 55 other than the beam piece 60.
The impact force meter 11 measures the magnitude of the impact force and transmits the measured magnitude of the impact force to the control unit 13.
The laser Doppler speedometer 12 acquires the time waveform W ₀ of the vibration speed shown in FIG. 9 without contacting the belt conveyor 50. In FIG. 9, the horizontal axis represents elapsed time, and the vertical axis represents vibration speed.
The laser Doppler velocimeter 12 transmits the acquired time waveform of the vibration speed to the control unit 13. That is, in this embodiment, the vibration of the belt conveyor 50 is measured using the laser Doppler velocimeter 12 in the spectrum acquisition step S1.
The vibration speed at the position P6 of the belt conveyor 50 is attenuated over time.
In this case, V ₀ has the maximum absolute value.

  Next, frequency analysis of the time waveform of the vibration velocity is performed to obtain a frequency-specific spectrum shown in FIG. A known Fourier transform or the like can be used for the frequency analysis. The horizontal axis in FIG. 10 represents the frequency, and the vertical axis represents the amplitude.

Control unit 13, a velocity spectral response values of the time waveform W ₀ of the vibration velocity normalized by dividing by the magnitude of the impact force, the time waveform W of the vibration velocity corresponding to the velocity spectrum response value normalized 9 ₁ is calculated. The velocity spectrum response value referred to here is obtained by vibration analysis of the time waveform of the vibration velocity, and means, for example, that expressed as a graph in which the horizontal axis is the frequency and the vertical axis is the response value. .
The normalized velocity spectrum response value and the vibration velocity time waveform W ₁ are stored in the memory of the control unit 13.
The laser Doppler velocimeter 12 is moved and the position where the laser beam L is irradiated is shifted according to the position of the belt conveyor 50 where the time waveform of the vibration velocity is desired and the number of laser Doppler velocimeters 12 included in the evaluation device 1. For example, the position where the laser beam L is irradiated is shifted to a position P7 along the vertical direction Z shown in FIG. 4 or to a position P8 along the longitudinal direction X. An operator applies an impact force to the belt conveyor 50 in a state where the laser beams L are irradiated to the positions P7 and P8, and the above-described processing is performed.

Thus, in the spectrum acquisition step S1, and the control unit 13 measures the magnitude of the impact force, and measuring the time waveform W ₀ of the vibration velocity, velocity spectral response values of the time waveform W ₀ of the vibration velocity Is divided multiple times by the magnitude of the impact force, and is normalized multiple times. The laser beam L is irradiated to different positions such as the longitudinal direction X of the belt conveyor 50, and the above-described processing is performed a plurality of times.
At this time, the magnitude of the impact force applied to the belt conveyor 50 may change every time the hammer 10 is hit, but it is preferable that the position where the belt conveyor 50 is hit with the hammer 10 is substantially the same.
Since the normalized velocity spectrum response value is a velocity spectrum response value per unit impact force, it is easy to compare even if the impact force applied to the belt conveyor 50 by the operator changes.
The control unit 13 performs a process of combining the normalized velocity spectrum response values for a plurality of times to obtain a velocity spectrum response value aggregate.

Next, in the specific process (step S3), the control unit 13 determines the frequency of the peak of the frequency in the spectrum for each frequency in each element such as the beam member 54, the upper and lower connecting member 55, and the beam piece 60 of the belt conveyor 50. Identify the natural frequency and vibration mode.
Then, for example, the natural frequency ω _{1 at} which the beam piece 60 vibrates and the natural frequency ω ₂ at which the thin-walled beam piece 60A vibrates in the same vibration mode of cross-sectional vibration are obtained. Since the natural frequency ω ₁ is a natural frequency with respect to the initial thickness of the beam piece 60, the natural frequency ω ₁ is a natural frequency registered in a database obtained in advance. On the other hand, the natural frequency ω ₂ is not registered in the database obtained in advance because it is the natural frequency for the thin-walled beam piece 60A having a reduced thickness.

FIG. 11 shows normalized velocity spectrum response values at the respective positions of the first plate member 60 a of the beam piece 60. The longer the length of the arrow, the larger the normalized velocity spectrum response value. As described above, the position at which the time waveform of the vibration speed is acquired is shifted from the position P1 to the positions P2, 3, etc., and the speed spectrum is obtained from the time waveform of the vibration speed and is normalized by dividing by the magnitude of the impact force. Note that the vibration mode of the cross-sectional vibration is a primary mode described later.
Since both ends in the longitudinal direction X of the beam piece 60 are fixed, it can be seen that the normalized velocity spectrum response value is 0 at both ends. It can be seen that the joint portion 60c of the beam piece 60 does not move, and the central portion in the longitudinal direction X of the first plate member 60a moves around the joint portion 60c. The normalized velocity spectrum response value increases as the distance from the joint 60c increases, and is maximized at the free end of the first plate member 60a.

Generally, as the thickness of the plate members 60 a and 60 b is reduced, the natural frequency of the thin beam piece 60 </ b> A becomes smaller than the natural frequency of the beam piece 60. In natural frequency omega _1, only the beam piece 60 is vibrated, the beam element 60 other than the members of the belt conveyor 50 does not vibrate. In natural frequency omega _2, only the thin beam pieces 60A vibrates, member other than the thin beam piece 60A of the belt conveyor 50 does not vibrate. By detecting the natural frequency that is not registered in the previously obtained database and specifying the position with respect to the detected natural frequency, the position of the thin beam piece 60A on the belt conveyor 50 is specified.

FIG. 12 shows the eigenvalue analysis results when the belt conveyor 50 is vibrated at the natural frequency ω ₁ at which the beam piece 60 vibrates. The normalized speed spectrum response values at the respective positions of the plate members 60a and 60b of the belt conveyor 50 are represented as widths L ₁ and L ₂ , respectively. It was found that the vibration speed at each position of the plate materials 60a and 60b was relatively large.
On the other hand, in the natural frequency omega _1, the thin plate 60aA of the thin beam pieces 60A, each position of the 60bA was found not to vibrate.
FIG. 13 shows an eigenvalue analysis result when the belt conveyor 50 is vibrating at the natural frequency ω ₂ at which the thin beam piece 60A vibrates. The normalized speed spectrum response values at the respective positions of the thin plate members 60aA and 60bA of the belt conveyor 50 are represented as widths L ₃ and L ₄ , respectively. It was found that the vibration speed at each position of the thin plate members 60aA and 60bA was relatively large. On the other hand, at the natural frequency ω ₂ , it was found that the positions of the plate members 60a and 60b of the beam piece 60 do not vibrate.

FIG. 14 shows the normalized velocity spectrum response value at the position P6 (see FIG. 4) which is the free end of the first plate member 60a. The horizontal axis in FIG. 14 represents the position in the longitudinal direction of the first plate member 60a, and the vertical axis represents the normalized velocity spectrum response value in the longitudinal direction X of the beam piece 60 shown in FIG. Since both ends in the longitudinal direction X of the beam piece 60 are fixed, the value obtained by normalizing the vibration velocity at which the absolute value at both ends is maximized is almost zero.
It was found that the vibration modes of the cross-sectional vibration include not only the primary mode indicated by ◯ but also the secondary mode indicated by □ and the tertiary mode indicated by Δ.

In the belt conveyor 50, for example, there is a vibration mode such as lateral vibration in which only the upper and lower connection member 55 vibrates, and there is a vibration mode such as lateral vibration in which only a member with a reduced thickness of the upper and lower connection member 55 vibrates. To do. In this case, in the specifying step S3, the natural frequency for the upper and lower connecting member 55 and the vibration mode that is the lateral vibration are specified from the spectrum for each frequency.
As described above, the natural frequencies ω ₁ and ω ₂ of a small and small member such as the beam piece 60 and the upper and lower connecting members 55 are shorter than 100 Hz as shown in FIG. On the other hand, the natural frequencies ω ₃ and ω ₄ of a relatively long member close to the overall size of the belt conveyor 50 such as the beam member 54 are generally about several Hz to several tens Hz. The natural frequency of about 100 Hz or less corresponding to the natural frequencies ω ₃ and ω ₄ is extremely insensitive to local damage of a relatively short small member constituting the structure, and the entire structure is considerably damaged. If not, the natural frequency will not change easily.

Next, in the frequency comparison step (step S5), and the difference between the natural frequency omega ₁ and the natural frequency omega ₂ of the thin beam pieces 60A of the beam member 60 in the same vibration mode, of the thin beam pieces 60A performance (damage ) Quantitatively. Here, the same vibration mode is not only the same vibration mode such as transverse vibration and cross-sectional vibration, but also the same order of vibration modes such as the first mode of cross-sectional vibration and the second mode of cross-sectional vibration. It means that.

The steps in the frequency comparison step S5 will be described using the flowchart of FIG. The steps in the frequency comparison step S5 are divided into an experimental step and an analysis step. For example, the thickness of the plate members 60a and 60b will be described as 6.0 mm.
First, in step S11, in the analysis, an analysis model is created using a known frequency analysis program. Here, an analysis model of the entire belt conveyor 50 is created. Note that an analysis model of only the thin beam piece 60A may be created. At this time, an analysis model capable of expressing the natural frequency ω ₂ of the vibration mode of the cross-sectional vibration specified in the specifying step S3 is created.
Next, in step S13, it is assumed that the thickness t _d of the thin plate members 60aA and 60bA is, for example, 6.0 mm. At this time, the position of the thin beam piece 60A specified in the specifying step S3 is used.
Next, in step S15, the natural frequency of the analysis model is calculated using a frequency analysis program.

Next, in step S17, the assumed thin plate 60Aa, calculates the CSMLF (Cross Sectional Mode based Local Flexibility matrix) ana to the thickness _{t d} of the 60Ba. CSLLF _ana is a part of a known flexibility matrix F for the belt conveyor 50. Here, first, the flexibility matrix F will be described.
A general definition of the flexible matrix F will be described using the vector equation (1).
P = Kx (1)
Here, P is an external force vector at each node (degree of freedom), K is a stiffness matrix, and x is a displacement vector representing an independent displacement of each node.
K ^-1 when the expression (1) is modified and expressed as the expression (2), that is, the inverse matrix of the stiffness matrix K is the flexibility matrix F.
x = K ⁻¹ P = FP (2)
The flexibility matrix F is expressed as in equation (3).

Here, φ is a mode shape matrix, and ω is a natural frequency matrix. φ _ji is the mode amplitude of the j-node in the i-th mode, and ω _i is the natural frequency of the i-th mode. N is the degree of freedom.
In this case, since the evaluation is mainly performed up to the superior third-order mode, CSMLF _ana which is a part of the flexible matrix F is expressed by Equation (4).

Thus, by performing an analysis to calculate the _{CSMLF ana} thin beam pieces 60A.
On the other hand, the CSMLF _exp of the thin-walled beam piece 60A is calculated in the same manner from the natural frequency and vibration mode specified in the specifying step S3 through experiments.
Next, in step S19, (5) the value of NE defined by equation, determines whether a predetermined tolerance (permissible value) V ₁ or less.

The value of NE is a value obtained by dividing the magnitude of the difference between CSMLF _ana and CSMLF _exp by the magnitude of CSMLF _exp . When the value of NE is determined YES in tolerance V ₁ or less and step S19, the thickness of the assumed thin beam pieces 60A, the estimated thickness of the measured thin beam piece 60A. That is, the measured thickness of the thin beam piece 60A is estimated to be 6.0 mm.
And frequency comparison process S5 is complete | finished and all the processes of this evaluation method are complete | finished.
Here, the tolerance _{V 1} was preferably 0.001 to 0.1.

On the other hand, when the value of NE is determined NO in tolerance _{V 1} increases step S19 than the thin plate 60aA proceeds to step S13, to vary the thickness _{t d} of the 60Ba. For example, assume a smaller value of 5.5 mm.
Steps S15 and 17 are performed, and steps S15, 17 and 19 are repeated until YES is determined in step S19. As shown in FIG. 16, by changing the thickness of the assumed thin beam pieces 60A, it will compare the value of NE and the tolerance V _1.
Thus, in this embodiment, the process of specific process S3 and frequency comparison process S5 is performed with respect to the normalized velocity spectrum response value aggregate | assembly.

  Even if the natural frequency at which the entire beam member 54 vibrates is measured, the natural frequency is smaller than about 100 Hz. Therefore, even if it is damaged, the natural frequency change is small and the sensitivity is low. It is not possible to specify the position where the thickness is reduced (damaged). By measuring the natural frequency of the beam piece 60 obtained by dividing the beam material 54 into a plurality of parts, the position where the beam piece 60 becomes thin and becomes the thin beam piece 60A can be specified, and the damage to the thin beam piece 60A can be evaluated. it can.

As described above, according to the evaluation method of the present embodiment, the thin-walled beam piece 60A and the beam piece 60, which are one of a plurality of specifications of the beam piece 60, have the same cross-sectional vibration. The natural frequency also differs in the order of. By selecting cross-sectional vibration as the vibration mode, the beam piece 60 and the thin beam piece 60A are evaluated with high sensitivity even if the beam piece 60 is a small member compared to the entire belt conveyor 50 such as a part of the belt conveyor 50. can do.
The natural frequency specified in the specifying step S3 is 100 Hz or more. Compared to the entire belt conveyor 50, the natural frequency of the small member is 100 Hz or more. By specifying the natural frequency of 100 Hz or higher, the beam piece 60 can be evaluated even if the beam piece 60 is a small member.

Among the specifications of the beam piece 60, the thickness of the plate members 60a and 60b of the beam piece 60 is reduced. Since the change in thickness is easily detected as a change in natural frequency, the beam piece 60 can be more reliably evaluated.
In frequency comparing step S7, the value of NE is permissible error V ₁ following evaluation object change portion on the assumption when it becomes thick, and estimates the thickness of the measured thin beam piece 60A. Therefore, the measured thickness of the thin beam piece 60A can be obtained quantitatively.

By evaluating the beam piece 60 in the vibration mode of the cross-sectional vibration, even if the beam piece 60 that is the evaluation target part is a part in the longitudinal direction X of the beam material 54, the beam piece 60 is thin. The position of the beam piece 60A can be specified.
In the spectrum acquisition step S1, by measuring the vibration of the belt conveyor 50 using a non-contact speedometer, a time waveform of the vibration speed can be acquired without directly contacting the belt conveyor 50. The time waveform of the vibration speed can be easily acquired even at a high place and a high temperature place where the operator cannot easily approach.
The velocity spectrum response value of the vibration velocity time waveform W ₀ is divided by the magnitude of the impact force and normalized. Therefore, the spectrum acquisition step S1 and the like can be performed by normalizing even the time waveform W ₀ of the vibration velocity applied with impact forces having different magnitudes.

Incidentally, in the frequency comparison step S5, in the present embodiment, thin plate member 60Aa, the thickness of the 60Ba when assumed thin plate 60Aa, gradually changing the thickness _{t d} of the 60Ba, the value of NE becomes minimum the t _d may be the thickness of the estimation of the thin beam pieces 60A measured.
Instead of CSMLF _ana and CSMLF _exp , an analysis flexibility matrix F _ana that is a flexibility matrix calculated by analysis and a measurement flexibility matrix F _exp that is a flexibility matrix calculated by experiment may be calculated and used. The analysis flexibility matrix F _ana and the measurement flexibility matrix F _exp are those of the thin beam piece 60A, but may be those of the entire belt conveyor 50.
In the frequency comparison step S5, from the difference between the natural frequency ω ₁ of the beam piece 60 and the natural frequency ω ₂ of the thin-walled beam piece 60A, for example, the thickness of the thin-walled beam piece 60A increases as the natural frequency difference increases. If it is thin, the performance of the thin beam piece 60A may be evaluated qualitatively.

Although the cross-sectional vibration of the beam piece 60 and the thin beam piece 60A is used as the same vibration mode in the frequency comparison step S5, the vibration mode is not limited to this, and the vibration mode by the transverse vibration shown in FIG. Vibration mode may be used. In the lateral vibration, the beam piece 60 and the thin-walled beam piece 60A vibrate like a string in the center in the longitudinal direction with both ends in the longitudinal direction being fixed.
Lateral vibration is suitable for the evaluation of the connecting members 55 and 57 and the diagonal members 56 and 58. When vibrating by lateral vibration, the natural frequency specified in the specific process is preferably 30 Hz or more.
In addition, the member that measures the vibration with the laser Doppler velocimeter 12 and the member that gives the impact with the hammer 10 having the impact force meter 11 are the same member, but the measurement member or the impact input member is different. Also good.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. 18, but the same parts as those of the above-described embodiment will be denoted by the same reference numerals, the description thereof will be omitted, and only different points will be described.
In FIG. 18, the evaluation apparatus 2 used suitably for this evaluation method is shown.
The evaluation device 2 includes a reference laser Doppler velocimeter (first non-contact velocimeter) 21 and a control unit 22 instead of the impact force meter 11 and the control unit 13 of the evaluation device 1 of the first embodiment. .
A reference laser Doppler velocimeter 21 having a known configuration can be used. The reference laser Doppler velocimeter 21 is connected to the control unit 22. The reference laser Doppler velocimeter 21 transmits a time waveform of the detected vibration speed to the control unit 22.
The control unit 22 is different from the above-described control unit 13 in the control program stored in the memory.

Next, the evaluation method of this embodiment for evaluating the belt conveyor 50 in the evaluation state will be described.
First, in the spectrum acquisition step (step S31 shown in FIG. 5), the vibration of the belt conveyor 50 is measured a plurality of times using the reference laser Doppler velocimeter 21 and the laser Doppler velocimeter 12. At this time, the member that measures vibration with the laser Doppler velocimeters 12 and 21 and the member that gives an impact with the hammer 10 are the same member.

Specifically, the laser Doppler velocimeters 12 and 21 are arranged, the belt conveyor 50 is struck with the hammer 10, and the reference laser Doppler velocimeter 21 is used to measure the vibration velocity at the predetermined position P10 of the beam piece 60 or the thin beam piece 60A. Measure the time waveform. A laser Doppler velocimeter 12 is used to measure the temporal waveform W ₀ of the vibration velocity in the beam piece 60 and the thin beam piece 60A.
The reference laser Doppler velocimeter 21 transmits a time waveform of the measured vibration speed, and the laser Doppler velocimeter 12 transmits the time waveform W ₀ of the measured vibration speed to the control unit 22. As in the first embodiment, the control unit 22 uses the reference laser Doppler velocimeter 21 to obtain the velocity spectrum response value obtained by frequency analysis of the vibration velocity time waveform W ₀ measured by the laser Doppler velocimeter 12. The time waveform of the measured vibration velocity is divided by the velocity spectrum response value obtained by frequency analysis and normalized. The normalized velocity spectrum response value is stored in the memory of the control unit 22.

The reference laser Doppler velocimeter 21 is moved without moving the laser Doppler velocimeter 12 to a desired position. The belt conveyor 50 is struck with the hammer 10, and the time waveform of the vibration speed at the predetermined position P10 of the beam piece 60 or the thin-walled beam piece 60A is measured using the reference laser Doppler velocimeter 21 in the same manner as described above. A laser Doppler velocimeter 12 is used to measure the temporal waveform W ₀ of the vibration velocity in the beam piece 60 and the thin beam piece 60A. Similarly, the normalized velocity spectrum response value is stored in the memory of the control unit 22.

As described above, in the spectrum acquisition step S31, the measurement of the time waveform of the vibration velocity using the laser Doppler velocimeters 12 and 21 and the normalization of the velocity spectrum response value are performed a plurality of times. The laser beam L of the laser Doppler velocimeter 12 is irradiated to different positions such as the longitudinal direction X of the belt conveyor 50, and the above processing is performed a plurality of times.
In this embodiment, the belt conveyor 50 is hit with the hammer 10, but the magnitude of the impact force is not measured.
The control unit 22 performs a process of combining the normalized velocity spectrum response values into a velocity spectrum response value aggregate. And the above-mentioned specific process S3 and frequency comparison process S5 are performed with respect to a velocity spectrum response value aggregate | assembly.

As described above, according to the evaluation method of the present embodiment, the beam piece 60 can be evaluated with high sensitivity even if the beam piece 60 is a smaller member than the entire belt conveyor 50.
Further, it is possible to perform processing of a plurality of velocity spectra and the like by normalizing even the time waveform W ₀ of the vibration velocity applied with the impact force having different magnitudes without measuring the magnitude of the impact force. it can.
Since this evaluation method does not need to measure the magnitude of the impact force, it can be applied to the case where vibration is generated by a method other than direct impact such as ultrasonic laser or sound wave.

In the present embodiment, the evaluation device 2 includes one laser Doppler velocimeter 12, but the evaluation device 2 may include two or more laser Doppler velocimeters 12.
Further, in this embodiment, the measurement member in the laser Doppler velocimeters 12 and 21 and the member that gives an impact with the hammer 10 are the same member, but the measurement member or the impact input member may be different from each other. .

As mentioned above, although 1st Embodiment and 2nd Embodiment of this invention were explained in full detail with reference to drawings, the concrete structure is not restricted to this embodiment, The structure of the range which does not deviate from the summary of this invention Changes, combinations, deletions, etc. are also included. Furthermore, it goes without saying that the configurations shown in the embodiments can be used in appropriate combinations.
For example, in the first embodiment and the second embodiment, the beam pieces 60 and the like are formed of angle members, but the configuration of the beam pieces 60 is not limited to this.
For example, as shown in FIG. 19, a beam piece 65 is configured as a so-called channel member by joining a first plate member 65a, a second plate member 65b, and a third plate member 65c at joint portions 65d and 65e. Also good. In this case, the joint portions 65d and 65e do not move in the cross-sectional vibration, and the plate members 65a, 65b and 65c vibrate as indicated by arrows in the drawing.

  Further, as shown in FIG. 20, the beam piece 67 is configured as a so-called H-shaped steel by joining the first plate member 67a, the second plate member 67b, and the third plate member 67c at the joints 67d and 67e. May be. In this case, the joint portions 67d and 67e do not move during the cross-sectional vibration, and the plate members 67a, 67b and 67c vibrate as indicated by arrows in the drawing.

In the first embodiment and the second embodiment, the evaluation target portion is the beam piece 60. However, the evaluation target portion in the belt conveyor 50 is not particularly limited, and the vertical connection member 55, the vertical diagonal member 56, the left and right connection. The member 57 and the left and right diagonal members 58 may be used.
The non-contact speedometer is assumed to be a laser Doppler speedometer 12. However, the non-contact velocimeter is not limited to the laser Doppler velocimeter 12 and may be a non-contact velocimeter by another method.
When the vibration velocity time waveform W ₀ is measured only once, the vibration velocity time waveform W ₀ may not be normalized. A specific step and a frequency comparison step are performed on the time waveform W ₀ of the vibration velocity measured once.
Although the structure is the belt conveyor 50, the structure is not limited to the belt conveyor 50, and may be a pipe mount, a ramen structure building, a bridge, or the like.
A contact-type speedometer may be used instead of the non-contact speedometer to acquire the time waveform of the vibration speed.

12 Laser Doppler velocimeter (non-contact velocimeter, second non-contact velocimeter)
21 Standard non-contact speedometer (first non-contact speedometer)
50 Belt conveyor (structure)
60, 65, 67 Beam (evaluation target part)
60a, 65a, 67a First plate material 60A Thin-walled beam piece (evaluation target changing portion)
60b, 65b, 67b Second plate material 60c, 65d, 67d Joint D1 One side D2 Other side S1 Spectrum acquisition step S3 Specific step S5 Frequency comparison step t _d thickness T Reference plane V ₁ Tolerance (allowable value)
W ₀ Vibration velocity time waveform X Longitudinal direction (reference direction)
ω ₁ , ω ₂ natural frequency

Claims (17)

In the initial state, the plurality of specifications of the plurality of evaluation target parts are equal structures, and in the evaluation state, at least one of the plurality of evaluation target parts is the thickness of the evaluation target part. It is an evaluation method for a structure that evaluates what has become an evaluation target change part by becoming thinner ,
In the evaluation state, while measuring the vibration of the structure to obtain a time waveform of the vibration speed, a spectrum acquisition step of analyzing the frequency waveform of the vibration speed to obtain a frequency-specific spectrum;
A specific step of specifying a natural frequency and a vibration mode from the spectrum for each frequency;
Vibration that evaluates the performance of the evaluation target change unit from the difference between the natural frequency at which only the evaluation target unit vibrates in the same vibration mode order and the natural frequency at which only the evaluation target change unit vibrates A number comparison process;
The stomach line,
In the frequency comparison step,
From the natural frequency and the vibration mode specified in the specific step, calculate a measurement flexibility matrix that is a flexibility matrix of the evaluation object changing portion or the structure,
By performing analysis, calculate the analysis flexibility matrix that is the flexibility matrix of the evaluation object changing portion or the structure when the thickness of the evaluation object portion is changed,
The value obtained by dividing the magnitude of the difference between the analysis flexibility matrix and the measurement flexibility matrix by the size of the measurement flexibility matrix is equal to or less than a predetermined allowable value. The evaluation method of the structure which makes the thickness of the said evaluation object change part measured . In the initial state, the plurality of specifications of the plurality of evaluation objects are equal structures, and in the evaluation state, at least one of the plurality of evaluation objects is a plurality of the specifications. It is an evaluation method for a structure that evaluates what has become an evaluation object changing part by changing at least one of the following:
In the evaluation state, while measuring the vibration of the structure to obtain a time waveform of the vibration speed, a spectrum acquisition step of analyzing the frequency waveform of the vibration speed to obtain a frequency-specific spectrum;
A specific step of specifying a natural frequency and a vibration mode from the spectrum for each frequency;
Vibration that evaluates the performance of the evaluation target change unit from the difference between the natural frequency at which only the evaluation target unit vibrates in the same vibration mode order and the natural frequency at which only the evaluation target change unit vibrates A number comparison process;
The stomach line,
The same vibration mode in the frequency comparison step is a state in which both ends of the evaluation object part and the evaluation object change part are fixed, and a central part of the evaluation object part and the evaluation object change part is a string. The evaluation method of the structure which is a vibration mode by the transverse vibration which vibrates like this . The structural evaluation method according to claim 2 , wherein the change of at least one of the plurality of specifications is a reduction in thickness of the evaluation target portion. In the frequency comparison step,
From the natural frequency and the vibration mode specified in the specific step, calculate a measurement flexibility matrix that is a flexibility matrix of the evaluation object changing portion or the structure,
By performing analysis, calculate the analysis flexibility matrix that is the flexibility matrix of the evaluation object changing portion or the structure when the thickness of the evaluation object portion is changed,
The value obtained by dividing the magnitude of the difference between the analysis flexibility matrix and the measurement flexibility matrix by the size of the measurement flexibility matrix is equal to or less than a predetermined allowable value. The method for evaluating a structure according to claim 3 , wherein the measured thickness of the evaluation object changing portion is used. In the initial state, the plurality of specifications of the plurality of evaluation objects are equal structures, and in the evaluation state, at least one of the plurality of evaluation objects is a plurality of the specifications. It is an evaluation method for a structure that evaluates what has become an evaluation object changing part by changing at least one of the following:
In the evaluation state, while measuring the vibration of the structure to obtain a time waveform of the vibration speed, a spectrum acquisition step of analyzing the frequency waveform of the vibration speed to obtain a frequency-specific spectrum;
A specific step of specifying a natural frequency and a vibration mode from the spectrum for each frequency;
Vibration that evaluates the performance of the evaluation target change unit from the difference between the natural frequency at which only the evaluation target unit vibrates in the same vibration mode order and the natural frequency at which only the evaluation target change unit vibrates A number comparison process;
The stomach line,
The evaluation target portion is configured by joining a first plate member and a second plate member extending in a reference direction at a joint portion,
The same vibration mode in the frequency comparison step is moved in a state where both ends of the evaluation object part and the evaluation object change part are fixed, and the joint part of the evaluation object part and the evaluation object change part moves. The evaluation method for a structure that is a vibration mode in which portions other than the joint portion of the evaluation target portion and the evaluation target changing portion vibrate around the joint portion on a reference plane orthogonal to the reference direction . The structural evaluation method according to claim 5 , wherein the change of at least one of the plurality of specifications is a reduction in thickness of the evaluation target portion. In the frequency comparison step,
From the natural frequency and the vibration mode specified in the specific step, calculate a measurement flexibility matrix that is a flexibility matrix of the evaluation object changing portion or the structure,
By performing analysis, calculate the analysis flexibility matrix that is the flexibility matrix of the evaluation object changing portion or the structure when the thickness of the evaluation object portion is changed,
The value obtained by dividing the magnitude of the difference between the analysis flexibility matrix and the measurement flexibility matrix by the size of the measurement flexibility matrix is equal to or less than a predetermined allowable value. The method for evaluating a structure according to claim 6 , wherein the measured thickness of the evaluation object changing portion is used. The same vibration mode in the frequency comparison step is
A state in which the central portion of the first plate member rotates to one side around the joint portion and the central portion of the second plate member rotates to the other side around the joint portion; and the central portion of the first plate member 8. The vibration mode according to claim 5, wherein the rotation mode alternately repeats a state in which the second plate member rotates around the joint portion to the other side and a center portion of the second plate rotates around the joint portion toward the one side . The method for evaluating a structure according to any one of the above. The spectrum acquisition step, evaluation method of a structure according to any one of claims 1 to 8, by applying an impact force to vibrate the structure in the structure. The method for evaluating a structure according to any one of claims 1 to 9 , wherein in the spectrum acquisition step, vibration of the structure is measured using a non-contact velocimeter. In the spectrum acquisition step,
Using the first non-contact speedometer and one or more second non-contact speedometers, the time waveform of the vibration speed of the structure at a predetermined position of the evaluation object part or the evaluation object change part is measured. And
The velocity spectrum response value obtained by frequency analysis of the time waveform of the vibration velocity in the evaluation object portion and the evaluation object changing portion measured by one or more second non-contact velocimeters is obtained as the first spectral response value. Dividing the time waveform of the vibration velocity measured using a non-contact velocimeter with the velocity spectrum response value obtained by frequency analysis and normalizing it is performed a plurality of times,
Wherein for the second speed spectral response values assembly that combines the speed spectral response value normalized measured in a non-contact velocimeter, said specifying step, and from the claims 1 to perform the frequency comparison step 10 The method for evaluating a structure according to any one of the above. In the spectrum acquisition step, the magnitude of the applied impact force is measured, the time waveform of the vibration speed is measured, and the velocity spectrum response value of the vibration speed time waveform is determined as the magnitude of the impact force. Divide by to normalize multiple times in pairs,
The structure evaluation method according to claim 9 , wherein the specifying step and the frequency comparison step are performed on a velocity spectrum response value aggregate obtained by combining the normalized velocity spectrum response values. In the initial state, the plurality of specifications of the plurality of evaluation objects are equal structures, and in the evaluation state, at least one of the plurality of evaluation objects is a plurality of the specifications. It is an evaluation method for a structure that evaluates what has become an evaluation object changing part by changing at least one of the following:
In the evaluation state, while measuring the vibration of the structure to obtain a time waveform of the vibration speed, a spectrum acquisition step of analyzing the frequency waveform of the vibration speed to obtain a frequency-specific spectrum;
A specific step of specifying a natural frequency and a vibration mode from the spectrum for each frequency;
Vibration that evaluates the performance of the evaluation target change unit from the difference between the natural frequency at which only the evaluation target unit vibrates in the same vibration mode order and the natural frequency at which only the evaluation target change unit vibrates A number comparison process;
The stomach line,
In the spectrum acquisition step, an impact force is applied to the structure to vibrate the structure,
In the spectrum acquisition step, the magnitude of the applied impact force is measured, the time waveform of the vibration speed is measured, and the velocity spectrum response value of the vibration speed time waveform is determined as the magnitude of the impact force. Divide by to normalize multiple times in pairs,
A structure evaluation method for performing the specifying step and the frequency comparison step on a velocity spectrum response value aggregate obtained by combining the normalized velocity spectrum response values . In the initial state, the plurality of specifications of the plurality of evaluation objects are equal structures, and in the evaluation state, at least one of the plurality of evaluation objects is a plurality of the specifications. It is an evaluation method for a structure that evaluates what has become an evaluation object changing part by changing at least one of the following:
In the evaluation state, while measuring the vibration of the structure to obtain a time waveform of the vibration speed, a spectrum acquisition step of analyzing the frequency waveform of the vibration speed to obtain a frequency-specific spectrum;
A specific step of specifying a natural frequency and a vibration mode from the spectrum for each frequency;
Vibration that evaluates the performance of the evaluation target change unit from the difference between the natural frequency at which only the evaluation target unit vibrates in the same vibration mode order and the natural frequency at which only the evaluation target change unit vibrates A number comparison process;
The stomach line,
In the spectrum acquisition step,
Using the first non-contact speedometer and one or more second non-contact speedometers, the time waveform of the vibration speed of the structure at a predetermined position of the evaluation object part or the evaluation object change part is measured. And
The velocity spectrum response value obtained by frequency analysis of the time waveform of the vibration velocity in the evaluation object portion and the evaluation object changing portion measured by one or more second non-contact velocimeters is obtained as the first spectral response value. Dividing the time waveform of the vibration velocity measured using a non-contact velocimeter with the velocity spectrum response value obtained by frequency analysis and normalizing it is performed a plurality of times,
A structure evaluation method for performing the specifying step and the frequency comparison step on a velocity spectrum response value set obtained by combining the velocity spectrum response values measured and normalized by the second non-contact velocimeter . The structure evaluation method according to claim 14 , wherein in the spectrum acquisition step, an impact force is applied to the structure to vibrate the structure. The structure evaluation method according to claim 14 or 15 , wherein in the spectrum acquisition step, the vibration of the structure is measured using a non-contact velocimeter. The method for evaluating a structure according to any one of claims 13 to 16 , wherein the change of at least one of the plurality of specifications is that the thickness of the evaluation target portion is reduced.

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