JPH063436B2 - Method and apparatus for diagnosing deterioration of article - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to the inspection or diagnosis of structural articles and products,
The present invention relates to a method of diagnosing deterioration of an article capable of detecting the amount of corrosion or the amount of cracks and the tension applied. The present invention also relates to an apparatus for diagnosing deterioration of an article, which has a function of detecting corrosion, cracks, etc., and detecting tension applied by using the method.

(Prior Art) Conventionally, there have been the following methods for detecting the tension applied to a structural article and the thickness / crack amount. A method of detecting a crack amount from a resonance frequency and a damping coefficient of an article having a constant shape under free vibration. A method of detecting tension or structure from the resonance frequency of longitudinal vibration or transverse vibration of an article whose both ends are fixed. However, there is no method capable of simultaneously detecting the amount of thinning or the amount of cracks and the tension of an article having one end fixed.

FIG. 8 shows the above-mentioned method and its apparatus configuration. Reference numeral 1 is a vibration sensor, 2 is an amplifier, 3 is a calculation unit, and 4 is a display unit. Further, 5 is a subject, 6 is a vibration isolator, and 7 is a vibrator. Next, its operation and effect will be described. The subject 5 vibrated by the vibration exciter 7 freely vibrates and is converted into an electric signal through the vibration sensor 1. The converted electric signal is amplified by the amplifier 2, the frequency and the damping coefficient are measured by the arithmetic unit 3, and the relationship between the frequency and the damping coefficient of the subject having the given shape and material as shown in FIG. Deteriorate the degree of deterioration from. This technology uses the fact that the frequency and damping coefficient uniquely change along the deterioration direction according to the amount of cracks that develop and propagate in the subject. It is possible to quantitatively detect the degree of deterioration and the service life.

FIG. 10 shows the above-mentioned method and its apparatus configuration. Reference numeral 1 is a vibration sensor, 2 is an amplifier, 3'is a calculation unit, and 4 is a display unit. Reference numeral 5'denotes a subject, 6'denotes an object for fixing or supporting the subject, and 7 a vibrator. Next, its operation and effect will be described. The subject 5 ′ vibrates due to the vibrator 7 or constant vibration in the natural environment. This vibration is converted into an electric signal through the vibration sensor 1 and the amplifier 2 and amplified, and the frequency is measured by the arithmetic unit 3 '. Furthermore, the first
As shown in FIG. 1, the tension applied to the subject is calculated from the resonance frequency based on the length, cross-sectional area and material of the subject 5'given in advance. With this technology, the tension applied to both ends of the object can be measured from the vibration frequency of the object, which is unique to the shape and material, and therefore the strength safety and life of the structure can be quantitatively detected. .

However, there has been no method for simultaneously detecting the tension applied to a structure whose both ends are supported or fixed and the degree of deterioration or shape thereof.

(Problems to be Solved by the Invention) The conventional method for diagnosing deterioration of articles has a problem in that it is not possible to simultaneously quantify the degree of deterioration caused by the tension applied to an article or structure having a constant material and size and a structure, and corrosion.
Therefore, the following problems to be solved remain.
Quantitatively detect the amount of deterioration or corrosion of a structure where both ends are fixed and tension is applied. Quantitatively detecting changes in the size and shape of structures that are fixed at certain points.

As a result, there has been a problem that the accuracy of the structure deterioration diagnosis and its application range are limited.

The present invention has been made based on the above circumstances, and a deterioration diagnosing method for an article capable of simultaneously and accurately detecting the degree of deterioration of a structure or structural article having a constant shape and the tension applied thereto and the like. The purpose is to provide the device.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention uses the above-mentioned article from both the resonance frequency of longitudinal vibration and the resonance frequency of transverse vibration of a structure and a structural article to be inspected. The gist is to quantify the degree of deterioration, tension, etc. Furthermore, the present invention provides a vibration sensor that is attached to one end of a structure or a structural article that is a subject, a vibrating section that excites vibration at the other end of the subject, and a resonance frequency of longitudinal vibration and lateral vibration of the subject. The gist of the present invention is to have a calculation unit for calculating the degree of deterioration and the tension and a display unit for outputting the result.

(Operation) In the present invention, the resonance frequencies of the longitudinal vibration and the lateral vibration of the article are calculated, and the degree of deterioration of the article and the applied tension are detected based on these information.

(Embodiment) FIG. 1 is a configuration diagram of a method and apparatus for diagnosing deterioration of an article according to an embodiment of the present invention. Reference numeral 1'denotes a vibration sensor, 2 an amplifier, 3 "an arithmetic unit, 4 a display unit, 5" an object (bar-shaped article), 6 a fixed or support, and 7 an exciter. Note that the fixed or support 6 ″ is the subject 5 ″
Is loaded with tension. First, the subject 5 ″ vibrated by the vibrator 7 vibrates. At this time, the rod-shaped subject 5 undergoes lateral vibration (vibration whose displacement has a mode perpendicular to the longitudinal direction of the rod) and longitudinal vibration (displacement). Is a vibration with a mode parallel to the longitudinal direction of the rod)
Both of them take a combined vibration. Therefore, the vibration sensor 1 '
Then, this mechanical vibration is converted into an electric signal and amplified by the amplifier 2. Based on the vibration waveform obtained through the amplifier 2, the calculation unit 3 ″ calculates the resonance frequencies of the horizontal vibration and the vertical vibration of the subject 5 ″. Then, the lateral vibration and the longitudinal vibration calculated in advance by the calculation unit 3 ″ in accordance with the tension and the degree of deterioration applied to the subject whose dimensions (rod length and cross-sectional shape), Young's modulus, and density are known in advance. The tension and the degree of deterioration of the subject 5 ″ are calculated based on the resonance frequency of. Finally, the display unit 4 displays the result obtained by the calculation unit 3 ″.

FIG. 2 shows a lateral vibration waveform and a vibration spectrum distribution of an iron bar having both ends fixed as a subject. 20 in FIG. 2 is
It is a transverse vibration waveform after the above-mentioned iron bar was subjected to impulse excitation. Second
Reference numeral 21 in the figure is a spectral distribution of lateral vibration obtained by subjecting the vibration waveform to A / D conversion and then performing a fast Fourier transform (FFT) process. In this figure, A, B, and C are frequency peaks, respectively. Further, FIG. 3 shows a longitudinal vibration waveform of a steel bar having both ends fixed as a subject and its vibration spectrum distribution. Third
Reference numeral 30 in the figure is a vertical vibration waveform of the iron bar after impulse excitation. Reference numeral 31 in FIG. 3 is a spectral distribution of longitudinal vibration obtained by A / D converting the vibration waveform and then performing a fast Fourier transform (FFT) process. In this figure, A ', B', and C'are frequency peaks, respectively. Based on these frequency peaks, the resonant frequencies of lateral vibration and longitudinal vibration are measured. That is, in the measurement of the lateral vibration spectrum distribution, three frequency peaks A, B, and C are calculated, and for these three peaks, the resonance frequency of the lateral vibration is a specific numerical value of 18H _Z. ，
41H _Z and 86H _Z are read, of which the lowest resonance frequency A (18H _Z ) is used for deterioration diagnosis. Similarly, in the measurement of the longitudinal vibration spectrum distribution of FIG. 3, A ′,
B, C three frequency peaks of 'is calculated, as the resonant frequency of the longitudinal vibration to the three, which is a specific numerical 480H _Z, 1040H _Z, but reading 1820H _Z, This out degradation diagnosis Lowest resonance frequency A '(4
80H _Z ) is used. Deterioration diagnosis is performed from the lowest resonance frequencies of both vibrations by referring to FIGS. 5 and 6.

FIG. 4 shows an experimental configuration diagram of an example of diagnosis of the above-mentioned tension and deterioration degree of the iron rod. 1'is a vibration sensor 7'is an impact hammer (vibrator), 5'is an object to be inspected, 9 is a connecting wire for giving a tension to the object to be inspected 5 ', 8 is a load cell for applying tension, and 10 is an object to be inspected 5 It is a support plate of '. In this experiment, the subject 5 is a 22 mmφ × 1800 mm iron bar, and the wire 9 is 1200 mm long.
The measurement results are shown below. The subject 5 '
As for the steel bar, assuming that it is deteriorated by corrosion near the support plate 10, the thinned portion 11 has a length of 200 mm and a cross-sectional area of 20 to 100%.
The thickness is reduced by processing in 5 stages in the range of. further,
This is a sensor that can detect lateral vibration and longitudinal vibration of the subject 5'of the vibration sensor 1'at the same time, 600 mm from the tip of the iron bar.
Is attached to. The striking by the striking hammer 7'was made with the tip of the iron rod, and tension was applied from 0 to 2 t by the load cell 8. FIG. 5 and FIG. 6 show the results of the diagnosis performed on the iron bar. FIG. 5 shows the relationship between the resonance frequency ft of the horizontal vibration of the iron bar and the processed cross-sectional area ratio. The resonance frequency ft does not change even if the cross-sectional area decreases, but increases as the tension increases. Therefore, the tension applied to the iron bar can be detected from the resonance frequency ft. Fig. 6 shows the resonance frequency of the longitudinal vibration of the iron bar.
The relationship between fl and the processed cross-sectional area ratio is shown. The resonance frequency fl decreases as the cross-sectional area decreases, and the higher the tension, the higher the resonance frequency. Therefore, if the tension applied to the iron rod is known, the cross-sectional area with the reduced thickness can be obtained from the resonance frequency fl. From these results, it is possible to obtain the tension applied to the steel bar from the resonance frequency of the horizontal vibration and the deterioration degree by reducing the thickness from the resonance frequency of the longitudinal vibration.

FIG. 7 is a flow chart showing the operation of the method for diagnosing deterioration of an article according to this embodiment. The processing flow of this deterioration diagnosis method will be described according to this flow. First, the subject (bar-shaped article) having tension applied to both ends is vibrated (100). The lateral vibration waveform of the electric signal is taken in through the vibration sensor (11
0), followed by capturing the electrical signal longitudinal vibration waveform (12
0). The captured vibration waveform is sampled and A / D converted (130). Fast Fourier transform (FFT) processing is performed on the digitized signal to draw a spectrum distribution of vibration (140). The resonance frequency ft of the lateral vibration is obtained from the calculated peak of the spectral distribution (150), and further the resonance frequency fl of the longitudinal vibration is obtained (160). Therefore, the degree of deterioration (in this case, the amount of thinning) is calculated from the resonance frequency fl of the lateral vibration (180). To calculate the tension and the degree of deterioration, the resonance frequency ft of the lateral vibration and the resonance frequency fl of the longitudinal vibration, which are stored in a database for each given size, shape and material of the specific specimen, are digitized and stored. (1
90). Finally, the tension and degree of deterioration of the diagnosed subject are displayed (200).

In addition, in the above embodiment, a case where a constant tension is applied to the metal rod whose thickness is partially reduced is described, but the present invention is not limited to this, and for example, a crack is formed instead of the thickness reduction. It can also be applied when existing or when a mechanical force such as compressive force or shearing force is applied instead of tension.

(Effect of the Invention) As described above, according to the present invention, the tension or the like and the degree of deterioration are detected from the resonance frequencies of longitudinal vibration and lateral vibration of a structure or structural article having a constant shape and material. Therefore, for example, mechanical strength, structural stability and deterioration degree such as corrosion amount and crack amount of long structural articles such as rods, beams, and wires fixed or supported on the structure can be easily, accurately and accurately determined. Can be detected.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a method and apparatus for diagnosing deterioration of an article according to the present invention, and FIG. 2 is a characteristic diagram showing a transverse vibration waveform of a steel bar and its spectrum distribution shown in the embodiment of the present invention. FIG. 3 is a characteristic diagram showing a longitudinal vibration waveform of an iron rod and its spectrum distribution shown in an embodiment of the present invention, FIG. 4 is a deterioration diagnosing method of an iron rod shown in an embodiment of the present invention and its experimental configuration diagram, and FIG. FIG. 6 is a characteristic diagram showing the relationship between the resonance frequency of the lateral vibration and the reduced cross-sectional area of the steel rod according to the change of the tension of the iron rod shown in FIG. FIG. 7 is a characteristic diagram showing the relationship between the resonance frequency of vibration and the reduced cross-sectional area, FIG. 7 is a flow chart showing the operation of the deterioration diagnosis method in the embodiment of the present invention, and FIG. 8 is a deterioration diagnosis method by the conventional vibration analysis method. Fig. 9 is a schematic diagram of the configuration of the conventional vibration analysis method. Degradation diagnosis view by, Figure 10 is schematic diagram of the structure of the tension measuring method according to the conventional vibration analysis method, FIG. 11 is a characteristic diagram showing the frequency relationship between the tension by conventional vibration analysis. 1 ... Vibration sensor, 1 '... Vibration sensor according to the present invention, 2 ...
Amplifier, 3 ... Conventional computing unit, 3 '... Conventional computing unit, 3 "
... Calculation unit for deterioration diagnosis according to the present invention, 4 ... Display unit, 5 ... Inspected object, 5 '... Inspected object (beam, wire, etc.), 5''... Inspected object (rod-shaped article), 6 ... Vibration isolator, 6' ... Fixed or supported object, 6 "... Fixed or supported object (when tension is applied to the subject), 7 ... Exciter, 7 '... Impact hammer (exciter), 8 ...
Load cell, 9 ... Connecting wire, 10 ... Support plate, 11 ... Thinned portion.

Claims (2)

[Claims] 1. A mechanical vibration is applied to a rod-shaped object to which a mechanical force such as tension is applied, and a lateral vibration waveform and a longitudinal vibration waveform of an electric signal are extracted from the object by a sensor. The vertical vibration waveform is converted to a digital signal, and the digital signal is processed by fast Fourier transform to calculate the vibration spectrum distribution. From the peak of this spectrum distribution, the lowest resonance frequency of lateral vibration and the lowest resonance of vertical vibration are calculated. By calculating the frequency, the size, shape, and
And mechanical force such as tension applied to the subject from the resonance frequency calculated based on the material, and based on the mechanical force such as tension, the resonance frequency of longitudinal vibration is used to reduce the amount of thinning of the subject. A method for diagnosing deterioration of an article, which comprises calculating the degree of deterioration. 2. A vibrating section for exciting mechanical vibrations in a rod-shaped subject whose both ends or fixed portions are fixed and tension is applied, and lateral and longitudinal vibrations of the vibrating portion attached to the subject are electrically signaled. And the analog vibration waveform obtained by this sensor part are converted into digital signals, and these digital signals are subjected to fast Fourier transform processing to calculate the lowest resonance frequencies of lateral vibration and longitudinal vibration, and A calculation unit that determines the mechanical strength such as tension applied to the subject and the degree of deterioration such as the amount of thinning of the subject from the resonance frequency calculated based on the dimension, shape, and material of the subject being measured. A deterioration diagnosis device for articles, comprising: a display unit for displaying a diagnosis result.