JPH08304236A - Method and device for forecasting limit of life of object to be measured - Google Patents

Abstract

PURPOSE: To forecast the limit of the life of an object to be measured including a safety factor by spectrum-analyzing vibrations obtained by vibrating the object and finding a frequency difference, and then, referring to a previously found relation between the frequency difference and degree of deterioration by using the found frequency difference. CONSTITUTION: An object 41 to be measured provided with a first part which is a main used part and second part which is united with the first part in one body or joined to the first part is vibrated 42 at the second part. The frequency difference Δf between the nth-order spectrum and (n+1)th-order spectrum (n>=2) of the longitudinal waves of the standing wave vibrations generated in the object 41 change in accordance with the degree of deterioration of the object 41. When the frequency difference Δf is found, the limit of the life of the object 41 can be forecast by utilizing this relation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects the degree of deterioration of a part of a device under test, which is mainly used, and predicts the life of the device under test. The present invention relates to a life prediction method and an apparatus thereof.

[0002]

2. Description of the Related Art Defects such as cracks, cavities, and dents in parts of machines and products can cause serious danger due to breakage of the parts. Therefore, it is desirable to detect and remove parts having defects such as cracks, cavities, and dents before assembling and manufacturing machines and products.

Non-destructive inspection methods have been conventionally known for detecting defects of this kind. For example, a method by reflection of ultrasonic waves or a method by sound when a crack is generated by AE (acoustic emission) is known. , CCD camera observation method, X-ray photography method, and color check method.

[0004]

By the way, the above-described method for detecting a defect or the like is to detect whether or not a defect or the like has occurred in an object to be measured, and how safe the object to be measured is. It is unsuitable for knowing the life of a measured object that can be used for.

However, the parts are gradually deteriorated by use. For example, in the case of turbine blades (wings) used in a turbine engine used in an aircraft, their life is predicted and defective. It is important to prevent the occurrence of serious accidents by replacing them at an appropriate time before the occurrence of such problems.

In this case, a blade portion (blade portion) of the turbine blade is mainly deteriorated by use, and a pedestal portion such as a so-called platform portion to which the blade portion is connected is formed. It is expected that the deterioration will progress faster than that. Therefore, it is important to detect the degree of deterioration of the blade portion.

In view of the above points, the present invention has a first portion which is a main use portion and a second portion which is integrally connected to the first portion or is joined to the first portion.
It is an object of the present invention to provide a method and an apparatus capable of detecting the degree of deterioration of the first portion of an object to be measured including the portion and predicting its life.

[0008]

[Means for Solving the Problems] When the object to be measured is vibrated,
In general, a longitudinal wave (longitudinal vibration = bending vibration mode), a transverse wave, and a torsional wave (torsional vibration mode) form a pair on the object to be measured. For ease of explanation, consider a cylindrical body 1 having a diameter d and a length h as shown in FIG. 2A, for example. Now, assuming that a minute unit cylinder 2 having a length Δh is assumed for this cylindrical object 1, when this cylindrical object 1 is vibrated, as shown in FIGS. 2B, 2C, and 2D, the unit cylinder is vibrated according to the vibration position. 2 produces three types of varying oscillating waves.

That is, FIG. 2B illustrates a longitudinal wave, which is a wave that oscillates so that the unit cylinder 2 changes only in the longitudinal direction. The frequency f of this longitudinal wave is
It depends on the length h between the opposed circular end faces of the cylindrical object 1. In other words, if the speed of the sound wave is c, then f = c · n / 2h (1) Note that n indicates the order of harmonics.

Further, FIG. 2C illustrates a transverse wave, which has a diameter d without changing the length Δh of the unit cylinder 2.
It is a wave that oscillates so that it changes only in the direction. further,
FIG. 2D illustrates a torsional wave, which is a wave that, when propagating from one circular end face to the other circular end face, causes a torsional rotation about a center line of a cylinder, and a transverse wave. Occurs with.

Each vibration wave described above has a frequency determined according to the shape and size of the object to be measured. For example, except for the position of the center of gravity, the measured object is excited at a position where longitudinal vibration and torsional vibration (including transverse waves in this specification) occur, and the steady vibration wave generated on the measured object at that time is excited. When picked up in a non-contact manner and spectrally analyzing it, some spectral peaks stand in order from a low frequency.

As a result of the study by the inventor of the present invention, focusing on the difference Δf between the frequency of the nth-order spectrum of the longitudinal wave and the frequency of the (n + 1) th-order spectrum, this difference Δf indicates that the measured object is deteriorated. It is one-to-one correspondence, and it has been found that the difference Δf exponentially increases as the deterioration progresses.

This can be considered as follows. That is, due to the vibration, the measured object produces a standing wave vibration that is peculiar to it, and due to the vibration, as described above,
It is possible to observe the primary, secondary, ... Spectra standing at the natural frequency position determined by the shape and size. Then, unless the degree of deterioration of the object to be measured does not change, the frequency position at which each spectrum stands does not change.

However, in general, as the deterioration of the object to be measured progresses, the particles constituting the substance become coarse and harden. Then, this deterioration progresses by a predetermined amount or more, the degree of coarsening exceeds a threshold value, and in the case of a casting or the like, if segregation of graphite progresses, cracks (losses) occur.

When the particles are coarsened or hardened,
The speed of the sound wave propagating through the substance becomes faster, and the higher the vibration, the higher the frequency. Therefore, it is considered that the difference Δf between the frequency at which the nth-order spectrum stands and the frequency at which the (n + 1) th-order spectrum stands becomes larger as the deterioration progresses. Therefore, it is considered that by monitoring the frequency difference Δf, it is possible to detect the deterioration of the object to be measured and predict the life.

By the way, it is preferable that the life of the object to be measured is determined mainly by the deterioration of the portion used. However, in general, the object to be measured has a structure in which a portion mainly used for use is connected to other portions such as a pedestal and a base. Therefore, it is desirable to remove the influence of small cracks or holes generated in the pedestal or the base so as to detect the deterioration of the main use portion.

According to the research conducted by the inventor of the present invention, it has been found that longitudinal waves are less susceptible to defects such as cracks than torsional vibration waves. It was also found that higher-order longitudinal waves are less susceptible to defects.

Therefore, the DUT is vibrated in the main use portion and the spectrum analysis as described above is performed, and the frequency difference Δf between the high-order n-th order spectrum of the longitudinal wave and the (n + 1) -th order spectrum. Can be detected. However, in general, when an object to be measured is vibrated and its vibration wave is picked up and spectrum-analyzed, the energy of the low-order spectrum is large and it becomes difficult to detect the high-order spectrum.

As a result of further research, the inventor of the present invention excites not the main use part but the pedestal or the base to which the main use part is connected, thereby increasing the vibration wave of the main use part. It was discovered that the following spectra can be obtained stably.

The method of predicting the life of an object to be measured according to the present invention is based on the above-mentioned research results. The first part, which is the main part to be used, is integrated with the first part or is joined to the first part. A method of predicting the life of an object to be measured by detecting the degree of deterioration of the object to be measured, the method comprising: The object to be measured is vibrated, the stationary vibration wave generated in the object to be measured is subjected to spectrum analysis, and the nth order of the longitudinal wave (n is an integer of 2 or more) in the spectrum group of the stationary vibration wave
Of the spectrum of (1) and the frequency of the spectrum of the (n + 1) th order are detected, the degree of deterioration of the first portion of the measured object is detected to predict the life of the measured object. It is characterized by

[0021]

In the present invention having the above-mentioned structure, the vibration obtained by vibrating the object to be measured is spectrally analyzed to obtain the frequency difference Δ
Find f. By referring to the relationship between the frequency difference Δf and the degree of deterioration obtained in advance from the obtained frequency difference Δf, it is possible to estimate the safety factor and predict how much life will be left.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the method and apparatus for predicting the life of an object to be measured according to the present invention will be described below with reference to the drawings.
The embodiment described below is an example in which the DUT is a turbine blade of an aircraft engine.

The inventor of the present invention studied the deterioration of turbine blades made of a material containing titanium as a main component. First, the structure of the turbine blade targeted in this example will be described.

That is, the turbine blade of this example is
For example, it has a shape and structure as shown in FIG.
3A is a perspective view of a turbine blade, and FIG. 3B is a cross-sectional view of the blade portion (X-X cross-sectional view of FIG. 3A).
Is. As shown in FIG. 3, the turbine blade includes a blade (blade) portion 11, a platform portion 12 to which the blade portion 11 is joined, and a platform portion 1.
It is composed of a leg portion 13 which is continuous with 2.

In this case, the turbine blade is not solid inside, and the leg portion 13 is shown as indicated by an arrow in FIG. 3A.
A hollow portion is provided as a flow passage for sending air into the blade portion 11 from the side and discharging the air from the blade portion 11. As shown in the cross-sectional view of FIG. 3B, the blade portion 11 has a streamlined shape as a whole, but since it has a hollow portion communicating with the hollow portion of the leg portion 13 inside, it has a streamlined curved surface. The two plate portions 14 and 15 have a structure in which they are adhered in a state of facing each other with a predetermined gap. The plate portion 14 and the plate portion 15 of the blade portion 11 are connected by several bridging portions 16 so as to form a predetermined air flow passage.

By the way, the blade portion 11 is formed when the plate portion 14 and the plate portion 15 are formed separately by joining them at the bridging portion 16, and when the blade portion 11 is formed as a whole. In some cases, it is generally generated separately from the platform section 12. And
The blade portion 11 is a surface 12a of the platform portion 12.
On the other hand, the turbine blade is configured by joining the surface 12a and the plate portion 14 and the plate portion 15 in the plate surface direction orthogonal to each other at the joint portion 17.

In this turbine blade, the blade portion 11 is mainly used and deteriorates. Therefore, it is important to know the deterioration of the blade portion 11.
In this embodiment, in order to know the deterioration of the blade portion 11 of the turbine blade, the turbine blade is vibrated and its vibration wave is spectrally analyzed.
The vibration position is not the blade part 11, but the predetermined position of the platform part 12 or the leg part 13 where a longitudinal wave is always generated.

FIG. 4 is a diagram for explaining a vibration position with respect to the turbine blade and an arrangement example of a vibration sensor such as a microphone for picking up a vibration wave of the turbine blade when vibration is performed at the vibration position. . In FIG. 4, reference numeral 18 denotes a cushion material, and the turbine blade is placed on the cushion material 18 when being vibrated.

In FIG. 4, position Pa is an example of a vibration position when vibration is applied to the platform portion 12.
That is, as shown in the drawing, this position Pa is present on one of the lip portions 12R, 12L which projects laterally in a direction intersecting the thickness direction of the blade portion 11 of the platform portion 12. In the case of this example, the lip portion 12
When the length of the R blade portion 11 in the thickness direction is L1, the vibration position Pa is determined by the blade portion 11 of the lip portion 12R.
Is at a distance of L1 / 3 from the end of the convex curved surface side. Then, this position Pa is, as shown by an arrow in the figure,
The lip portion 12R is vibrated by applying an impact, for example, from the side in which the lip portion 12R extends.

On the other hand, the vibration sensor 19 is provided on the side of the lip portion 12L opposite to the lip portion 12R.
In the case of this example, the vibration sensor 19 is provided so as to face the end surface 13E of the leg portion 13 on the lip portion 12L side. In this case, the center position Po of the vibration sensor 19 is arranged so as to match the center position of the thickness L2 of the end surface 13E of the leg portion 13. Further, the center position P of the vibration sensor 19
o is, for example, about 15 mm below the lower end of the lip portion 12L.

In FIG. 4, the position Pb is the leg 1
3 is an example of a vibration position when vibration is applied to No. 3. That is, as shown in FIG. 4A, this position Pb is
End face 1 of the platform portion 12 on the lip portion 12R side
The position is within 3F and below the lip portion 12R that substantially coincides with the center position Po of the vibration sensor 19. Then, as shown in FIG. 4B, in this example, when the length of the blade portion 11 of the leg portion 13 in the thickness direction is L2, the vibration position P
b is a distance of L2 / 3 from the convex curved end of the blade portion 11 of the leg portion 13. Then, the position Pb is vibrated by applying a shock, for example, from the projecting direction side of the lip portion 12R as indicated by an arrow in the figure. Even in the case of this vibration position Pb, the position of the vibration sensor 19 may be as shown in FIG.

The turbine blade is vibrated at these positions Pa and Pb, the vibration wave is picked up by the vibration sensor 19 and the spectrum is analyzed.
The following is a comparison with the case where the part 1 is excited.

That is, the inventor conducted the vibration analysis at the position Pc of the blade portion 11 shown in FIG. 4 and the spectrum analysis result and the spectrum analysis result of the vibration results at the positions Pa and Pb. Compared. Here, the position Pc
Is a position excluding the position of the center of gravity of the blade portion 11 and excluding the center position of the second moment of area of the blade portion 11, and is a position where a bending vibration mode (longitudinal wave) and a torsional vibration mode occur.

FIG. 5 is a spectrum distribution diagram when vibration is applied at the position Pc. As shown in FIG. 5, the peaks 21, 22, 23, 2 of the spectrum are located at frequency positions corresponding to the size of the blade portion 11 and the components of the respective vibration modes.
4, 25, 26, 27 are obtained. The frequencies at which the peaks 21 to 27 of these spectra stand are set in order from the lowest to f
1, f2, f3, f4, f5, f6, and f7, the spectra of frequencies f1, f2, and f3 are respectively the first bending vibration mode, the first torsional vibration mode, and the first both vibration modes. It is a group of spectra due to
The spectra of frequencies f4, f5, f6, and f7 are a group of spectra obtained by mixing the secondary bending vibration mode, the secondary torsional vibration mode, and the secondary both vibration modes, respectively.

Here, the spectrum 2 of frequencies f4 to f7
In the group of 4 to 27, the blade portion 11 is the plate portion 14 and the plate portion 15.
In general, this is a component that occurs when the plate portion 14 and the plate portion 15 have different lateral dimensions (the curved lengths of the curved surfaces of the plate portions 14 and 15) of the blade portion 11 in FIG.
The blade portion 11 does not consist of two plate portions, but 1
In the case of one plate, the spectra 21 to 23
, But the groups of spectra 24-27 do not.

The spectrum of the frequency f3 is a component when the vibration of one of the plate portion 14 and the plate portion 15 changes to the longitudinal vibration of the other plate portion, and the frequency f3
6 and the frequency f7 are considered to be components when the vibration of the other plate portion of the plate portion 14 or the plate portion 15 transits to the vibration of the higher harmonic wave of the one plate portion. Frequency f6 and frequency f7
The reason why the vibration frequency is divided into two is that when the vibration is of a second or higher order, the vibration frequency starts to differ based on the difference in thickness between the plate portion 14 and the plate portion 15. Therefore, if the plate portion 14 and the plate portion 15 have different thicknesses (generally, this is the case), for higher-order vibrations, the peaks of the four spectra will be grouped into spectra corresponding to one plate portion. Can be thought of as

The spectrum of the frequency f8 that does not appear in FIG. 5 is the secondary component of the longitudinal wave generated when one plate is not divided into the plate portion 14 and the plate portion 15. It becomes a longitudinal wave as a wave. However, as can be inferred from FIG. 5, since the energy of the first-order spectrum f1 is large, it is difficult to detect the higher-order spectrum since it is considerably attenuated.
Illustrations of higher-order spectra at frequencies f8 and above in this case are omitted.

On the other hand, the position Pa of the platform portion 12 other than the blade portion 11 or the position P of the leg portion 13
When vibrating at b, it is possible to relatively stably obtain a high spectral component of the frequency f8 or higher. FIG. 6 shows an example of the spectrum distribution at the frequency f8 or higher at this time. The frequency f1 at the vibration position Pa or Pb
Illustrations of the spectral distributions of to f7 are omitted.

In FIG. 6, nine spectrum peaks 31 to 39 having frequencies f8 to f16 are obtained. Among them, the spectrum 31 of the frequency f8 and the spectrum 39 of the frequency f16 are the plate portion 14 and the plate. These are the secondary and tertiary components of the longitudinal wave generated when a single plate is not divided into the part 15. Then, from the spectrum 31 of the frequency f8 to the spectrum 34 of the frequency f11, the plate portion 14 and the plate portion 1
5 is a spectrum group by one side, and the spectrum 35 of the frequency f12 to the spectrum 38 of the frequency f15 is a spectrum group by the other side of the plate portion 14 and the plate portion 15.

In this specification, for convenience of explanation, the frequency f
8 spectrum is the secondary spectrum of the longitudinal wave, frequency f1
The spectrum of No. 6 will be referred to as a longitudinal wave third-order spectrum hereinafter.

The inventor of the present invention, as described above,
The frequency f8 at which the secondary spectrum of the longitudinal wave stands and the longitudinal wave of 3
Regarding the difference Δf with the frequency f16 at which the next spectrum stands, as a result of measuring the relationship between the number of times the turbine blade is used, for example, the so-called number of flights of the aircraft, or the operating time, for example, the flight time, a relationship curve as shown in FIG. 7 is obtained. It was The function of this curve is an exponential function represented by Δf = exp (am) (2). Here, the constant a is a value according to the size of the turbine blade, and can be easily determined by actually measuring the turbine blade. m is the number of times of use or the time of use, which is the number of flights in this example. Hereinafter, this curve will be referred to as a life prediction curve.

That is, from the life prediction curve of FIG.
It has been found that the frequency difference Δf exponentially increases as the number of times the turbine blade is used increases and deteriorates. Then, on this exponential function, the frequency difference Δ
It has been found that when f exceeds a predetermined threshold value th, defects such as cracks occur in the turbine blade.

In this case, the threshold value is the tangent of the inclination angle θ (see FIG. 7) of the life prediction curve, that is, tan θ.
The frequency difference Δf when the value of tan θ exceeds the set value is the threshold value th.

From the above, after the turbine blade has been used, it is vibrated by a vibrating method such as an impact method, the vibration is picked up, and the spectrum is analyzed to obtain the frequency difference Δf. By checking the position of Δf on the above life prediction curve, it is possible to use it up to the threshold value th, how many times or for hours, even if the actual number of times of use (the number of flights) is unknown. It is possible to predict the life of the turbine blade.

Next, an embodiment of the life predicting apparatus to which the above-mentioned method is applied will be described with reference to the drawings. FIG.
Shows an embodiment of the device of this example, 41 is the object to be measured, in this example, a turbine blade. Although not shown in FIG. 1, the DUT 41 is placed on the cushion material as shown in the diagram for explaining the vibration position in FIG. Four
Reference numeral 2 is a vibration device, and 43 is a control device having, for example, a microcomputer.

The control device 43 drives the vibration device 42,
The turbine blade that is the object 41 to be measured is vibrated at the vibration position Pa or position Pb shown in FIG.
In this example, the vibrating device 42 impacts the DUT 41 with, for example, a pendulum-like impacting object such as a weight. The drive mechanism of the weight is configured by a cam mechanism or the like so that the weight is immediately separated from the object to be measured after the impact. It should be noted that the vibration may be performed a plurality of times instead of once, and the vibration may be performed at both the positions P1 and P2 instead of at the same position.

The object to be measured 4 vibrated as described above
The vibration of No. 1 is contactlessly detected by the vibration sensor 45 of the output vibration receiving device 44, converted into an electric signal, and subjected to predetermined signal processing by the signal conditioner 46. The sensor 45 is installed at the position of the sensor 19 shown in FIG. Any sensor can be used as the sensor 45 as long as it can detect vibration, and a displacement meter or the like can also be used. However, in order to prevent noise and vibration from the surroundings to be picked up as much as possible, it is preferable to have a sharp directivity in the direction of the DUT 41.

In the signal conditioner 46, the electric signal is amplified, and unnecessary high and low frequency components are removed (trend is removed).

The electric signal from the output vibration receiver 44 is
It is supplied to the arithmetic processing / determination device 50. This calculation process
The determination device 50 has, for example, a microcomputer,
The calculation processing and the determination operation described later are performed by software, and this processing is shown in a functional block diagram of FIG.
become that way.

By the way, the vibrations of concern here are the natural vibrations of the shape of the object to be measured. However, when the measured object is forcibly vibrated, the forced vibration and the like are mixed with the natural vibration (longitudinal vibration as a standing wave).
Therefore, it is desirable to remove as much as possible other than these natural vibrations. In this example, this requirement is satisfied as follows.

With respect to the forced vibration, the influence is removed by setting the measurement start point of the signal from the sensor 45 to the time point when a predetermined time has elapsed after the vibration. That is, when the object 41 to be measured is vibrated by the impulse impact method, the measurement is started from a point in time just after a short time has passed immediately after vibrating by giving an impact or the like.

In this case, the time from the time of impact to the start of measurement can be determined as follows. That is, the velocity c of the sound wave propagating through the DUT 41 differs depending on the Young's modulus E (elastic coefficient) and the density ρ of the object, and has a relationship of c ² = E / ρ. Then, for example, in the case of the impulse impact method of this example, the time series waveform of the vibration picked up immediately after the impact is as shown in FIG. 8A.

As can be seen from the waveform of FIG. 8A, since the vibration after the vibration is the same as that of the seismic wave, the longitudinal wave and the slow wave having a high velocity are mixed as described above, and the vibration However, the forced vibration remains, and the natural vibration waveform peculiar to the shape of the DUT 41 is not formed. It is considered that the natural vibration wave peculiar to this shape is observed shortly before the stop, for example, in the “small motion” of the top. For this reason, we set a rectangular wave window W1 as shown in Fig. 8B,
In this example, an oscillating wave is extracted by this window W1.

That is, the electric signal input to the arithmetic processing / determination device 50 is supplied to the gate means 51. Then, by the window signal W1 from the window W1 forming means 52, the object 41 to be measured after the vibration, that is, the impact.
The natural vibration component of the shape of the DUT 41 is extracted from the vibration. The window forming means 52 receives the information on the start of vibration from the control device 43, and immediately after the impact, the window W
Set the time until the start-up of 1 and the window width. In the example of FIG. 8, the window W1 is started up at a time point 20 msec after the impact and a window width of 200 msec is set.

As described above, the natural vibration component of the shape of the DUT 41 is extracted by the window W1. Then, the natural vibration portion is converted into digital data by the A / D conversion means 53 and written in the memory means 54. Then, this digital data is read from the memory means 54, supplied to the spectrum analysis means 55, and spectrum-analyzed. Then, in the spectrum analysis means 55,
The peaks of the spectrum are detected in order from the lowest frequency,
Second-order spectrum of longitudinal wave 3 as 8th and 16th
The spectrum 39 of the first and third orders is detected, and their frequencies f8 and f16 are detected.

Δf in the latter stage of the spectrum analysis means 55
The calculation means 56 receives the frequency f8 and the frequency f16 from the spectrum analysis result, and determines the frequency difference Δf between them.
= F16-f8 is calculated. Then, the calculated value of the frequency difference Δf is sent to the life prediction judgment means 57.

A life prediction curve memory 58 is connected to the life prediction determination means 57. The life prediction curve memory 58 stores a constant a relating to the size of the object to be measured.
Using as a parameter, information on a plurality of life prediction curves is stored. This information also includes the life threshold value for the safety factor.

Then, the life prediction judging means 57 reads information on the life prediction curve of the constant a from the memory 58 based on the constant a given in advance as a parameter, and stores it in, for example, a built-in buffer memory.

Then, the frequency difference Δf calculated by the calculating means 56 is collated with the life prediction curve stored in the buffer memory, and the life is predicted by referring to the threshold value. Then, the prediction result, for example, the information on the number of times of possible use and the time thereafter is sent to the control device 53.

The controller 53 outputs the prediction result to the output means 60.
Send to The output unit 60 displays information about the number of times the prediction result can be used and the usable time on a display, or prints out the information on recording paper. Alternatively, voice notification is given.

In the above example, the life of the object to be measured is predicted based on the frequency difference between the second-order and third-order longitudinal wave spectra. However, when higher-order spectra can be stably obtained. May of course use the frequency difference of higher order spectra.

[0062]

As described above, according to the present invention, the first portion, which is the main usage portion, and the first portion, which is integrally connected to the first portion or joined to the first portion, are joined together. An object to be measured having two parts is vibrated by the second part, and a second or higher order n-th spectrum of a longitudinal wave spectrum of a standing wave vibration generated in the object to be measured and (n +
1) By utilizing the fact that the frequency difference Δf from the next spectrum changes according to the degree of deterioration of the measured object, the life of the measured object can be predicted by obtaining the frequency difference Δf. .

In the present invention, it is possible to detect the spectrum of a higher-order longitudinal wave by vibrating the object to be measured with the second part, not the first part, which is the part used as means for the object to be measured. It's easy. Further, since the longitudinal wave is less likely to be affected by scratches and the higher the order is, the more difficult it is to be affected by scratches. Therefore, according to the present invention, it is possible to stably use the frequency difference of the higher-order spectrum. It is possible to predict the life of the measured object.

In the case of the present invention, the life of the sensor can be predicted by vibrating the object to be measured and picking up the resulting standing wave vibration of the object to be measured without contact. As in the case of contacting the object to be measured, the object to be measured is not scratched, and the object to be measured is not deteriorated for life prediction.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of an apparatus for predicting the life of an object to be measured according to the present invention.

FIG. 2 is a diagram for explaining standing wave vibration occurring in an object to be measured.

FIG. 3 is a diagram for explaining an example of the structure of a turbine blade that is an example of an object to be measured.

FIG. 4 is a diagram for explaining an example of a vibration position of an object to be measured in the method and apparatus according to the present invention.

FIG. 5 is a diagram for explaining a spectral distribution of a stationary vibration wave obtained when a main use portion of the measured object is vibrated.

FIG. 6 is a diagram for explaining a higher-order spectrum distribution of a stationary vibration wave obtained when a measured object is excited by the method according to the present invention.

FIG. 7 is a diagram showing an example of a life prediction curve used in the life prediction apparatus according to the present invention.

FIG. 8 is a diagram for explaining a part of the example in FIG. 1.

[Explanation of symbols]

 41 Object to be Measured 42 Vibrating Device 43 Control Device 44 Output Vibration Receiving Device 55 Spectral Analysis Means 56 Δf Calculating Means 57 Life Prediction Means 58 Life Prediction Curve Memory

Claims (3)

[Claims] 1. A first part, which is a main use part, and an integral part of the first part, or a joint with the first part,
A method of predicting the life of an object to be measured by detecting the degree of deterioration of the object to be measured, which comprises a second part connected to the object to be measured. An object is vibrated, a stationary vibration wave generated in the measured object is spectrum-analyzed, and a frequency of an nth-order (n is an integer of 2 or more) spectrum of a longitudinal wave in a spectrum group of the stationary vibration wave,
(N + 1) The degree of deterioration of the first portion of the measured object is detected by the change in the difference Δf from the frequency at which the next spectrum stands, and the lifetime of the measured object is predicted. Life prediction method. 2. A first portion, which is a main use portion, and an integral part of the first portion, or by being joined to the first portion,
A vibrating means for vibrating the object to be measured, which includes the second part connected to the second part, and a pick-up means for picking up the vibration of the object to be measured and converting it into an electric signal; Receiving a signal from the means, spectrum-analyzing the stationary vibration wave of the object to be measured, and in the spectrum group of the stationary vibration wave, a frequency at which an nth-order (n is an integer of 2 or more) spectrum of a longitudinal wave stands. A means for obtaining a difference Δf from the frequency at which the (n + 1) th-order spectrum stands, and a degree of deterioration of the first portion of the measured object is detected from a relationship curve between the difference Δf and the usage state of the measured object. And a life predicting device for predicting the life, and a life predicting device for an object to be measured, which comprises an output means for outputting the result of the prediction. 3. The life predicting apparatus for an object to be measured according to claim 2, wherein the predicting means and the difference Δf from the usage status of the object to be measured.
It has a storage means for storing information indicating a relationship curve with, and the obtained difference Δf is referred to by referring to the information in the storage means.
From the above, a life predicting apparatus for a measured object, which predicts the life of the measured object.