Original fatigue quality evaluation method for notched component

Abstract

The invention provides an original fatigue quality evaluation method for a notched component, and relates to the technical field of reliability design. The method comprises the following steps: obtaining a long crack propagation threshold value of a notched component, a long crack propagation threshold value of a smooth component, a fatigue limit and elliptical geometric parameters of a fatigue source area based on test data of a crack propagation test and a high-cycle fatigue test on the notched component and the smooth component; the equivalent initial crack size of the smooth component is determined; determining equivalent circle parameters of a fatigue source area; determining a fatigue notch factor of the notched component according to the equivalent circle parameter of the fatigue source area, the elliptical geometric parameter of the fatigue source area and the equivalent initial crack size of the smooth component; and the equivalent initial crack size of the notched component is determined according to the long crack propagation threshold value, the geometrical shape factor and the fatigue notch factor of the notched component and the equivalent initial crack size of the smooth component. According to the invention, accurate original fatigue quality evaluation of notched components based on different hole making processes can be realized.

Description

Technical Field

[0001] The present disclosure relates to the technical field of reliability design, and particularly to a method for evaluating the original fatigue quality of a notched component, a device for evaluating the original fatigue quality of a notched component, and an electronic device. Background Art

[0002] The fatigue performance of mechanical structures such as airplanes, automobiles, and ships greatly affects their service performance and reliability. Fatigue failure is usually a process of gradual crack growth from areas with large original damage, following the sequence of microcracks, small cracks, and long cracks. For most components, the crack initiation stage occupies the majority of the fatigue life. The life of this stage not only varies depending on the material type but is also closely related to the randomness of original fatigue defects and manufacturing quality. These factors can be collectively referred to as the uncertain factors of the Initial Fatigue Quality (IFQ).

[0003] When analyzing the fatigue life of a structure, it is crucial to evaluate the original fatigue quality. In actual engineering, most components have notches, such as having circular holes on the surface. Compared with smooth components, the stress distribution of notched components is more complex. In related technologies, the accuracy of evaluating the original fatigue quality of notched components is limited, or the evaluation results strongly depend on test conditions, making it difficult to provide reference value for actual components. Summary of the Invention

[0004] The present disclosure provides a method for evaluating the original fatigue quality of a notched component, a device for evaluating the original fatigue quality of a notched component, and an electronic device, so as to improve the evaluation accuracy to at least a certain extent.

[0005] According to a first aspect of the present disclosure, there is provided a method for evaluating the original fatigue quality of a notched component, including: obtaining the long crack propagation threshold value of the notched component, the long crack propagation threshold value, fatigue limit, and elliptical geometric parameters of the fatigue source region of the smooth component based on the test data of crack propagation tests and high-cycle fatigue tests on the notched component and the smooth component; determining the equivalent initial crack size of the smooth component according to the long crack propagation threshold value and fatigue limit of the smooth component; determining the equivalent circle parameters of the fatigue source region according to the elliptical geometric parameters of the fatigue source region of the smooth component; determining the fatigue notch factor of the notched component according to the equivalent circle parameters of the fatigue source region, the elliptical geometric parameters of the fatigue source region, and the equivalent initial crack size of the smooth component; and determining the equivalent initial crack size of the notched component according to the long crack propagation threshold value, geometric shape factor, fatigue notch factor, and equivalent initial crack size of the smooth component of the notched component.

[0006] According to a second aspect of the present disclosure, there is provided an original fatigue quality evaluation device for a notched component, including: a first data processing module configured to obtain the long crack propagation threshold value of the notched component, the long crack propagation threshold value of the smooth component, the fatigue limit, and the elliptical geometric parameters of the fatigue source region of the smooth component based on the test data of crack propagation tests and high-cycle fatigue tests on the notched component and the smooth component; a second data processing module configured to determine the equivalent initial crack size of the smooth component according to the long crack propagation threshold value and the fatigue limit of the smooth component; a third data processing module configured to determine the equivalent circle parameters of the fatigue source region according to the elliptical geometric parameters of the fatigue source region of the smooth component; a fourth data processing module configured to determine the fatigue notch factor of the notched component according to the equivalent circle parameters of the fatigue source region, the elliptical geometric parameters of the fatigue source region, and the equivalent initial crack size of the smooth component; and a fifth data processing module configured to determine the equivalent initial crack size of the notched component according to the long crack propagation threshold value, the geometric shape factor, the fatigue notch factor of the notched component, and the equivalent initial crack size of the smooth component.

[0007] According to a third aspect of the present disclosure, there is provided a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, it implements the original fatigue quality evaluation method of the first aspect and its possible implementation manners.

[0008] According to a fourth aspect of the present disclosure, there is provided an electronic device, including: a processor; and a memory for storing executable instructions of the processor; wherein the processor is configured to execute the original fatigue quality evaluation method of the first aspect and its possible implementation manners by executing the executable instructions.

[0009] The technical solution of the present disclosure has the following beneficial effects:

[0010] On the one hand, a method for quickly calculating the EIFS value is provided, which can achieve efficient and accurate evaluation of the original fatigue quality of components, is applicable to notched components including air film hole structures, and can evaluate the original fatigue quality of notched components based on different hole-making processes. On the other hand, the evaluation results of this solution do not depend on test conditions. For example, corresponding evaluation results can be obtained for different stress conditions, and the fatigue quality dispersion law of components can be reflected, which has high reference value for the actual use of mechanical products. On the other hand, the test process is simple and the calculation amount is small, which is beneficial to reducing the implementation cost of the solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 A flowchart of an original fatigue quality evaluation method for a notched component in an exemplary embodiment is shown.

[0012] Figure 2 Schematic diagram showing the preparation of a notched member and a smooth member in this exemplary embodiment.

[0013] Figure 3 Schematic diagram showing the relationship between fatigue strength and fracture mechanics in this exemplary embodiment.

[0014] Figure 4A Showing the ΔK of the notched member based on the EDM process in this exemplary embodiment th,l,notch distribution map.

[0015] Figure 4B Showing the ΔK of the notched member based on the LDM process in this exemplary embodiment th,l,notch distribution map.

[0016] Figure 5 Showing the ΔK of the notched member based on different hole-making processes in this exemplary embodiment th,l,notch and the survival rate curve graph.

[0017] Figure 6 Showing the fracture surface morphology diagram of the smooth member in this exemplary embodiment.

[0018] Figure 7 Showing the fatigue limit diagram of the smooth member and the notched members based on two hole-making processes of EDM and LDM in this exemplary embodiment.

[0019] Figure 8 Showing the linear fitting diagram of the survival rate and the fatigue limit in this exemplary embodiment.

[0020] Figure 9 Showing the schematic diagram of the ellipse and the equivalent circle in the fatigue source area in this exemplary embodiment.

[0021] Figure 10 Showing the relationship diagram between the aspect ratio of the major and minor axes of the ellipse in the fatigue source area and the ratio of the stress intensity factor K of cracks with different geometric forms in this exemplary embodiment.

[0022] Figure 11 Showing the crack propagation curve graph in this exemplary embodiment.

[0023] Figure 12A Showing the EIFS values under different survival rates in this exemplary embodiment.

[0024] Figure 12B Showing the linear description of the notched member based on the EDM process under different survival rates and the crack geometry correction factor in this exemplary embodiment.

[0025] Figure 12CShows the linear description of the notched component based on the LDM process in different survival rates and crack geometry correction factors in this exemplary embodiment.

[0026] Figure 13 Shows a schematic structural diagram of an electronic device in this exemplary embodiment. Detailed implementation manners

[0027] The following will more comprehensively describe the exemplary embodiments of the present disclosure in conjunction with the accompanying drawings.

[0028] The accompanying drawings are schematic illustrations of the present disclosure and are not necessarily drawn to scale. Some of the block diagrams shown in the accompanying drawings may be functional entities and do not necessarily correspond to physically or logically independent entities. The embodiments can be implemented in various forms and should not be construed as limited to the examples set forth herein. The features, structures, or characteristics described in the present disclosure can be combined in any suitable manner in one or more embodiments. In the following description, many specific details are provided to give a full understanding of the embodiments of the present disclosure. However, those skilled in the art should be aware that one or more specific details may be omitted when implementing the technical solutions of the present disclosure, or other materials, methods, components, devices, steps, etc. may be used to replace one or more specific details.

[0029] The original fatigue quality assessment is an important part of reliability design. The original fatigue quality represents the original manufacturing state or original defect state of mechanical structure products such as airplanes, automobiles, and ships before they are put into use. EIFS (Equivalent Initial Flaw Size) takes into account the defects generated in the detailed structure of the material and the characteristics of the material, and EIFS can be used to characterize the original fatigue quality. EIFS is a hypothetical crack size. Assuming that this hypothetical crack exists in the structural details before being put into use, the EIFS distribution has the following characteristics: The EIFS distribution depends only on material properties, processing technology, and assembly state, and does not depend on usage conditions (such as spectra or stress levels). The data under different usage conditions can be used to deduce the same EIFS distribution (i.e., the "universal EIFS distribution"); The EIFS distribution is not the real physical defect or crack distribution in the original material, but a mathematical representative quantity of the original fatigue quality. However, after a certain period of hypothetical crack propagation starting from the EIFS distribution, it coincides with the real crack propagation.

[0030] Regarding the failure of components such as turbine single crystal blades to fracture, after analysis, it shows that most fractures are caused by surface quality defects of the blades and fatigue damage caused by film cooling holes. Therefore, understanding the EIFS situation of key parts for accurate original quality assessment helps to formulate a reasonable maintenance cycle and improve reliability.

[0031] In the related art, the EIFS distribution is obtained by the TTCI (Time To Crack Initiation) back-calculation method and the EIFS fitting method. Its disadvantages are that the experiment is complex, the calculation amount is large, and the cost is high. Although there are some other methods to obtain EIFS, which are closely related to the experimental conditions, it obviously violates the principle that EIFS is not related to the experimental conditions; moreover, the fatigue quality dispersion law of the specimen itself is not well demonstrated.

[0032] In view of one or more of the above problems, the exemplary embodiments of the present disclosure provide a method for evaluating the original fatigue quality of a notched component. Figure 1 The exemplary process of the method is shown and may include the following steps S110 to S150:

[0033] Step S110, based on the test data of crack propagation tests and high-cycle fatigue tests on the notched component and the smooth component, obtain the long crack propagation threshold value of the notched component, the long crack propagation threshold value, fatigue limit, and elliptical geometric parameters of the fatigue source region of the smooth component.

[0034] Step S120, determine the equivalent initial crack size of the smooth component according to the long crack propagation threshold value and fatigue limit of the smooth component;

[0035] Step S130, determine the equivalent circle parameters of the fatigue source region according to the elliptical geometric parameters of the fatigue source region of the smooth component;

[0036] Step S140, determine the fatigue notch factor of the notched component according to the equivalent circle parameters of the fatigue source region, the elliptical geometric parameters of the fatigue source region, and the equivalent initial crack size of the smooth component;

[0037] Step S150, determine the equivalent initial crack size of the notched component according to the long crack propagation threshold value, geometric shape factor, fatigue notch factor, and equivalent initial crack size of the smooth component of the notched component.

[0038] Based on Figure 1 The method shown, on the one hand, provides a method for quickly calculating the EIFS value, which can achieve efficient and accurate evaluation of the original fatigue quality of components, is applicable to notched components including air film hole structures, etc., and can evaluate the original fatigue quality of notched components based on different hole-making processes. On the other hand, the evaluation results of this solution do not depend on the experimental conditions. For example, corresponding evaluation results can be obtained for different stress conditions, and the fatigue quality dispersion law of the components can be reflected, which has a high reference value for the actual use of mechanical products. On the other hand, the test process is simple and the calculation amount is small, which is beneficial to reducing the implementation cost of the solution.

[0039] Next, for Figure 1Specifically describe each step in it.

[0040] In step S110, based on the test data of crack propagation tests and high-cycle fatigue tests on the notched component and the smooth component, the long crack propagation threshold value of the notched component, the long crack propagation threshold value of the smooth component, the fatigue limit, and the elliptical geometric parameters of the fatigue source region are obtained.

[0041] Among them, a notch refers to a discontinuous area on the outer surface of a component, such as a hole, etc. There is a notch on the outer surface of the notched component. For example, it can be a component simulating the film cooling hole structure of an aero turbine blade, and the notch is the film cooling hole. Due to the structural mutation at the notch part, stress concentration is likely to occur, which affects the original fatigue quality of the component. Correspondingly, a smooth component is a component without a notch. In this exemplary embodiment, the notched component and the smooth component are made of the same material and have the same or similar profiles and dimensions. For example, the notched component and the smooth component are made of the same metal or alloy material, both are in the shape of a cuboid, and the length, width, and height are equal. The difference is that there is an opening (i.e., a notch) on the outer surface of the notched component, and the outer surface of the smooth component is smooth and intact. This facilitates comparing the test results of the notched component and the smooth component to calculate the notch effect. The notch of the notched component can be prepared based on different hole-making processes, such as EDM (electrical discharge machining) process, LDM (laser) process, etc.

[0042] Figure 2 The schematic diagram of preparing test components is shown. The second-generation nickel-based single-crystal superalloy DD6 in China is used as the component material. After the unprocessed blank material is subjected to standard heat treatment to ensure equal primary orientations, two forms of flat parts are respectively made, including a pure rectangular flat part and a dog-bone-shaped flat part, so that as many test components as possible can be made on the same blank material with a limited size. Prepare a flat part without an opening as the smooth component, and prepare a flat part with an opening (such as simulating a film cooling hole) as the notched component. The hole-making processes can adopt two types: EDM and LDM. Exemplarily, the thickness of the rectangular flat part can be designed to be 0.8 mm, the diameter of the film cooling hole is 0.8 mm, the thickness of the dog-bone-shaped flat part is 1.0 mm, and the diameter of the film cooling hole is 0.5 mm.

[0043] The crack propagation test refers to applying cyclic stress to the component specimen and observing the crack propagation situation. The difference between the high-cycle fatigue test and the crack propagation test lies in the different number of times of applying cyclic stress. The number of times of cyclic stress in the crack propagation test is usually of the order of 10 5 magnitude, and the number of times of cyclic stress in the high-cycle fatigue test is usually of the order of 10 7The above magnitude. Table 1 shows the conditions of the crack propagation test and the high-cycle fatigue test. For the notched components prepared by the two hole-making processes, 5 sets of cyclic stresses are applied respectively at room temperature. For the smooth components, one or more sets of cyclic stresses are applied at room temperature. The frequency is 78 Hz; σ max represents the stress amplitude, that is, the maximum stress in cyclic loading. The stress ratio of 0.1 is adopted under all conditions, that is, the ratio of the minimum stress to the maximum stress in cyclic loading is 0.1. For each test condition, multiple effective specimens can be set to repeat the test to ensure the stability and accuracy of the test results.

[0044] Table 1

[0045]

[0046] During the test, the crack propagation of the component with the cyclic stress loading is detected, and the test data are recorded, including the crack size (a) under different stress cycle numbers (N), and the fatigue crack growth rate is calculated

[0047] According to the test data, the crack propagation threshold value, fatigue limit, and elliptical geometric parameters of the fatigue source area can be obtained. The crack propagation threshold value is described below.

[0048] The nucleation and propagation of cracks can generally be described according to the Griffith condition. The elastic relationship between the crack size a and the required stress σ can refer to the following formula (1):

[0049]

[0050] Among them, E represents the elastic modulus (MPa); q represents the surface energy (J·m -2 ).

[0051] The crack propagation threshold value refers to the alternating value of the stress intensity factor at which the component with cracks will not undergo fatigue propagation under alternating loads, denoted by ΔK th (or simply written as ΔK). In this exemplary embodiment, two crack propagation threshold values are considered, namely the intrinsic crack propagation threshold value, denoted by ΔK th,eff , and the long crack propagation threshold value, denoted by ΔK th,l .

[0052] Assume that there is a critical crack a 0 , such that when the actual crack length a < a 0 , the crack propagation threshold value decreases with the decrease of the crack length. When a > a 0 , the crack propagation threshold value is independent of the crack size. Further, a < a 0Generally represents the stage of small crack propagation. At this time, the stress state is difficult to be fully described by linear elasticity. For simplicity, the fatigue limit for different crack lengths can be linearly described. Refer to the following formula (2):

[0053]

[0054] El-Haddad et al. reported an interpretation model based on the K-T diagram (Kitagawa-Takahashi diagram) of linear elastic fracture mechanics, and proposed an arbitrary imaginary crack size a 0,l as the transition crack size to reflect the phenomenon that the fatigue limit increases with the decrease of the crack. Refer to the following formula (3):

[0055]

[0056] Among them, ΔK th,l represents the long crack propagation threshold value (MPa·m 0.5 ); Δσ e represents the fatigue limit (MPa); Y represents the crack geometry correction factor.

[0057] When the crack length a is significantly small, Δσ th = Δσ e , and Y = 1. At the same time, a 0,l can be regarded as the critical value of continuous crack propagation. There is the following relationship:

[0058]

[0059] Based on this, since the material cannot withstand high stress, local plastic damage occurs under repeated fatigue loads. Strain gradients are generated by dislocation pile-up, slip bands, intrusion and extrusion, resulting in local stress concentration to form internal stress. This explains why when the crack (or equivalent defect) size is less than a 0,l , and the nominal stress is greater than Δσ e , damage still causes component failure. Obviously, the conditions required by the crack propagation threshold value cannot be achieved in this region (the region where the crack size is less than a 0,l , and the nominal stress is greater than Δσ e ). Therefore, there may be another threshold value smaller than ΔK th,l in the stage of small crack propagation, that is, the intrinsic crack propagation threshold value ΔK th,eff .

[0060] Figure 3 The relationship between fatigue strength and fracture mechanics is described by multiple related curve graphs. Figure 3The da / dN-ΔK curve in [it] describes the propagation of long cracks. Shifting it forward in the direction of short crack propagation, based on the changes in the mechanical behavior of different crack propagation stages, the crack propagation successively experiences three stages: microstructural short cracks, mechanical short cracks, and long cracks, which are the three stages shown in the K-T diagram. In stage I, the crack size is only limited to a microscopic scale, and the crack sizes are generally arranged in the order of microstructural features such as grain size. Within this scale range, the microstructure becomes the dominant factor in crack propagation, and the corresponding crack driving force (or crack driving load) can be described by microstructural fracture mechanics. When the microstructure is insufficient to inhibit crack propagation, such as when the crack exceeds 1-2 grain sizes (as shown in stage II of the K-T diagram), the crack propagation is dominated by the surrounding grains, and the plastic zone size is too large, and for small cracks, most cannot be ignored. When the crack size is less than a 0,l , the ΔK of linear elastic fracture mechanics is not applicable th,l .

[0061] The microstructural mechanism has an important influence on the fatigue crack propagation of superalloys. In the case of relatively small defects, the propagation of shorter fatigue cracks needs to be considered. In addition to the influence of the plastic zone and the microstructure at the crack tip, the biggest difference between long cracks and short cracks is the influence of the closure effect. When using the fracture mechanics method to solve the EIFS value, the plastic zone of small cracks is involved, and the solution of the true stress intensity factor requires correction of the crack size. From the Figure 3 cyclic R curve, it can be seen that for a microstructural short crack to propagate, it must overcome the inherent crack propagation threshold of the material and structure, that is, the intrinsic crack propagation threshold ΔK th,eff , to enter stage II. In polycrystalline materials, a 0,l can be used as a characteristic size and regarded as the boundary point between long and short cracks, but this value is not conservative. The crack first needs to resist the influence of the microstructure, such as grain boundaries. At the same time, this is also the demarcation point between macroscopic cracks and microscopic cracks. For nickel-based single crystal materials (without grains), the characteristic size cannot be expressed by the grain size. Under the action of internal stress, cracks smaller than the critical crack size can still fracture within 10 7 cycles. If the critical crack size can be overcome, then a 0 can be used to describe the EIFS to solve the problem of evaluating different initial hole-making damages. When the crack size is small, the plastic zone is more likely to form. Generally speaking, under the same stress intensity factor, the plastic zone of a short crack is about 8 times that of a long crack, and may even be equivalent to the size of a short crack. Thus, it can be seen that the plastic zone plays an important role that cannot be ignored in the stress field of the elastic zone. Intrinsic crack propagation thresholds and long crack propagation thresholds are introduced at the two demarcation points of the entire crack respectively, corresponding to the crack propagation resistance curve (R curve). According to the different stress fields, the a 0 point is taken as the limit state of elastoplastic description.

[0062] In one embodiment, based on the test data of crack growth tests and high-cycle fatigue tests on notched components and smooth components, obtaining the long crack growth threshold value of the notched component, the long crack growth threshold value of the smooth component, the fatigue limit, and the elliptical geometric parameters of the fatigue source region may include the following steps:

[0063] Based on the test data of crack growth tests and high-cycle fatigue tests on the notched component, obtain the fatigue crack growth rate corresponding to different equivalent stress intensity factors;

[0064] Fit the test data with the fatigue crack growth rate within a preset numerical range, and obtain the long crack growth threshold value of the notched component and the long crack growth threshold value of the smooth component according to the fitting result.

[0065] Among them, the long crack growth threshold value ΔK th,l can be used as a material parameter, and ΔK under normal temperature conditions th,l can be used to calculate the EIFS of the smooth component.

[0066] Figure 4A Shows the ΔK eq -da / dN curve of the notched component based on the EDM process, Figure 4B shows the ΔK eq -da / dN curve of the notched component based on the LDM process. The abscissa in the figure is the equivalent stress intensity factor ΔK eq (MPa·m 0.5 ), which can be calculated through the stress (such as the stress amplitude σ max ) loaded in the crack growth test and high-cycle fatigue test and the dimensions of the notched component, etc. The ordinate is the fatigue crack growth rate da / dN (mm / cycle), that is, the crack growth length for each cycle of loading stress. By conducting crack growth tests and high-cycle fatigue tests on the notched component, the fatigue crack growth rate corresponding to different equivalent stress intensity factors can be obtained, forming the Figure 4A or Figure 4B data points. The figure shows the data of each effective specimen tested under different stress amplitudes at normal temperature. For example, "180-1" represents the data of effective specimen 1 tested with a stress amplitude of 180 MPa. The figure also shows the fitting region (Fitting zone) and fitting curve (Fitting curve) based on the survival rate (Ps). The fitting curve is an exponential fitting curve with an error band of 30% and a survival rate of 50%.

[0067] To establish a probability-based statistical model, the test data with the fatigue crack growth rate within a preset numerical range can be fitted. The preset numerical range can be determined according to specific requirements and can be an ideal numerical range for the fatigue crack growth rate, such as 10 -7 -10 -6 mm / cycle. Exemplarily, the test data with the fatigue crack growth rate within 10 -7 -10 -6 mm / cycle is fitted to obtain the long crack growth threshold values of the notched components based on the EDM process and the LDM process respectively. Figure 4A Shows the ΔK of the notched component based on the EDM process th,l,notch distribution map. Figure 4B Shows the ΔK of the notched component based on the LDM process th,l,notch distribution map.

[0068] In one embodiment, based on the test data of the crack growth test and the high-cycle fatigue test on the notched component, the fatigue crack growth rate corresponding to different equivalent stress intensity factors is obtained, including:

[0069] Based on the test data of the crack growth test and the high-cycle fatigue test on the notched component under normal temperature conditions, the fatigue crack growth rate corresponding to different equivalent stress intensity factors under normal temperature conditions is obtained.

[0070] Correspondingly, the above-mentioned fitting of the test data with the fatigue crack growth rate within a preset numerical range and obtaining the long crack growth threshold value of the notched component and the long crack growth threshold value of the smooth component according to the fitting result may include the following steps:

[0071] Fit the test data with the fatigue crack growth rate within a preset numerical range under normal temperature conditions to obtain the long crack growth threshold values of the notched component under different survival rates under normal temperature conditions;

[0072] Based on the Weibull probability distribution, fit the long crack growth threshold values of the notched component under different survival rates under normal temperature conditions to obtain the long crack growth threshold value of the smooth component under the target survival rate under normal temperature conditions.

[0073] Referring to the above Figure 4A or Figure 4B shown, based on the test data under normal temperature conditions, obtain the fatigue crack growth rate da / dN corresponding to different equivalent stress intensity factors ΔK eq under normal temperature conditions. Select the test data with the fatigue crack growth rate within a preset numerical range for fitting to obtain the long crack growth threshold value ΔK of the notched component under different survival rates under normal temperature conditions th,l,notch , based on the ΔK of the notched component with different hole-making processesth,l,notch The curve related to the survival rate can be referred to Figure 5 as shown

[0074] To make full use of the data, the crack growth data of notched components under normal temperature conditions are used for the calculation of the long crack growth threshold value of smooth components, which can simplify the test process. Due to the dispersion of test results and the size of the influence zone at the hole edge, the long crack growth threshold value at a relatively high survival rate (such as 99.9%) is generally selected as the long crack growth threshold value of smooth components. Exemplarily, the ΔK th,l obtained at different survival rates satisfies the three-parameter Weibull (Weibull 3P) probability distribution, referring to the following formula:

[0075]

[0076] where P represents the survival rate, and α, β, and γ are the parameters of the three-parameter Weibull probability distribution. The values of α, β, and γ can be obtained by the least variance fitting, as shown in Table 2. As mentioned above, the long crack growth threshold value ΔK of smooth components under normal temperature conditions can be obtained at a 99% survival rate th,l,smooth is approximately 1.93 MPa·m 0.5 .

[0077] Table 2

[0078]

[0079] In one embodiment, the smooth component can be tested under normal temperature conditions, and the test data can be fitted to obtain the long crack growth threshold value ΔK of the smooth component th,l,smooth .

[0080] The fatigue limit and the elliptical geometric parameters of the fatigue source region are described below

[0081] The EIFS value of the notched component (such as the air film hole) is smaller than a 0,l which can ensure the structural safety. Assuming that the of the smooth component is transformed, the safe EIFS can be obtained as From this, the corresponding safe fatigue limit is solved as:

[0082]

[0083] The above formula can be further rewritten as:

[0084] Δσ 0 = A·a M (7)

[0085] where A is a constant closely related to the material. Taking the logarithm of equations (6) and (7) respectively and differentiating with respect to lna, we get:

[0086]

[0087] Furthermore, the following relationships can be obtained:

[0088]

[0089] When a = a 0 at this time, To determine the fatigue limit actually corresponding to the crack size, Equation (6) can be rewritten as:

[0090]

[0091] Based on a large number of test results, the value of m can be obtained as -1 / 3 or -1 / 6.

[0092] Figure 6 The fracture morphology diagram of the smooth component is shown. It can be seen that the overall fracture presents three distinct fracture ranges: namely, the fatigue source area at the geometric size mutation, the crack propagation area (with obvious fatigue striations), and the instantaneous fracture and tearing area (the protruding ductile fracture surface). The fatigue source area can be approximated as an ellipse or a semi-ellipse (such as Figure 6 approximating the fatigue source area as a semi-ellipse in ). By measuring the geometric dimensions of the fatigue source area, etc., the elliptical geometric parameters of the fatigue source area can be obtained. The elliptical geometric parameters of the fatigue source area can include the major semi-axis, minor semi-axis length, and the ratio of the major axis to the minor axis of the ellipse in the fatigue source area.

[0093] In the initial stage of hole making, the early crack propagation is strongly affected by the crack-free microstructure of the material. The survival rate can be introduced to obtain the P-S-N (survival rate - stress amplitude - life) curve, which can better reflect the data discreteness compared with the S-N curve. To eliminate the interference of factors such as the original material processing factors and the geometric dimensions of the component, the fatigue limit test of the smooth component under normal temperature conditions is carried out by the staircase method to obtain the fatigue limit of the smooth component.

[0094] Figure 7 The fatigue limit diagrams of the smooth component and the notched components based on two hole-making processes, EDM and LDM, are shown. The solid line in the middle of the figure is the fatigue limit fitting line of the notched component based on the EDM process at different survival rates, from bottom to top are the fatigue limits at 99.99%, 50%, and 0.01% survival rates respectively. The dotted line in the middle of the figure is the fatigue limit fitting line of the notched component based on the LDM process at different survival rates, from bottom to top are the fatigue limits at 99.99%, 50%, and 0.01% survival rates respectively. Referring to Figure 7 as shown, at a 50% survival rate, the Δσ of the smooth component e is 377.6 MPa (L in the figure sHorizontal line), under the same test environment, the fatigue limits of notched components based on EDM and LDM processes are 55.113 MPa and 47.0 MPa respectively at a survival rate of 99.99% and a confidence level of 95%; while at a survival rate of 50% and a confidence level of 95%, the Δσ of notched components for both processes e are 59.2 MPa and 47.6 MPa respectively (L in the figure e and L l horizontal line). Assuming that the fatigue life under the same stress level satisfies the normal distribution, considering five survival rates of 0.01%, 20%, 50%, 80% and 99.99%, the relationship between the survival rate and the fatigue limit is obtained by linear fitting, which can be referred to Figure 8 as shown. It can be seen that the survival rate and the fatigue limit approximately satisfy a linear relationship, and the fitting curves are y = 65.235 - 10.523x and y = 51.368 - 5.062x respectively, and the range of EDM is greater than that of LDM.

[0095] Based on the linear expression of the stress intensity factor, for any object with a surface crack of size a, under a uniaxial remote tensile stress σ ∞ perpendicular to the crack plane, the stress intensity factor can be written as where F is the geometric correction factor of the actual specimen. For a crack in the notched stress field, the stress intensity solution is asymptotically the same as that of a surface crack in a smooth solid, except that the remote stress is amplified by the stress concentration factor K t = σ max / σ ∞ . Therefore, when a → 0, there is the following relationship:

[0096]

[0097] where F 0 represents the geometric factor of the surface crack of the smooth component. For a crack located in the notched stress field, the asymptotic solution of the geometric factor F is:

[0098] F = F 0 K t (12)

[0099] When the crack extends beyond the notched stress field, the remote stress field dominates the stress intensity factor, which can be expressed by Equation (13):

[0100]

[0101] where d is the notch depth. The following Equation (14) can be further obtained:

[0102]

[0103] In the formula, F ∞is the reference geometric factor. When d / a << 1, F can asymptotically approach a constant, i.e., F = F 0 . At this time, the upper and lower bound values of the geometric factor F are F 0 , F 0 K t . Using these asymptotic solutions, a simple formula for the geometric factor F caused by the notch root of any size can be established.

[0104] For a through crack located at the notch root, the geometric factor F of the "equivalent" surface crack depth is restricted by the upper and lower asymptotes, such that 1 < F / F 0 <K t . The geometric factor F can be written as:

[0105]

[0106] where D is the "equivalent" surface crack depth, which can be determined by the following formula:

[0107]

[0108] where

[0109] The general formula for the asymptotic solution of the stress intensity factor can be expressed as:

[0110]

[0111] It should be noted that after introducing a notch, the fatigue limits of smooth and notched components can no longer be simply calculated based on K t because the "similarity" of the high-stress material surface cannot be satisfied. The fatigue notch factor is defined as K f , that is, the effective stress concentration factor, and the specific expression is:

[0112]

[0113] where σ smooth,e represents the fatigue limit of the smooth component, and σ notch,e represents the fatigue limit of the notched component.

[0114] To consider the fatigue notch effect, it is assumed that the smooth component has a semi-circular micro-notch with a length of the same order of magnitude as the EIFS. The following is a detailed discussion of the fatigue notch factor using the asymptotic stress intensity factor solution and the ElFS model. Considering the asymptotic solution of the notch crack, when the applied stress intensity factor is equal to the stress intensity factor threshold value, the smooth component reaches the fatigue limit σ smooth,e , and introducing a finite geometric correction factor, there is the following relationship:

[0115]

[0116] Among them, a represents the conservative EIFS crack size (mm) of the smooth component; d r represents the equivalent size of the microdefects in the fatigue source region of the smooth component (mm); α represents the geometric correction factor for a crack length of a + d in a specimen of finite size, which can be obtained from the Anderson fracture mechanics handbook or finite element calculations.

[0117] Similarly, the fatigue limit σ notch,e and the stress intensity factor threshold value K th,notch of the notched component are related as follows:

[0118]

[0119] In the formula, d n represents the true notch size (mm).

[0120] By combining equations (18) to (20), we can obtain:

[0121]

[0122] It should be understood that EIFS is usually several orders of magnitude smaller than the specimen size (such as microns relative to millimeters or higher orders of magnitude), and equation (21) can be simplified to:

[0123]

[0124] When , that is, when the equivalent size of the microdefects is much larger than EIFS, K f = 1, and the notch effect can be ignored at this time; when , that is, when the equivalent size of the microdefects is much smaller than EIFS, K f = K t .

[0125] Continuing to refer to Figure 1 , in step S120, according to the long crack propagation threshold value and fatigue limit of the smooth component, the equivalent initial crack size of the smooth component is determined.

[0126] As mentioned above, the EIFS of the smooth component can be calculated through or .

[0127] Continuing to refer to Figure 1 , in step S130, according to the elliptical geometric parameters of the fatigue source region of the smooth component, the equivalent circular parameters of the fatigue source region are determined.

[0128] The inclusion area (or microdefects) in the fatigue source region can be approximated as an ellipse or a semi-ellipse, that is, the actual "EIFS" is in a two-dimensional state. The ellipse or semi-ellipse is approximately transformed into an equivalent circle, the equivalent circle parameters are determined, and the "equivalent" dimensionality reduction of EIFS is realized.

[0129] In one embodiment, the elliptical geometric parameters of the fatigue source region include: the length of the major semi-axis and the length of the minor semi-axis of the ellipse when the fatigue source region is approximated as an ellipse or a semi-ellipse; the equivalent circle parameters of the fatigue source region include: the radius of the equivalent circle.

[0130] Reference Figure 9 As shown, considering an elliptical crack with a minor semi-axis a and a major semi-axis c embedded in an infinite solid, subjected to a uniform tension σ perpendicular to the plane of the fatigue source region (xz plane). The geometric correction factor for a crack size of a + d is F(α). According to the Anderson handbook, the stress intensity factor for a semi-elliptical crack can be:

[0131]

[0132] The above formula can be simplified to:

[0133]

[0134] From the equal area formula, α can be expressed as (a / r) 2 , then the ratio relationship of the stress intensity factors between the two geometric forms of the ellipse and the equivalent circle is:

[0135]

[0136] Reference Figure 10 As shown, comparing the stress intensity factors K of cracks in different geometric forms, the results show that the maximum ratio between the two is about 1.091, and at this time α = 0.489; at the same time, when α varies between 0.2 - 1, K 椭 / K 圆 The magnitude of the ratio changes by only within 9.1%. By observing the actual value of α of the smooth component, K 圆 and the crack radius length r (i.e., the radius of the equivalent circle) after dimensionality reduction of the crack size can be determined, and it is regarded as d r .

[0137] Continuing to refer to Figure 1 , in step S140, according to the equivalent circle parameters of the fatigue source region, the elliptical geometric parameters of the fatigue source region, and the equivalent initial crack size of the smooth component, the fatigue notch factor of the notched component is determined.

[0138] For notched components, the original K-T diagram obtained using smooth components cannot describe the crack initiation and propagation behavior because crack initiation and propagation are affected not only by the inherent defects of the material but also by the stress concentration of the geometric dimensions. Refer to Figure 11 As shown, the inherent defects of the material are regarded as a 0,l , when there is a central sharp crack, a 0,l can reflect the crack initiation behavior of the component. Under the action of the notch, when fatigue sensitivity is not considered, the equivalent defect value of the notched component can be further expressed as:

[0139]

[0140] where is the fatigue notch factor, including the inherent defect factor Y of the material and the actual geometric factor of the notch (before the crack appears) and a 0,l is obtained when Y is 1.

[0141] In one implementation, the fatigue notch factor of the notched component can be calculated by the following formula:

[0142]

[0143] where F(a) represents the fatigue notch factor, a represents the crack size, c represents the notch size, such as the radius of a circular hole notch, W represents the width of the notched component, which can be the size of the notched component along the crack propagation direction, and l = a + c.

[0144] Continue to refer to Figure 1 , in step S150, determine the equivalent initial crack size of the notched component according to the long crack propagation threshold value, geometric shape factor, fatigue notch factor, and equivalent initial crack size of the smooth component of the notched component.

[0145] In one implementation, determining the equivalent initial crack size of the notched component according to the long crack propagation threshold value, geometric shape factor, fatigue notch factor, and equivalent initial crack size of the smooth component of the notched component may include the following steps:

[0146] Determine the intrinsic crack propagation threshold value of the notched component according to the long crack propagation threshold value and material properties of the notched component;

[0147] Determine the equivalent initial crack size of the notched component according to the intrinsic crack propagation threshold value, geometric shape factor, fatigue notch factor, and equivalent initial crack size of the smooth component of the notched component.

[0148] where, when considering the non-conservative EIFS value of the real specimen, there is the following relationship:

[0149]

[0150] By using the plane (intrinsic) fatigue limit Δσ smooth,e and the functional relationship of the strongest microstructure hindrance size d, the minimum intrinsic resistance (microstructure threshold ΔK th,eff ) for microcrack propagation is defined. Refer to the following functional expression:

[0151]

[0152] To consider the temperature sensitivity of the nickel-based single crystal microstructure and the fact that the two phases are cut differently according to different temperatures, d here can be defined as the size of the matrix phase or the strengthening phase at different temperatures, which depends on in which component phase the dislocations first appear. Further, it can be obtained that:

[0153]

[0154] where ΔK th,eff,notch represents the intrinsic crack propagation threshold value of the notched component, ΔK th,l,notch represents the long crack propagation threshold value of the notched component, d represents the strongest microstructure hindrance size determined by the material properties of the notched component. For nickel-based single crystals, this size can be the size of the matrix phase or the strengthening phase, and a 0,l represents the transition crack size determined by the smooth component. The intrinsic crack propagation threshold value of the notched component can be calculated by Equation (30).

[0155] Refer to Figure 11 As shown, the corrected K-T of the real specimen can be described as a parallel segment, indicating the macroscopic crack nucleation difference under the action of the notch crack coupling coefficient. For an ideal pure notch structure, the critical notch depth a p for long crack initiation is the intersection of ΔK th,l and Δσ ZM[[th,] / K t , that is:

[0156]

[0157] The actual critical notch depth is:

[0158]

[0159] Considering the notch sensitivity during crack propagation, the critical notch depth a p for long crack initiation is the intersection of ΔK th,l and Δσ ZM[[th,] λ / K t , refer to Figure 13 As shown. At this time, Equations (31) and (32) can be rewritten as:

[0160]

[0161] Since the size of the plastic zone cannot be ignored within this scale range of the crack, for simplicity, the plastic zone at the crack tip in the two-dimensional mode can be corrected to meet the conditions of linear elastic fracture mechanics. The size of the effective plastic zone r of the nickel-based single crystal material e can be obtained through experiments and numerical solutions with a very high degree of coincidence. Greater plasticity will occur on the surface of the component relative to the interior. When the two-dimensional anisotropic material is in a plane stress state (z = 0), the stress and displacement on both sides of the hole can be determined by the following formula:

[0162]

[0163] When the structure and load are symmetric about the x-axis and y-axis, the above formula can be further expressed as:

[0164]

[0165] Based on the finite element results of nickel-based single crystals combined with the Dugdale model and the Antolovich model, the following relationship is obtained:

[0166]

[0167] In one implementation, determining the equivalent initial crack size of the notched component based on the intrinsic crack growth threshold value, geometric shape factor, fatigue notch factor, and equivalent initial crack size of the smooth component of the notched component may include the following steps:

[0168] Determine the safe fatigue limit of the smooth component based on the equivalent initial crack size and fatigue limit of the smooth component;

[0169] Calculate the equivalent initial crack size of the notched component through the following formula:

[0170]

[0171] where EIFS mod,notch represents the equivalent initial crack size of the notched component, K t / λ represents the fatigue notch factor of the notched component, ΔK th,eff represents the intrinsic crack growth threshold value of the notched component, η represents the plastic zone correction coefficient of the notched component, Δσ 0 represents the safe fatigue limit of the smooth component, and F(aη) represents the geometric shape factor of the notched component, which can be calculated through Equation (27).

[0172] By further deriving Equation (37), we can obtain:

[0173]

[0174] It should be noted that ΔK th,eff is essentially a basic property of the material. For the same process, ΔK th,eff can be regarded as unchanged. However, for different processes and different temperatures, especially in the evaluation of notched (film cooling hole) components prepared by different hole-making processes, the material properties at the hole edge change, resulting in ΔK th,eff not being consistent. At this time, it needs to be evaluated separately. The EIFS of the notched component determined under normal temperature conditions can be used to further deduce ΔK under different temperature conditions th,eff .

[0175] Figure 12A The EIFS values at different survival rates are shown Figure 12B A linear description of the notched component based on the EDM process at different survival rates and the crack geometry correction factor is shown Figure 12C A linear description of the notched component based on the LDM process at different survival rates and the crack geometry correction factor is shown. As Figure 12A shown, the EIFS values of the notched components prepared by the two hole-making processes of EDM and LDM are quite different. At a 95% confidence level and a 50% survival rate, the EIFS value of EDM is about 0.022 mm, while that of LDM is about 0.047 mm. According to the test data satisfying different survival rates (0 - 100%), the EIFS value of EDM is between 0.0188 - 0.0273 mm, while that of LDM is between 0.0423 - 0.0530 mm. When a certain definite stress is applied, the calculated EIFS interval range will be further reduced, and the interval changes of EDM and LDM are generally within 0.01 mm. It should be noted that when considering three stress levels (the stress level changes by more than 20%), the interval peaks (the maximum and minimum values) of EIFS only increase by about 2% respectively. Compared with the common calculation method in which the EIFS value is closely related to the stress magnitude, this change trend can be ignored. At different survival rates, there is a strong linear relationship between the EIFS value and the survival rate and between the crack geometry correction factor, and the crack geometry correction factor also only changes slightly (such as in Figure 12B , F remains at about 1.53). After determining the specific correlation function, it is more valuable for the universality of predicting EIFS in engineering practice

[0176] An exemplary embodiment of the present disclosure also provides an original fatigue quality evaluation device for a notched component. The device may include the following program modules

[0177] The first data processing module is configured to obtain the long crack propagation threshold value of the notched component, the long crack propagation threshold value of the smooth component, the fatigue limit, and the elliptical geometric parameters of the fatigue source region of the smooth component based on the test data of crack propagation tests and high-cycle fatigue tests on the notched component and the smooth component;

[0178] The second data processing module is configured to determine the equivalent initial crack size of the smooth component according to the long crack propagation threshold value and the fatigue limit of the smooth component;

[0179] The third data processing module is configured to determine the equivalent circular parameters of the fatigue source region according to the elliptical geometric parameters of the fatigue source region of the smooth component;

[0180] The fourth data processing module is configured to determine the fatigue notch factor of the notched component according to the equivalent circular parameters of the fatigue source region, the elliptical geometric parameters of the fatigue source region, and the equivalent initial crack size of the smooth component;

[0181] The fifth data processing module is configured to determine the equivalent initial crack size of the notched component according to the long crack propagation threshold value, the geometric shape factor, the fatigue notch factor, and the equivalent initial crack size of the smooth component of the notched component.

[0182] In one implementation manner, based on the test data of crack propagation tests and high-cycle fatigue tests on the notched component and the smooth component, obtaining the long crack propagation threshold value of the notched component, the long crack propagation threshold value of the smooth component, the fatigue limit, and the elliptical geometric parameters of the fatigue source region of the smooth component includes: based on the test data of crack propagation tests and high-cycle fatigue tests on the notched component, obtaining the fatigue crack growth rate corresponding to different equivalent stress intensity factors; fitting the test data with the fatigue crack growth rate within a preset numerical range, and obtaining the long crack propagation threshold value of the notched component and the long crack propagation threshold value of the smooth component according to the fitting result.

[0183] In one embodiment, based on the test data of crack growth tests and high-cycle fatigue tests on notched components, the fatigue crack growth rates corresponding to different equivalent stress intensity factors are obtained, including: based on the test data of crack growth tests and high-cycle fatigue tests on notched components under normal temperature conditions, the fatigue crack growth rates corresponding to different equivalent stress intensity factors under normal temperature conditions are obtained; the test data with the fatigue crack growth rate within a preset numerical range are fitted, and according to the fitting results, the long crack growth threshold value of the notched component and the long crack growth threshold value of the smooth component are obtained, including: the test data with the fatigue crack growth rate within a preset numerical range under normal temperature conditions are fitted to obtain the long crack growth threshold values of the notched component at different survival rates under normal temperature conditions; based on the Weibull probability distribution, the long crack growth threshold values of the notched component at different survival rates under normal temperature conditions are fitted to obtain the long crack growth threshold value of the smooth component at the target survival rate under normal temperature conditions.

[0184] In one embodiment, according to the long crack growth threshold value of the notched component, the geometric shape factor, the fatigue notch factor, and the equivalent initial crack size of the smooth component, the equivalent initial crack size of the notched component is determined, including: according to the long crack growth threshold value of the notched component and the material properties, the intrinsic crack growth threshold value of the notched component is determined; according to the intrinsic crack growth threshold value of the notched component, the geometric shape factor, the fatigue notch factor, and the equivalent initial crack size of the smooth component, the equivalent initial crack size of the notched component is determined.

[0185] In one embodiment, according to the long crack growth threshold value of the notched component and the material properties, the intrinsic crack growth threshold value of the notched component is determined, including: calculating the intrinsic crack growth threshold value of the notched component through the following formula:

[0186]

[0187] where ΔK th,eff,notch represents the intrinsic crack growth threshold value of the notched component, ΔK th,l,notch represents the long crack growth threshold value of the notched component, d represents the size of the strongest microstructural obstacle determined by the material properties of the notched component, and a 0,l represents the transition crack size determined by the smooth component.

[0188] In one embodiment, according to the intrinsic crack growth threshold value of the notched component, the geometric shape factor, the fatigue notch factor, and the equivalent initial crack size of the smooth component, the equivalent initial crack size of the notched component is determined, including: according to the equivalent initial crack size of the smooth component and the fatigue limit, the safe fatigue limit of the smooth component is determined; calculating the equivalent initial crack size of the notched component through the following formula:

[0189]

[0190] Among them, EIFS mod,notch represents the equivalent initial crack size of the notched component, and K t / λ represents the fatigue notch factor of the notched component, and ΔK th,eff represents the intrinsic crack growth threshold of the notched component, η represents the plastic zone correction factor of the notched component, and Δσ 0 represents the safe fatigue limit of the smooth component, and F(aη) represents the geometric shape factor of the notched component.

[0191] In one embodiment, the elliptical geometric parameters of the fatigue source region include: the major semi-axis length and the minor semi-axis length of the ellipse when the fatigue source region is approximated as an ellipse or a semi-ellipse; the equivalent circle parameters of the fatigue source region include: the equivalent circle radius; determining the equivalent circle parameters of the fatigue source region according to the elliptical geometric parameters of the fatigue source region of the smooth component, including: calculating the equivalent circle parameters of the fatigue source region through the following formula:

[0192]

[0193]

[0194] Among them, a represents the minor semi-axis length of the ellipse, c represents the major semi-axis length of the ellipse, α represents the ratio of the major axis to the minor axis of the ellipse, σ represents the vertical tension received by the fatigue source region, and r represents the equivalent circle radius.

[0195] In one embodiment, determining the fatigue notch factor of the notched component according to the equivalent circle parameters of the fatigue source region, the elliptical geometric parameters of the fatigue source region, and the equivalent initial crack size of the smooth component, including: calculating the fatigue notch factor of the notched component through the following formula:

[0196]

[0197] Among them, F(a) represents the fatigue notch factor, a represents the crack size, c represents the notch size, W represents the width of the notched component, and l = a + c.

[0198] The specific details of each part in the above device have been described in detail in the embodiments of the method part. The details not disclosed can be referred to the content of the embodiments in the method part, and thus will not be elaborated here.

[0199] Exemplary embodiments of the present disclosure also provide a computer-readable storage medium, which can be implemented in the form of a program product, including program code. When the program product runs on an electronic device, the program code is used to cause the electronic device to execute the steps according to various exemplary embodiments of the present disclosure described in the "Exemplary Method" section above in this specification. In an alternative embodiment, the program product can be implemented as a portable compact disc read-only memory (CD-ROM) and includes program code, and can run on an electronic device, such as a personal computer. However, the program product of the present disclosure is not limited thereto. In this document, the readable storage medium can be any tangible medium that contains or stores a program, and the program can be used by or in combination with an instruction execution system, apparatus, or device.

[0200] The program product can adopt any combination of one or more readable media. The readable media can be a readable signal medium or a readable storage medium. The readable storage medium can be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination of the above. More specific examples (non-exhaustive list) of the readable storage medium include: an electrical connection having one or more wires, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0201] The computer-readable signal medium can include a data signal propagated in a baseband or as part of a carrier wave, in which the readable program code is carried. Such a propagated data signal can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. The readable signal medium can also be any readable medium other than the readable storage medium, and the readable medium can send, propagate, or transmit a program for use by or in combination with an instruction execution system, apparatus, or device.

[0202] The program code contained on the readable medium can be transmitted by any suitable medium, including but not limited to wireless, wired, optical fiber, RF, etc., or any suitable combination of the above.

[0203] Program code for performing the operations of the present disclosure can be written in any combination of one or more programming languages, including object-oriented programming languages such as Java, C++, etc., and also including conventional procedural programming languages such as the "C" language or similar programming languages. The program code can be executed entirely on the user's computing device, partially on the user's device, executed as a stand-alone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server. In cases involving a remote computing device, the remote computing device can be connected to the user's computing device through any type of network, including a local area network (LAN) or a wide area network (WAN), or, alternatively, can be connected to an external computing device (e.g., by connecting through the Internet using an Internet service provider).

[0204] Exemplary embodiments of the present disclosure also provide an electronic device, which may include a processor and a memory. The memory stores executable instructions for the processor, such as program code. The processor executes the methods in the exemplary embodiments by executing the executable instructions. In addition, the electronic device may further include a display for displaying a graphical user interface.

[0205] Reference is made below Figure 13 to an electronic device in the form of a general-purpose computing device for exemplary illustration. It should be understood that Figure 13 the electronic device 1300 shown is merely an example and should not impose limitations on the functions and scope of use of the embodiments of the present disclosure.

[0206] As Figure 13 shown, the electronic device 1300 may include: a processor 1310, a memory 1320, a bus 1330, an I / O (input / output) interface 1340, a network adapter 1350, and a display 1360.

[0207] The memory 1320 may include volatile memory, such as RAM 1321 and a cache unit 1322, and may also include non-volatile memory, such as ROM 1323. The memory 1320 may further include one or more program modules 1324, and such program modules 1324 include but are not limited to: an operating system, one or more application programs, other program modules, and program data. Implementations of a network environment may be included in each or some combination of these examples. For example, the program module 1324 may include the respective modules in the above-mentioned device.

[0208] The processor 1310 may include one or more processing units. For example, the processor 1310 may include an AP (Application Processor), a modem processor, a GPU (Graphics Processing Unit), an ISP (Image Signal Processor), a controller, an encoder, a decoder, a DSP (Digital Signal Processor), a baseband processor, and / or an NPU (Neural-Network Processing Unit), etc.

[0209] The processor 1310 can be used to execute the executable instructions stored in the memory 1320, such as executing any one or more of the method steps in this exemplary embodiment.

[0210] The bus 1330 is used to implement connections between different components of the electronic device 1300 and may include a data bus, an address bus, and a control bus.

[0211] The electronic device 1300 can communicate with one or more external devices 1400 (such as a keyboard, a mouse, an external controller, etc.) through the I / O interface 1340.

[0212] The electronic device 1300 can communicate with one or more networks through the network adapter 1350. For example, the network adapter 1350 can provide mobile communication solutions such as 3G / 4G / 5G, or provide wireless communication solutions such as a wireless local area network, Bluetooth, and near field communication. The network adapter 1350 can communicate with other modules of the electronic device 1300 through the bus 1330.

[0213] The electronic device 1300 can display a graphical user interface through the display 1360, such as displaying an experimental data processing interface, etc.

[0214] Although Figure 13 not shown in the figure, other hardware and / or software modules can also be provided in the electronic device 1300, including but not limited to: microcode, device drivers, redundant processors, external disk drive arrays, RAID systems, tape drives, and data backup storage systems, etc.

[0215] It should be noted that although several modules or units of a device for action execution are mentioned in the above detailed description, this division is not mandatory. In fact, according to the exemplary embodiments of the present disclosure, the features and functions of two or more modules or units described above can be embodied in one module or unit. Conversely, the features and functions of one module or unit described above can be further divided and embodied by multiple modules or units.

[0216] Those skilled in the art can understand that various aspects of the present disclosure can be implemented as a system, a method, or a program product. Therefore, various aspects of the present disclosure can be specifically implemented in the following forms, namely: a complete hardware implementation, a complete software implementation (including firmware, microcode, etc.), or an implementation combining hardware and software aspects, which can be collectively referred to as "circuitry", "module", or "system" here. Those skilled in the art will readily think of other embodiments of the present disclosure after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present disclosure, which follow the general principles of the present disclosure and include the well-known common knowledge or conventional technical means in the technical field not disclosed in the present disclosure. The specification and embodiments are only regarded as exemplary, and the true scope and spirit of the present disclosure are pointed out by the claims.

[0217] It should be understood that the present disclosure is not limited to the exact structures already described and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the present disclosure is only defined by the appended claims.

Claims

1. A method for evaluating the original fatigue quality of a notched component, characterized in that: include: Based on the test data of crack propagation test and high cycle fatigue test on notched components and smooth components, the long crack propagation threshold value of the notched components, the long crack propagation threshold value, fatigue limit and fatigue source zone ellipse geometric parameters of the smooth components are obtained; Determining the equivalent initial crack size of the smooth component according to the long crack extension threshold value and fatigue limit of the smooth component; Determining the equivalent circle parameters of the fatigue source area according to the ellipse geometric parameters of the fatigue source area of ​​the smooth component; Determining the fatigue notch factor of the notched component according to the equivalent circle parameters of the fatigue source area, the ellipse geometric parameters of the fatigue source area, and the equivalent initial crack size of the smooth component; The equivalent initial crack size of the notched component is determined according to the long crack extension threshold value of the notched component, the geometric shape factor, the fatigue notch factor, and the equivalent initial crack size of the smooth component.

2. The method according to claim 1, characterized in that The long crack extension threshold value of the notched component, the long crack extension threshold value of the smooth component, the fatigue limit, and the fatigue source zone ellipse geometric parameters are obtained based on the test data of the crack extension test and the high cycle fatigue test on the notched component and the smooth component, including: Based on the test data of crack growth test and high cycle fatigue test on notched components and smooth components, the fatigue crack growth rate corresponding to different equivalent stress intensity factors is obtained; The test data of fatigue crack growth rate within a preset value range are fitted, and the long crack growth threshold value of the notched component and the long crack growth threshold value of the smooth component are obtained according to the fitting results.

3. The method according to claim 2, characterized in that The fatigue crack growth rates corresponding to different equivalent stress intensity factors are obtained based on the test data of crack growth tests and high cycle fatigue tests on notched components and smooth components, including: Based on the test data of crack growth test and high cycle fatigue test on notched components at room temperature, the fatigue crack growth rate corresponding to different equivalent stress intensity factors at room temperature is obtained; The test data with fatigue crack growth rate within a preset value range are fitted, and the long crack growth threshold value of the notched component and the long crack growth threshold value of the smooth component are obtained according to the fitting results, including: Fitting the test data of fatigue crack growth rate within a preset value range under normal temperature conditions to obtain the long crack growth threshold value of the notched component under different survival rates under normal temperature conditions; Based on the Weibull probability distribution, the long crack extension threshold values ​​of the notched component at different survival rates under normal temperature conditions are fitted to obtain the long crack extension threshold value of the smooth component at the target survival rate under normal temperature conditions.

4. The method according to claim 1, characterized in that Determining the equivalent initial crack size of the notched component according to the long crack extension threshold value of the notched component, the geometric shape factor, the fatigue notch factor, and the equivalent initial crack size of the smooth component includes: Determining an intrinsic crack extension threshold value of the notched component according to the long crack extension threshold value and material properties of the notched component; The equivalent initial crack size of the notched component is determined according to the intrinsic crack extension threshold value of the notched component, the geometric shape factor, the fatigue notch factor, and the equivalent initial crack size of the smooth component.

5. The method according to claim 4, characterized in that Determining the intrinsic crack extension threshold value of the notched component according to the long crack extension threshold value and material properties of the notched component includes: The intrinsic crack extension threshold of the notched component is calculated by the following formula: Among them, ΔK th,eff,notch represents the intrinsic crack extension threshold of the notched component, ΔK th,l,notch represents the long crack extension threshold of the notched component, d represents the strongest microstructural barrier size determined by the material properties of the notched component, a 0,l represents the transition crack size determined by the smooth component.

6. The method according to claim 4, characterized in that Determining the equivalent initial crack size of the notched component according to the intrinsic crack extension threshold value of the notched component, the geometric shape factor, the fatigue notch factor, and the equivalent initial crack size of the smooth component includes: Determining the safety fatigue limit of the smooth component according to the equivalent initial crack size and fatigue limit of the smooth component; The equivalent initial crack size of the notched component is calculated by the following formula: Among them, EIFS mod,notch represents the equivalent initial crack size of the notched component, K t / λ represents the fatigue notch factor of the notched component, ΔK th,eff represents the intrinsic crack extension threshold value of the notched component, η represents the plastic zone correction coefficient of the notched component, Δσ0 represents the safety fatigue limit of the smooth component, and F(aη) represents the geometric shape factor of the notched component.

7. The method according to claim 1, characterized in that The fatigue source area ellipse geometric parameters include: the length of the major semi-axis and the minor semi-axis when the fatigue source area is approximated as an ellipse or a semi-ellipse; the fatigue source area equivalent circle parameters include: the equivalent circle radius; the fatigue source area equivalent circle parameters are determined according to the fatigue source area ellipse geometric parameters of the smooth component, including: The equivalent circle parameters of the fatigue source area are calculated by the following formula: Among them, a represents the length of the minor axis of the ellipse, c represents the length of the major axis of the ellipse, α represents the ratio of the major and minor axes of the ellipse, σ represents the vertical tension in the fatigue source area, and r represents the equivalent circle radius.

8. The method according to claim 1, characterized in that The step of determining the fatigue notch factor of the notched component according to the equivalent circle parameter of the fatigue source area, the ellipse geometric parameter of the fatigue source area, and the equivalent initial crack size of the smooth component comprises: The fatigue notch factor of the notched component is calculated by the following formula: Wherein, F(a) represents fatigue notch factor, a represents crack size, c represents notch size, W represents width of the notched component, and l=a+c.

9. An original fatigue quality assessment device for a notched component, characterized in that: include: A first data processing module is configured to obtain a long crack extension threshold value of the notched component, a long crack extension threshold value of the smooth component, a fatigue limit, and a fatigue source zone ellipse geometric parameter based on test data of crack extension tests and high cycle fatigue tests on notched components and smooth components; A second data processing module is configured to determine an equivalent initial crack size of the smooth component according to a long crack extension threshold value and a fatigue limit of the smooth component; A third data processing module is configured to determine the fatigue source area equivalent circle parameters according to the fatigue source area ellipse geometric parameters of the smooth component; a fourth data processing module, configured to determine the fatigue notch factor of the notched component according to the fatigue source area equivalent circle parameter, the fatigue source area ellipse geometric parameter, and the equivalent initial crack size of the smooth component; The fifth data processing module is configured to determine the equivalent initial crack size of the notched component according to the long crack extension threshold value of the notched component, the geometric shape factor, the fatigue notch factor, and the equivalent initial crack size of the smooth component.

10. An electronic device, characterized in that: include: processor; A memory, configured to store executable instructions of the processor; The processor is configured to perform the method according to any one of claims 1 to 8 by executing the executable instructions.

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