JP5507777B2 - Crack growth estimation method and information processing apparatus - Google Patents

Description

  The present invention relates to a crack progress estimation method and an information processing apparatus, and particularly to a technique for accurately and simply estimating the progress of a crack.

  In Patent Document 1, in the device life evaluation method for evaluating the device life due to the structural damage of the device based on creep or fatigue, the progress of the micro crack is considered by regarding the damage of the device structure based on creep or fatigue as the progress of the micro crack. It is described to predict and evaluate the equipment life.

  Further, Patent Document 2 discloses that stress or strain and displacement of a welded part are continuously measured for the purpose of accurately estimating the fatigue life of a steel structure including many welded parts. Calculate the frequency of the amplitude of the stress, measure the measurement period of the stress or strain and displacement, calculate the slope in the relationship between the stress or strain and displacement, determine the fatigue crack initiation life based on the amount of change in the slope, Alternatively, it is described that the fatigue damage degree and the remaining fatigue life are calculated based on the data on the frequency of strain amplitude, the measurement period, and the fatigue life, and the remaining fatigue life is corrected based on the fatigue crack initiation life.

JP 2010-2261 A JP 2003-322593 A

  Analysis of cracks occurring in structures used at high temperatures, such as steam turbines and boilers in thermal power plants and nuclear power plants, is performed separately from the generation and progress of cracks. In addition, when cracks are found in the actual machine at the site, the cracks are often scraped immediately, and the crack propagation behavior is not necessarily grasped.

  In addition, if it is going to accurately estimate the growth of cracks, it is necessary to perform numerical analysis by the finite element method (FEM), but it is necessary to recut the mesh (FEM model) for each crack depth that progresses by estimation. Therefore, a great deal of labor is required, and it is necessary to use a high-performance information processing apparatus, which is uneconomical.

  The present invention has been made in view of such a background, and an object thereof is to provide a crack progress estimation method and an information processing apparatus capable of accurately and easily estimating the progress of a crack.

One aspect of the present invention for solving the above-described problem is a method for estimating the progress of a crack generated in a member, in which the information processing apparatus applies a stress range to a predetermined portion of the member for which the progress of the crack is to be estimated. Each of which stores a plurality of stress-strain characteristics, and selects one of the plurality of stored stress-strain characteristics that satisfies the following relationship:
1 / N _f = 1 / N _pp + 1 / N _cp
Δε _cp = A2 · N _cp ^−α2
Δε _pp = A1 · N _pp ^-α1
(Where Nf is the number of known crack occurrences in the region, N _cp is the number of crack occurrences of the cp type (tensile creep strain + compression plastic strain) in the strain range division method, and N _pp is the pp type (tensile in the strain range division method). The number of crack occurrences (plastic strain + compression plastic strain), Δε _cp is the cp-type strain range in the strain range division method, Δε _pp is the pp-type strain range in the strain range division method, and A1, A2, α1, α2 are all Experimentally determined constant)
Based on the selected stress-strain characteristics, a stress distribution Δσ (0) of the part when the part is not cracked is obtained, and a numerical analysis is performed based on the Δσ (0). Obtain the stress distribution Δσ (a) in the depth direction of the part when it does not occur,
The obtained stress distribution Δσ (a) and the following relationship (Paris law)
da / dN = C · (ΔK) ^m
ΔK = Δσ (a) · (π · a) ^1/2
(Where a is the crack depth, N is the number of occurrences of repeated stress, C and m are constants determined according to the member, and ΔK is the stress intensity factor range)
Based on the above, the progress of cracks in the part is estimated.

  According to the present invention, the numerical analysis is performed only for the stress distribution Δσ (0) of the part in the case where no crack has occurred in the part where the crack growth is to be estimated, and the Paris law is used for the subsequent crack development. Therefore, the progress of the crack can be estimated accurately and simply using the information processing apparatus 100 such as a personal computer.

  In another aspect of the present invention, there is provided the crack propagation estimation method, wherein the information processing apparatus calculates a creep contribution in a depth of a crack that progresses when estimating the progress of the crack, and calculates the calculated creep. The parameters C and m are determined according to the degree of contribution, and the crack progress at the depth is estimated using the determined parameters C and m.

  According to the present invention, since the crack progress is estimated based on the Paris law by appropriately selecting the parameters C and m in accordance with the creep contribution in the depth of the progressing crack, it is possible to improve the estimation accuracy of the crack progress. Can do.

  Note that the information processing apparatus, for example, obtains an actual measurement value of the time series change of the stress at the depth of the crack in which the member propagates, the creep rupture characteristics, and the number of times the repeated stress is generated until the crack is generated. Based on these, the creep contribution in the depth of the crack that develops is calculated.

  In addition, the information processing apparatus stores, for example, a relationship between a Paris law constant and a holding time, and the creep contribution degree of the relation coincides with the calculated creep contribution degree in the progressing crack depth. And the parameters C and m are determined based on the specified relationship, and the crack propagation at the depth is estimated using the determined parameters C and m.

  In addition, the subject which this application discloses, and its solution method are clarified by the column of the form for inventing, and drawing.

  According to the present invention, the progress of a crack can be estimated accurately and simply.

2 is a diagram illustrating a main hardware configuration of an information processing apparatus 100. FIG. 2 is a diagram illustrating main functions of the information processing apparatus 100. FIG. It is a flowchart explaining crack progress estimation processing S300. It is an example of a stress-strain characteristic. It is a figure explaining the calculation method of stress distribution (DELTA) (sigma) (a) of the depth direction in an object site | part. It is an example of the time-sequential change 600 of the stress in the depth of the crack which progresses. It is an example of the creep rupture characteristic 700. It is an example of the relationship 800 of a Paris law constant and retention time. It is a figure which shows the example which selected the parameters C and m of the Paris rule according to the creep contribution in the depth of the crack to advance. It is an example of the estimation result of the progress of a crack. It is an example of the estimation result of the progress of a crack. It is an example of the estimation result of the progress of a crack.

  Hereinafter, embodiments will be described with reference to the drawings.

  FIG. 1 shows a main hardware configuration of an information processing apparatus 100 used for realizing a crack growth analysis system described as an embodiment. The crack growth analysis system according to the present embodiment analyzes and diagnoses high-temperature cracks and fatigue cracks generated in members such as structures and various devices used at high temperatures such as steam turbines and boilers of thermal power plants and nuclear power plants. Used for.

  As shown in the figure, the information processing apparatus includes a central processing unit 101 (CPU, MPU, etc.), a main storage device 102 (ROM, RAM, NVRAM, etc.), and an auxiliary storage device 103 (hard disk drive, magneto-optical disk drive, SSD). (Solid State Drive, etc.), an input device 104 (keyboard, mouse, touch panel, etc.), an output device 105 (liquid crystal monitor, organic EL panel, etc.), and a communication device 106 (NIC, etc.).

  FIG. 2 shows main functions provided by the information processing apparatus 100. As shown in the figure, the information processing apparatus 100 includes a stress-strain characteristic storage unit 201, a crack occurrence number storage unit 202, a stress-strain characteristic selection unit 203, a stress distribution Δσ (0) calculation unit 204, a stress distribution Δσ ( a) The functions of the calculation unit 205, the crack propagation estimation processing unit 206, the creep contribution calculation unit 207, the Paris law parameter determination unit 208, the creep rupture property storage unit 209, and the Paris law constant-retention time storage unit 210 are provided. .

  These functions are realized by the central processing unit 101 reading and executing a program stored in the main storage device 102 or the auxiliary storage device, or by functions provided in the hardware of the information processing device 100. .

  Among the functions shown in the figure, the stress-strain characteristic storage unit 201 is configured for each stress range with respect to one or more parts (for example, a predetermined position on the surface of the structure) of the member for which the progress of the crack is estimated. Multiple stress-strain characteristics are stored.

  The crack occurrence number storage unit 202 is one or more parts (for example, a surface part of a structure) of a member (hereinafter, referred to as a target member) that is acquired via the input device 104 or the like and that is to be estimated. ) Is stored.

The stress-strain characteristic selection unit 203 performs, for each stress range stored in the stress-strain characteristic storage unit 201, for a predetermined part (hereinafter referred to as a target part) for which the progress of the crack of the target member is to be estimated. Among the plurality of stress-strain characteristics, one that satisfies the following relationship is selected.
1 / N _f = 1 / N _pp + 1 / N _cp Formula 1
Δε _cp = A2 · N _cp ^−α2 Formula 2
Δε _pp = A1 · N _pp ^−α1 Equation 3

Nf is the number of cracks generated in the target region, N _cp is the number of cracks of cp type (tensile creep strain + compression plastic strain) in the strain range division method, and N _pp is the pp type (tensile plastic strain + compression in the strain range division method). The number of cracks of plastic strain), Δε _cp is the cp-type strain range in the strain range division method, Δε _pp is the pp-type strain range in the strain range division method, and A1, A2, α1, α2 are all determined by experiments. Constants (for example, Reference 1 “Damage Analysis and Material Evaluation of Turbine Stop Valves / Control Valves in Ultra High Pressure and High Temperature Plants”, Thermal Nuclear Power Generation, Vol. 35, No. 11, Nov. 1984, Masahiro Nakashiro et al. See page 48.).

  The stress distribution Δσ (0) calculation unit 204 calculates the stress distribution Δσ (0) in the target part when no crack is generated in the target part based on the stress-strain characteristic selected by the stress-strain characteristic selection unit 203. Ask.

  The stress distribution Δσ (a) calculation unit 205 performs numerical analysis (for example, analysis by the finite element method (FEM)) using Δσ (0) obtained by the stress distribution Δσ (0) calculation unit 204, The stress distribution Δσ (a) in the depth direction at the target site is obtained when no cracks are generated.

  In addition, the stress distribution Δσ (a) calculation unit 205 obtains a time-series change 600 (FIG. 6) of stress for each depth of a crack that will be described later in the numerical analysis.

Based on the stress distribution Δσ (a) obtained by the stress distribution Δσ (a) calculation unit 205 and the following Paris rule, the crack propagation estimation processing unit 206 estimates the crack progress in the target portion.
da / dN = C · (ΔK) ^m Expression 4
ΔK = Δσ (a) · (π · a) ^1/2 Formula 5

  Here, a is the crack depth, N is the number of occurrences of repeated stress, C and m are constants determined according to the target member, and ΔK is the stress intensity factor range.

  The creep contribution calculation unit 207 obtains the creep contribution in the depth of the crack that progresses in the estimation by the crack propagation estimation processing unit 206.

  The Paris law parameter determining unit 208 uses the Paris used when the crack progress estimation processing unit 206 estimates the progress of the crack at the depth of the crack that progresses according to the creep contribution obtained by the creep contribution calculating unit 207. The rule parameters C and m are determined.

  The creep rupture characteristic storage unit 209 stores a creep rupture characteristic 700 (for example, a creep rupture characteristic obtained by an experiment for the same material as the target member) described later (FIG. 6).

  The Paris law constant-holding time storage unit 210 stores a relation 800 (FIG. 8) between a Paris law constant C, m, which will be described later, and a holding time.

  FIG. 3 is a flowchart for explaining a process (hereinafter referred to as a crack progress estimation process S300) performed by the information processing apparatus 100 when the user estimates crack progress using the crack progress analysis system. Hereinafter, the crack growth estimation process S300 will be described with reference to FIG.

  First, the information processing apparatus 100 accepts designation of a target member and a target part from the user via the input device 104 (S311).

  Next, the information processing apparatus 100 acquires the number of crack occurrences Nf and a plurality of stress-strain characteristics for each stress range stored for the received target part (S312 and S313).

  FIG. 4 shows an example of stress-strain characteristics (extracted from Reference 1). The stress-strain characteristic storage unit 201 stores a plurality of stress-strain characteristics as shown in the figure for each stress range.

  Subsequently, the information processing apparatus 100 selects a plurality of stress-strain characteristics for each stress range that satisfy the above-described relations of Expressions 1 to 3 (S314).

  Next, the information processing apparatus 100 obtains the stress distribution Δσ (0) in the target part when there is no crack in the target part based on the selected stress-strain characteristics (S315).

  Next, the information processing apparatus 100 performs numerical analysis (for example, analysis by a finite element method) based on the obtained Δσ (0), and stress in the depth direction in the target part when no crack is generated in the target part. A distribution Δσ (a) is obtained (S316).

A specific example is shown in FIG. In this example, Δσ (a) is obtained based on the stress distribution on the straight line in the crack depth direction at the target site, which is obtained by the numerical analysis. That is, in this example, the absolute value of the stress distribution Δσ _A (a) at the time (t _A ) at which the compression is maximum in the numerical analysis and the stress distribution Δσ at the time (t _B ) at which the tension is maximum in the numerical analysis. The sum of _B (a) and the absolute value is obtained as the stress distribution Δσ (a) of the target part when no crack occurs in the target part.

  Returning to FIG. 3, subsequently, the information processing apparatus 100 determines the progress of cracks (the number N of repeated stress occurrences) in the target region based on the obtained stress distribution Δσ (a) and the above-described Paris rule (Equations 3 and 4). (Relationship with crack depth) is estimated (S317 to S319).

  In general, the shape of the target member, the nature of the material, and the environment (temperature, pressure, etc.) in which the target member is placed vary depending on the depth of the crack that develops. It is considered that the creep contribution varies depending on the depth of the crack that develops. Specifically, when the information processing apparatus 100 estimates the progress of a crack for each depth of a crack that develops, the information processing apparatus 100 obtains a creep contribution at the depth of the crack, and according to the obtained creep contribution, Select (determine) parameters C and m.

但しｔは時刻、Ｎｒは対象部位に亀裂が発生するまでに作用した繰り返し応力の発生回数、ｔ_ｒ（Δσ（ｔ））は応力Δσ（ｔ）を作用させた場合における破断時間である。The creep contribution in the depth of the crack that propagates here is, for example, the time series change 600 of the stress in the depth of the crack that progresses as illustrated in FIG. The figure is obtained by applying Reference 2 “NIMS / CDS / No.31B / 1994 p.10” to the following equation.

Where t is time, Nr is the number of occurrences of the repeated stress acting on until a crack is generated in the target _{site, t r (Δσ (t)} ) is the rupture time when an acting stress .DELTA..sigma (t).

For example, in the time series change 600 of FIG. 6, Δσ (t _B ) = 180 MPa, Δσ (t _C ) = 20 MPa, Δσ (t _D ) = 140 MPa, time t _A ′ −time t _B ′ = 3 hours, time t _{Assume that} B′−time t _C = 150 hours and time t _C −time t _E = 3 hours.

と求められる。This case 7, rupture time corresponding to 180MPa at time _{t B} (time-to rupture) is 2000 hours, break time corresponding to 180MPa at time _{t B} is 1.0E + 07 (exponential notation) 2000 hours, the time _{t D} Since the fracture time corresponding to 140 MPa at 50,000 hours can be obtained as 50,000 hours, for example, if Nr is 617 times, the creep contribution in the depth of the crack progressing from Equation 6 is

Is required.

  The information processing apparatus 100 determines the parameters C and m of the Paris rule used when estimating the progress of the crack, according to the creep contribution degree in the depth of the crack that has been thus obtained.

  FIG. 8 is an example of the relationship 800 between the Paris law constant and the retention time stored in the information processing apparatus 100. The figure is measured for a test piece (Cr—Mo—V cast steel) under a predetermined environment (temperature: 550 ° C., stress: ± 220 MPa), excluding data held for 10,000 minutes. Note that the data held for 10,000 minutes is estimated based on the graph for holding for 1 minute to 1000 minutes.

Here, the respective creep contributions of each data (each straight line) shown in the figure can be obtained as follows, for example. For example, assuming that the number of occurrences of repeated stress until the test piece breaks is 50 under the conditions of a temperature of 550 ° C., a stress of 140 MPa, and a holding time of 167 hours, the creep rupture characteristic 700 in FIG. Since the rupture time in the case of only creep can be obtained as 50,000 hours, the creep contribution degree of the data held for 10,000 minutes is
Creep contribution (holding for 10,000 minutes) = 50 × (167/50000) = 17%
It becomes.

Further, for example, assuming that the number of occurrences of repeated stress until the test piece reaches breakage is 110 times under the conditions of a temperature of 550 ° C., a stress of 140 MPa, and a holding time of 16.7 hours, data for holding 1000 minutes The creep contribution of
Creep contribution (holding 1000 minutes) = 110 × (16.7 / 50000) = 3.7%
It becomes.

Further, for example, assuming that the number of occurrences of repeated stress until the test piece breaks is 422 under the conditions of a temperature of 550 ° C., a stress of 140 MPa, and a holding time of 1.67 hours, data of holding for 100 minutes The creep contribution of
Creep contribution (retained for 100 minutes) = 110 × (1.67 / 50000) = 1.4%
It becomes.

For example, assuming that the number of occurrences of repeated stress until the test piece breaks is 1025 times under the conditions of a temperature of 550 ° C., a stress of 140 MPa, and a holding time of 0.167 hours, data of 10 minutes holding The creep contribution of
Creep contribution (10 minutes hold) = 1025 x (0.167 / 50000) = 0.34%
It becomes.

Further, assuming that the number of occurrences of repeated stress until the test piece is ruptured is 2300 times under the conditions of a temperature of 550 ° C., a stress of 140 MPa, and a holding time of 0.0167 hours, the creep of the 1-minute holding data The contribution is
Creep contribution (1 minute hold) = 2300 × (0.0167 / 50000) = 0.34%
It becomes.

  The information processing apparatus 100 compares the respective creep contributions of the respective graphs shown in FIG. 8 obtained as described above with the creep contribution obtained from the equation 6, and further performs logarithmic interpolation when necessary. 8, the data corresponding to the creep contribution degree and the value obtained from Equation 6 are identified, and the parameters C and m determined based on the identified data are determined at the depth of the crack to be propagated. It is used as a parameter of the Paris rule used when estimating the progress of the.

  FIG. 9 shows an example in which the parameters C and m of the Paris rule are determined in accordance with the degree of creep contribution in the depth of the crack that develops. In this example, when the depth of the crack is 1 mm or more and less than 3 mm, the parameter C, m of the Paris rule based on the data held for 10,000 minutes, and when the depth of the crack is 3 mm or more and less than 5 mm, the parameter of the Paris law based on the data held for 1000 minutes. When C and m are 5 mm or more and less than 20 mm, the parameters C and m of the Paris law based on the data held for 100 minutes are used as the parameters of the Paris law used when estimating the progress of the crack at the depth of the crack that progresses, respectively. Used.

  Returning to FIG. 3, the information processing apparatus 100 outputs the result to the output device 105 (S <b> 320) when the estimation of the crack progress is completed (S <b> 319: YES). In addition, the information processing apparatus 100 ends the estimation of the progress of a crack when, for example, the number N of occurrences of repeated stress exceeds a predetermined number.

  FIG. 10 to FIG. 12 show an example of the estimation result of the crack progress output from the information processing apparatus 100.

  FIG. 10 is a result of estimating the progress of a crack when the depth of the crack is 1 mm or more and 3 mm or less (accuracy is not guaranteed in the range exceeding 3 mm) using the parameters C and m of the Paris rule based on the data held for 10,000 minutes. It is. From the figure, it can be seen that, for example, when the repeated stress is generated 50 times, the depth of the crack reaches 3 mm (3.0E-03 m).

  FIG. 11 uses parameters C and m of the Paris rule based on the data held for 1000 minutes, and the crack depth between 3 mm and 5 mm (accuracy is not guaranteed in the range of less than 3 mm and in the range of more than 5 mm). It is the result of estimating the progress. From the figure, it can be seen that, for example, the crack depth reaches 5 mm (5.0E-03 m) when the stress is generated 19 times after the crack depth exceeds 3 mm.

  FIG. 12 uses the parameters C and m of the Paris rule based on the data held for 100 minutes, and the crack depth is between 5 mm and 20 mm (accuracy is not guaranteed in the range of less than 5 mm and in the range of more than 20 mm). It is the result of estimating the progress. From the figure, for example, it can be seen that the crack depth reaches 20.9 mm (20.9E-03 m) when the stress is generated 500 times after the crack depth exceeds 5 mm. Further, from the figure, it can be estimated that the progress of the crack stops when the depth of the crack is about 30.0 mm (30.0E-03 m).

  As described above, in the crack growth analysis system according to the present embodiment, only the stress distribution Δσ (0) of the part in the case where no crack has occurred in the part where crack propagation is to be estimated is numerically analyzed. Since the subsequent crack progress is estimated using the Paris rule, the progress of the crack can be accurately and easily estimated using the information processing apparatus 100 such as a personal computer.

  In addition, when maintaining cracks in structures used at high temperatures such as steam turbines and boilers in thermal power plants and nuclear power plants, operations are often carried out to repair these cracks as soon as they occur. According to the crack growth analysis system of the embodiment, when a crack occurs, the subsequent crack growth can be easily estimated. For this reason, when a crack occurs, it is possible to determine a response to the crack (whether quick repair is necessary, etc.), and to efficiently maintain the crack of the structure.

  In the crack growth analysis system of the present embodiment, when estimating the progress of the crack, the parameters C and m are determined according to the degree of creep contribution in the depth of the crack that propagates, and the Paris law is applied to the determined parameter. Therefore, it is possible to improve the estimation accuracy of the crack progress.

  Embodiment described above is for making an understanding of this invention easy, and does not limit this invention. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes the equivalents thereof.

DESCRIPTION OF SYMBOLS 100 Information processing apparatus 201 Stress-strain characteristic memory | storage part 202 Crack generation frequency memory | storage part 203 Stress-strain characteristic selection part 204 Stress distribution (DELTA) (sigma) (0) calculation part 205 Stress distribution (DELTA) (sigma) calculation part 206 Crack progress estimation process part 207 Creep Contribution calculation unit 208 Paris rule parameter selection unit 209 Creep rupture property storage unit 210 Paris rule constant-holding time storage unit S300 Crack growth estimation processing 500 Time series change of stress at depth of progressing crack 600 Creep rupture property 700 Paris rule Relationship between constant and retention time

Claims (8)

A method of estimating the progress of a crack generated in a member,
Information processing device
Stores multiple stress-strain characteristics for each stress range for a given part of a member whose crack is to be estimated.
Select one of the plurality of stored stress-strain characteristics that satisfies the following relationship:
1 / N _f = 1 / N _pp + 1 / N _cp
Δε _cp = A2 · N _cp ^−α2
Δε _pp = A1 · N _pp ^-α1
(Where Nf is the number of known crack occurrences in the region, N _cp is the number of crack occurrences of the cp type (tensile creep strain + compression plastic strain) in the strain range division method, and N _pp is the pp type (tensile in the strain range division method). The number of crack occurrences (plastic strain + compression plastic strain), Δε _cp is the cp-type strain range in the strain range division method, Δε _pp is the pp-type strain range in the strain range division method, and A1, A2, α1, α2 are all Experimentally determined constant)
Based on the selected stress-strain characteristics, the stress distribution Δσ (0) of the part in the case where no crack occurs in the part,
Performing a numerical analysis based on the Δσ (0) to obtain a stress distribution Δσ (a) in the depth direction of the part when no crack occurs in the part,
The obtained stress distribution Δσ (a) and the following relationship (Paris law)
da / dN = C · (ΔK) ^m
ΔK = Δσ (a) · (π · a) ^1/2
(Where a is the crack depth, N is the number of occurrences of repeated stress, C and m are constants determined according to the member, and ΔK is the stress intensity factor range)
Based on the above, a crack progress estimation method for estimating the progress of a crack in the part. The crack growth estimation method according to claim 1,
The information processing apparatus is
In estimating the progress of the crack, the creep contribution at the depth of the crack that develops is calculated, the parameters C and m are determined according to the calculated creep contribution, and the parameters C and m are used to determine the crack contribution. A crack growth estimation method that estimates crack growth at depth. The crack growth estimation method according to claim 2,
The information processing apparatus includes:
Stores the time-series change of stress at the depth of the crack in which the member develops, the creep rupture characteristics, and the actual measurement value of the number of occurrences of repeated stress until the crack occurs at the site, and the crack that propagates based on these values A crack growth estimation method that calculates the creep contribution at depth. A crack growth estimation method according to claim 2 or 3,
The information processing apparatus includes:
Memorize the relation between the Paris law constant and the retention time,
Among the relations, the creep contribution degree that matches the creep contribution degree at the calculated depth of the progressing crack is specified, the parameters C and m are determined based on the specified relation, and the determined parameter C , M is used to estimate crack growth at the depth. An information processing apparatus including a CPU and a memory,
Means for storing a plurality of stress-strain characteristics for each stress range for a predetermined portion of a member to be estimated for crack propagation;
Means for selecting one of the plurality of stored stress-strain characteristics satisfying the following relationship:
1 / N _f = 1 / N _pp + 1 / N _cp
Δε _cp = A2 · N _cp ^−α2
Δε _pp = A1 · N _pp ^-α1
(Where Nf is the number of known crack occurrences in the region, N _cp is the number of crack occurrences of the cp type (tensile creep strain + compression plastic strain) in the strain range division method, and N _pp is the pp type (tensile in the strain range division method). The number of crack occurrences (plastic strain + compression plastic strain), Δε _cp is the cp-type strain range in the strain range division method, Δε _pp is the pp-type strain range in the strain range division method, and A1, A2, α1, α2 are all Experimentally determined constant)
Based on the selected stress-strain characteristics, means for obtaining a stress distribution Δσ (0) of the part in the case where no crack is generated in the part;
Means for performing a numerical analysis based on the Δσ (0) and obtaining a stress distribution Δσ (a) in the depth direction of the portion when no crack is generated in the portion;
The obtained stress distribution Δσ (a) and the following relationship (Paris law)
da / dN = C · (ΔK) ^m
ΔK = Δσ (a) · (π · a) ^1/2
(Where a is the crack depth, N is the number of occurrences of repeated stress, C and m are constants determined according to the member, and ΔK is the stress intensity factor range)
An information processing apparatus comprising: means for estimating the progress of a crack in the part based on the above. The information processing apparatus according to claim 5,
In estimating the progress of the crack, the creep contribution at the depth of the crack that develops is calculated, the parameters C and m are determined according to the calculated creep contribution, and the parameters C and m are used to determine the crack contribution. An information processing apparatus further comprising: means for estimating crack propagation at depth. The information processing apparatus according to claim 6,
Stores the time-series change of stress at the depth of the crack in which the member develops, the creep rupture characteristics, and the actual measurement value of the number of occurrences of repeated stress until the crack occurs at the site, and the crack that propagates based on these values An information processing apparatus further comprising: means for calculating a creep contribution degree at a depth of. The information processing apparatus according to claim 6 or 7,
Means for storing the relationship between the Paris constant and the retention time;
Among the relations, the creep contribution degree that matches the creep contribution degree at the calculated depth of the progressing crack is specified, the parameters C and m are determined based on the specified relation, and the determined parameter C , M, and means for estimating the progress of a crack at the depth.

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