Method for original fatigue quality evaluation of notched members

Abstract

The present disclosure provides a method for evaluating the original fatigue quality of a notched member, and relates to the technical field of reliability design. The method comprises the following steps: obtaining a long crack propagation threshold value of the notched member, a long crack propagation threshold value, a fatigue limit and an elliptical geometric parameter of a fatigue source area of a smooth member based on test data obtained by conducting crack propagation tests and high-cycle fatigue tests on the notched member and the smooth member; determining an equivalent initial crack size of the smooth member; determining an equivalent circle parameter of the fatigue source area; determining a fatigue notch factor of the notched member 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 member; and determining an equivalent initial crack size of the notched member according to the long crack propagation threshold value of the notched member, a geometric shape factor, the fatigue notch factor and the equivalent initial crack size of the smooth member. The present disclosure can accurately evaluate the original fatigue quality of the notched member based on different hole forming processes.

Description

Technical Field

[0001] This disclosure relates to the field of reliability design technology, and in particular to a method for assessing the original fatigue quality of a notched component, a device for assessing the original fatigue quality of a notched component, and an electronic device. Background Technology

[0002] The fatigue performance of mechanical structures such as aircraft, automobiles, and ships greatly affects their service performance and reliability. Fatigue failure is usually a process of gradual propagation from the area with the largest initial damage, progressing from microcracks to small cracks and then to long cracks. For most components, the crack initiation stage accounts for the vast majority of the fatigue life. The life of this stage varies not only with the type of material but is also closely related to the initial fatigue defects and the randomness of manufacturing quality. These factors can be collectively referred to as the uncertainties of Initial Fatigue Quality (IFQ).

[0003] Analyzing the fatigue life of a structure and assessing its initial fatigue quality is crucial. In practical engineering, most components have notches, such as circular holes on their surfaces. Compared to smooth components, the stress distribution in notched components is more complex. Current technologies for assessing the initial fatigue quality of notched components have limited accuracy, or the assessment results are heavily dependent on experimental conditions, making them difficult to apply to actual components. Summary of the Invention

[0004] This disclosure provides a method, apparatus, and electronic device for assessing the original fatigue quality of a notched component, to at least improve the accuracy of the assessment to a certain extent.

[0005] According to a first aspect of this disclosure, a method for assessing the initial fatigue quality of a notched component is provided, comprising: obtaining, based on test data from crack propagation tests and high-cycle fatigue tests on a notched component and a smooth component, a long crack propagation threshold value for the notched component, a long crack propagation threshold value for the smooth component, a fatigue limit, and elliptical geometric parameters of the fatigue origin region; determining, based on the long crack propagation threshold value and fatigue limit of the smooth component, an equivalent initial crack size of the smooth component; determining, based on the elliptical geometric parameters of the fatigue origin region of the smooth component, an equivalent circle parameter of the fatigue origin region; determining, based on the equivalent circle parameter of the fatigue origin region, the elliptical geometric parameters of the fatigue origin region, and the equivalent initial crack size of the smooth component, a fatigue notch factor of the notched component; and determining, based on the long crack propagation threshold value, geometric shape factor, fatigue notch factor, and the equivalent initial crack size of the smooth component, an equivalent initial crack size of the notched component.

[0006] According to a second aspect of this disclosure, an initial fatigue quality assessment device for a notched member is provided, comprising: a first data processing module configured to obtain, based on test data from crack propagation tests and high-cycle fatigue tests performed on the notched member and a smooth member, a long crack propagation threshold value for the notched member, a long crack propagation threshold value for the smooth member, a fatigue limit, and elliptical geometric parameters of the fatigue origin region; a second data processing module configured to determine, based on the long crack propagation threshold value and fatigue limit of the smooth member, an equivalent initial crack size for the smooth member; and a third data processing module configured to... The first module is configured to determine the equivalent circle parameter of the fatigue source region based on the elliptical geometric parameters of the fatigue source region of the smooth component; the second module is configured to determine the fatigue notch factor of the notched component based on the equivalent circle parameter 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 third module is configured to determine the equivalent initial crack size of the notched component based on the long crack propagation threshold value, geometric shape factor, fatigue notch factor, and the equivalent initial crack size of the smooth component.

[0007] According to a third aspect of this disclosure, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the original fatigue quality assessment method of the first aspect described above and its possible implementations.

[0008] According to a fourth aspect of this disclosure, an electronic device is provided, comprising: a processor; and a memory for storing executable instructions of the processor; wherein the processor is configured to perform the original fatigue quality assessment method of the first aspect and its possible implementations thereof by executing the executable instructions.

[0009] The technical solution disclosed herein has the following beneficial effects:

[0010] On the one hand, this method provides a rapid approach to calculating EIFS values, enabling efficient and accurate assessment of the original fatigue quality of components. It is applicable to notched components, including those with film pore structures, and can assess the original fatigue quality of notched components based on different pore-forming processes. On the other hand, the assessment results of this method are independent of experimental conditions. For example, it can obtain corresponding assessment results for different stress conditions and can reflect the dispersion pattern of fatigue quality in components, providing high reference value for the actual use of mechanical products. Furthermore, the experimental process is simple and the computational load is small, which helps reduce the implementation cost of the method. Attached Figure Description

[0011] Figure 1 A flowchart illustrating the original fatigue quality assessment method for a notched component in this exemplary embodiment is shown.

[0012] Figure 2 This illustration shows a schematic diagram of the fabrication of a notched component and a smooth component according to this exemplary embodiment.

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

[0014] Figure 4A This exemplary embodiment illustrates a notched component based on EDM technology. K th,l,notch Distribution map.

[0015] Figure 4B This exemplary embodiment illustrates a notched component based on the LDM process. K th,l,notch Distribution map.

[0016] Figure 5 This exemplary embodiment illustrates notched components based on different hole-making processes. K th,l,notch A graph showing the relationship between survival rate and other metrics.

[0017] Figure 6 A fracture surface diagram of the smooth component in this exemplary embodiment is shown.

[0018] Figure 7 The fatigue limit diagrams of the smooth component and the notched component based on EDM and LDM hole-making processes in this exemplary embodiment are shown.

[0019] Figure 8 The diagram shows a linear fit between survival rate and fatigue limit in this exemplary embodiment.

[0020] Figure 9 This diagram illustrates the fatigue origin ellipse and equivalent circle in this exemplary embodiment.

[0021] Figure 10 The diagram shows the relationship between the ratio of the major and minor axes of the fatigue origin ellipse and the ratio of the stress intensity factor K for different geometric crack shapes in this exemplary embodiment.

[0022] Figure 11 A crack propagation curve is shown in this exemplary embodiment.

[0023] Figure 12A The EIFS values ​​at different survival rates are shown in this exemplary embodiment.

[0024] Figure 12B This illustrates a linear description of the notched component based on the EDM process in this exemplary embodiment under different survival rates and crack geometry correction factors.

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

[0026] Figure 13 A schematic diagram of the structure of an electronic device in this exemplary embodiment is shown. Detailed Implementation

[0027] Exemplary embodiments of this disclosure will be described more fully below with reference to the accompanying drawings.

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

[0029] Initial fatigue quality assessment is a crucial step in reliability design. Initial fatigue quality represents the original manufacturing state or initial defect state of mechanical structural products such as aircraft, automobiles, and ships before they are put into service. Equivalent Initial Flaw Size (EIFS) considers defects arising in the detailed structure of the material and the material's properties, and can be used to characterize initial fatigue quality. EIFS is a hypothetical crack size, assuming that the hypothetical crack exists in the structural details before service. The EIFS distribution has the following characteristics: The EIFS distribution depends only on material properties, manufacturing process, and assembly state, and does not depend on usage conditions (such as spectrum or stress level). Data under different usage conditions can deduce the same EIFS distribution (i.e., a "universal EIFS distribution"); the EIFS distribution is not the distribution of actual physical defects or cracks in the original material, but rather a mathematical representation of initial fatigue quality. However, after a certain period of hypothetical crack propagation starting from the EIFS distribution, it matches the actual crack propagation.

[0030] Analysis of component fractures, such as turbine single-crystal blades, indicates that most fractures are caused by surface quality defects and fatigue failure due to film cooling holes. Therefore, understanding the EIFS (Effective Inertial Focal Surface) status of critical components for accurate initial quality assessment helps in developing reasonable maintenance schedules and improving reliability.

[0031] In related technologies, the EIFS distribution is obtained through the TTCI (Time To Crack Initiation) back-calculation method and the EIFS fitting method. However, these methods suffer from drawbacks such as complex experiments, high computational load, and high cost. Although some other methods can obtain EIFS and are closely related to experimental conditions, these clearly violate the principle that EIFS is independent of experimental conditions; furthermore, the fatigue mass dispersion law of the specimen itself is not well represented.

[0032] In view of one or more of the above-mentioned problems, exemplary embodiments of this disclosure provide a method for assessing the original fatigue quality of a notched member. Figure 1 An exemplary flow of the method is shown, which may include the following steps S110 to S150:

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

[0034] Step S120: Determine the equivalent initial crack size of the smooth component based on the long crack propagation threshold and fatigue limit of the smooth component.

[0035] Step S130: Determine the equivalent circle parameters of the fatigue source region based on 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 based on the equivalent circle parameters of the fatigue initiation zone, the elliptical geometric parameters of the fatigue initiation zone, and the equivalent initial crack size of the smooth component.

[0037] Step S150: Determine the equivalent initial crack size of the notched component based on the long crack propagation threshold value, geometric shape factor, fatigue notch factor, and equivalent initial crack size of the smooth component.

[0038] based on Figure 1 The method presented offers several advantages. First, it provides a rapid method for calculating EIFS values, enabling efficient and accurate assessment of the original fatigue quality of components. This method is applicable to notched components, including those with film pore structures, and can assess the original fatigue quality of notched components based on different pore-forming processes. Second, the assessment results of this method are independent of experimental conditions. For example, it can obtain corresponding assessment results for different stress conditions and can reflect the dispersion of fatigue quality in components, providing high reference value for the practical use of mechanical products. Third, the experimental process is simple and the computational load is small, which helps reduce the implementation cost of the method.

[0039] The following is about Figure 1 Each step in the process will be explained in detail.

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

[0041] In this context, a notch refers to a discontinuous area on the outer surface of a component, such as a hole. A notched component has a notch on its outer surface; for example, it could be a component simulating the film cooling hole structure of an aero-turbine blade, where the notch is a film cooling hole. Because the notch causes a structural abrupt change, stress concentration can easily occur, affecting the original fatigue quality of the component. In contrast, a smooth component is a component without notches. In this exemplary embodiment, the notched component and the smooth component are made of the same material and have the same or similar contours and dimensions. For example, the notched component and the smooth component are made of the same metal or alloy material, both are cuboid in shape, and have equal length, width, and height. The difference lies in the presence of an opening (i.e., a notch) on the outer surface of the notched component, while the smooth component has a smooth and complete outer surface. This facilitates the comparison of experimental results between the notched component and the smooth component to calculate the notch effect. The notch in the notched component can be prepared using different hole-making processes, such as EDM (Electrical Discharge Machining) and LDM (Laser Discharge Machining).

[0042] Figure 2 A schematic diagram of the fabrication process for the experimental components is shown. DD6, a second-generation nickel-based single-crystal high-temperature alloy from my country, was used as the component material. After standard heat treatment of the unprocessed blank material, two types of flat plates were fabricated to ensure equal orientation: a pure rectangular plate and a dog-bone shaped plate. This allows for the fabrication of as many experimental components as possible from the same finite-sized blank material. Flat plates without openings were fabricated as smooth components, while flat plates with openings (such as simulated film vents) were fabricated as notched components. Both EDM and LDM processes can be used for hole fabrication. For example, the rectangular plate could be designed with a thickness of 0.8 mm and a film vent diameter of 0.8 mm, while the dog-bone shaped plate could have a thickness of 1.0 mm and a film vent diameter of 0.5 mm.

[0043] Crack propagation testing involves applying cyclic stress to a component specimen and observing crack propagation. The difference between high-cycle fatigue testing and crack propagation testing lies in the number of cyclic stresses applied; crack propagation testing typically involves 10 cycles. 5 The magnitude of the stress cycles in high-cycle fatigue tests is typically 10. 7The above orders of magnitude. Table 1 shows the conditions for crack propagation and high-cycle fatigue tests. For notched components prepared by the two drilling processes, five sets of cyclic stresses were applied at room temperature; for smooth components, one or more sets of cyclic stresses were applied at room temperature. The frequency was 78 Hz; σ max This represents the stress amplitude, i.e., the maximum stress during cyclic loading. A stress ratio of 0.1 is used under all conditions, meaning the ratio of the minimum stress to the maximum stress during cyclic loading is 0.1. For each test condition, multiple valid specimens can be used to repeat the test, ensuring the stability and accuracy of the test results.

[0044] Table 1

[0045]

[0046] During the experiment, the crack propagation of the component under cyclic stress was monitored, and experimental data were recorded, including crack size (a) at different stress cycles (N), and the fatigue crack propagation rate was calculated. .

[0047] Based on the experimental data, the crack propagation threshold, fatigue limit, and geometric parameters of the fatigue origin ellipse can be obtained. The crack propagation threshold is explained below.

[0048] Crack nucleation and propagation can generally be described by the Griffith condition. The elastic relationship between crack size a and required stress σ can be found in the following formula (1):

[0049] (1)

[0050] Where 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 a cracked component will not undergo fatigue propagation under alternating loads. K th (or abbreviated as) K) represents the crack propagation threshold value. In this exemplary embodiment, two types of crack propagation threshold values ​​are considered: the intrinsic crack propagation threshold value and the... K th,eff This indicates, and the threshold value for long crack propagation, in order to K th,l express.

[0052] Assume that there exists a critical crack \(a_0\) such that when the actual crack length \(a < a_0\), the crack growth threshold decreases with the decrease of the crack length, and when \(a > a_0\), the crack growth threshold is independent of the crack size. Further, \(a < a_0\) generally represents the stage of small crack growth, and the stress state at this time is difficult to be fully described by linear elasticity. For simplicity, the fatigue limit for different crack lengths can be linearly described, referring to the following formula (2):

[0053] (2)

[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 to use 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, referring to the following formula (3):

[0055] (3)

[0056] Where K th,l represents the long crack growth threshold (\(MPa\cdot m\) 0.5 ); \(\sigma\) e represents the fatigue limit (\(MPa\)); Y represents the crack geometry correction factor.

[0057] When the crack length \(a\) is significantly small,[[]][[ID=3)]] \(\sigma\) th = \(\sigma\) e , Y = 1. At the same time, \(a\) 0,l can be regarded as the critical value of continuous crack growth. There is the following relationship:

[0058] (4)

[0059] Based on this, due to the fact that the material cannot withstand high stresses, local plastic damage occurs under repeated fatigue loads, and strain gradients are generated by dislocation pile-up, slip bands, intrusions and extrusions, resulting in the formation of internal stresses due to local stress concentration. This explains why when the crack (or equivalent defect) size is less than \(a\) 0,l , and the nominal stress is greater than \(\sigma\) e , damage still occurs leading to component failure. Obviously, the conditions required by the crack growth threshold 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 \(\sigma\) e ). Therefore, there may be another one in the stage of small crack growth that is larger than K th,lA smaller threshold value, i.e., the intrinsic crack propagation threshold value. K th,eff .

[0060] Figure 3 The relationship between fatigue strength and fracture mechanics is described using multiple relevant graphs. Figure 3 da / dN- The K-curve describes the propagation of long cracks, shifting it forward towards shorter cracks. Based on the changes in mechanical behavior at different crack propagation stages, crack propagation sequentially goes through three stages: microstructural short crack, mechanical short crack, and long crack, as shown in the KT diagram. In stage I, the crack size is limited to a small scale, generally arranged in order of microstructural features such as grain size. Within this scale range, microstructure dominates 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 suppress crack propagation, such as when the crack exceeds 1-2 grain sizes (as shown in stage II of the KT diagram), crack propagation is dominated by the surrounding grains, and the plastic zone size becomes too large, often not negligible for small cracks. When the crack size is less than a... 0,l At that time, linear elastic fracture mechanics is not applicable. K th,l concept.

[0061] Microstructure mechanisms significantly influence fatigue crack propagation in high-temperature alloys. When defects are relatively small, shorter fatigue crack propagation needs to be considered. Besides the influence of the plastic zone and crack tip microstructure, the biggest difference between long and short cracks lies in the closure effect. Solving for the EIFS value using fracture mechanics methods involves the small crack plastic region, and the solution for the true stress intensity factor requires correction for the crack size. Figure 3 The cyclic R-curve shows that for a short crack in the microstructure to propagate, it must overcome the inherent crack propagation threshold of the material and structure, i.e., the intrinsic crack propagation threshold. K th,eff Only then can it enter stage II. In polycrystalline materials, a 0,l This can be used as a characteristic size, considered as the boundary point between long and short cracks, but this value is not conservative. Cracks first need to resist the influence of microstructures, such as grain boundaries. Simultaneously, this is also the dividing point between macroscopic and microscopic cracks. For nickel-based single-crystal materials (without grains), the characteristic size cannot be represented by the grain size. Under internal stress, cracks smaller than the limiting crack size can still occur within 10... 7Fracture within the second cycle. If the limiting crack size can be overcome, a0 can be used to describe the EIFS, thus solving the problem of evaluating initial damage in different hole formations. When the crack size is small, the plastic zone is more likely to form. Generally, 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. It can be seen that the plastic zone plays an important role in the stress field of the elastic zone. Intrinsic crack propagation threshold and long crack propagation threshold are introduced at the two boundary points of the entire crack, respectively, corresponding to the crack propagation resistance curve (R curve). Depending on the stress field, point a0 is taken as the limiting state of the elastoplastic description.

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

[0063] Based on the experimental data from crack propagation tests and high-cycle fatigue tests on notched components, the fatigue crack propagation rates corresponding to different equivalent stress strength factors were obtained.

[0064] The test data with fatigue crack propagation rates within a preset range are fitted, and the long crack propagation threshold values ​​for notched components and smooth components are obtained based on the fitting results.

[0065] Among them, the threshold value for long crack propagation K th,l It can be used as a material parameter under normal temperature conditions. K th,l It can be used to calculate the EIFS of smooth components.

[0066] Figure 4A This illustrates a notched component based on EDM technology. K eq -da / dN curve, Figure 4B This illustrates a notched component based on the LDM process. K eq -da / dN curve. The horizontal axis in the figure represents the equivalent stress intensity factor. K eq (MPa·m) 0.5 The stress (such as stress amplitude σ) applied in crack propagation tests and high-cycle fatigue tests can be used to determine the stress level. maxThe fatigue crack growth rate (da / dN) is calculated based on the dimensions of the notched component, with the vertical axis representing the crack propagation rate (da / dN) per cycle of applied stress, i.e., the crack length after each cycle of stress. By conducting crack propagation tests and high-cycle fatigue tests on the notched component, the fatigue crack growth rate corresponding to different equivalent stress strength factors can be obtained, forming... Figure 4A or Figure 4B The figure shows the data points. It illustrates the data for each effective specimen tested under different stress amplitudes at room temperature. For example, "180-1" represents the data for effective specimen 1 tested at a stress amplitude of 180 MPa. The figure also shows the fitting zone and 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, experimental data with fatigue crack propagation rates within a preset range can be fitted. This preset range can be determined based on specific needs and can be a relatively ideal range for fatigue crack propagation rates, such as 10... -7 -10 -6 mm / cycle. For example, the fatigue crack propagation rate is 10 mm / cycle. -7 -10 -6 The experimental data within mm / cycle were fitted to obtain the long crack propagation threshold values ​​of notched components based on EDM and LDM processes, respectively. Figure 4A This illustrates a notched component based on EDM technology. K th,l,notch Distribution map. Figure 4B This illustrates a notched component based on the LDM process. K th,l,notch Distribution map.

[0068] In one embodiment, the above-mentioned method of obtaining fatigue crack propagation rates corresponding to different equivalent stress strength factors based on experimental data from crack propagation tests and high-cycle fatigue tests on notched components includes:

[0069] Based on experimental data from crack propagation tests and high-cycle fatigue tests on notched components under ambient temperature conditions, the fatigue crack propagation rates corresponding to different equivalent stress strength factors under ambient temperature conditions were obtained.

[0070] Accordingly, fitting the experimental data where the fatigue crack propagation rate is within a preset range, and obtaining the long crack propagation threshold values ​​for notched components and smooth components based on the fitting results, may include the following steps:

[0071] By fitting the experimental data of fatigue crack propagation rate within a preset range under normal temperature conditions, the long crack propagation threshold value of notched components under different survival rates under normal temperature conditions is obtained.

[0072] Based on the Weibull probability distribution, the long crack propagation threshold value of notched components under different survival rates at room temperature is fitted to obtain the long crack propagation threshold value of smooth components under the target survival rate at room temperature.

[0073] Refer to the above Figure 4A or Figure 4B As shown, based on experimental data under normal temperature conditions, different equivalent stress intensity factors under normal temperature conditions were obtained. K eq The corresponding fatigue crack growth rate da / dN. Experimental data with fatigue crack growth rates within a preset range were fitted to obtain the long crack growth threshold values ​​for notched components at different survival rates under room temperature conditions. K th,l,notch Notched components based on different hole-making processes K th,l,notch The curve showing the survival rate can be referenced. Figure 5 As shown.

[0074] To fully utilize the data, crack propagation data of notched components under ambient temperature conditions were used to calculate the long crack propagation threshold value for smooth components, thus simplifying the experimental process. Due to the dispersion of experimental results and the size of the influence zone at the hole edge, the long crack propagation threshold value at a relatively high survival rate (e.g., 99.9%) is generally selected as the long crack propagation threshold value for smooth components. For example, the long crack propagation threshold values ​​obtained at different survival rates are... K th,l It satisfies the three-parameter Weibull (Weibull 3P) probability distribution, as shown in the following formula:

[0075] (5)

[0076] Where P represents the survival rate, and α, β, and γ are parameters of the three-parameter Weibull probability distribution, which can be obtained by minimum variance fitting, as shown in Table 2. As mentioned earlier, the long crack propagation threshold value of smooth components under room temperature conditions can be obtained at a 99% survival rate. K th,l,smooth Approximately 1.93 MPa·m 0.5 .

[0077] Table 2

[0078]

[0079] In one embodiment, the smooth component can be tested at room temperature, and the test data can be fitted to obtain the long crack propagation threshold value of the smooth component. K th,l,smooth .

[0080] The fatigue limit and the geometric parameters of the fatigue origin ellipse are explained below.

[0081] The EIFS value of notched components (such as film vents) is higher than that of a. 0,l Small enough to ensure structural safety, assuming smooth components. After transformation, a secure EIFS can be obtained as follows: Therefore, the corresponding safe fatigue limit can be calculated as follows:

[0082] (6)

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

[0084] (7)

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

[0086] (8)

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

[0088] (9)

[0089] When a = a0 To determine the fatigue limit corresponding to the actual crack size, equation (6) can be rewritten as:

[0090] (10)

[0091] Through numerous experiments, it can be determined that the value of m is either -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 surface exhibits three distinct fracture zones: the fatigue initiation zone (located at abrupt geometric changes), the crack propagation zone (with obvious fatigue striations), and the instantaneous tensile fracture zone (a protruding ductile fracture surface). The fatigue initiation zone can be approximated as an ellipse or semi-ellipse (e.g., ...). Figure 6 The fatigue origin region is approximated as a semi-ellipse. By measuring the geometric dimensions of the fatigue origin region, the geometric parameters of the fatigue origin region ellipse are obtained. The geometric parameters of the fatigue origin region ellipse may include the lengths of the major and minor semi-axes, and the ratio of the major to the minor axis.

[0093] In the early stages of hole fabrication, the early propagation of microcracks is strongly influenced by the crack-free microstructure of the material. A survival rate can be introduced to obtain a PSN (survival rate-stress amplitude-life) curve, which better reflects data dispersion compared to the SN curve. To isolate the interference from original material processing factors and component geometry, a lifting-lowering method was used to conduct fatigue limit tests on smooth components under room temperature conditions, obtaining the fatigue limit of the smooth components.

[0094] Figure 7 The diagram shows fatigue limit graphs for smooth components and notched components based on EDM and LDM hole-making processes. The solid line in the middle of the graph represents the fatigue limit fitting lines for the notched component based on the EDM process at different survival rates, from bottom to top: 99.99%, 50%, and 0.01%. The dashed line in the middle of the graph represents the fatigue limit fitting lines for the notched component based on the LDM process at different survival rates, from bottom to top: 99.99%, 50%, and 0.01%. (Reference) Figure 7 As shown, at a 50% survival rate, the smooth component's σ e It is 377.6 MPa (L in the figure) s (Horizontal line), under the same test environment, the fatigue limits of notched components based on EDM and LDM processes were 55.113 MPa and 47.0 MPa, respectively, with a 99.99% survival rate and 95% confidence level; while at a 50% survival rate and 95% confidence level, the fatigue limits of notched components based on the two processes were... σ e The pressures are 59.2 MPa and 47.6 MPa respectively (L in the figure). e and L l (Horizontal line). Assuming that fatigue life follows a normal distribution under the same stress level, considering five survival rates of 0.01%, 20%, 50%, 80%, and 99.99%, the relationship between survival rate and fatigue limit is obtained through linear fitting. (See reference...) Figure 8 As shown, the survival rate and fatigue limit roughly satisfy a linear relationship, with fitting curves of 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*, the uniaxial long-range tensile stress σ perpendicular to the crack plane is... ∞ Under these conditions, the stress intensity factor can be written as F is the geometric correction factor for the actual specimen. For a crack in a notched stress field, the stress intensity solution is asymptotically the same as that for a surface crack in a smooth solid, except that the stress at the distal end passes through the stress concentration factor K. t=σ max / σ ∞ It is magnified. Therefore, when a→0, the following relationship holds:

[0096] (11)

[0097] Where F0 represents the geometric factor of a crack on the surface of a smooth component. For a crack located in a notched stress field, the asymptotic solution of the geometric factor F is:

[0098] (12)

[0099] When the crack extends beyond the notch stress field, the stress intensity factor is dominated by the distal stress field, which can be expressed by equation (13):

[0100] (13)

[0101] Where d is the notch depth. This can be further expressed by the following equation (14):

[0102] (14)

[0103] In the formula F ∞ The geometric factor F is a reference geometric factor. When d / a << 1, F asymptotically approaches a constant, i.e., F = F0. In this case, the upper and lower bounds of the geometric factor F are F0 and F0K, respectively. t Using these asymptotic solutions, a simple formula can be established for the geometric factor F of arbitrary size caused by the notch root.

[0104] For a through crack located at the root of the notch, the geometric factor F of the “equivalent” surface crack depth is constrained by the upper and lower asymptotes, making 1 <F / F0<K t The geometric factor F can be written as:

[0105] (15)

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

[0107] (16)

[0108] in, .

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

[0110] (17)

[0111] It should be noted that after introducing the notch, the fatigue limit for both smooth and notched members can no longer be simply determined by K.t Calculations are performed because the surface "similarity" of high-stress materials cannot be satisfied. The fatigue notch factor is defined as K. f The effective stress concentration factor is expressed as follows:

[0112] (18)

[0113] Where, σ smooth,e σ represents the fatigue limit of a smooth component. notch,e This indicates the fatigue limit of a notched component.

[0114] To account for the fatigue notch effect, it is assumed that the smooth member has a semi-circular micro-notch with a length on 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, the smooth member reaches the fatigue limit σ when the applied stress intensity factor equals the stress intensity factor threshold value. smooth,e Introducing a finite geometric correction factor, the following relationship holds:

[0115] (19)

[0116] Where a represents the conservative EIFS crack size (mm) of the smooth component; d r α represents the equivalent size (mm) of micro-defects in the fatigue origin region of a smooth component; α represents the geometric correction factor for crack length a+d in a finite-size specimen, which can be obtained from Anderson's Fracture Mechanics Handbook or finite element calculation.

[0117] Similarly, the fatigue limit σ of a notched component notch,e and stress intensity factor threshold value K th,notch It has the following connection:

[0118] (20)

[0119] In the formula, d n Indicates the actual notch size (mm).

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

[0121] (twenty one)

[0122] It should be understood that EIFS is typically several orders of magnitude smaller than the sample size (e.g., micrometers relative to millimeters or even larger), and equation (21) can be simplified to:

[0123] (twenty two)

[0124] when At that time, the equivalent size of the micro-defect is much larger than that of EIFS, K f =1, at which point the gap effect can be ignored; when At that time, the equivalent size of the micro-defect is much smaller than that of the EIFS, K f =K t .

[0125] Continue to refer to Figure 1 In step S120, the equivalent initial crack size of the smooth component is determined based on the long crack propagation threshold and fatigue limit of the smooth component.

[0126] As mentioned earlier, it can be done through ,or Calculate the EIFS of smooth components.

[0127] Continue to refer to Figure 1 In step S130, the equivalent circle parameters of the fatigue source region are determined based on the elliptical geometric parameters of the fatigue source region of the smooth component.

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

[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] refer to Figure 9 As shown, consider 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 fatigue origin plane (xz plane). The geometric correction factor for the crack size a+d is F(α). According to the Anderson handbook, the stress intensity factor for a semi-elliptical crack can be:

[0131] (twenty three)

[0132] The above formula can be simplified to:

[0133] (twenty four)

[0134] According to the formula for equal area, α can be expressed as (A / r). 2 The ratio of stress intensity factors for the two geometric forms, ellipse and equivalent circle, is as follows:

[0135] (25)

[0136] refer to Figure 10As shown, the stress intensity factor K for cracks with different geometries is compared. The results show that the maximum ratio between the two is approximately 1.091, at which point α = 0.489; meanwhile, when α varies between 0.2 and 1, K... 椭 / K 圆 The ratio varies by less than 9.1%. K can be determined by observing the actual value of α for the smooth component. 圆 The crack radius length r (i.e., the equivalent circle radius) after the crack size is reduced in dimension, and is regarded as d. r .

[0137] Continue to refer to Figure 1 In step S140, the fatigue notch factor of the notched component is determined based on the equivalent circle parameter of the fatigue source region, the elliptical geometric parameter of the fatigue source region, and the equivalent initial crack size of the smooth component.

[0138] For notched members, the original KT diagram obtained using smooth members cannot describe the crack initiation and propagation behavior because crack initiation and propagation are influenced not only by the material's inherent defects but also by the stress concentration caused by geometric dimensions. (Reference) Figure 11 As shown, the inherent defects of the material are considered as a 0,l When a central sharp crack exists, a 0,l It can reflect the crack initiation behavior of a component. Under the action of a notch, without considering fatigue sensitivity, the equivalent defect value of a notched component can be further expressed as:

[0139] (26)

[0140] Where F=Y· , which is the fatigue notch factor, includes the material's inherent defect factor Y and the actual notch geometry factor (before cracks appear). , and a 0,l It is obtained when Y is 1.

[0141] In one implementation, the geometry factor of the notched member can be calculated using the following formula:

[0142] (27)

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

[0144] Continue to refer to Figure 1In step S150, the equivalent initial crack size of the notched component is determined based on the long crack propagation threshold value, geometric shape factor, fatigue notch factor, and equivalent initial crack size of the smooth component.

[0145] In one embodiment, determining the equivalent initial crack size of the notched member based on the long crack propagation threshold value, geometric shape factor, fatigue notch factor, and equivalent initial crack size of the smooth member may include the following steps:

[0146] Based on the long crack propagation threshold value and material properties of the notched component, the intrinsic crack propagation threshold value of the notched component is determined.

[0147] The equivalent initial crack size of the notched member is determined based on the intrinsic crack propagation threshold, geometric shape factor, fatigue notch factor, and equivalent initial crack size of the smooth member.

[0148] When considering the non-conservative EIFS values ​​of real samples, the following relationship holds:

[0149] (28)

[0150] By using the plane (inherent) fatigue limit σ smooth,e The functional relationship between the strongest microstructure resistance to size d is defined as the minimum intrinsic resistance to microcrack propagation (microstructure threshold). K th,eff (Refer to the following function expression:)

[0151] (29)

[0152] To account for the temperature sensitivity of the microstructure of nickel-based single crystals, and considering that the cutting of the two phases differs depending on the temperature, d here can be defined as the size of the matrix phase or the reinforcing phase at different temperatures, which depends on in which compositional phase the dislocations first appear. Furthermore, we can derive:

[0153] (30)

[0154] in, K th,eff,notch This represents the intrinsic crack propagation threshold value for a notched component. K th,l,notch The notched component represents the long crack propagation threshold value, where d represents the strongest microstructural barrier size determined by the material properties of the notched component. For example, for nickel-based single crystals, this size can be the matrix phase or the reinforcing phase size. 0,lThis represents the transition crack size determined by the smooth component. The intrinsic crack propagation threshold value of the notched component can be calculated using equation (30).

[0155] refer to Figure 11 As shown, the modified KT of the real sample can be described as a parallel segment, representing the difference in macroscopic crack nucleation under the influence of the notch-crack coupling coefficient. For an ideal pure notch structure, the critical notch depth 'a' for long crack initiation... p for K th,l and The line of intersection, that is:

[0156] (31)

[0157] The actual critical gap depth is:

[0158] (32)

[0159] Considering the notch sensitivity during crack propagation, the critical notch depth 'a' for long crack initiation... p for K th,l and The intersection line, for reference Figure 13 As shown. At this point, equations (31) and (32) can be rewritten as:

[0160] (33)

[0161] Since the size of the plastic zone in this scale is not negligible, for simplification, the crack tip plastic zone in the two-dimensional model can be modified to meet the linear elastic fracture mechanics conditions. The effective plastic zone size of nickel-based single-crystal materials. It can be solved experimentally and numerically with a very high degree of agreement. The surface of the component exhibits greater plasticity than the interior. In the plane stress state (z=0) of a two-dimensional anisotropic material, the stress and displacement on both sides of the hole edge can be determined by the following formula:

[0162] (34)

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

[0164] (35)

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

[0166] (36)

[0167] In one embodiment, determining the equivalent initial crack size of the notched member based on the intrinsic crack propagation threshold value, geometry factor, fatigue notch factor, and equivalent initial crack size of the smooth member may include the following steps:

[0168] The safe fatigue limit of a smooth component is determined based on its equivalent initial crack size and fatigue limit.

[0169] The equivalent initial crack size of the notched member can be calculated using the following formula:

[0170] (37)

[0171] Among them, EIFS mod,notch K represents the equivalent initial crack size of the notched component. t / λ represents the fatigue notch factor of the notched component. K th,eff η represents the intrinsic crack propagation threshold value of the notched member, and η represents the plastic zone correction factor of the notched member. σ0 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 by equation (27).

[0172] Further derivation of equation (37) yields:

[0173] (38)

[0174] It is important to note that K th,eff Essentially, it's a fundamental property of the material; for the same process, K th,eff While it can be considered constant, the material properties at the hole edge change during the evaluation of notched (film pore) components prepared using different processes and temperatures, especially with different hole-making techniques. K th,eff The results are inconsistent, requiring separate evaluation. One approach is to use the EIFS of the notched component determined under normal temperature conditions to further deduce the results under different temperature conditions. K th,eff .

[0175] Figure 12A The EIFS values ​​are shown for different survival rates. Figure 12B The paper presents a linear description of notched components based on EDM process under different survival rates and crack geometry correction factors. Figure 12C A linear description of notched components based on LDM process and crack geometry correction factors at different survival rates is shown. Figure 12AAs shown, the EIFS values ​​of notched components prepared by EDM and LDM drilling processes differ significantly. With a 95% guarantee rate and a 50% survival rate, the EIFS value for EDM is approximately 0.022 mm, while that for LDM is approximately 0.047 mm. Based on test data meeting different survival rates (0-100%), the EIFS value for EDM ranges from 0.0188 to 0.0273 mm, while that for LDM ranges from 0.0423 to 0.0530 mm. Under a specific stress, the calculated EIFS range narrows further, with the range variation for EDM and LDM approximately within 0.01 mm. It should be noted that when considering three stress levels (stress level variation exceeding 20%), the peak values ​​(maximum and minimum) of the EIFS range only increase by about 2% each. Compared to common calculation methods where EIFS values ​​are closely related to stress magnitude, this trend is negligible. At different survival rates, the EIFS value and the survival rate, as well as the crack geometry correction factor, exhibit a strong linear correlation, and the crack geometry correction factor only undergoes minor changes (e.g., at...). Figure 12B In the meantime, F remains around 1.53. Once the specific correlation function is determined, it becomes more valuable for predicting the generalizability of EIFS in practical engineering applications.

[0176] Exemplary embodiments of this disclosure also provide an apparatus for assessing the initial fatigue quality of a notched member. This apparatus 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, fatigue limit, and fatigue source region elliptical geometric parameters of the smooth component based on the test data of crack propagation test and high cycle fatigue test on notched and smooth components.

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

[0179] The third data processing module is configured to determine the equivalent circle parameters of the fatigue source region based on 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 based on 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.

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

[0182] In one embodiment, based on experimental data from crack propagation tests and high-cycle fatigue tests on notched and smooth components, 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 origin region are obtained. This includes: obtaining the fatigue crack propagation rate corresponding to different equivalent stress intensity factors based on experimental data from crack propagation tests and high-cycle fatigue tests on notched components; fitting experimental data with fatigue crack propagation rates within a preset range; and obtaining the long crack propagation threshold values ​​of the notched component and the smooth component based on the fitting results.

[0183] In one embodiment, based on experimental data from crack propagation tests and high-cycle fatigue tests on notched components, fatigue crack propagation rates corresponding to different equivalent stress intensity factors are obtained, including: obtaining fatigue crack propagation rates corresponding to different equivalent stress intensity factors at room temperature based on experimental data from crack propagation tests and high-cycle fatigue tests on notched components under room temperature conditions; fitting experimental data with fatigue crack propagation rates within a preset range, and obtaining long crack propagation threshold values ​​for notched components and smooth components based on the fitting results, including: fitting experimental data with fatigue crack propagation rates within a preset range at room temperature to obtain long crack propagation threshold values ​​for notched components at different survival rates at room temperature; fitting long crack propagation threshold values ​​for notched components at different survival rates at room temperature based on the Weibull probability distribution to obtain long crack propagation threshold values ​​for smooth components at a target survival rate at room temperature.

[0184] In one embodiment, determining the equivalent initial crack size of a notched member based on the long crack propagation threshold value, geometry factor, fatigue notch factor, and equivalent initial crack size of a smooth member includes: determining the intrinsic crack propagation threshold value of the notched member based on the long crack propagation threshold value and material properties; and determining the equivalent initial crack size of the notched member based on the intrinsic crack propagation threshold value, geometry factor, fatigue notch factor, and equivalent initial crack size of a smooth member.

[0185] In one embodiment, determining the intrinsic crack propagation threshold value of the notched member based on its long crack propagation threshold value and material properties includes: calculating the intrinsic crack propagation threshold value of the notched member using the following formula:

[0186] ;

[0187] in, K th,eff,notch This represents the intrinsic crack propagation threshold value of a notched component. Kth,l,notch The notched member represents the long crack propagation threshold value, d represents the strongest microstructural barrier size determined by the material properties of the notched member, and a represents the maximum microstructural barrier value. 0,l This indicates the size of the transition crack as determined by the smooth component.

[0188] In one embodiment, determining the equivalent initial crack size of the notched member based on its intrinsic crack propagation threshold, geometry factor, fatigue notch factor, and equivalent initial crack size of the smooth member includes: determining the safe fatigue limit of the smooth member based on its equivalent initial crack size and fatigue limit; and calculating the equivalent initial crack size of the notched member using the following formula:

[0189] ;

[0190] Among them, EIFS mod,notch K represents the equivalent initial crack size of the notched component. t / λ represents the fatigue notch factor of the notched component. K th,eff η represents the intrinsic crack propagation threshold value of the notched member, and η represents the plastic zone correction factor of the notched member. σ0 represents the safe fatigue limit of a smooth component, and F(aη) represents the geometric shape factor of a notched component.

[0191] In one embodiment, the elliptical geometric parameters of the fatigue origin region include: the length of the major semi-axis and the length of the minor semi-axis of the ellipse when the fatigue origin region is approximated as an ellipse or semi-ellipse; the equivalent circle parameters of the fatigue origin region include: the radius of the equivalent circle; determining the equivalent circle parameters of the fatigue origin region based on the elliptical geometric parameters of the fatigue origin region of the smooth component includes: calculating the equivalent circle parameters of the fatigue origin region using the following formula:

[0192]

[0193]

[0194] Where 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 axis to the minor axis of the ellipse, σ represents the vertical tension in the fatigue source region, and r represents the radius of the equivalent circle.

[0195] The specific details of each part of the above-mentioned device have been described in detail in the method section of the implementation plan. For any undisclosed details, please refer to the implementation plan of the method section, and therefore will not be repeated here.

[0196] Exemplary embodiments of this disclosure also provide a computer-readable storage medium that can be implemented as a program product including program code, which, when run on an electronic device, causes the electronic device to perform the steps described in the "Exemplary Methods" section of this specification according to various exemplary embodiments of this disclosure. In an alternative embodiment, the program product can be implemented as a portable compact disc read-only memory (CD-ROM) including program code and can run on an electronic device, such as a personal computer. However, the program product of this disclosure is not limited thereto. In this document, the readable storage medium can be any tangible medium that contains or stores a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0197] The program product may employ any combination of one or more readable media. A readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of readable storage media (a non-exhaustive list) include: electrical connections having one or more wires, portable disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0198] Computer-readable signal media may include data signals propagated in baseband or as part of a carrier wave, carrying readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A readable signal medium may also be any readable medium other than a readable storage medium, capable of sending, propagating, or transmitting programs for use by or in conjunction with an instruction execution system, apparatus, or device.

[0199] The program code contained on the readable medium may be transmitted using any suitable medium, including but not limited to wireless, wired, optical fiber, RF, etc., or any suitable combination thereof.

[0200] Program code for performing the operations of this disclosure can be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Java and C++, and conventional procedural programming languages ​​such as C or similar languages. The program code can execute entirely on the user's computing device, partially on the user's computing device, as a standalone 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 remote computing devices, the remote computing devices can be connected to the user's computing device via any type of network, including a local area network (LAN) or a wide area network (WAN), or can be connected to an external computing device (e.g., via the Internet using an Internet service provider).

[0201] Exemplary embodiments of this disclosure also provide an electronic device that may include a processor and a memory. The memory stores executable instructions of the processor, such as program code. The processor executes the executable instructions to perform the methods of this exemplary embodiment. Furthermore, the electronic device may also include a display for displaying a graphical user interface.

[0202] The following is for reference. Figure 13 The electronic device is illustrated by way of a general-purpose computing device. It should be understood that... Figure 13 The electronic device 1300 shown is merely an example and should not be construed as limiting the functionality and scope of the embodiments disclosed herein.

[0203] like Figure 13 As 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.

[0204] Memory 1320 may include volatile memory, such as RAM 1321 and cache unit 1322, and may also include non-volatile memory, such as ROM 1323. Memory 1320 may also include one or more program modules 1324, such program modules 1324 including, but not limited to: operating system, one or more application programs, other program modules, and program data. Each or some combination of these examples may include an implementation of a network environment. For example, program module 1324 may include the modules in the above-described apparatus.

[0205] The processor 1310 may include one or more processing units, such as 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).

[0206] The processor 1310 can be used to execute executable instructions stored in the memory 1320, such as performing any one or more method steps in this exemplary embodiment.

[0207] Bus 1330 is used to connect different components of electronic device 1300 and may include a data bus, an address bus and a control bus.

[0208] Electronic device 1300 can communicate with one or more external devices 1400 (such as keyboard, mouse, external controller, etc.) through I / O interface 1340.

[0209] Electronic device 1300 can communicate with one or more networks via network adapter 1350. For example, network adapter 1350 can provide mobile communication solutions such as 3G / 4G / 5G, or wireless communication solutions such as wireless LAN, Bluetooth, and near-field communication. Network adapter 1350 can communicate with other modules of electronic device 1300 via bus 1330.

[0210] The electronic device 1300 can display a graphical user interface, such as a test data processing interface, through the display 1360.

[0211] although Figure 13 As not shown in the diagram, other hardware and / or software modules may also be configured 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.

[0212] It should be noted that although several modules or units for the device used to perform actions have been mentioned in the detailed description above, this division is not mandatory. In fact, according to exemplary embodiments of this 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.

[0213] Those skilled in the art will understand that various aspects of this disclosure can be implemented as systems, methods, or program products. Therefore, various aspects of this disclosure can be embodied in entirely hardware implementations, entirely software implementations (including firmware, microcode, etc.), or implementations combining hardware and software aspects, collectively referred to herein as “circuit,” “module,” or “system.” Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and embodiments are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the claims.

[0214] It should be understood that this disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is defined only by the appended claims.

Claims

1. A method for assessing the initial 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 and smooth components, the long crack propagation threshold value of the notched component, the long crack propagation threshold value, fatigue limit, and fatigue source region elliptical geometric parameters of the smooth component are obtained. The equivalent initial crack size of the smooth component is determined based on the long crack propagation threshold and fatigue limit of the smooth component. Based on the elliptical geometric parameters of the fatigue origin region of the smooth component, determine the equivalent circle parameters of the fatigue origin region; The fatigue notch factor of the notched component is determined based on the equivalent circle parameters of the fatigue origin region, the elliptical geometric parameters of the fatigue origin region, and the equivalent initial crack size of the smooth component. The equivalent initial crack size of the notched component is determined based on the long crack propagation threshold value, geometric shape factor, fatigue notch factor, and equivalent initial crack size of the smooth component. The step of determining the equivalent initial crack size of the notched component based on the long crack propagation threshold value, geometric shape factor, fatigue notch factor, and equivalent initial crack size of the smooth component includes: Based on the long crack propagation threshold value and material properties of the notched component, the intrinsic crack propagation threshold value of the notched component is determined. The safe fatigue limit of the smooth component is determined based on the equivalent initial crack size and fatigue limit of the smooth component. The equivalent initial crack size of the notched member is calculated using the following formula: ； Among them, EIFS mod,notch K represents the equivalent initial crack size of the notched member. t / λ represents the fatigue notch factor of the notched component. K th,eff η represents the intrinsic crack propagation threshold value of the notched member, and η represents the plastic zone correction coefficient of the notched member. σ0 represents the safe fatigue limit of the smooth component, and F(aη) represents the geometric shape factor of the notched component; The geometric shape factor of the notched member is calculated using the following formula: ； Where F(a) represents the geometric shape factor, a represents the crack size, c represents the notch size, W represents the width of the notched component, and l = a + c.

2. The method according to claim 1, characterized in that, Based on the test data from crack propagation tests and high-cycle fatigue tests on notched and smooth components, the long crack propagation threshold value of the notched component, the long crack propagation threshold value, fatigue limit, and fatigue origin region elliptical geometric parameters of the smooth component are obtained, including: Based on the experimental data from crack propagation tests and high-cycle fatigue tests on notched and smooth components, the fatigue crack propagation rates corresponding to different equivalent stress strength factors were obtained. The test data with fatigue crack propagation rates within a preset range are fitted, and the long crack propagation threshold values ​​of the notched component and the smooth component are obtained based on the fitting results.

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

4. The method according to claim 1, characterized in that, The step of determining the intrinsic crack propagation threshold value of the notched component based on its long crack propagation threshold value and material properties includes: The intrinsic crack propagation threshold value of the notched member is calculated using the following formula: in, K th,eff,notch This represents the intrinsic crack propagation threshold value of the notched component. K th,l,notch The notched member represents the long crack propagation threshold value, d represents the strongest microstructural barrier size determined by the material properties of the notched member, and a represents the maximum crack propagation threshold value. 0,l This indicates the size of the transition crack as determined by the smooth component.

5. The method according to claim 1, characterized in that, 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 semi-ellipse; the equivalent circle parameters of the fatigue source region include: the radius of the equivalent circle; determining the equivalent circle parameters of the fatigue source region based on the elliptical geometric parameters of the fatigue source region of the smooth component includes: The equivalent circle parameters of the fatigue origin region are calculated using the following formula: Where 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 axis to the minor axis of the ellipse, σ represents the vertical tension in the fatigue source region, and r represents the radius of the equivalent circle.

6. A device for assessing the initial fatigue quality of a notched component, configured to perform the method according to any one of claims 1 to 5, characterized in that, The device includes: The first data processing module is configured to obtain, based on test data from crack propagation tests and high-cycle fatigue tests on notched and smooth components, the long crack propagation threshold value of the notched component, the long crack propagation threshold value, fatigue limit, and fatigue source region elliptical geometric parameters of the smooth component; The second data processing module is configured to determine the equivalent initial crack size of the smooth component based on the long crack propagation threshold and fatigue limit of the smooth component. The third data processing module is configured to determine the equivalent circle parameters of the fatigue source region based on the elliptical geometric parameters of the fatigue source region of the smooth component. The fourth data processing module is configured to determine the fatigue notch factor of the notched component based on the equivalent circle parameter of the fatigue source region, the elliptical geometric parameter of the fatigue source region, 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 based on the long crack propagation threshold value, geometric shape factor, fatigue notch factor, and equivalent initial crack size of the smooth component.

7. An electronic device, characterized in that, include: processor; Memory for storing the executable instructions of the processor; The processor is configured to perform the method as described in any one of claims 1 to 5 by executing the executable instructions.

Images