CN113361092A - Simple and convenient evaluation method and system for fatigue crack propagation behavior of material - Google Patents

Simple and convenient evaluation method and system for fatigue crack propagation behavior of material Download PDF

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CN113361092A
CN113361092A CN202110609180.3A CN202110609180A CN113361092A CN 113361092 A CN113361092 A CN 113361092A CN 202110609180 A CN202110609180 A CN 202110609180A CN 113361092 A CN113361092 A CN 113361092A
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fatigue crack
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CN113361092B (en
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朱明亮
轩福贞
庄彬彬
朱刚
王宇超
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East China University of Science and Technology
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Abstract

The invention relates to the technical field of fatigue crack propagation, in particular to a simple and convenient evaluation method, a system and a medium for material fatigue crack propagation behavior. The invention provides a simple and convenient evaluation method for the fatigue crack propagation behavior of a material, which comprises the following steps: step S1, acquiring a standard fatigue crack propagation curve; step S2, obtaining the stress intensity factor range delta K of the turning point under any stress ratio RT(R)(ii) a Step S3, obtaining a prediction curve of the Paris area; step S4, obtaining the expansion rate (da/dN) of the turning point of the fatigue crack expansion curveT(R)(ii) a Step S5, obtaining a fatigue threshold value delta K of a fatigue crack propagation curve under the stress ratio Rth(R)(ii) a Step S6, obtaining an evaluation curve of a near threshold value area; step S7, obtaining a fatigue crack propagation curve under the stress ratio R, and carrying out fatigue crackPredictive evaluation of extended behavior. The method takes a small amount of experimental data as a support, accurately predicts the crack propagation behavior under any stress ratio, and avoids the complicated process of multiple experiments.

Description

Simple and convenient evaluation method and system for fatigue crack propagation behavior of material
Technical Field
The invention relates to the technical field of fatigue crack propagation, in particular to a simple and convenient evaluation method, a system and a medium for material fatigue crack propagation behavior.
Background
Fatigue failure is one of the most common failure modes in the engineering field, and most mechanical structures are subjected to alternating loads under actual working conditions.
Statistically, mechanical structural damage due to fatigue accounts for 50-90%, and fatigue cracks are generally sudden fractures without significant plastic deformation, which is extremely dangerous to personnel and property safety. The fatigue damage of the mechanical structure is reasonably predicted and evaluated, and potential safety hazards caused by the fatigue damage can be effectively prevented.
A fatigue crack propagation (FCG) curve is a curve that describes the stress intensity factor range Δ K of a crack during propagation versus the propagation rate da/dN.
Typical long crack FCG curves are characterized by a fatigue crack propagation threshold Δ KthAnd fracture toughness Δ KICThe boundary is divided into three stages.
In particular, in 1963, Paris proposed a famous Paris formula on the basis of a fracture mechanics method to describe the fatigue crack propagation law.
The specific expression of Paris's formula is:
Figure BDA0003094882320000011
wherein C is a correlation coefficient, and m is a power law exponent.
From the form of the Paris formula, the FCG curve is a straight line in a log-log coordinate system. However, through numerous subsequent studies, it was found that the FCG curve is generally in the FCG curveThe second stage presents a bilinear relationship, and fig. 1 shows a typical fatigue crack propagation curve, as shown in fig. 1, according to the turning point Δ KTThe FCG curve may be divided into a Paris zone and a near threshold zone.
The FCG curve is generally evaluated by a bilinear model and a single-linear model, and compared with the bilinear model, the bilinear model can better reflect the real condition of the fatigue crack propagation behavior of the material, and the evaluation level of the bilinear model is more credible and accurate. A reasonable and reliable bilinear model is established and is the key for evaluating whether the result is credible.
In the existing design standards, such as standards like ASME, JSME, FEM, etc., only the most conservative single linear model is specified, and the situations of different stress ratios are not considered, thereby causing the waste of material performance.
Under some rare special working conditions, the existing standard based on an empirical formula cannot effectively predict and evaluate the crack propagation behavior of the material. If the material is under some comparatively extreme operating modes, the cost of experiment is too high, and large-scale experimental determination is too time-consuming and laborious.
Therefore, at present, no simple and accurate method for predicting and evaluating the fatigue crack propagation behavior of the material exists.
Disclosure of Invention
The invention aims to provide a simple and convenient evaluation method, a system and a medium for the fatigue crack propagation behavior of a material, and solves the problems of low accuracy and high test cost of the prediction and evaluation of the fatigue crack propagation behavior of the existing material.
In order to achieve the above object, the present invention provides a simple method for evaluating fatigue crack propagation behavior of a material, comprising the following steps:
step S1, acquiring a standard fatigue crack propagation curve under a specified stress ratio;
step S2, according to the turning point of the reference fatigue crack propagation curve, obtaining the stress intensity factor range delta K of the turning point of the fatigue crack propagation curve under any stress ratio RT(R)；
Step S3, obtaining a prediction curve of the Paris area;
step S4, the stress intensity factor range Delta K of the turning point under the stress ratio R of the step S2T(R)Substituting the prediction curve of the Paris area in the step S3 to obtain the expansion rate (da/dN) of the turning point of the fatigue crack expansion curveT(R)；
Step S5, obtaining a fatigue threshold value delta K of the fatigue crack propagation curve under the stress ratio R according to the fatigue threshold value of the reference fatigue crack propagation curveth)R)；
Step S6, connecting the threshold point under the stress ratio R obtained in step S5 with the turning point under the stress ratio R obtained in step S2 to obtain an evaluation curve of a near threshold region;
and step S7, combining the prediction curve of the Paris area obtained in step S3 and the evaluation curve of the near-threshold area obtained in step S6, and taking the coordinates of the turning point under the stress ratio R obtained in step S2 and step S4 as a boundary to obtain a fatigue crack propagation curve under the stress ratio R, and performing prediction and evaluation on the fatigue crack propagation behavior.
In one embodiment, in the step S1, the reference fatigue crack growth curve at the stress ratio R0 is specified as the fatigue crack growth curve at the stress ratio R0 equal to 0.9.
In one embodiment, in the step S2, the stress intensity factor range Δ K of the turning point of the fatigue crack propagation curve under any stress ratio RT(R)The corresponding expression is:
Figure BDA0003094882320000031
wherein, Δ KT(0.9)The stress intensity factor range of the turning point of the reference fatigue crack propagation curve. In an embodiment, the prediction curve of the Paris zone in step S3 corresponds to the following expression:
(da/dN)＝C0(exp(αR)ΔK)m；
wherein α is a constant associated with the material, C0Is the correlation coefficient of the reference fatigue crack propagation curve, m is the power law index of the reference fatigue crack propagation curve, and delta K is the stress intensityThe range of degree factors.
In one embodiment, the fatigue threshold Δ K in step S5th(R)The corresponding expression is:
Figure BDA0003094882320000032
wherein, Δ Kth(R0)A fatigue threshold value of a reference fatigue crack propagation curve;
a (R) is a first parameter related to stress ratio R;
b (R) is a second parameter related to the stress ratio R.
In one embodiment, the fatigue threshold Δ K in step S5th(R)The corresponding expression is:
Figure BDA0003094882320000033
wherein, Δ Kth(0.9)A fatigue threshold value of a reference fatigue crack propagation curve;
A(R)＝0.14+0.24R2+0.83R3；
B(R)＝0.9-R。
in one embodiment, the fatigue threshold Δ K isthThat means that the fatigue crack growth rate da/dN is 1X 10-7mm/cyc, corresponding stress intensity factor range values.
In order to achieve the above object, the present invention provides a simple evaluation system for fatigue crack propagation behavior of a material, comprising:
a memory for storing instructions executable by the processor;
a processor for executing the instructions to implement the method of any one of the above.
To achieve the above object, the present invention provides a computer readable medium having stored thereon computer instructions, wherein the computer instructions, when executed by a processor, perform the method as described in any one of the above.
According to the simple evaluation method, the system and the medium for the fatigue crack propagation behavior of the material, provided by the invention, the crack propagation behavior under any stress ratio is accurately predicted by taking a small amount of experimental data as a support according to the internal rule of an FCG curve, the defect of relevant standards can be filled by the evaluation method, and meanwhile, the complicated process of multiple experiments is avoided.
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The above and other features, properties and advantages of the present invention will become more apparent from the following description of the embodiments with reference to the accompanying drawings in which like reference numerals denote like features throughout the several views, wherein:
FIG. 1 shows a typical fatigue crack propagation graph;
FIG. 2 is a flow chart of a short-cut evaluation method of fatigue crack growth behavior of a material according to an embodiment of the invention;
FIG. 3 is a graph showing the effect of a short-cut evaluation of fatigue crack growth behavior of a material according to an embodiment of the present invention;
FIG. 4 shows a schematic block diagram of a short-cut evaluation system for fatigue crack propagation behavior of a material according to an embodiment of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The invention provides a simple and convenient evaluation method, a system and a medium for a material fatigue crack propagation behavior, and relates to a simplified method for a fatigue crack propagation curve under any stress ratio and a conservative evaluation method for a threshold value.
Fig. 2 shows a flowchart of a brief evaluation method for a material fatigue crack propagation behavior according to an embodiment of the present invention, and as shown in fig. 2, the brief evaluation method for a material fatigue crack propagation behavior proposed by the present invention includes the following steps:
s1, acquiring a reference fatigue crack propagation curve under the specified stress ratio R0;
step S2, according to the turning point of the reference fatigue crack propagation curve, obtaining the stress intensity factor range delta K of the turning point of the fatigue crack propagation curve under any stress ratio RT(R)；
Step S3, obtaining a prediction curve of the Paris area;
step S4, the stress intensity factor range Delta K of the turning point under the stress ratio R of the step S2T(R)Substituting the prediction curve of the Paris area in the step S3 to obtain the expansion rate (da/dN) of the turning point of the fatigue crack expansion curveT(R)；
Step S5, obtaining a fatigue threshold value delta K of the fatigue crack propagation curve under the stress ratio R according to the fatigue threshold value of the reference fatigue crack propagation curveth(R)；
Step S6, connecting the fatigue threshold point under the stress ratio R obtained in the step S5 with the turning point under the stress ratio R obtained in the step S2 to obtain an evaluation curve of a near threshold region;
and step S7, combining the prediction curve of the Paris area obtained in step S3 and the evaluation curve of the near-threshold area obtained in step S6, and taking the coordinates of the turning point under the stress ratio R obtained in step S2 and step S4 as a boundary to obtain a fatigue crack propagation curve under the stress ratio R, and performing prediction and evaluation on the fatigue crack propagation behavior.
Further, in the prediction curve of the Paris zone in step S3, the corresponding expression is:
(da/dN)＝C0(exp(aR)ΔK)m；
wherein α is a constant associated with the material, C0Is the correlation coefficient of the standard fatigue crack propagation curve, m is the power law index of the standard fatigue crack propagation curve, and delta K is the range of the stress intensity factor.
Further, the fatigue threshold Δ K in step S5th(R)The corresponding expression is:
Figure BDA0003094882320000051
wherein, Δ Kth(R0)A fatigue threshold value of a reference fatigue crack propagation curve;
a (R) is a first parameter related to stress ratio R;
b (R) is a second parameter related to the stress ratio R.
In the present embodiment, the fatigue crack growth threshold value Δ K is as shown in fig. 1thThat means that the fatigue crack growth rate da/dN is 1X 10-7mm/cyc, corresponding stress intensity factor range value delta K.
R represents stress ratio, which is the ratio of the minimum stress and the maximum stress in the test. Generally, a difference in stress ratio has a relatively large influence on the fatigue crack propagation curve (FCG curve).
In a preferred embodiment, in step S1, the reference fatigue crack growth curve at the stress ratio R0 is specified as the fatigue crack growth curve at the stress ratio R0 of 0.9. When the stress ratio R0 is set to be 0.9, the crack closing effect can be ignored, and on the basis of the crack closing effect, a semi-empirical prediction formula for fitting the turning point and threshold value prediction can be derived by combining a crack closing theory.
The following describes in detail the simple evaluation method of the fatigue crack growth behavior of a material according to the present invention, using the FCG curve with R0 ═ 0.9 as the reference fatigue crack growth curve.
And step S1, acquiring a reference fatigue crack propagation curve under the specified stress ratio R0.
A reference FCG curve of a certain material under a specified service condition of R0-0.9 is obtained through experiments, and fatigue crack propagation behavior of the material under any stress ratio under the condition is evaluated on the basis of the reference FCG curve.
Step S2, according to the turning point of the reference fatigue crack propagation curve, obtaining the stress intensity factor range delta K of the turning point of the fatigue crack propagation curve under any stress ratio RT(R)。
The transition point of the FCG curve under any stress ratio R corresponds to the stress intensity factorSub-range Δ KT(R)The method can be predicted by an inflection point prediction model considering the crack closure effect, and the corresponding expression is as follows:
Figure BDA0003094882320000061
wherein, Δ KT(R)The inflection point at any stress ratio,
ΔKT(0.9)the turning point of the reference FCG curve when R is 0.9 corresponds to the range of stress intensity factors.
And step S3, acquiring a prediction curve of the Paris area.
For the plot of Paris zone, due to its characteristic of small slope change, it can be predicted by the following formula:
(da/dN)＝C0(exp(aR)ΔK)m；
wherein α is a constant associated with the material, C0The correlation coefficient of the reference FCG curve at 0.9 is R0, m is the power law index of the reference FCG curve at 0.9 is R0, and Δ K is the stress intensity factor range.
Step S4, the stress intensity factor range Delta K of the turning point under the stress ratio R of the step S2T(R)' substitution into the prediction curve of Paris region of step S3, obtaining the propagation rate (da/dN) of the inflection point of the fatigue crack propagation curveT(R)。
As shown in FIG. 1, the ordinate (da/dN) for the turning pointT(R)Since the turning point is in the near threshold region and Paris region at the same time, the stress ratio R is divided into delta KT(R)By substituting the plot in the Paris region (da/dN)T(R)。
Step S5, obtaining a fatigue threshold value delta K of the fatigue crack propagation curve under the stress ratio R according to the fatigue threshold value of the reference fatigue crack propagation curveth(R)。
Fatigue threshold value delta K of FCG curve under any stress ratio Rth(R)Its prediction model can also be by Δ Kth(0.9)The conversion is obtained, and the corresponding expression is as follows:
Figure BDA0003094882320000071
wherein: Δ Kth(0.9)The fatigue threshold value of the reference FCG curve under the condition that R0 is 0.9;
A(R)＝0.14+0.24R2+0.83R3；
B(R)＝0.9-R。
step S6, connecting the fatigue threshold point under the stress ratio R obtained in step S5 with the inflection point under the stress ratio R obtained in step S2, and obtaining an evaluation curve in the near-threshold region.
As shown in FIG. 1, the threshold point Δ K at the stress ratio R is obtained by joint predictionth(R)And turning point delta KT(R)The evaluation curve of the near-threshold region can be obtained.
And step S7, combining the prediction curve of the Paris zone obtained in step S3 and the evaluation curve of the near-threshold zone obtained in step S6, and taking the coordinate of the turning point under the stress ratio R obtained in step S2 and step S4 as a boundary, so as to obtain a bilinear curve, namely, the fatigue crack propagation behavior prediction curve under the stress ratio R, and perform prediction evaluation on the fatigue crack propagation behavior.
The following presents a brief evaluation method of fatigue crack propagation behavior of a material according to the present invention with specific examples.
The 25Cr2Ni2MoV steel is a common material of a steam turbine rotor, and the steam turbine rotor is always subjected to fatigue load in the operation process and is also influenced by fatigue damage in the process of continuously starting and stopping. Therefore, the fatigue performance evaluation of the 25Cr2Ni2MoV steel is significant for the safe and stable operation of the steam turbine set.
The FCG curve of the 25Cr2Ni2MoV steel welding joint base metal under the condition that R is 0.3 is predicted and evaluated by the simple evaluation method provided by the invention.
In the example, the FCG curve of the base material of the 25Cr2Ni2MoV steel weld joint was set to 0.3.
The data of step S1 specifying the reference fatigue crack propagation curve at a stress ratio R0 of 0.9 is shown in table 1 below:
TABLE 1
Near threshold region Paris region
m＝5.2795，InC＝-20.2572 m＝2.73，InC＝-17.4993
Calculating the turning point at which R is 0.9
Figure BDA0003094882320000081
The threshold value when R is 0.9 is
Figure BDA0003094882320000082
C is the correlation coefficient of the standard fatigue crack propagation curve, and m is the power law index of the standard fatigue crack propagation curve.
In step S2, the stress intensity factor range Δ K of the FCG curve turning point when R is 0.3T(0.3)By Δ KT(0.9)It can be calculated that:
Figure BDA0003094882320000083
in step S3, if the constant α associated with the material is 0.45, then:
when R is 0.3, the plot of Paris area is
(da/dN)＝9.103E-9(exp(0.45*0.3)ΔK)2.73。
Step S4, since the turning point is also a point on the Paris area, the Δ K in step S2T(0.3)The Paris field in step S3 is substituted to obtain the corresponding R ═ 0.3Rate of expansion of the transition point of the FCG curve:
(da/dN)T(0.3)＝2.723385×10-6mm/cycle。
in step S5, the threshold value of the FCG curve at R ═ 0.3 can be obtained from the threshold value data of the reference FCG curve at R ═ 0.9:
Figure BDA0003094882320000091
step S6, connecting the turning point and the threshold point when R is 0.3, to obtain an evaluation curve of the FCG curve near the threshold region when R is 0.3;
when R is 0.3, the corresponding expression is: (da/dN) =6.94662E-14(Δ K)8.95066。
In step S7, when R is equal to the evaluation curve of the near-threshold region of the FCG curve in step S3, the evaluation effect is shown in fig. 3, and it can be seen that the predicted data is very consistent with the experimental data.
FIG. 4 shows a block diagram of a short-cut evaluation system for fatigue crack propagation behavior of a material according to an embodiment of the invention. A straightforward evaluation system for material fatigue crack propagation behavior may include an internal communication bus 501, a processor 502, a Read Only Memory (ROM)503, a Random Access Memory (RAM)504, a communication port 505, and a hard disk 507. The internal communication bus 501 may enable data communication between components of a straightforward evaluation system for fatigue crack propagation behavior of a material. The processor 502 may make the determination and issue the prompt. In some embodiments, the processor 502 may be comprised of one or more processors.
The communication port 505 can realize data transmission and communication between a simple evaluation system of the fatigue crack propagation behavior of the material and an external input/output device. In some embodiments, a straightforward evaluation system of material fatigue crack propagation behavior may send and receive information and data from a network through the communication port 505. In some embodiments, a short-cut evaluation system of material fatigue crack propagation behavior may communicate and transmit data between the input/output end 506 and an external input/output device in a wired manner.
The straightforward evaluation system of the fatigue crack propagation behavior of a material may also comprise different forms of program storage units as well as data storage units, such as a hard disk 507, a Read Only Memory (ROM)503 and a Random Access Memory (RAM)504, capable of storing various data files for computer processing and/or communication use, as well as possible program instructions executed by the processor 502. The processor 502 executes these instructions to implement the main parts of the method. The results processed by the processor 502 are transmitted to an external output device through the communication port 505 and displayed on the user interface of the output device.
For example, the implementation process file of the above-mentioned brief evaluation method for material fatigue crack propagation behavior may be a computer program, stored in the hard disk 507, and recorded in the processor 502 for execution, so as to implement the method of the present application.
When the implementation process file of the simple evaluation method for the fatigue crack propagation behavior of the material is a computer program, the implementation process file can also be stored in a computer readable storage medium as a product. For example, computer-readable storage media can include but are not limited to magnetic storage devices (e.g., hard disk, floppy disk, magnetic strips), optical disks (e.g., Compact Disk (CD), Digital Versatile Disk (DVD)), smart cards, and flash memory devices (e.g., electrically Erasable Programmable Read Only Memory (EPROM), card, stick, key drive). In addition, various storage media described herein can represent one or more devices and/or other machine-readable media for storing information. The term "machine-readable medium" can include, without being limited to, wireless channels and various other media (and/or storage media) capable of storing, containing, and/or carrying code and/or instructions and/or data.
According to the simple evaluation method, the system and the medium for the fatigue crack propagation behavior of the material, provided by the invention, the crack propagation behavior under any stress ratio is accurately predicted by taking a small amount of experimental data as a support according to the internal rule of an FCG curve so as to fill the defect of standard design and avoid the complicated process of multiple experiments.
While, for purposes of simplicity of explanation, the methodologies are shown and described as a series of acts, it is to be understood and appreciated that the methodologies are not limited by the order of acts, as some acts may, in accordance with one or more embodiments, occur in different orders and/or concurrently with other acts from that shown and described herein or not shown and described herein, as would be understood by one skilled in the art.
As used in this application and the appended claims, the terms "a," "an," "the," and/or "the" are not intended to be inclusive in the singular, but rather are intended to be inclusive in the plural unless the context clearly dictates otherwise. In general, the terms "comprises" and "comprising" merely indicate that steps and elements are included which are explicitly identified, that the steps and elements do not form an exclusive list, and that a method or apparatus may include other steps or elements.
Those of skill would further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
The embodiments described above are provided to enable persons skilled in the art to make or use the invention and that modifications or variations can be made to the embodiments described above by persons skilled in the art without departing from the inventive concept of the present invention, so that the scope of protection of the present invention is not limited by the embodiments described above but should be accorded the widest scope consistent with the innovative features set forth in the claims.

Claims (9)

1. A simple and direct evaluation method for the fatigue crack propagation behavior of a material is characterized by comprising the following steps:
s1, acquiring a reference fatigue crack propagation curve under the specified stress ratio R0;
step S2, according to the turning point of the reference fatigue crack propagation curve, obtaining the stress intensity factor range delta K of the turning point of the fatigue crack propagation curve under any stress ratio RT(R)；
Step S3, obtaining a prediction curve of the Paris area;
step S4, the stress intensity factor range Delta K of the turning point under the stress ratio R of the step S2T(R)Substituting the prediction curve of the Paris area in the step S3 to obtain the expansion rate (da/dN) of the turning point of the fatigue crack expansion curveT(R)；
Step S5, obtaining a fatigue threshold value delta K of the fatigue crack propagation curve under the stress ratio R according to the fatigue threshold value of the reference fatigue crack propagation curveth(R)；
Step S6, connecting the fatigue threshold point under the stress ratio R obtained in the step S5 with the turning point under the stress ratio R obtained in the step S2 to obtain an evaluation curve of a near threshold region;
and step S7, combining the prediction curve of the Paris area obtained in step S3 and the evaluation curve of the near-threshold area obtained in step S6, and taking the coordinates of the turning point under the stress ratio R obtained in step S2 and step S4 as a boundary to obtain a fatigue crack propagation curve under the stress ratio R, and performing prediction and evaluation on the fatigue crack propagation behavior.
2. The short-cut evaluation method of the fatigue crack propagation behavior of the material according to claim 1, characterized in that:
in step S1, the reference fatigue crack growth curve at the stress ratio R0 is specified as a fatigue crack growth curve at a stress ratio R0 of 0.9.
3. The short-cut evaluation method of material fatigue crack propagation behavior according to claim 2,
in step S2, the stress intensity factor range Δ K of the inflection point of the fatigue crack propagation curve under any stress ratio RT(R)Corresponding expression is：
Figure FDA0003094882310000021
Wherein, Δ KT(0.9)The stress intensity factor range of the turning point of the reference fatigue crack propagation curve.
4. The short-cut evaluation method of material fatigue crack propagation behavior according to claim 1,
in the prediction curve of the Paris zone in the step S3, the corresponding expression is:
(da/dN)＝C0(exp(αR)ΔK)m；
wherein α is a constant associated with the material, C0Is the correlation coefficient of the standard fatigue crack propagation curve, m is the power law index of the standard fatigue crack propagation curve, and delta K is the range of the stress intensity factor.
5. The short-cut evaluation method of material fatigue crack propagation behavior according to claim 1,
the fatigue threshold value Δ K in step S5th(R)The corresponding expression is:
Figure FDA0003094882310000022
wherein, Δ Kth(R0)A fatigue threshold value of a reference fatigue crack propagation curve;
a (R) is a first parameter related to stress ratio R;
b (R) is a second parameter related to the stress ratio R.
6. The short-cut evaluation method of material fatigue crack propagation behavior according to claim 2,
the fatigue threshold value Δ K in step S5th(R)The corresponding expression is:
Figure FDA0003094882310000023
wherein, Δ Kth(0.9)A fatigue threshold value of a reference fatigue crack propagation curve;
A(R)＝0.14+0.24R2+0.83R3；
B(R)＝0.9-R。
7. the method for the short-cut evaluation of the fatigue crack growth behavior of the material according to claim 1, wherein the fatigue threshold value Δ K isthThat means that the fatigue crack growth rate da/dN is 1X 10-7mm/cyc, corresponding stress intensity factor range values.
8. A simple evaluation system for fatigue crack propagation behavior of a material comprises:
a memory for storing instructions executable by the processor;
a processor for executing the instructions to implement the method of any one of claims 1-7.
9. A computer readable medium having computer instructions stored thereon, wherein the computer instructions, when executed by a processor, perform the method of any of claims 1-7.
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102778404A (en) * 2012-06-19 2012-11-14 中国人民解放军空军工程大学 Metal structure fatigue crack propagation life prediction method based on material R curve
US20130333481A1 (en) * 2011-03-04 2013-12-19 The Japan Steel Works, Ltd. Method of determining fatigue crack lifetime in high-pressure hydrogen environment
CN103760007A (en) * 2014-01-16 2014-04-30 清华大学 Method for predicting fatigue crack expanding threshold value under different stress ratios

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20130333481A1 (en) * 2011-03-04 2013-12-19 The Japan Steel Works, Ltd. Method of determining fatigue crack lifetime in high-pressure hydrogen environment
CN102778404A (en) * 2012-06-19 2012-11-14 中国人民解放军空军工程大学 Metal structure fatigue crack propagation life prediction method based on material R curve
CN103760007A (en) * 2014-01-16 2014-04-30 清华大学 Method for predicting fatigue crack expanding threshold value under different stress ratios

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
李继山;赵军;李和平;林祜亭;: "锻钢制动盘疲劳裂纹扩展速率试验研究", 铁道机车车辆, no. 05 *

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