CN115931532A - Electric power high-temperature component damage state judgment method based on modified time fraction method - Google Patents
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Abstract
The invention discloses a method for judging damage states of electric power high-temperature components based on a modified time fraction method, which comprises the following steps: obtaining a plurality of samples with the same material and dividing the samples into three parts; carrying out a fatigue test on the first part of samples, carrying out a creep test on the second part of samples, and carrying out a creep fatigue test on the third part of samples; acquiring fatigue damage parameters based on the fatigue test data, and acquiring creep damage parameters based on the creep test data; determining fatigue damage based on the fatigue behavior of the creep fatigue test, and determining creep damage based on the creep behavior of the creep fatigue test; predicting the cycle life of the creep fatigue sample based on the fatigue damage and the creep damage; the total damage state of the power high-temperature component at any time is determined based on the accumulated fatigue damage and the accumulated creep damage. The method is corrected based on a widely recognized time fraction method, has clear physical significance by coupling the classical energy viewpoint of creep strain dissipation, is suitable for various creep fatigue loads, and has high prediction precision.
Description
Technical Field
The invention belongs to the field of life prediction and damage assessment, and particularly relates to a method for judging damage states of electric power high-temperature components based on a modified time fraction method.
Background
In the fields of aviation, aerospace, petrochemical industry and the like, a plurality of components such as transmission rotation, compression bearing and the like operate in a severe high-temperature variable-load environment for a long time. The numerous and costly failure cases in the past led scientists to recognize that failure of typical life-limiting components, such as steam turbine rotors, nuclear reactor components, and aircraft engine turbine components, was not caused by a single fatigue damage, most often failure caused by the interaction of fatigue and creep at high temperatures. Therefore, damage assessment and life prediction techniques under creep-fatigue interaction loading are one of the most important concerns for equipment design and manufacture.
The linear damage accumulation method is the most common creep fatigue damage assessment method, and the method is premised on accurately calculating the fatigue damage and the creep damage in the cyclic loading process. Fatigue damage is generally expressed by a life fraction method, but calculation of creep damage is difficult due to stress relaxation introduced by load retention, and a plurality of versions are deduced at present. Creep damage, where time fraction is indicative, is widely recognized and has been adopted by ASME III-NH (boiler and pressure vessel design codes) and RCC-MR (nuclear island mechanical plant design and construction codes). The accuracy of this method has proven to be significantly lower than the creep damage representation method which takes into account energy dissipation. Furthermore, the hybrid control of creep fatigue loading by stress-strain developed in recent years presents a significant challenge to existing approaches. Therefore, the method for judging the creep fatigue damage state of the high-temperature component based on the time fraction method and the energy dissipation concept is needed to be invented so as to meet the identification and judgment of the damage state under various creep fatigue loads.
Disclosure of Invention
The invention aims to provide a method for judging the damage state of a high-temperature power component based on a modified time fraction method, which aims to solve the problems in the prior art.
In order to achieve the above object, the present invention provides a method for determining a damage state of a high-temperature power component based on a modified time fraction method, comprising the steps of:
obtaining a plurality of samples with the same material, and dividing the plurality of samples into a first part sample, a second part sample and a third part sample;
carrying out fatigue test on the first part of samples to obtain fatigue test data;
carrying out creep test on the second part of the test sample to obtain creep test data;
performing creep fatigue test on the third part of the test sample to obtain creep fatigue data;
acquiring a fatigue damage parameter based on the fatigue test data, and acquiring a creep damage parameter based on the creep test data;
acquiring the fatigue damage of the creep fatigue test based on the fatigue damage parameters and the fatigue behavior of the creep fatigue test; acquiring creep damage of the creep fatigue test based on the creep damage parameters and creep behavior of the creep fatigue test;
predicting a cycle life of a creep fatigue specimen based on the fatigue damage and the creep damage;
the total damage state of the power high-temperature component at any time is determined based on the accumulated fatigue damage and the accumulated creep damage.
Optionally, obtaining a fatigue damage parameter based on the fatigue test data, and obtaining a creep damage parameter based on the creep test data, where the process includes:
obtaining a relation between a fatigue strain amplitude and a cycle life based on the fatigue test data;
obtaining key variables and relations among the key variables based on the creep test data, wherein the key variables comprise creep life, creep rupture strain, creep strain energy dissipation rate, critical creep strain energy dissipation rate and initial creep evolution.
Optionally, obtaining a critical creep strain energy dissipation rate based on the creep test data, the process comprising:
the critical creep strain energy dissipation rate
Determined according to the distribution of creep test points in a base-10 log-log coordinate system, wherein the abscissa of the log-log coordinate system is the creep strain energy dissipation rate ≥>
The ordinate is creep rupture strain ε f (ii) a Under the coordinate system, all creep test points show two possible trends; first, if the creep rupture strain ε f Always dissipating a rate of energy with the creep strain>
Is increased, it is deemed that there is no critical creep strain energy dissipation rate @>
Second, if rate of dissipation of energy is dependent on creep>
Increase of creep rupture strain ε f If a saturation value exists, the minimum creep strain energy dissipation rate corresponding to the saturation value is considered to be the critical creep strain energy dissipation rate>
Optionally, the fatigue damage of the creep fatigue test is obtained based on the fatigue damage parameter and the fatigue behavior of the creep fatigue test, and the process includes:
based on fatigueThe relation between the strain amplitude and the cycle life and the fatigue strain of the creep fatigue test half life cycle evolve along with time, the strain amplitude born in the actual loading process is obtained by adopting a rain flow counting method, and then the fatigue damage of the creep fatigue test is determined
As shown in the following formula:
wherein Ni (Δε i ) For a strain amplitude of Δ ε i Cycle life of fatigue test, strain amplitude Δ ε i Determination of the post-actual bearing strain amplitude, p, for the rain-flow method i Is the magnitude of the strain Deltaε i The ratio of (a) to (b).
Optionally, obtaining creep damage of the creep fatigue test based on the creep damage parameters and the creep behavior of the creep fatigue test, where the process includes:
obtaining a creep strain energy dissipation rate evolution rule based on the creep behavior of the creep fatigue test in a half-life cycle, wherein the creep strain energy dissipation rate evolution of indexes is followed by both the strain control creep fatigue test and the stress-strain hybrid control creep fatigue test, as shown in the following formula,
wherein 
Representing the creep strain energy dissipation rate at the moment of load retention t, p representing a dissipation rate evolution coefficient, and q representing a dissipation rate evolution index;
obtaining creep strain evolution term of correction time fraction method
As shown in the following formula: />
Wherein the creep coefficient C 1 Creep time dependent index C 2 The creep stress related index k is the creep damage parameter; the modulus of elasticity E is the basic property of the test material, the dwell time t d And the holding stress sigma of the hybrid control creep fatigue test d Are all test conditions of creep fatigue test; relaxation stress of half life cycle of strain control creep fatigue test
Peak stress sigma of first week of strain controlled creep fatigue test 0 And creep strain in a half cycle life of a hybrid controlled creep fatigue test>
All are test data obtained by creep fatigue test;
obtaining creep strain energy dissipation rate related term R of modified time fraction method ENE As shown in the following formula:
wherein the stress-induced creep failure coefficient S, the stress-induced creep failure index n, and the failure coefficient E based on the dissipation rate of creep strain energy c And the failure index m based on the creep strain energy dissipation rate is the creep damage parameter sigma d (t) evolution of the holding stress over time, given by:
wherein the stress relaxation coefficient p r Stress relaxation index q r Obtained by fitting the stress relaxation curve during strain holding(ii) a For hybrid control creep fatigue, the holding stress is a test input parameter, is constant, and is always held at σ d ；
Evolution of creep strain
Term R related to creep strain energy dissipation rate ENE Multiplied by the mean to obtain the fatigue damage->
As shown in the following formula:
optionally, predicting the cycle life of the creep fatigue test specimen based on the fatigue damage and the creep damage, wherein the process comprises:
and predicting the cycle life of the creep fatigue sample by utilizing a linear damage accumulation rule based on the fatigue damage and the creep damage.
Optionally, the total damage state of the electric high-temperature component at any time is judged based on the accumulated fatigue damage and the accumulated creep damage, and the process includes:
accumulating according to cycle times based on the fatigue damage and the creep damage to obtain accumulated fatigue damage and accumulated creep damage so as to obtain a continuous creep fatigue failure envelope curve;
and calculating the accumulated fatigue damage and the accumulated creep damage of any creep fatigue loaded component, and finally judging the damage state of the creep fatigue loaded component at any time by using the continuous creep fatigue failure envelope: and if the damage state point is outside the failure envelope curve, judging that the material fails, otherwise, judging that the material does not fail.
The invention has the technical effects that:
(1) The invention brings the influence of the changed strain amplitude into the fatigue damage, so that the fatigue damage is more accurate;
(2) The method is corrected based on a widely recognized time fraction method, and has clear physical significance by coupling the classical energy viewpoint of creep strain dissipation;
(3) The invention has wide applicability, which is mainly reflected in material applicability and creep fatigue load applicability;
(4) The method has high service life prediction precision, and can judge the damage state of the material at any time of creep fatigue loading.
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The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the application and, together with the description, serve to explain the application and are not intended to limit the application. In the drawings:
FIG. 1 is a flow chart of a method for determining damage status of a high-temperature power component based on a modified time fraction method according to the present invention;
FIG. 2 is a graph of predicted life results for P92 steel in an example of the present invention;
FIG. 3 is a graph of predicted life results for 304 stainless steel in an example of the present invention;
FIG. 4 is a graph of predicted life results for GH4169 alloys in an example of the invention;
FIG. 5 is a continuous creep fatigue failure envelope for an embodiment of the present invention;
FIG. 6 is a diagram showing creep fatigue damage state determination in the example of the present invention.
Detailed Description
It should be noted that, in the present application, the embodiments and features of the embodiments may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.
It should be noted that the steps illustrated in the flowcharts of the figures may be performed in a computer system such as a set of computer-executable instructions and that, although a logical order is illustrated in the flowcharts, in some cases, the steps illustrated or described may be performed in an order different than presented herein.
Example one
As shown in fig. 1, the present embodiment provides a method for determining a damage state of a high-temperature power component based on a modified time fraction method, including the steps of:
step S1, taking a plurality of samples of the same material, and carrying out three different types of tests at the same temperature. Performing a strain control fatigue test with the same strain rate and different strain amplitudes on the first part of samples to obtain fatigue test data (national standard GB/T26077-2010), and turning to step S2; carrying out creep tests with different stresses on the second part of samples, acquiring creep test data (national standard GB/T2039-2012), and turning to the step S3; the third part of the samples were subjected to creep Fatigue tests (including strain-controlled creep Fatigue test [ US Standard ASTM E2714-13 ] and stress-strain hybrid control creep Fatigue test [ Zhang T, wang X, ji Y, et al. Cyclic development and large mechanisms of 9-Cr steel under hybrid stress-strain linkage [ J ]. International Journal of Fatigue, (2021), 151 106357 ]) to obtain creep Fatigue data, and the process was shifted to step S4 and step S5;
s2, obtaining the relation between the fatigue strain amplitude and the cycle life according to the strain control fatigue test result, as a formula (1),
in the formula (1), E represents the elastic modulus, the fatigue strength coefficient sigma' and the fatigue strength index n of the material at the test temperature 1 Coefficient of fatigue ductility ε' and fatigue ductility index m 1 Can be obtained by fitting.
Proceed to step S4.
S3, obtaining a plurality of key parameters such as creep life, fracture strain, creep strain energy dissipation rate, critical creep strain energy dissipation rate and initial creep evolution and relations among the key parameters according to creep test data, wherein the key parameters are as follows:
step S31, creep life t f Is a basic test result parameter, canEasily obtained and then obtained according to the applied creep stress sigma and the creep life t f And obtaining the relation between the stress-induced creep failure coefficient S and the stress-induced creep failure index n, wherein the stress-induced creep failure coefficient S and the stress-induced creep failure index n are obtained by fitting the two test data.
t f ＝S·σ n (2)
Step S32, creep rupture strain ε f Also is a basic test result parameter, which can be easily obtained.
Step S33, creep strain energy dissipation Rate
Following equation (3), where σ is the creep stress, ε f For creep rupture strain, t f Creep life is considered. Dissipating rate based on the obtained creep strain energy>
And creep life t in step S31 f The relationship between the two can be obtained as shown in formula (4). Failure coefficient E based on creep strain energy dissipation rate c And a failure index m based on the creep strain energy dissipation rate is fitted from the two test data.
Step S34, critical creep strain energy dissipation rate
Can be determined from the distribution of creep test points in a base-10 log-log coordinate system having a creep strain energy dissipation rate ≥ based on the abscissa>
The ordinate is creep rupture strain ε f . In this coordinate system, all creep test points exhibit two possible trends. First, strain at creep rupture ∈ f Always Rate of energy dissipation with creep Strain>
Is greater than or equal to (b), it is considered that there is no critical creep strain energy dissipation rate->
Second, if the rate of energy dissipation is greater than or equal to creep strain>
Increase of creep rupture strain ε f If a saturation value exists, the minimum creep strain energy dissipation rate corresponding to the saturation value is considered to be the critical creep strain energy dissipation rate->
Step S35, the initial creep evolution shows the creep strain epsilon in the first stage of creep c (t) a relation with the creep time t, which follows equation (5), wherein C 1 As the creep coefficient, C 2 And k is a creep time-related index and a creep stress-related index. These parameters can all be obtained by fitting the creep first stage of a plurality of creep tests under different stresses.
Proceed to step S5.
S4, based on the fatigue strain evolution of the creep fatigue test in the half-life cycle along with time, obtaining the strain amplitude born in the actual loading process by adopting a rain flow counting method, and further determining the fatigue damage of the creep fatigue test
As shown in formula (6):
wherein Ni (Δε i ) Representing fatigue tests (strain amplitude. DELTA.. Epsilon.) i ) The specific relationship of the cycle life of (c) is given by the formula (1). Amplitude of strain Δ ε i Determining the post-actual bearing strain amplitude, p, for rain flow methods i Is the magnitude of the strain Deltaε i The ratio of (a) to (b).
Proceed to step S6.
S5, calculating creep damage of each week by using a modified time fraction method according to the creep strain energy dissipation rate evolution of the creep fatigue test in the half-life week, wherein the method specifically comprises the following steps:
step S51, obtaining a creep strain energy dissipation rate evolution rule of a creep fatigue test half-life cycle, and performing the creep strain energy dissipation rate evolution with the strain control creep fatigue load and the stress-strain hybrid control creep fatigue load following indexes, as shown in formula (7),
wherein 
The creep strain energy dissipation rate at the moment of overload t is represented, p represents a dissipation rate evolution coefficient, and q represents a dissipation rate evolution index.
Step S52, obtaining a creep strain evolution item of the correction time fraction method
As shown in formula (8).
WhereinCreep coefficient C 1 Creep time dependent index C 2 The creep stress-related index k is obtained in step S35. The modulus of elasticity E is the basic property of the material tested in step S1, the retention time t d And holding stress sigma of hybrid control creep fatigue test d Are all input parameters for the creep fatigue test carried out in step S1. Relaxation stress of half life cycle of strain control creep fatigue test
Peak stress sigma of first cycle of strain controlled creep fatigue test 0 And creep strain for half life cycle of hybrid control creep fatigue test>
Are the results of the creep fatigue test conducted in step S1.
Step S53, obtaining a creep strain energy dissipation rate related term R of the modified time fraction method ENE As shown in formula (9), wherein the critical creep strain energy dissipation rate
Derived from step S34, if there is no critical creep strain energy dissipation rate ^ according to step S34>
The first term of equation (9) is 0, leaving only the second term at 0-t d The integral of (c).
Further, the dissipation ratio evolution coefficient p, dissipation ratio evolution index q in the equation (9) is obtained by step S51. The stress-induced creep failure coefficient S and the stress-induced creep failure index n are obtained in step S31, and the failure coefficient E is based on the dissipation rate of creep strain energy c And a failure index m based on the creep strain energy dissipation rate is obtained by step S33. Sigma d (t) is holding stress over timeEvolution, given by equation (10), where the stress relaxation coefficient p r Stress relaxation index q r Obtained by fitting a stress relaxation curve during strain holding. For the hybrid control creep fatigue, the holding stress belongs to the test input parameter and is constant and always kept as sigma d 。
Step S54, the creep strain evolution item in the step S52
Term R associated with creep strain energy dissipation rate in step S53 ENE Multiplied to obtain fatigue damage in creep fatigue test>
As shown in equation (11), the parameters are explained in the previous steps.
Proceed to step S6.
Step S6, utilizing linear damage accumulation rule to obtain fatigue damage
And creep damage>
Predicting the cycle life N of the material under creep fatigue loading c-f Represented by formula (12):
proceed to step S7.
Step S7Calculating accumulated fatigue damage D according to a large amount of creep fatigue failure data f (n) and accumulated creep damage D c (n) is represented by the formula (13), wherein n represents the number of cycles. Finally, the control parameter α in the continuous creep fatigue failure envelope is determined, wherein the continuous creep fatigue failure envelope is expressed by the equation (14).
Wherein D in formula (14) c Indicates the total creep damage sustained during creep fatigue failure, D f Representing the total fatigue damage sustained at creep fatigue failure.
Proceed to step S8.
Step S8, for any creep fatigue loaded component, based on the determined accumulated fatigue damage D f (n) accumulated creep damage D c (n) and the continuous creep fatigue failure envelope determined in step S7, and finally determining the damage state of the creep fatigue loaded member at any time:
and if the damage state point is outside the failure envelope curve, judging that the material fails, otherwise, judging that the material does not fail.
Example two
As shown in fig. 2 to 4, the cycle life of different temperatures and different materials under the strain-controlled and stress-strain hybrid-controlled creep fatigue loads is predicted by the method for determining the damage state of the high-temperature power component based on the modified time fraction method according to the present invention.
The materials are selected from P92 steel, 304 stainless steel and GH4169 alloy.
For P92 steel, strain control Fatigue test data refer to paper data [ Wang X, zhang W, zhang T, et al. A New Empirical Life Prediction Model for 9-12% ] Cr Steels under Low Cycle fatigues and deep Fatigue Interaction loads J ]. Metals,2019,9 (2) ], different stress Creep test reference data [ Kimura K, takahashi Y.evaluation of Long-Term build Strength of ASME Grades 91,92, and 122Type steps [ C ]// ASME 2012pressure Vessels and Ping conference.2012 ], strain-controlled Creep Fatigue test reference paper data [ Zhang T, wang X, zhang W, et al.Fatisue-street Interaction of P92 step and modified consistent modification for correlation of the stresses [ J ] Metals, (2020), 10 307; zhang T, wang X, zhou D, et al.a. Natural consistent model for hybrid stress-string controlled street-rule formation [ J ]. International Journal of Mechanical Sciences, (2022), 225:107369. stress-strain hybrid controlled creep Fatigue test reference paper data [ Zhang T, wang X, ji Y, et al. P92 step street-Fatigue interaction stresses unit hybrid stress-strain controlled loading and a life prediction model [ J ]. International Journal of Fatigue, (2020): 105837; zhang T, wang X, ji Y, et al. Cyclic conversion and dam mechanisms of 9% by weight Cr steel under hybrid stress-string controlled street facial texture access [ J ]. International Journal of facial texture, (2021), 151: 106357);
for 304 stainless steel, strain control Fatigue testing and strain control creep Fatigue testing reference is made to paper data [ Conway J, stentz R, berling J, fatigue, tension, and relaxation history of stress steels.No. TID-26135.Mar-Test, inc., cincinnati, ohio (USA), 1975 ], creep testing for different stresses [ Sikka V, booker M, assessment of tension and cruise data for Types304and 316 steady steel, journal of Pressure steel Technology (1977) 298-313 ];
for GH4169 alloy, strain control fatigue tests, creep tests and strain control creep fatigue tests reference is made to paper data [ wangchang [ creep-fatigue life prediction model and application based on energy density dissipation criterion [ D ]. University of eastern china, 2019 ].
Firstly, according to the step S2 of the invention, the relation between the fatigue strain amplitude and the cycle life is obtained according to the strain control fatigue test result; secondly, determining a plurality of key parameters such as creep life, fracture strain, creep strain energy dissipation rate, critical creep strain energy dissipation rate, initial creep evolution and the like and relations among the key parameters according to the step S3; determining fatigue damage according to the relation between the fatigue strain amplitude and the cycle life obtained in the step S2 and a fatigue strain evolution and rain flow method of creep fatigue test half life cycle; simultaneously determining creep damage by using a modified time fraction method according to the creep test key parameters and the relation thereof obtained in the step S3 and the creep strain energy dissipation rate evolution of the creep fatigue test half-life cycle; finally, the cycle life of the material under the creep fatigue load is predicted according to the fatigue damage and the creep damage by utilizing a linear damage accumulation rule.
From the results of fig. 2, 3 and 4, it can be seen whether P92 steel, 304 stainless steel or GH4169 alloy; no matter the creep fatigue test of strain control or stress-strain hybrid control, the service life predicted by the method is within 2 times of the error band. Therefore, the creep fatigue damage state judgment method of the electric power high-temperature component based on the corrected time fraction method has universality on test materials, creep fatigue loads and test temperatures.
EXAMPLE III
As shown in fig. 5, the present embodiment determines a continuous creep fatigue failure envelope by using the method for determining the damage state of a high-temperature power component based on the modified time fraction method according to the present invention.
Again, this example uses the same test data as example 1, followed by the relationship between fatigue strain amplitude and cycle life according to the strain control fatigue test results, according to step S2 of the present invention; secondly, determining a plurality of key parameters such as creep life, fracture strain, creep strain energy dissipation rate, critical creep strain energy dissipation rate and initial creep evolution and relations between the key parameters according to the step S3; determining fatigue damage according to the relation between the fatigue strain amplitude and the cycle life obtained in the step S2 and a fatigue strain evolution and rain flow method of creep fatigue test half life cycle; simultaneously determining creep damage by using a modified time fraction method according to the creep test key parameters and the relation thereof obtained in the step S3 and the creep strain energy dissipation rate evolution of the creep fatigue test half-life cycle; and finally, calculating the accumulated creep damage and the accumulated fatigue damage according to a large amount of creep fatigue failure data, thereby determining a continuous creep fatigue failure envelope curve.
As can be seen from the results of FIG. 5, from the creep fatigue failure data, the formula (14) in the specification can be obtained.
Example four
As shown in fig. 6, the present example employs a method for determining a damaged state of a high-temperature power component by a modified time fraction method according to the present invention, and determines the damaged state of a material at any time of a strain-controlled and stress-strain-mixed controlled creep fatigue load.
Again, this example uses the same test data as example 1, followed by the relationship between fatigue strain amplitude and cycle life according to the strain control fatigue test results, according to step S2 of the present invention; secondly, determining a plurality of key parameters such as creep life, fracture strain, creep strain energy dissipation rate, critical creep strain energy dissipation rate, initial creep evolution and the like and relations among the key parameters according to the step S3; determining fatigue damage according to the relation between the fatigue strain amplitude and the cycle life obtained in the step S2 and a fatigue strain evolution and rain flow method of the creep fatigue test in a half-life cycle; determining creep damage by using a correction time fraction method according to the creep test key parameters and the relation thereof obtained in the step S3 and the creep strain energy dissipation rate evolution of the creep fatigue test half-life cycle; and finally, calculating the accumulated fatigue and accumulated creep damage of any creep fatigue loaded component, and finally judging the creep fatigue damage state of the component by matching with the determined continuous creep fatigue failure envelope curve: if the damage state point is outside the envelope curve, the material is judged to be failed, otherwise, the material is judged not to be failed.
As can be seen from the results of fig. 6, the multiple test damage state points (including different creep fatigue loads) are located within the continuous creep fatigue failure envelope, indicating that the test point-corresponding test samples do not fail and conform to the actual damage state; and other points are positioned outside the envelope curve, which indicates that the test points corresponding to the test points fail and are consistent with the actual damage state. Therefore, the present invention can determine the damage state of the material at the creep fatigue and the time.
From the results of example two, example three and example four, it is seen that: by adopting the method, the cycle life of different materials under the strain control and stress-strain mixed control creep fatigue load can be predicted, and the prediction precision is stabilized within a two-time error band. In addition, based on the creep and fatigue damage of the present invention, a common creep fatigue damage envelope can be given, and based on this envelope, the damage state of the material at any time under the creep fatigue load can be determined.
The above description is only for the preferred embodiment of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present application should be covered within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (7)
1. A method for judging damage states of electric power high-temperature components based on a modified time fraction method is characterized by comprising the following steps:
obtaining a plurality of samples with the same material, and dividing the plurality of samples into a first part sample, a second part sample and a third part sample;
carrying out fatigue test on the first part of samples to obtain fatigue test data;
carrying out creep test on the second part of the test sample to obtain creep test data;
performing creep fatigue test on the third part of the test sample to obtain creep fatigue data;
acquiring fatigue damage parameters based on the fatigue test data, and acquiring creep damage parameters based on the creep test data;
acquiring the fatigue damage of the creep fatigue test based on the fatigue damage parameters and the fatigue behavior of the creep fatigue test; acquiring creep damage of the creep fatigue test based on the creep damage parameters and creep behavior of the creep fatigue test;
predicting a cycle life of a creep fatigue specimen based on the fatigue damage and the creep damage;
the total damage state of the power high-temperature component at any time is determined based on the accumulated fatigue damage and the accumulated creep damage.
2. The method for determining the damage state of the high-temperature electric component according to claim 1, wherein the method comprises the steps of obtaining fatigue damage parameters based on the fatigue test data and obtaining creep damage parameters based on the creep test data, and the method comprises the following steps:
obtaining a relation between a fatigue strain amplitude and a cycle life based on the fatigue test data;
obtaining key variables and relations among the key variables based on the creep test data, wherein the key variables comprise creep life, creep rupture strain, creep strain energy dissipation rate, critical creep strain energy dissipation rate and initial creep evolution.
3. The method for determining the damage state of the high-temperature power component based on the modified time fraction method as claimed in claim 2, wherein the method for obtaining the critical creep strain energy dissipation rate based on the creep test data comprises the following steps:
the critical creep strain energy dissipation rate
Determined according to the distribution of creep test points in a base-10 log-log coordinate system, wherein the abscissa of the log-log coordinate system is the creep strain energy dissipation rate ≥>
The ordinate is creep rupture strain ε f (ii) a Under the coordinate system, all creep test points show two possible trends; first, if the creep rupture strain ε f Always dissipating a rate of energy with the creep strain>
Is increased, it is deemed that there is no critical creep strain energy dissipation rate @>
Second, if the rate of energy dissipation is greater than or equal to creep strain>
Increase of (2) creep rupture strain ε f If a saturation value exists, the minimum creep strain energy dissipation rate corresponding to the saturation value is considered to be the critical creep strain energy dissipation rate->
4. The method of determining a damage state of a high-temperature power component according to claim 1, wherein the step of obtaining the fatigue damage of the creep fatigue test based on the fatigue damage parameter and the fatigue behavior of the creep fatigue test includes:
based on the relation between the fatigue strain amplitude and the cycle life and the evolution of the fatigue strain of the creep fatigue test half-life cycle along with time, a rain flow counting method is adopted to obtain the strain amplitude born in the actual loading process, and then the fatigue damage of the creep fatigue test is determined
As shown in the following formula: />
wherein Ni (Δε i ) For a strain amplitude of Δ ε i Cycle life of fatigue test, strain amplitude Δ ε i Determining the post-actual bearing strain amplitude, p, for rain flow methods i Is the magnitude of the strain Deltaε i The ratio of (a) to (b).
5. The method of determining a damaged state of a high-temperature power component according to claim 1, wherein the creep damage in the creep fatigue test is obtained based on the creep damage parameter and a creep behavior in the creep fatigue test, and the method includes:
obtaining a creep strain energy dissipation rate evolution rule based on the creep behavior of the creep fatigue test in a half-life cycle, wherein the creep strain energy dissipation rate evolution of indexes is followed by both the strain control creep fatigue test and the stress-strain hybrid control creep fatigue test, as shown in the following formula,
wherein 
Representing the creep strain energy dissipation rate at the moment of load retention t, p representing a dissipation rate evolution coefficient, and q representing a dissipation rate evolution index;
obtaining creep strain evolution term of correction time fraction method
As shown in the following formula:
wherein the creep coefficient C 1 Creep time dependent index C 2 The creep stress related index k is the creep damage parameter; the modulus of elasticity E is the basic property of the test material, the retention time t d And holding stress sigma of hybrid control creep fatigue test d Are all test conditions of creep fatigue test; relaxation stress of half life cycle of strain controlled creep fatigue test
Peak stress sigma of first week of strain controlled creep fatigue test 0 And creep strain for half life cycle of hybrid control creep fatigue test>
All are test data obtained by creep fatigue test;
obtaining creep strain energy dissipation rate related term R of modified time fraction method ENE As shown in the following formula:
wherein the stress-induced creep failure coefficient S, the stress-induced creep failure index n, and the failure coefficient E based on the dissipation rate of creep strain energy c And the failure index m based on the creep strain energy dissipation rate is the creep damage parameter sigma d (t) evolution of the holding stress over time, given by:
wherein the stress relaxation coefficient p r And stress relaxation index q r Obtaining by fitting a stress relaxation curve during strain holding; for hybrid control creep fatigue, the holding stress is a test input parameter and is constant, and is always kept at σ d ；
Evolution of creep strain
Term R related to creep strain energy dissipation rate ENE Multiplied to obtain fatigue damage in creep fatigue test>
As shown in the following formula:
6. the method of determining a damaged state of a high-temperature electric component according to claim 1, wherein the step of predicting the cycle life of a creep fatigue specimen based on the fatigue damage and the creep damage comprises:
and predicting the cycle life of the creep fatigue sample by utilizing a linear damage accumulation rule based on the fatigue damage and the creep damage.
7. The method of determining a damaged state of a high-temperature power component according to claim 1, wherein the method of determining a total damaged state of a high-temperature power component at any time based on the accumulated fatigue damage and the accumulated creep damage comprises:
accumulating according to cycle times based on the fatigue damage and the creep damage to obtain accumulated fatigue damage and accumulated creep damage so as to obtain a continuous creep fatigue failure envelope curve;
and calculating the accumulated fatigue damage and the accumulated creep damage of any creep fatigue loaded component, and finally judging the damage state of the creep fatigue loaded component at any time by using the continuous creep fatigue failure envelope: and if the damage state point is outside the failure envelope curve, judging that the material fails, otherwise, judging that the material does not fail.
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