JP2001174380A - Method and apparatus for predicting remaining life of structural material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for predicting a remaining life of a structural member for accurately predicting the remaining life of the structural member with unknown history and condition of use. SOLUTION: The present invention comprises, when predicting a remaining life of a structural member, damage measurement preparation means 1 for polishing and cleaning a damaged part, damage measurement means 2 for measuring a crack in the damaged part, damage parameter evaluation means 3 for calculating, arranging and dividing an information on the measured crack into a crack length and a crack length density, use condition estimation means 4 for estimating use conditions of operation of the past by calculating a strain area and a temperature distribution and a stress to a depth direction of the structural member from the crack, threshold value setting means 5 for determining a threshold value to the direction of a depth from a stress expansion coefficient and a fracture toughness, use history estimating means 6 for calculating a number of repeated strain of the past, and remaining life estimating means 7 for estimating the remaining life of a structural member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for estimating the remaining life of a structural member, which predicts in advance the usable life of a structural member and the intervals between inspection and repair, and an apparatus for estimating the remaining life of a structural member used in this method.

[0002]

2. Description of the Related Art For example, in a power generation plant, from the viewpoint of effective use of energy and protection of the global environment, improvement of the plant thermal efficiency is required. The temperature and capacity of equipment used in prime mover equipment are rapidly increasing. For this reason, the use conditions of the structural member applied to the prime mover equipment have become more severe than ever.

Further, even in a power plant that has been used for many years, the number of repetitions of start / stop is increasing every day, and the number of repetitions of the impact strain applied to the structural members is also increased, resulting in a severe situation. Is exposed to various situations.

Particularly, in a high-temperature member used for a combustor liner, a turbine blade, a turbine rotor, or the like which is directly exposed to a high-temperature fluid, the temperature and the temperature of the fluid during start-up / stop or steady operation are reduced.
High thermal stress is generated due to pressure fluctuation, and cracks due to thermal fatigue due to the high thermal stress and damage due to creep due to centrifugal force, internal pressure stress and the like are increasing.

[0005] Under these circumstances, in recent power generation plants, the progress of damage due to thermal fatigue and creep is predicted in advance and accurately, and appropriate maintenance management measures are taken before structural members are damaged or destroyed. It is necessary to take measures, and many research results corresponding to this measure have been published.

[0006] However, the published literature merely discloses a solution from a one-sided perspective, and many problems still remain for practical application and are currently being explored. .

[0007]

For example, Japanese Patent Publication No. 6-76960 and "Measurement of High Temperature Fatigue Damage of Mod.9Cr-1Mo Steel by Microcrack Method" (Nonaka et al.) No. 96-1, The 7th Japan Society of Mechanical Engineers
There is a method for evaluating the remaining life of structural members, such as the 3rd Annual General Meeting Lecture Papers II, pp. 151-152, 1996).

[0008] The former is, as shown in FIG.
6. Using a measuring device 50 incorporating the arithmetic unit 47, the judging device 48, and the display device 49, and a master curve showing the relationship between the crack length and the life ratio shown in FIG. 27, the repetition rate ratio is Factor of 2 ( The life is predicted from the length of the crack within the range of (half the evaluation graph).

The repetition rate ratio is defined as the ratio between the number of repetitions of the load until the occurrence of the limit crack and the actual number of repetitions of the load applied to the structural member. When the current number of repetitions is known, the limit crack is generated. It is possible to estimate the number of repetitions before performing.

However, this remaining life prediction means does not include factors such as the number of repetitions of load fluctuations and the number of repetitions of drain flashes, and in practice, its application range is limited, and the accuracy of life prediction is low.

[0011] On the other hand, the latter, as shown in FIG. 28, is for estimating the life from the maximum crack length, but the strain range is univocal.
There are inconveniences and defects that can no longer predict the remaining life.

Further, in both the former and the latter, when the use history and use conditions of the structural member are unknown, the prediction of the remaining life evaluation of the actual machine is inaccurate.

The present invention has been made in light of such background art, and estimates the use conditions and usage history up to now from the actually measured values of cracks, and accurately estimates the remaining life from the estimated use conditions and usage history. It is an object of the present invention to provide a method for estimating a remaining life of a structural member and a device for estimating a remaining life of a structural member used in the method.

[0014]

According to a first aspect of the present invention, there is provided a method for estimating a remaining life of a structural member, comprising the steps of:
After cleaning with the cleaning liquid, the cracks in the damaged area were measured, and the measured crack information was imaged and compiled into a database.Based on the crack information in the database, the maximum crack length and crack length density were calculated and arranged. Using this damage parameter, calculate the strain range, temperature distribution and stress distribution in the depth direction of the specimen using this damage parameter, estimate the operating conditions in the past operation, and calculate the fracture toughness distribution from the above temperature distribution. Further, the stress intensity factor distribution is calculated from the stress distribution, and the critical crack depth is set by comparing the calculated fracture toughness distribution and the stress intensity factor distribution, while the maximum crack length, the crack length density, and the like. After calculating the number of strain cycles and estimating the usage history, calculate the maximum crack length and the depth of the subject to calculate the number of strain cycles until the critical burst depth is reached. The is set as the remaining life of the structural member.

According to a second aspect of the present invention, there is provided a method for estimating a remaining life of a structural member according to a second aspect of the present invention. And performs a binarization process.

According to a third aspect of the present invention, there is provided a method for estimating a remaining life of a structural member according to a third aspect of the present invention.
The strain range is obtained from a maximum crack length-crack length density diagram prepared in advance based on the maximum crack length and the strain repetition ratio and the crack length density and the strain repetition ratio.

According to a fourth aspect of the present invention, there is provided a method for estimating a remaining life of a structural member according to a fourth aspect of the present invention. The intersection with the coefficient distribution is set as the critical crack depth.

According to a fifth aspect of the present invention, there is provided an apparatus for estimating a remaining life of a structural member for measuring a large number of cracks distributed in a damaged portion of the structural member. Damage measurement preparation means for performing surface treatment and cleaning of the damage, damage measurement means for measuring the length of each of a large number of cracks distributed in a damaged portion, and at least two or more of the damage measurement amounts obtained from the damage measurement means. Damage parameter evaluation means for calculating a damage parameter, and past use conditions obtained by applying at least two or more damage parameters to a master curve obtained by an experiment for estimating use conditions from at least two or more damage parameters. Operating condition estimating means for estimating the damage condition; and limiting value setting means for determining a limit value of the damage parameter from the estimated operating condition and the fracture limit value of the structural member. Use history estimating means for determining a use history by applying at least two or more damage parameters to a master curve obtained by an experiment for estimating a use history from two or more damage parameters, and a crack length of a structural member And a remaining life estimating means for setting, as a remaining life, the number of strain repetitions until reaching the limit crack depth calculated based on the depth and the depth.

According to a sixth aspect of the present invention, there is provided an apparatus for estimating a remaining life of a structural member, wherein the damage measurement preparing means buffs a damaged portion of the subject. It is provided with a polishing device and a cleaning device for cleaning the damaged portion with methyl acetate after polishing.

Further, in order to achieve the above object, the apparatus for estimating the remaining life of a structural member according to the present invention is characterized in that the damage measuring means includes a replica device, a CCD camera, a laser microscope, an electric microscope. The apparatus includes an image processing device that selects any one of a resistance measuring device, an electromagnetic measuring device, and an ultrasonic device and that images crack information measured from a subject.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for estimating the remaining life of a structural member and an apparatus for estimating the remaining life of a structural member used in the method according to the present invention will be described below with reference to the drawings and the reference numerals attached to the drawings.

FIG. 1 is a block diagram used for explaining an embodiment of a method for estimating a remaining life of a structural member and an apparatus for estimating a remaining life of a structural member used in the method according to the present invention.

This embodiment comprises damage measurement preparation means 1, damage measurement means 2, damage parameter evaluation means 3, use condition estimation means 4, limit value setting means 5, use history estimation means 6, and remaining life estimation means 7. It is composed.

The damage measurement preparing means 1 is divided into a polishing step of polishing a damaged portion such as a crack generated in a structural member, and a cleaning step of cleaning the damaged portion after polishing.

As shown in FIG. 2, the polishing step is performed by sliding the polishing apparatus 8 against the damaged portion 10 of the subject 9. As shown in FIG. 3, the polishing device 8 includes a polishing head 12 that accommodates a grinder 11 and a grinder driving unit 13. The grinder driving unit 13 drives the grinder 11 to rotate and slide on the subject 9. The surface of the subject 9 is buffed and polished.

The cleaning step is performed using a cleaning device 14, as shown in FIG. This cleaning device 14
A cleaning liquid supply passage 17 provided with a nozzle 16 at the tip and housed in the cleaning header 15, a cleaning liquid recovery passage 18 for collecting the cleaning liquid, and after cleaning the subject 9, air is supplied to the subject 9 for cleaning.
And a dry air supply passage 19 for drying the surface of the test object 9 after polishing.

On the other hand, as shown in FIG. 6, the damage measuring means 2 includes a damage detecting section 20 for detecting a damaged section 10 of the subject 9.
And a damage measurement drive unit 21 that drives the damage detection unit 20 forward and backward with respect to the damaged part 10, an image processing device 22 that images crack information of the damaged part 10, and a creation based on the crack information of the damaged part 10. The crack length distribution obtained is arranged (specifically, the crack length distribution is created by rearranging the cracks in ascending or descending order) to provide a crack length distribution storage unit 25 for storing the crack information. At the time of image formation and storage, it is a statistical database capable of removing noise of information, performing binarization processing, and extracting only specific crack information.

The damage detector 20 may use a replica device 24 as shown in FIG. 5, for example. The replica device 24 is incorporated in a replica sampling head 25 and supplies a methyl acetate supply passage 26 that supplies methyl acetate to the damaged portion 10 of the subject 9, a replica supply roll 28 that supplies transfer paper 27 to the damaged portion 10, Supported by a spring 29,
When transferring the damaged portion 10 of the subject 9, a replica pressure bonding rod 30 is provided which applies a pressing force and moves from the transfer paper 27 after the transfer.

Further, as shown in FIG. 7, for example, the damage detecting section 20 includes a projection section 32 incorporated in an image input head 31.
Projecting light onto the damaged part 10 of the subject 9 from the
A laser microscope 3 that projects a laser beam onto a CD camera 33 or a lens 35 incorporated in a surface unevenness image input head 34 as shown in FIG.
As shown in FIG. 9 and FIG. 9, an electric resistance measuring device 39 including an electric resistance measuring head 37 and an electric resistance measuring terminal 38 for detecting a damaged portion 10 of the subject 9 based on a current change,
As shown in FIG. 10, the electromagnetic measuring device 42 detects the damaged portion 10 of the subject 9 based on the change in the magnetic field 41 with the electromagnetic measuring device 40, and the ultrasonic transmitting and receiving device 4 as shown in FIG.
In 3, an ultrasonic device 45 that detects the damaged portion 10 of the subject 9 based on a change in the ultrasonic wave 44 may be used. These damage detectors 20 are appropriately used depending on the material of the structural member, usage conditions, and the like, are connected to the image processing device 22 shown in FIG. 6, and are configured to collect data on the damaged part 10 of the subject 9. I have.

As shown in FIG. 12, the crack information in the statistical database created by the damage measuring means 2 shown in FIG. 1 has crack lengths 10, 2, 3,. And store them in a computer.

As described above, the damage parameter evaluation means 3 calculates the maximum crack length a
_max and the crack length density (the sum of the crack lengths divided by the observation area) 1 are calculated, the maximum crack length a _max is set as a parameter 1, the crack length density 1 is set as a parameter 2,
Sort and organize each.

The maximum crack length a _{max is set} to the parameter 1,
From the file in which the crack length density 1 is classified into parameters 2 and arranged, the use condition estimating means 4 estimates the plastic strain range Δεp of the structural member and the equivalent elastic stress range Δσ in the thickness direction thereof.

As shown in FIG. 13, the plastic strain range .DELTA..epsilon.p is obtained by plotting a curve conforming to both the parameter 1 (maximum crack length a _max ) and the parameter 2 (crack length density 1) from the respective diagrams. By selecting one, it can be estimated.

The plastic strain range curve group is created as follows. Now, in FIG. 13, the maximum crack length a
The relationship between _max and the strain repetition rate N / Nf and the relationship between the crack length density 1 and the strain repetition rate N / Nf are graphed and arranged. These relationships are expressed by the following equations (1) and (2). Here, N is the strain repetition number, and Nf is the reference strain repetition number based on the damage of the test piece.

[0035]

(Equation 1)

(Equation 2)

(Equation 3)

The relationship between the crack length density 1 and N / Nf can be expressed as a function of the lognormal distribution form having the same dispersion as the microstructure distribution form (lognormal distribution form) of the crystal grain size of the material used. Are obtained from experiments. That is, when the strain repetition rate ratio N / NF is eliminated from the equations (1) and (2), a _max , l and μ _Le
Are obtained, and when this is illustrated, the plastic strain range curve group Δεp = 0.1%, Δεp = 0.5%, Δεp = 1.
0%,.

In the low cycle fatigue test, there is a one-to-one proportional relationship between the total strain range Δεt and the plastic strain range Δεp, so that the total strain range Δεt can be estimated using the graph shown in FIG. it can.

On the other hand, the elasto-plastic stress range Δσ can be estimated from the cyclic stress-strain characteristics of the structural member using the total strain range Δεt as shown in FIG. It is necessary to determine Δσn (nominal stress when the structural member is assumed to be completely elastic).
FIG. 15 shows this method, in which the equivalent elastic stress range Δ
The following relationship exists between σn, elasto-plastic stress range Δσ, and total strain range Δεt.

[0039]

(Equation 4)

The repetitive stress-strain characteristic which is the material characteristic of the structural member represented by the equations (4) and (5)

(Equation 5) Gives a solution determined by the intersection on the graph obtained by simultaneous equations, and Δσn at this time is the equivalent elastic stress range.

Using this equivalent elastic stress range Δσn,
Maximum thermal stress parameter C _H when the thermal shock is caused can be calculated by the following equation.

[0042]

(Equation 6)

FIG. 16 shows the relationship between the equivalent elastic stress range Δσn and the maximum thermal stress parameter CH for each fluid temperature change width by the equation (6). Using FIG. 16, according to the fluid temperature change (temperature difference between working fluid and drain fluid),
From the equivalent elastic stress range Δσn estimated based on the maximum crack length a _max and the crack length density l, the maximum thermal stress parameter C
_H can be estimated.

The maximum thermal stress parameter _{C H} is a 0.5 in the steady state, Biot number is a non-steady state Bi =
bγ / λ, that is, as a function of the plate thickness b, the heat transfer coefficient γ, and the heat conductivity λ, depending on the use conditions. For step change from the temperature T1 to T _0, the maximum thermal stress parameter C _H is related shown in Figure 17 between the Biot number Bi, the thermal conductivity λ and the plate thickness of the structural member from the relationship b based on the obtained graph shown in FIG. 18, it is possible to estimate the γ heat transfer rate from the maximum thermal stress parameter C _H.

If the heat transfer coefficient γ and the temperature change width are known, the temperature distribution and the thermal stress distribution in the thickness direction can be estimated by heat transfer analysis.

Next, in the limit value setting means, the necessary stress distribution in the plate thickness direction is expressed by the following formula as a cubic function of the distance X in the plate thickness direction from the surface, for example, a value defined by heat transfer analysis. .

[0047]

(Equation 7)

From the equation (7), the stress intensity factor K assuming the crack depth a is calculated by the following equation by the influence function method.

[0049]

(Equation 8)

As described above, if the temperature distribution and the thermal stress distribution in the plate thickness direction are obtained by the use condition estimating means 4 and the stress intensity factor K is obtained for the imaginary crack depth a, the limit in the present embodiment is The process proceeds to the value setting means 5.

The limit value setting means 5, as shown in FIG. 19, in the already used condition estimating unit 4, the distribution line of the fracture toughness K _IC was created based on the plate thickness direction temperature distribution curve obtained from the heat transfer analysis And a distribution line of the stress intensity factor K created by using the expression (8) based on the stress distribution line in the plate thickness direction obtained from the expression (7). At this time, the intersection P between the distribution line of the fracture toughness K _{IC and} the distribution line of the stress intensity factor K
(The structural member is broken when K ≧ K _IC ) is set as the critical crack depth C _cr .

When the limit value setting means 5 sets the limit crack depth C _{cr in} this way, the process _proceeds to the use history estimating means 6.

The use history estimating means 6 estimates the number N of strain repetitions in the past operation, and can be obtained from the maximum crack length a _max and the crack length density 1 shown in FIG.

Maximum column length-history distortion repetition shown in FIG.
The graph of the number of return is the maximum crack length a _maxAnd crack length dense
If you select the degree l, the strain repetition repeated up to that point
The number N can be estimated. This graph is
Master curve from which the number of repeated strains N can be estimated
From the equations (1) and (2), the value of the crack length density l
Maximum crack length a for each_max, The relationship between the number of repetitions N
It is the one who asked for a clerk.

Finally, the present embodiment shifts to the remaining life estimating means 7. As shown in FIG. 21, the remaining life estimation means 7 can estimate the remaining life of the structural member from the surface crack length and the depth of the structural member.

In general, the growth law of the surface crack length of a structural member is given by equation (1), but the growth law in the depth direction grows according to the stress intensity factor K of equation (8). However, it is necessary to consider that equation (8) depends on the ratio between the crack length and its depth. Therefore, in the present embodiment, the following alternate calculation is performed.

The crack growth rule in the depth direction of the structural member is experimentally given by the following equation.

[0058]

(Equation 9)

Now, it is assumed that the maximum crack length a _max and the crack depth c have been measured in the crack measurement inspection. This crack growth is obtained by calculating the maximum a _max of the surface crack length by equation (1), calculating the depth c alternately by integration of equation (9), and reaching the limit crack depth C _cr. The number of repeated strains is set as the remaining life Nc of the structural member.

At this time, the maximum crack length a applied in FIG.
The relationship between _max and the repetitive strain ratio N / Nf is shown in FIG.
As shown in (1), there is a case where the relationship is further different depending on the difference in the plastic strain range. Therefore, when setting the actual remaining life, the number of occurrences of the minimum unit length
As i, as shown in FIG. 23, the maximum crack length _{a ma x}
And a strain repetition rate ratio (N−Ni) / (Nf / Ni) is obtained. A one-to-one proportional relationship is obtained. Further, as shown in FIGS. 24 and 25, the total strain range Δεt and the plastic strain range 24 and 25 since Δεp is obtained.
Alternatively, the number of strain repetitions may be obtained from the graph shown in, instead of Expression (1), and set as the remaining life Nc. In particular, this is effective when the value of the strain repetition ratio N / Nf is concentrated at the position indicated by the broken line in FIG.

As described above, the present embodiment measures the maximum crack length a _max and the crack length density 1 even if the past use history and use conditions of the structural member are unknown, and from these damage measurement values. The total strain range εt, the thermal stress parameter C _H ,
Since the stress intensity factor range ΔK and the like were calculated, the use history and use conditions of the structural member were estimated by back calculation from these calculated values, and the remaining life of the structural member was evaluated in consideration of the estimated use history and the like. It is possible to evaluate the remaining life with higher accuracy as compared with the above, and to accurately predict the time of the next periodic inspection, and to prepare for replacement or repair of a structural member.

[0062]

As described above, the method for estimating the remaining life of a structural member and the apparatus for estimating the remaining life of a structural member used in this method according to the present invention are based on the measured values and show the past unknown usage history and usage of the structural member. Since the conditions were estimated and the remaining life of the structural member was evaluated in consideration of the estimated use history, etc., it was possible to accurately evaluate the remaining life, and to operate the structural member in a stable state until the next periodic inspection. Can be.

[Brief description of the drawings]

FIG. 1 is a block diagram used to explain an embodiment of a method for estimating a remaining life of a structural member according to the present invention and a device for estimating a remaining life of a structural member used in the method.

FIG. 2 shows a method for estimating a remaining life of a structural member and a device for estimating a remaining life of a structural member used in the method according to the present invention;
FIG. 3 is a conceptual diagram used for explaining damage measurement preparation means.

FIG. 3 is a conceptual diagram used to explain a first modification of the damage measurement preparing means according to the present invention.

FIG. 4 is a conceptual diagram used for explaining a second modification of the damage measurement preparing means according to the present invention.

FIG. 5 is a conceptual diagram used for explaining a third modification of the damage measurement preparing means according to the present invention.

FIG. 6 shows a method for estimating a remaining life of a structural member and a device for estimating a remaining life of a structural member used in the method according to the present invention;
FIG. 4 is a conceptual diagram used for explaining a damage measuring unit.

FIG. 7 is a conceptual diagram used to explain a fourth modification of the damage measurement preparing means according to the present invention.

FIG. 8 is a conceptual diagram used to explain a fifth modification of the damage measurement preparing means according to the present invention.

FIG. 9 is a conceptual diagram used for describing a sixth modification of the damage measurement preparation unit according to the present invention.

FIG. 10 is a conceptual diagram used for describing a seventh modification of the damage measurement preparing means according to the present invention.

FIG. 11 is a conceptual diagram used to explain an eighth modification of the damage measurement preparing means according to the present invention.

FIG. 12 is a view used to explain damage parameter evaluation means in the method for estimating the remaining life of a structural member and the apparatus for estimating the remaining life of a structural member used in the method according to the present invention.

FIG. 13 is a view used to explain a use condition estimating means in the method for estimating the remaining life of a structural member and the apparatus for estimating the remaining life of a structural member used in the method according to the present invention.

FIG. 14 is a graph used to explain that the use condition estimating means according to the present invention obtains a total strain range from a plastic strain range.

FIG. 15 is a repetitive stress-strain specific diagram used for explaining that the use condition estimating means according to the present invention estimates a total stress range from a total strain range.

FIG. 16 is a graph used to explain that the use condition estimating means according to the present invention estimates a maximum thermal stress parameter from an equivalent elastic stress range.

FIG. 17 is a graph used to explain that the use condition estimating means according to the present invention estimates a Biot number from a maximum thermal stress parameter.

FIG. 18 is a graph used to explain estimating the thermal conductivity from the maximum thermal stress parameter in the use condition estimating means according to the present invention.

FIG. 19 is a view used to explain a limit value setting means in the method for estimating the remaining life of a structural member according to the present invention and the apparatus for estimating the remaining life of a structural member used in the method.

FIG. 20 is a view used to explain a use history estimating means in the method for estimating the remaining life of a structural member and the apparatus for estimating the remaining life of a structural member used in the method according to the present invention.

FIG. 21 is a view used to explain a remaining life estimating means in the method for estimating the remaining life of a structural member and the apparatus for estimating the remaining life of a structural member used in the method according to the present invention.

FIG. 22 is a graph used to explain that the maximum crack length and the repetition rate ratio depend on the strain range in the use condition estimating means according to the present invention.

FIG. 23 is a graph in which the relationship between the maximum crack length and the repetition rate ratio is corrected by the number of crack occurrences in the use condition estimating means according to the present invention.

FIG. 24 is a graph showing the relationship between the number of crack occurrences and the total strain range in the use condition estimating means according to the present invention.

FIG. 25 is a graph showing the relationship between the number of crack occurrences and the range of plastic strain in the use condition estimating means according to the present invention.

FIG. 26 is a block diagram used to explain a conventional method and apparatus for predicting and measuring remaining life of a structural member.

FIG. 27 is a graph showing a crack length-life ratio applied to a conventional method for measuring and predicting the remaining life of a structural member and its apparatus.

FIG. 28 is a graph showing another maximum crack length-life ratio applied to a conventional method for measuring and measuring the remaining life of a structural member and its apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 damage measurement preparation means 2 damage measurement means 3 damage evaluation parameter evaluation means 4 use condition estimation means 5 limit value setting means 6 usage history estimation means 7 remaining life estimation means 8 polishing apparatus 9 subject 10 damaged part 11 grinder 12 polishing head 13 Grinder drive unit 14 Cleaning device 15 Cleaning header 16 Nozzle 17 Cleaning liquid supply passage 18 Cleaning liquid collection passage 19 Dry air supply passage 20 Damage detection unit 21 Damage measurement drive unit 22 Image processing device 23 Crack length distribution file unit 24 Replica device 25 Replica collection Head 26 Methyl acetate supply passage 27 Transfer paper 28 Replica supply roll 29 Spring 30 Replica pressure rod 31 Image input head 32 Projection unit 33 CCD camera 34 Surface unevenness image input head 35 Lens 36 Laser microscope 37 Electric resistance measurement head 38 Electricity Resistance measuring terminal 39 an electric resistance measuring device 40 electromagnetically Keisokuko 41 field 42 electromagnetic measurement apparatus 43 ultrasonic Sojushinko 44 Ultrasonic 45 ultrasonic device 46 detector 47 calculator 48 determines 49 the display device 50 measuring device

Continuation of the front page (72) Inventor Yasushi Hirasawa 2-4 Suehirocho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture F-term (reference) 2K024 AD05 BA12 CA30 DA30 FA02 2G053 AA11 AA14 AB01 BA24 BB02 2G060 AA09 AD04 AE01 AF06 EA05 EB05 2G061 BA03 CB13 EA10 EB06 EB07 EB08 EC03 EC05

Claims (7)

[Claims] After polishing a damaged portion of an object, the sample is washed with a cleaning liquid, cracks in the washed damaged portion are measured, and the measured crack information is imaged and stored in a database. The maximum crack length and the crack length density are calculated and arranged based on the damage parameters, and the damage range is used to calculate the strain range, the temperature distribution in the depth direction of the specimen, and the stress distribution. Estimate the operating conditions in operation, calculate the fracture toughness distribution from the above temperature distribution, and calculate the stress intensity factor distribution from the stress distribution, and compare the calculated fracture toughness distribution with the stress intensity factor distribution to determine the critical crack depth. On the other hand, after setting the number of strain cycles from the maximum crack length and the crack length density and estimating the use history, the maximum crack length and the depth of the subject are calculated. A method of estimating the remaining life of a structural member, wherein the number of strain repetitions up to a critical burst depth is set as the remaining life of the structural member. 2. The method for estimating the remaining life of a structural member according to claim 1, wherein when the measured crack information is imaged and converted into a database, noise of the crack information is removed and binarization processing is performed. 3. When estimating a use condition in a past operation, a strain range is determined by a maximum crack length and a strain repetition rate ratio, and a maximum crack length created based on a crack length density and a strain repetition rate ratio in a graph. 2. The method for predicting the remaining life of a structural member according to claim 1, wherein the method is obtained from a sa-crack length density diagram. 4. The method according to claim 1, wherein when setting the critical crack depth, an intersection of the fracture toughness distribution and the stress intensity factor distribution is set as the critical crack depth. 5. A damage measurement preparation means for performing surface treatment and cleaning for measuring a number of cracks distributed in a damaged portion of a structural member, and a damage for measuring individual lengths of the number of cracks distributed in the damaged portion. Measuring means; damage parameter evaluating means for calculating at least two or more damage parameters from the damage measurement amount obtained from the damage measuring means;
The master curve obtained experimentally to estimate the operating conditions from one or more damage parameters should have at least 2
A use condition estimating means for estimating past use conditions by applying one or more damage parameters; a limit value setting means for determining a limit value of a damage parameter from the estimated use conditions and a fracture limit value of a structural member; A use history estimating means for determining a use history by applying at least two or more damage parameters to a master curve obtained by an experiment to estimate a use history from the above damage parameters; and a crack length and a depth of a structural member. And a remaining life estimating means for setting as a remaining life the number of strain repetitions until reaching a limit crack depth calculated based on the remaining life. 6. A damage measuring preparation means, comprising: a polishing device for buffing a damaged portion of a subject; and a polishing device for polishing the damaged portion.
6. The apparatus according to claim 5, further comprising a cleaning device for cleaning with methyl acetate. 7. The damage measuring means is a replica device, a CCD,
A camera, a laser microscope, an electric resistance measuring device, an electromagnetic measuring device, or an ultrasonic device, and an image processing device for imaging crack information measured from the subject while selecting any of the devices. Item 6. An apparatus for estimating a remaining life of a structural member according to Item 5.