Method, device and equipment for rapidly testing and verifying S-N curve and medium

Abstract

The embodiment of the invention discloses a rapid testing and verifying method, device and equipment for an S-N curve and a medium, and belongs to the technical field of material fatigue performance testing, and the method at least comprises a rapid testing process. According to the embodiment of the invention, the S-N curve of the material used by the fatigue sample can be determined based on the data of the fatigue life test under the two oblique line segment test stress values (equivalent to two stress levels) and the fatigue ultimate strength measured by the lifting method. Compared with conventional test methods such as a grouping method and the like which can draw a stable and reliable S-N curve only by testing the fatigue life of a material with more than five stress levels, the embodiment of the invention can significantly reduce the number of test samples of the S-N curve by reducing the stress levels, thereby facilitating simplification of the test process of the S-N curve, shortening the test period of the S-N curve, and improving the test efficiency of the S-N curve. And the test cost of the S-N curve is reduced.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of material fatigue performance testing, and in particular, to a method, device, equipment and medium for rapid testing and verification of S-N curves. Background Art

[0002] The S-N curve of a material is one of the important indicators for evaluating the mechanical properties of materials and parts. Current reliability designs of parts usually require material fatigue performance data as the design basis, and the development of new processes and new materials also requires material fatigue performance data as technical support.

[0003] Currently, the S-N curve of a material is mostly obtained through conventional test methods. For example, the slope segment of the curve is determined by testing the fatigue life at more than 5 stress levels through the grouped method. In this way, testing a stable and reliable S-N curve based on the existing technology requires a large number of samples. The increase in the number of samples means that the test process is repetitive and cumbersome, which leads to a relatively long test cycle and high test costs for the existing S-N curve. Summary of the Invention

[0004] The embodiments of the present invention provide a method, device, equipment and medium for rapid testing and verification of S-N curves, so as to reduce the number of test samples of the S-N curve by reducing the stress levels, which is beneficial to streamlining the test process of the S-N curve, shortening the test cycle of the S-N curve, and reducing the test costs of the S-N curve.

[0005] In a first aspect, the embodiments of the present invention provide a method for rapid testing and verification of an S-N curve, which at least includes a rapid test process; the rapid test process at least includes the following steps:

[0006] S1. Process and handle a plurality of fatigue specimens made of the same material so that multiple characteristic parameters of each processed fatigue specimen meet preset conditions;

[0007] S2. Determine at least two test stress values of the slope segments of the target S-N curve corresponding to the material used for the fatigue specimen based on the material tensile properties of the fatigue specimen;

[0008] S3. Divide all the fatigue specimens into two groups, and perform fatigue life tests with a stress ratio less than 1 on one group of the fatigue specimens at each of the test stress values of the slope segments, and record the fatigue cycle times of each fatigue specimen to obtain the fatigue life data of the two groups of fatigue specimens;

[0009] S4. Select the first set of valid data from the two sets of fatigue life data according to a preset selection criterion, verify the distribution compliance of the first set of valid data to obtain the second set of valid data, and then calculate the preset reliability, preset confidence level, and the credible logarithmic life and credible fatigue life of the two sets of fatigue specimens under each inclined line segment test stress value based on the second set of valid data;

[0010] S5. Substitute the credible fatigue life and the inclined line segment test stress value corresponding to the two sets of fatigue specimens into the empirical formula of the inclined line segment of the S-N curve to obtain the inclined line segment formula of the target S-N curve;

[0011] S6. Measure the fatigue limit strength of the material used for the fatigue specimens by the up-and-down method, and then draw the target S-N curve according to the fatigue limit strength and the inclined line segment formula of the target S-N curve.

[0012] Optionally, step S1 specifically includes:

[0013] S11. Process a plurality of the fatigue specimens using the same material according to a preset processing method and preset specimen size, and at least make the continuous radius size between the clamping ends of each fatigue specimen meet the first preset condition;

[0014] S12. Perform fillet rounding on the side edges of the continuous radius between the clamping ends of each fatigue specimen according to the test requirements and polish the fillets, and at least make the fillet size, polishing direction, and surface roughness of the polished fillets of each fatigue specimen meet the second preset condition;

[0015] S13. Test each fatigue specimen to at least make each fatigue specimen meet the preset standard requirements and make the tolerance parallelism, coaxiality, perpendicularity, and surface roughness at the continuous radius between the clamping ends of each fatigue specimen meet the third preset condition.

[0016] Optionally, step S4 specifically includes:

[0017] S41. Substitute the maximum value and the minimum value in each set of fatigue life data into the data validity calculation formula respectively to obtain the first maximum value validity calculation result and the first minimum value validity calculation result;

[0018] S42. When both the first maximum value validity calculation result and the first minimum value validity calculation result are not greater than the preset threshold, determine that this set of fatigue life data is the first set of valid data;

[0019] S43. When the first maximum value validity calculation result is not greater than the preset threshold, but the first minimum value validity calculation result is greater than the preset threshold, then discard the minimum value corresponding to the first minimum value validity calculation result from the set of fatigue life data, re-determine the minimum value, and substitute it into the data validity calculation formula to obtain the second minimum value validity calculation result, and then compare the size relationship between the second minimum value validity calculation result and the preset threshold, and so on, until any minimum value validity calculation result is not greater than the preset threshold, and determine the fatigue life data that has been data-screened and corresponds to this minimum value validity calculation result as the first valid data;

[0020] S44. When the first minimum value validity calculation result is not greater than the preset threshold, but the first maximum value validity calculation result is greater than the preset threshold, then discard the maximum value corresponding to the first maximum value validity calculation result from the set of fatigue life data, re-determine the maximum value, and substitute it into the data validity calculation formula to obtain the second maximum value validity calculation result, and then compare the size relationship between the second maximum value validity calculation result and the preset threshold, and so on, until any maximum value validity calculation result is not greater than the preset threshold, and determine the fatigue life data that has been data-screened and corresponds to this maximum value validity calculation result as the first valid data;

[0021] S45. When both the first maximum value validity calculation result and the first minimum value validity calculation result are greater than the preset threshold, then discard the maximum value corresponding to the first maximum value validity calculation result and the minimum value corresponding to the first minimum value validity calculation result from the set of fatigue life data respectively, re-determine the maximum value and the minimum value, and substitute them into the data validity calculation formula to obtain the second maximum value validity calculation result and the second minimum value validity calculation result, and then compare the size relationship between the second maximum value validity calculation result and the preset threshold, and the size relationship between the second minimum value validity calculation result and the preset threshold respectively, and so on, until both the maximum value validity calculation result and the minimum value validity calculation result are not greater than the preset threshold, and determine the fatigue life data that has been data-screened and corresponds to this maximum value validity calculation result and this minimum value validity calculation result as the first valid data.

[0022] Optionally, the data validity calculation formula is at least

[0023] where x represents the data number of any one of the fatigue life data, N xLet \(\xi\) represent a single piece of the fatigue life data, and \(\sigma\) represent the variance of the logarithmic life data obtained by taking the logarithm of each group of the fatigue life data with or without data reduction. The logarithmic operation at least means taking the logarithm to the base 10 of any piece of the fatigue life data.

[0024] Optionally, the distribution compliance verification at least includes one of logarithmic normal distribution compliance verification, Weibull distribution compliance verification, and exponential distribution compliance verification.

[0025] Optionally, the tensile properties of the material at least include the yield strength;

[0026] The selection interval of the test stress value is at least one of 50% - 60% of the yield strength, 60% - 70% of the yield strength, 50% - 70% of the yield strength, 60% - 80% of the yield strength, and 60% - 90% of the yield strength.

[0027] Optionally, it at least further includes a curve verification process; the curve verification process at least includes the following steps:

[0028] S7. Based on the conventional method, perform tests on the verification fatigue specimens at at least 6 verification stress levels to obtain the preset reliability, the preset confidence level, and the verification fatigue life data of the verification fatigue specimens at each verification stress level;

[0029] S8. Draw a verification S - N curve according to the verification stress level and the corresponding verification fatigue life data, and then verify the target S - N curve by judging the coincidence degree between the target S - N curve and the verification S - N curve.

[0030] In a second aspect, the embodiments of the present invention further provide a device for rapid testing and verification of an S - N curve, which at least includes a rapid testing module; the rapid testing module at least includes:

[0031] A processing module, configured to process multiple fatigue specimens made of the same material so that multiple characteristic parameters of each processed fatigue specimen meet the preset conditions;

[0032] A stress determination module, at least configured to determine two test stress values of the inclined line segments of the target S - N curve corresponding to the material used for the fatigue specimen according to the tensile properties of the material of the fatigue specimen;

[0033] A grouped testing module, configured to divide all the fatigue specimens into two groups, perform fatigue life tests with a stress ratio less than 1 on one group of the fatigue specimens at each of the test stress values of the inclined line segments, and record the fatigue cycle times of each fatigue specimen to obtain the fatigue life data of the two groups of fatigue specimens;

[0034] A screening calculation module, configured to screen out first valid data from the two sets of fatigue life data according to a preset selection criterion, verify the compliance of the distribution of the first valid data to obtain second valid data, and then calculate a preset reliability, a preset confidence level, and the credible logarithmic life and credible fatigue life of the two sets of fatigue specimens under each of the inclined line segment test stress values based on the second valid data;

[0035] A formula acquisition module, configured to substitute the credible fatigue life and the inclined line segment test stress value corresponding to the two sets of fatigue specimens into the empirical formula of the inclined line segment of the S-N curve to obtain the inclined line segment formula of the target S-N curve;

[0036] A curve plotting module, configured to measure the fatigue limit strength of the material used for the fatigue specimens by the up-and-down method, and then plot the target S-N curve according to the fatigue limit strength and the inclined line segment formula of the target S-N curve.

[0037] In a third aspect, an embodiment of the present invention further provides an electronic device, including a processor and a memory, where the memory stores computer-readable instructions, and when the computer-readable instructions are executed by the processor, the steps in the fast test and verification method of the S-N curve as described in the first aspect are run.

[0038] In a fourth aspect, an embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored, and when the program is executed by a processor, the steps in the fast test and verification method of the S-N curve as described in the first aspect are implemented.

[0039] The technical solution provided by the embodiment of the present invention is as follows. First, a plurality of fatigue specimens made of the same material are processed and treated so that multiple characteristic parameters of each processed fatigue specimen meet preset conditions. Further, at least two test stress values of the target S-N curve corresponding to the material used for the fatigue specimen are determined according to the tensile properties of the material of the fatigue specimen. Further, all the fatigue specimens are divided into two groups, and a fatigue life test with a stress ratio less than 1 is performed on one group of fatigue specimens at each test stress value of the oblique line segment, and the fatigue cycle times of each fatigue specimen are recorded to obtain the fatigue life data of the two groups of fatigue specimens. Further, first valid data is screened from the two groups of fatigue life data according to a preset selection criterion, and the distribution compliance of the first valid data is verified to obtain second valid data. Then, based on the second valid data, the preset reliability, preset confidence level, and the credible logarithmic life and credible fatigue life of the two groups of fatigue specimens at each test stress value of the oblique line segment are calculated. Further, the credible fatigue life and the test stress value of the oblique line segment corresponding to the two groups of fatigue specimens are substituted into the empirical formula of the oblique line segment of the S-N curve to obtain the oblique line segment formula of the target S-N curve. Finally, the fatigue limit strength of the material used for the fatigue specimen is measured by the up-and-down method, and then the target S-N curve is drawn according to the fatigue limit strength and the oblique line segment formula of the target S-N curve.

[0040] It can be seen from this that the embodiment of the present invention can determine the S-N curve of the material used for the fatigue specimen based on the data of the fatigue life test at two test stress values of the oblique line segment (equivalent to two stress levels) and the fatigue limit strength measured by the up-and-down method. Obviously, compared with the conventional test methods such as the group method, which require testing the fatigue life of materials at more than 5 stress levels to draw a stable and reliable S-N curve, the embodiment of the present invention can significantly reduce the number of test samples of the S-N curve by reducing the stress levels, which is beneficial to streamlining the test process of the S-N curve, shortening the test cycle of the S-N curve, and reducing the test cost of the S-N curve. Description of the Drawings

[0041] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0042] Figure 1 is a flowchart of a method for quickly testing and verifying an S-N curve provided by an embodiment of the present invention;

[0043] Figure 2 is a schematic diagram of the structural dimensions of a fatigue specimen provided by an embodiment of the present invention;

[0044] Figure 3 It is a flowchart of another method for rapid testing and verification of S-N curves provided by an embodiment of the present invention;

[0045] Figure 4 It is a logarithmic life probability diagram at a stress level of 440 MPa provided by an embodiment of the present invention;

[0046] Figure 5 It is a logarithmic life probability diagram at a stress level of 400 MPa provided by an embodiment of the present invention

[0047] Figure 6 It is an S-N curve of axial tension and compression of materials provided by an embodiment of the present invention;

[0048] Figure 7 It is a schematic diagram of the coincidence of the target S-N curve and the verification S-N curve provided by an embodiment of the present invention;

[0049] Figure 8 It is a schematic structural diagram of a device for rapid testing and verification of S-N curves provided by an embodiment of the present invention;

[0050] Figure 9 It is a schematic structural diagram of an electronic device provided by an embodiment of the present invention. Detailed implementation manners

[0051] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the scope of protection of the present application.

[0052] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The singular forms "a", "the" and "said" used in the embodiments of the present application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. "Plural" generally includes at least two.

[0053] It should be understood that the term " / and" used herein is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " herein generally represents an "or" relationship between the associated objects before and after.

[0054] It should be understood that although terms such as first, second, and third may be used in the embodiments of the present application for description, these descriptions should not be limited to these terms. These terms are only used to distinguish the descriptions. For example, without departing from the scope of the embodiments of the present application, the first may also be referred to as the second, and similarly, the second may also be referred to as the first.

[0055] Depending on the context, the words "if" or "when" as used herein may be interpreted as "when...", "when...", "in response to determining", or "in response to detecting". Similarly, depending on the context, the phrase "if determined" or "if detected (stated condition or event)" may be interpreted as "when determined", "in response to determining", "when detecting (stated condition or event)", or "in response to detecting (stated condition or event)".

[0056] It should also be noted that the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a commodity or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such commodity or device. Without further limitation, the element defined by the statement "including one..." does not exclude the existence of additional identical elements in the commodity or device including the said element.

[0057] It should be particularly noted that symbols and / or numbers existing in the specification, if not marked in the figure description, are not figure reference numerals.

[0058] Figure 1 is a flowchart of a method for rapid testing and verification of an S-N curve provided by an embodiment of the present invention. This embodiment is applicable to S-N curve test scenarios of various materials, such as metal materials, fiber-reinforced materials, etc. The method for rapid testing and verification of the S-N curve can, but is not limited to, be executed by the rapid testing and verification device for the S-N curve in the embodiments of the present invention as the execution subject, and the execution subject can be implemented in software and / or hardware. As Figure 1 shown, the method for rapid testing and verification of the S-N curve at least includes a rapid testing process; the rapid testing process at least includes the following steps:

[0059] S1. Process and handle multiple fatigue specimens made of the same material so that multiple characteristic parameters of each processed fatigue specimen meet preset conditions.

[0060] Among them, there can be various materials for making the fatigue specimens, such as the aforementioned metal materials, fiber-reinforced materials, etc. Exemplarily, Figure 2It is a schematic diagram of the structural dimensions of a fatigue specimen provided by an embodiment of the present invention. It can be understood that the processing methods of the fatigue specimen may include polishing, chamfering, etc.

[0061] In a specific embodiment, if the material of the fatigue specimen is metal, the fatigue specimen may specifically be a specimen with a rectangular cross-section of uniform thickness having a tangential transition arc between the parallel part and the clamping end or a continuous radius between the clamping ends as specified in the national standard GB / T 3075-2021 "Method for Axial Force Control in Fatigue Testing of Metallic Materials". The characteristic parameter of the fatigue specimen may be, but is not limited to, the continuous radius between the clamping ends.

[0062] S2. Determine at least two test stress values of the slant segments of the target S-N curve corresponding to the material of the fatigue specimen based on the tensile properties of the fatigue specimen.

[0063] Among them, the tensile properties of the fatigue specimen may include, for example, tensile strength, elongation after fracture, etc. In another specific embodiment, optionally, the tensile properties of the material include at least the yield strength; the selection range of the test stress value is at least one of 50% - 60% of the yield strength, 60% - 70% of the yield strength, 50% - 70% of the yield strength, 60% - 80% of the yield strength, and 60% - 90% of the yield strength.

[0064] Exemplarily, the tensile properties of the fatigue specimen may be as shown in Table 1.

[0065] Table 1

[0066] Serial number Tensile strength / MPa Yield strength / MPa Elongation after fracture % / A 1# 728 683 17 2# 720 677 18 3# 713 674 18 Mean value 720.3 678 17.7

[0067] Referring to Table 1, the magnitudes of the two test stress values of the slant segments of the target S-N curve corresponding to the material of the fatigue specimen can be adaptively selected within the range of 50% - 70% of the average yield strength according to the actual test requirements of the fatigue specimen; for example, 440 MPa and 400 MPa can be respectively selected as the test stress values of the S-N curve slant segments.

[0068] S3. Divide all the fatigue specimens into two groups, and perform fatigue life tests with a stress ratio less than 1 on one group of fatigue specimens at each test stress value of the slant segment, and record the fatigue cycle times of each fatigue specimen to obtain the fatigue life data of the two groups of fatigue specimens.

[0069] Among them, the stress ratio may refer to the ratio of the minimum stress to the maximum stress in any single fatigue cycle during the fatigue test; the fatigue cycle times may refer to the number of times of the minimum cyclic periodic repetition of functions such as stress-time.

[0070] Exemplarily, the number of fatigue specimens can be 20 (of course, under other working conditions, the number of fatigue specimens can also be 10, 15, 25, 30, etc.); step S3 can specifically be to conduct fatigue life tests at the test stress values (i.e., 440 MPa and 400 MPa) of the two selected S-N curve oblique line segments. The stress ratio can be selected as -1. 10 fatigue specimens are tested at the test stress value of each S-N curve oblique line segment, and the fatigue cycle times of each fatigue specimen are recorded. The fatigue life data obtained from the tests can be as shown in Table 2.

[0071] Table 2

[0072]

[0073]

[0074] S4. Select the first valid data from the two groups of fatigue life data according to the preset selection and rejection criteria, and conduct distribution compliance verification on the first valid data to obtain the second valid data. Then, based on the second valid data, calculate the preset reliability, preset confidence level, and the credible logarithmic life and credible fatigue life of the two groups of fatigue specimens at the test stress value of each oblique line segment.

[0075] Among them, the preset selection and rejection criteria can be used for the processing of abnormal data in the fatigue life column shown in Table 2. The first valid data can be the normal data remaining after screening out the abnormal data in the fatigue life.

[0076] It can be known that the second valid data can refer to the first valid data whose data distribution conforms to any function law. The aforementioned function law can be, for example, the lognormal distribution law, the exponential distribution law, etc. In another specific implementation manner, optionally, the distribution compliance verification includes at least one of lognormal distribution compliance verification, Weibull distribution compliance verification, and exponential distribution compliance verification.

[0077] In addition, the preset reliability and preset confidence level can be adaptively selected according to the actual application scenario of the material and the desired fatigue test accuracy. For example, the preset reliability can be 90%, and the preset confidence level can be 95%. Generally, the fatigue life used for reliability calculation is usually R90C90, and it can also be R95C95, R99C99, etc. according to the reliability calculation requirements. It can be understood that the credible logarithmic life is the calculation result obtained by taking the logarithm of the credible fatigue life. For example, taking the logarithm to the base 10 of the credible fatigue life to obtain the credible logarithmic life.

[0078] S5. Substitute the credible fatigue life and the test stress value of the oblique line segment corresponding to the two groups of fatigue specimens into the empirical formula of the S-N curve oblique line segment to obtain the oblique line segment formula of the target S-N curve.

[0079] Among them, the empirical formula of the inclined line segment of the S-N curve can be SN m = C, e mS N = C, S = alog d N + b, log d S = alog d N + b, S = aN m etc.; in the above formulas, S represents stress, N represents life, m represents the power function exponent, and C, a, b, and d are all constants. It can be understood that when returning to step S5, S is substituted with the inclined line segment test stress value, and N is substituted with the credible fatigue life; taking the empirical formula of the inclined line segment of the S-N curve as SN m = C as an example, substituting the credible fatigue life N and the inclined line segment test stress value S corresponding to the two groups of fatigue specimens into the empirical formula of the inclined line segment of the S-N curve, and solving the equations simultaneously to obtain the values of m and C, the inclined line segment formula of the target S-N curve can be determined.

[0080] S6. Measure the fatigue limit strength of the material used for the fatigue specimen by the up-and-down method, and then draw the target S-N curve according to the fatigue limit strength and the inclined line segment formula of the target S-N curve.

[0081] Among them, the fatigue limit strength is the fatigue strength, which generally refers to the maximum stress at which the material will not be damaged under the action of infinite repeated alternating loads.

[0082] The technical solution provided by this embodiment is as follows: First, process and treat multiple fatigue specimens made of the same material so that multiple characteristic parameters of each processed fatigue specimen meet the preset conditions; further, determine at least two inclined line segment test stress values corresponding to the material used for the fatigue specimen of the target S-N curve according to the material tensile properties of the fatigue specimen; further, divide all the fatigue specimens into two groups, and perform fatigue life tests with a stress ratio less than 1 on one group of fatigue specimens at each inclined line segment test stress value, and record the fatigue cycle times of each fatigue specimen to obtain the fatigue life data of the two groups of fatigue specimens; further, screen out the first valid data from the two groups of fatigue life data according to the preset selection criteria, and perform distribution compliance verification on the first valid data to obtain the second valid data, and then calculate the preset reliability, preset confidence level, and the credible logarithmic life and credible fatigue life of the two groups of fatigue specimens at each inclined line segment test stress value based on the second valid data; further, substitute the credible fatigue life and the inclined line segment test stress value corresponding to the two groups of fatigue specimens into the empirical formula of the inclined line segment of the S-N curve to obtain the inclined line segment formula of the target S-N curve; finally, measure the fatigue limit strength of the material used for the fatigue specimen by the up-and-down method, and then draw the target S-N curve according to the fatigue limit strength and the inclined line segment formula of the target S-N curve.

[0083] It can be seen from this that based on the data of fatigue life tests at two inclined line segment test stress values (equivalent to two stress levels) and the fatigue limit strength measured by the up-and-down method in this embodiment, the S-N curve of the material used for the fatigue specimen can be determined. Obviously, compared with conventional test methods such as the grouped method that require testing the fatigue life of materials at more than 5 stress levels to draw a stable and reliable S-N curve, this embodiment can significantly reduce the number of test samples for the S-N curve by reducing the stress levels, which is conducive to streamlining the test process of the S-N curve, shortening the test cycle of the S-N curve, and reducing the test cost of the S-N curve.

[0084] Based on the above embodiments or implementation manners, the following will refine the processes such as the processing of the fatigue specimen (i.e., the aforementioned step S1) and the determination of the first effective data (i.e., the aforementioned step S4), etc., but it does not constitute a limitation to the present invention. Figure 3 It is a flowchart of another rapid test and verification method for the S-N curve provided by the embodiment of the present invention. Refer to Figure 3 , the rapid test and verification method for the S-N curve at least includes the following steps:

[0085] S11. Process a plurality of fatigue specimens using the same material according to a preset processing method and preset specimen size, and at least make the continuous radius size between the clamping ends of each fatigue specimen meet the first preset condition.

[0086] Among them, step S11 can be specifically: Process 20 fatigue specimens according to the specimen size shown in Figure 1 . The continuous radius size between the clamping ends of the fatigue specimen can preferably be 75 mm, and the processing method of the fatigue specimen is carried out in accordance with national standard GB / T 3075-2021.

[0087] S12. Perform filleting on the side edges of the continuous radius between the clamping ends of each fatigue specimen according to the test requirements and polish the fillets, so that at least the fillet size, polishing direction, and surface roughness of the polished fillet of each fatigue specimen meet the second preset condition.

[0088] Among them, step S12 can be specifically: To avoid the influence of the sharp corners of the side edges on the fatigue life, filleting can be performed on the side edges of the continuous radius between the clamping ends according to the test requirements. The fillet size is configured as R0.5, and the fillets are polished. The polishing direction is along the edge line direction, and the surface roughness Ra of the polished fillet is ≤0.2 μm.

[0089] S13. Test each fatigue specimen so that at least each fatigue specimen meets the preset standard requirements and the tolerance parallelism, coaxiality, perpendicularity, and surface roughness at the continuous radius between the clamping ends of each fatigue specimen meet the third preset condition.

[0090] Among them, step S13 can be specifically: test the dimensional accuracy and roughness of each specimen to ensure compliance with the requirements of the drawing and the national standard GB / T 3075-2021. The specimen tolerances of parallelism, coaxiality, and perpendicularity are all not greater than 0.005d, and the surface roughness Ra at the continuous radius between the clamping ends is ≤ 0.2μm.

[0091] S2. Determine at least two test stress values of the slant segments of the target S-N curve corresponding to the material used for the fatigue specimens based on the tensile properties of the fatigue specimens.

[0092] S3. Divide all the fatigue specimens into two groups, and perform a fatigue life test with a stress ratio less than 1 on one group of fatigue specimens at each test stress value of the slant segments, and record the fatigue cycle times of each fatigue specimen to obtain the fatigue life data of the two groups of fatigue specimens.

[0093] S41. Substitute the maximum value and the minimum value in each group of fatigue life data into the data validity calculation formula respectively to obtain the first maximum value validity calculation result and the first minimum value validity calculation result.

[0094] S42. When both the first maximum value validity calculation result and the first minimum value validity calculation result are not greater than the preset threshold, determine that this group of fatigue life data is the first valid data.

[0095] S43. When the first maximum value validity calculation result is not greater than the preset threshold, but the first minimum value validity calculation result is greater than the preset threshold, then discard the minimum value corresponding to the first minimum value validity calculation result from this group of fatigue life data, re-determine the minimum value, and substitute it into the data validity calculation formula to obtain the second minimum value validity calculation result, and then compare the size relationship between the second minimum value validity calculation result and the preset threshold, and so on, until any minimum value validity calculation result is not greater than the preset threshold, and determine the fatigue life data after data screening corresponding to this minimum value validity calculation result as the first valid data.

[0096] S44. When the first minimum value validity calculation result is not greater than the preset threshold, but the first maximum value validity calculation result is greater than the preset threshold, then discard the maximum value corresponding to the first maximum value validity calculation result from this group of fatigue life data, re-determine the maximum value, and substitute it into the data validity calculation formula to obtain the second maximum value validity calculation result, and then compare the size relationship between the second maximum value validity calculation result and the preset threshold, and so on, until any maximum value validity calculation result is not greater than the preset threshold, and determine the fatigue life data after data screening corresponding to this maximum value validity calculation result as the first valid data.

[0097] S45. When both the first maximum value validity calculation result and the first minimum value validity calculation result are greater than the preset threshold, the maximum value corresponding to the first maximum value validity calculation result and the minimum value corresponding to the first minimum value validity calculation result are respectively discarded from this set of fatigue life data, and then the maximum value and the minimum value are re-determined and substituted into the data validity calculation formula to obtain the second maximum value validity calculation result and the second minimum value validity calculation result. Furthermore, the magnitude relationship between the second maximum value validity calculation result and the preset threshold, and the magnitude relationship between the second minimum value validity calculation result and the preset threshold are respectively compared, and so on, until both the maximum value validity calculation result and the minimum value validity calculation result are not greater than the preset threshold. The fatigue life data corresponding to the maximum value validity calculation result and the minimum value validity calculation result after data screening are determined as the first valid data.

[0098] Among them, the preset threshold may refer to the standard normal deviation U p , which is related to the survival rate p (equivalent to R in the aforementioned R90), and can be obtained by querying the U p -p numerical table.

[0099] In a specific implementation manner, optionally, the data validity calculation formula is at least

[0100] Among them, x represents the data number of any fatigue life data, N x represents a single fatigue life data, σ represents the variance of the logarithmic life data obtained by logarithmic operation on each group of fatigue life data with or without data screening, and the logarithmic operation at least refers to taking the logarithm to the base 10 of any fatigue life data.

[0101] Based on this, steps S41 to S45 can be specifically as follows:

[0102] Substitute the maximum value and the minimum value in the two sets of data in Table 2 into the formula The calculation result (the calculation result obtained by substituting the first maximum value into the formula is the first maximum value validity calculation result, and the calculation result obtained by substituting the first minimum value into the formula is the first minimum value validity calculation result) is compared with U p . If the preset reliability selects R90, then p takes 90%. When the value of the calculation result is not greater than U p , this fatigue life data is considered valid; when the value of the calculation result is greater than U p , this fatigue life data is default discarded, and the maximum value and / or the minimum value are re-selected and substituted into the formula for calculation, and then the magnitude relationship between the new calculation result and U p is judged, and so on, until the data is valid. After calculation, the data tested under the stresses of 440 MPa and 400 MPa in Table 2 are all valid.

[0103] S46. Perform distribution compliance verification on the first valid data to obtain second valid data, and then calculate the preset reliability, preset confidence level, and the credible logarithmic life and credible fatigue life of the two groups of fatigue specimens under each inclined line segment test stress value based on the second valid data.

[0104] Among them, step S46 can be specifically as follows:

[0105] Use MINITAB software to perform logarithmic normal distribution compliance verification on the two groups of first valid data. Figure 4 It is the logarithmic life probability diagram of the 440 MPa stress level provided by the embodiment of the present invention. Figure 5 It is the logarithmic life probability diagram of the 400 MPa stress level provided by the embodiment of the present invention. See Figure 4 and Figure 5 , and the normal distribution characteristic values ( Figure 4 and Figure 5 are both represented by P values in) are 0.855 and 0.521 respectively. If the two groups of logarithmic data conform to the normal distribution, they are the second valid data. Continue to use the reliability and confidence level calculation functions of MINITAB software to calculate the R90C90 logarithmic life (equivalent to the aforementioned credible logarithmic life) and R90C90 fatigue life (equivalent to the aforementioned credible fatigue life) of the two groups of fatigue lives under 440 MPa and 400 MPa stresses, which are 5.0471 (life value 111455) and 5.305 (life value 201837) respectively. See the data in Table 3.

[0106] Table 3

[0107]

[0108] S5. Substitute the credible fatigue life corresponding to the two groups of fatigue specimens and the inclined line segment test stress value into the S-N curve inclined line segment empirical formula to obtain the inclined line segment formula of the target S-N curve.

[0109] Among them, step S5 can be specifically as follows: Substitute the two pairs of R90C90 arrays (111455, 440) and (201837, 400) calculated in step S46 into the S-N curve inclined line segment empirical formula SN m = C. Solve the simultaneous equations to obtain m = 0.16 and C = 2824. Thus, the inclined line segment formula of the S-N curve of the material R90C90 (i.e., the inclined line segment formula of the target S-N curve) is SN 0.16 = 2824.

[0110] S6. Use the staircase method to measure the fatigue limit strength of the material used for the fatigue specimens, and then draw the target S-N curve based on the fatigue limit strength and the inclined line segment formula of the target S-N curve.

[0111] Among them, the fatigue life under the staircase method condition is 5 million times, and the test results are shown in Table 4. The fatigue strength limit value of R90C90 is calculated to be 323 MPa using MINITAB software.

[0112] Table 4

[0113] Serial number Test stress / MPa Pass or fail 1 345 Fail 2 345 Fail 3 345 Fail 4 345 Fail 5 335 Pass 6 335 Pass 7 335 Pass 8 335 Pass 9 335 Fail 10 335 Fail 11 325 Pass 12 325 Pass

[0114] In addition, according to the test and calculation results of the foregoing steps, the S-N curve of material R90C90 can be plotted. According to the formula of the inclined line segment of the S-N curve of this material SN 0.16 = 2824, the fatigue life N values are calculated by taking stresses of 440 MPa, 420 MPa, 400 MPa, 380 MPa, 360 MPa, and 340 MPa respectively. An N and S array (111455, 440), (148798, 420), (201837, 400), (278136, 380), (389954, 360), (557392, 340) is formed. Then, the fatigue limit strength value of material R90C90 is obtained by the staircase method as 32,3 MPa, and thus the complete S-N curve of this material can be plotted. Figure 6 is the axial tension-compression S-N curve diagram of the material provided by the embodiment of the present invention. Refer to Figure 6 , and the curve formula is S = 2824 × N -0.16 .

[0115] S7. Test the calibration fatigue specimens at at least 6 calibration stress levels based on a conventional method to obtain the preset reliability, preset confidence level, and calibration fatigue life data of the calibration fatigue specimens at each calibration stress level.

[0116] S8. Plot the calibration S-N curve according to the calibration stress level and the corresponding calibration fatigue life data, and then verify the target S-N curve by judging the coincidence degree of the target S-N curve and the calibration S-N curve.

[0117] Among them, the conventional method can be the group method mentioned in the background technology. The life data obtained by testing six stress levels using the conventional method are shown in Table 5. The life of R90C90 can be calculated using MINITAB software. The formula of the S-N curve obtained based on the conventional method is S = 2542.6N -0.151 .

[0118] Table 5

[0119] Serial number Test stress / MPa R90C90 life 1 440 111455 2 420 168539 3 400 201837 4 385 230994 5 370 363831 6 355 469678

[0120] Furthermore, on the basis of Figure 6 , continue to plot the S-N curve obtained by the conventional method. Figure 7It is a schematic diagram showing the coincidence of the target S-N curve and the verification S-N curve provided by the embodiments of the present invention. As Figure 7 shown, the S-N curve obtained according to the method of the present invention (see the black dots and lines in Figure 7 ) almost coincides with the S-N curve obtained by the conventional test method (see the dots and lines represented by gray scale in Figure 7 ), thus verifying the test accuracy of the method described in the present invention.

[0121] It can be seen from this that based on the fatigue life test data at two oblique line segment test stress values (equivalent to two stress levels) and the fatigue limit strength measured by the up-and-down method in this embodiment, the S-N curve of the material used for the fatigue specimen can be determined. Obviously, compared with the conventional test methods such as the group method that require testing the fatigue life of materials at more than 5 stress levels to draw a stable and reliable S-N curve, this embodiment can significantly reduce the number of test samples for the S-N curve by reducing the stress levels, which is beneficial to streamlining the test process of the S-N curve, shortening the test cycle of the S-N curve, and reducing the test cost of the S-N curve.

[0122] Figure 8 It is a schematic structural diagram of a device for rapid testing and verification of an S-N curve provided by the embodiments of the present invention. This embodiment is applicable to various S-N curve test scenarios of materials, such as metal materials, fiber-reinforced materials, etc. The device for rapid testing and verification of the S-N curve can be implemented in software and / or hardware. As Figure 8 shown, the device for rapid testing and verification of the S-N curve at least includes a rapid testing module 100; the rapid testing module 100 at least includes:

[0123] A processing module 110, configured to process and process a plurality of fatigue specimens made of the same material, so that multiple characteristic parameters of each processed fatigue specimen meet preset conditions;

[0124] A stress determination module 120, at least configured to determine two oblique line segment test stress values of the target S-N curve corresponding to the material used for the fatigue specimen according to the material tensile properties of the fatigue specimen;

[0125] A grouped testing module 130, configured to divide all fatigue specimens into two groups, and perform fatigue life tests with a stress ratio less than 1 on one group of fatigue specimens at each oblique line segment test stress value, and record the fatigue cycle times of each fatigue specimen to obtain the fatigue life data of the two groups of fatigue specimens;

[0126] A screening calculation module 140, configured to screen out first valid data from two sets of fatigue life data according to a preset selection criterion, verify the distribution compliance of the first valid data to obtain second valid data, and then calculate a preset reliability, a preset confidence level, and the credible logarithmic life and credible fatigue life of two sets of fatigue specimens under each test stress value of the oblique line segment based on the second valid data;

[0127] A formula acquisition module 150, configured to substitute the credible fatigue life corresponding to two sets of fatigue specimens and the test stress value of the oblique line segment into the empirical formula of the oblique line segment of the S-N curve to obtain the oblique line segment formula of the target S-N curve;

[0128] A curve drawing module 160, configured to measure the fatigue limit strength of the material used for the fatigue specimens by the staircase method, and then draw the target S-N curve according to the fatigue limit strength and the oblique line segment formula of the target S-N curve.

[0129] Optionally, the processing module 110 is specifically configured to: process a plurality of fatigue specimens using the same material according to a preset processing method and a preset specimen size, and at least make the continuous radius size between the clamping ends of each fatigue specimen meet a first preset condition;

[0130] Perform a chamfering process on the side edges of the continuous radius between the clamping ends of each fatigue specimen according to the test requirements and polish the chamfer, and at least make the chamfer size, the polishing direction, and the surface roughness of the chamfered surface of each fatigue specimen meet a second preset condition;

[0131] Test each fatigue specimen to at least make each fatigue specimen meet the preset standard requirements and make the tolerance parallelism, coaxiality, perpendicularity, and the surface roughness at the continuous radius between the clamping ends of each fatigue specimen meet a third preset condition.

[0132] Optionally, the screening calculation module 140 is specifically configured to:

[0133] Substitute the maximum value and the minimum value in each set of fatigue life data into the data validity calculation formula respectively to obtain a first maximum value validity calculation result and a first minimum value validity calculation result;

[0134] When both the first maximum value validity calculation result and the first minimum value validity calculation result are not greater than a preset threshold, determine that this set of fatigue life data is the first valid data;

[0135] When the calculation result of the first maximum value validity is not greater than the preset threshold, but the calculation result of the first minimum value validity is greater than the preset threshold, then after discarding the minimum value corresponding to the calculation result of the first minimum value validity from this set of fatigue life data, re-determine the minimum value and substitute it into the data validity calculation formula to obtain the second minimum value validity calculation result, and then compare the size relationship between the second minimum value validity calculation result and the preset threshold, and so on, until the calculation result of any minimum value validity is not greater than the preset threshold, and determine the fatigue life data after data screening corresponding to the calculation result of this minimum value validity as the first valid data;

[0136] When the calculation result of the first minimum value validity is not greater than the preset threshold, but the calculation result of the first maximum value validity is greater than the preset threshold, then after discarding the maximum value corresponding to the calculation result of the first maximum value validity from this set of fatigue life data, re-determine the maximum value and substitute it into the data validity calculation formula to obtain the second maximum value validity calculation result, and then compare the size relationship between the second maximum value validity calculation result and the preset threshold, and so on, until the calculation result of any maximum value validity is not greater than the preset threshold, and determine the fatigue life data after data screening corresponding to the calculation result of this maximum value validity as the first valid data;

[0137] When both the calculation result of the first maximum value validity and the calculation result of the first minimum value validity are greater than the preset threshold, then respectively discard the maximum value corresponding to the calculation result of the first maximum value validity and the minimum value corresponding to the calculation result of the first minimum value validity from this set of fatigue life data, re-determine the maximum value and the minimum value and substitute them into the data validity calculation formula to obtain the second maximum value validity calculation result and the second minimum value validity calculation result, and then respectively compare the size relationship between the second maximum value validity calculation result and the preset threshold, and the size relationship between the second minimum value validity calculation result and the preset threshold, and so on, until both the maximum value validity calculation result and the minimum value validity calculation result are not greater than the preset threshold, and determine the fatigue life data after data screening corresponding to the maximum value validity calculation result and the minimum value validity calculation result as the first valid data.

[0138] Optionally, the data validity calculation formula is at least

[0139] where x represents the data number of any fatigue life data, N x represents a single fatigue life data, σ represents the variance of the logarithmic life data obtained by logarithmic operation on each group of fatigue life data with or without data screening, and the logarithmic operation at least means taking the logarithm to the base 10 of any fatigue life data.

[0140] Optionally, the distribution compliance verification includes at least one of lognormal distribution compliance verification, Weibull distribution compliance verification, and exponential distribution compliance verification.

[0141] Optionally, the tensile properties of the material include at least the yield strength;

[0142] The selected interval of the test stress value is at least one of 50% - 60% of the yield strength, 60% - 70% of the yield strength, 50% - 70% of the yield strength, 60% - 80% of the yield strength, and 60% - 90% of the yield strength.

[0143] Optionally, it further includes a curve verification module 200; the curve verification module 200 at least includes:

[0144] A verification test module 210, configured to perform tests on the verification fatigue specimens at at least 6 verification stress levels based on a conventional method to obtain preset reliability, preset confidence level, and verification fatigue life data of the verification fatigue specimens at each verification stress level;

[0145] A curve verification module 220, configured to draw a verification S - N curve according to the verification stress level and the corresponding verification fatigue life data, and then verify the target S - N curve by judging the coincidence degree between the target S - N curve and the verification S - N curve.

[0146] For the technical solution provided in this embodiment, first, a plurality of fatigue specimens made of the same material are processed and treated by a processing module so that multiple characteristic parameters of each processed fatigue specimen meet preset conditions; further, a stress determination module determines at least two test stress values of the slant segments of the target S - N curve corresponding to the material used for the fatigue specimens based on the tensile properties of the fatigue specimens; further, a grouping test module divides all the fatigue specimens into two groups, and performs fatigue life tests with a stress ratio less than 1 on one group of fatigue specimens at each test stress value of the slant segment, records the fatigue cycle times of each fatigue specimen to obtain the fatigue life data of the two groups of fatigue specimens; further, a screening and calculation module screens out the first valid data from the two groups of fatigue life data according to a preset selection criterion, performs distribution compliance verification on the first valid data to obtain the second valid data, and then calculates the preset reliability, preset confidence level, and the credible logarithmic life and credible fatigue life of the two groups of fatigue specimens at each test stress value of the slant segment based on the second valid data; further, a formula acquisition module substitutes the credible fatigue life and the test stress value of the slant segment corresponding to the two groups of fatigue specimens into the S - N curve slant segment empirical formula to obtain the slant segment formula of the target S - N curve; finally, a curve drawing module measures the fatigue limit strength of the material used for the fatigue specimens by the up - and - down method, and then draws the target S - N curve according to the fatigue limit strength and the slant segment formula of the target S - N curve.

[0147] It can be seen from this that based on the fatigue life test data at two oblique line segment test stress values (equivalent to two stress levels) and the fatigue limit strength measured by the up-and-down method in this embodiment, the S-N curve of the material used for the fatigue specimen can be determined. Obviously, compared with the conventional test methods such as the grouped method that require testing the fatigue life of materials at more than 5 stress levels to draw a stable and reliable S-N curve, this embodiment can significantly reduce the number of test samples for the S-N curve by reducing the stress levels, which is beneficial to streamlining the test process of the S-N curve, shortening the test cycle of the S-N curve, and reducing the test cost of the S-N curve.

[0148] The embodiment of the present invention also provides an electronic device. Figure 9 It is a schematic structural diagram of an electronic device provided by the embodiment of the present invention. Refer to Figure 9 , the electronic device 1000 includes a processor 1001 and a memory 1002. The memory 1002 stores computer-readable instructions. When the computer-readable instructions are executed by the processor 1001, the steps in any one of the above S-N curve rapid test and verification methods are run. Through the above technical solution, the processor 1001 and the memory 1002 are interconnected and communicate with each other through a communication bus and / or other forms of connection mechanisms (not marked). The memory 1002 stores a computer program executable by the processor. When the electronic device 1000 runs, the processor 1001 executes the computer program to execute the S-N curve rapid test and verification method in any optional implementation manner of the above embodiment, so as to at least implement the following functions: processing and processing a plurality of fatigue specimens made of the same material so that multiple characteristic parameters of each processed fatigue specimen meet preset conditions; determining at least two oblique line segment test stress values of the target S-N curve corresponding to the material used for the fatigue specimen according to the material tensile properties of the fatigue specimen; dividing all the fatigue specimens into two groups, performing a fatigue life test with a stress ratio less than 1 on one group of fatigue specimens at each oblique line segment test stress value, and recording the fatigue cycle times of each fatigue specimen to obtain the fatigue life data of the two groups of fatigue specimens; screening out the first valid data from the two groups of fatigue life data according to a preset selection criterion, and performing a distribution compliance verification on the first valid data to obtain the second valid data, and then calculating a preset reliability, a preset confidence level, and the credible logarithmic life and credible fatigue life of the two groups of fatigue specimens at each oblique line segment test stress value based on the second valid data; substituting the credible fatigue life and the oblique line segment test stress value corresponding to the two groups of fatigue specimens into the S-N curve oblique line segment empirical formula to obtain the oblique line segment formula of the target S-N curve; measuring the fatigue limit strength of the material used for the fatigue specimen by the up-and-down method, and then drawing the target S-N curve according to the fatigue limit strength and the oblique line segment formula of the target S-N curve.

[0149] The embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored. When the program is executed by a processor, it implements the method for rapid testing and verification of the S-N curve provided by all the inventive embodiments of the present application: processing a plurality of fatigue specimens made of the same material to make multiple characteristic parameters of each processed fatigue specimen meet preset conditions; determining at least two test stress values of the slant segments of the target S-N curve corresponding to the material used for the fatigue specimens according to the tensile properties of the materials of the fatigue specimens; dividing all the fatigue specimens into two groups, performing fatigue life tests with a stress ratio less than 1 on one group of fatigue specimens at each test stress value of the slant segment, and recording the fatigue cycle times of each fatigue specimen to obtain the fatigue life data of the two groups of fatigue specimens; screening out the first valid data from the two groups of fatigue life data according to a preset selection criterion, and performing distribution compliance verification on the first valid data to obtain the second valid data, and further calculating a preset reliability, a preset confidence level, and the credible logarithmic life and the credible fatigue life of the two groups of fatigue specimens at each test stress value of the slant segment based on the second valid data; substituting the credible fatigue life and the test stress value of the slant segment corresponding to the two groups of fatigue specimens into the empirical formula of the slant segment of the S-N curve to obtain the formula of the slant segment of the target S-N curve; measuring the fatigue limit strength of the material used for the fatigue specimens by the up-and-down method, and then drawing the target S-N curve according to the fatigue limit strength and the formula of the slant segment of the target S-N curve.

[0150] One or more computer-readable media can be used in any combination. The computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. A computer-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 computer-readable storage medium include: an electrical connection having one or more wires, a portable computer 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 disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In this document, the computer-readable storage medium can be any tangible medium that contains or stores a program, which can be used by or in combination with an instruction execution system, apparatus, or device.

[0151] A computer-readable signal medium may include a data signal propagated in a baseband or as part of a carrier wave, in which computer-readable program code is carried. Such a propagated data signal may take many forms, including - but not limited to - electromagnetic signals, optical signals, or any suitable combination of the foregoing. A computer-readable signal medium may also be any computer-readable medium other than a computer-readable storage medium, which can send, propagate, or transmit a program for use by or in connection with an instruction execution system, apparatus, or device.

[0152] The program code contained on a computer-readable medium may be transmitted using any appropriate medium, including - but not limited to - wireless, wire, optical fiber cable, RF, and the like, or any suitable combination of the foregoing.

[0153] The computer program code for performing the operations of the present invention may be written in one or more programming languages or combinations thereof. The programming languages include object-oriented programming languages such as Java, Smalltalk, C++, and also include conventional procedural programming languages such as the "C" language or similar programming languages. The program code may be executed entirely on the user's computer, partially on the user's computer, executed as a stand-alone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., through the Internet using an Internet service provider).

[0154] The above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A rapid testing and verification method for S-N curves, characterized in that, At least include a rapid test process; the rapid test process at least includes the following steps: S1. Process and handle a plurality of fatigue specimens made of the same material so that multiple characteristic parameters of each processed fatigue specimen meet preset conditions; S2. Determine at least two inclined segment test stress values corresponding to the target S-N curve of the material used for the fatigue specimen according to the tensile properties of the material of the fatigue specimen; S3. Divide all the fatigue specimens into two groups evenly, and perform a fatigue life test with a stress ratio less than 1 on one group of the fatigue specimens at each of the inclined segment test stress values, and record the fatigue cycle times of each fatigue specimen to obtain the fatigue life data of the two groups of fatigue specimens; S4. Screen out the first valid data from the two groups of fatigue life data according to the preset selection criterion, and perform a distribution compliance verification on the first valid data to obtain the second valid data, and then calculate the preset reliability, preset confidence level and the credible logarithmic life and credible fatigue life of the two groups of fatigue specimens at each of the inclined segment test stress values based on the second valid data; S5. Substitute the credible fatigue life and the inclined segment test stress value corresponding to the two groups of fatigue specimens into the empirical formula of the inclined segment of the S-N curve to obtain the inclined segment formula of the target S-N curve; S6. Measure the fatigue limit strength of the material used for the fatigue specimen by the up-and-down method, and then draw the target S-N curve according to the fatigue limit strength and the inclined segment formula of the target S-N curve.

2. The rapid testing and verification method of the S-N curve according to claim 1, characterized in that Step S1 specifically includes: S11. Process a plurality of the fatigue specimens using the same material according to a preset processing method and preset specimen size, and at least make the continuous radius size between the clamping ends of each fatigue specimen meet the first preset condition; S12. Perform a fillet treatment on the side edges of the continuous radius between the clamping ends of each fatigue specimen according to the test requirements and polish the fillets, and at least make the fillet size, polishing direction, and surface roughness of the polished fillets of each fatigue specimen meet the second preset condition; S13. Test each fatigue specimen so that at least each fatigue specimen meets the preset standard requirements and the tolerance parallelism, coaxiality, perpendicularity and surface roughness at the continuous radius between the clamping ends of each fatigue specimen meet the third preset condition.

3. The rapid testing and calibration method of the S-N curve according to claim 1, characterized in that Step S4 specifically includes: S41. Substitute the maximum value and the minimum value in each group of fatigue life data into the data validity calculation formula respectively to obtain the first maximum value validity calculation result and the first minimum value validity calculation result; S42. When both the first maximum value validity calculation result and the first minimum value validity calculation result are not greater than the preset threshold, determine that the fatigue life data of this group is the first valid data; S43. When the first maximum value validity calculation result is not greater than the preset threshold, but the first minimum value validity calculation result is greater than the preset threshold, then after discarding the minimum value corresponding to the first minimum value validity calculation result from the set of fatigue life data, re - determine the minimum value and substitute it into the data validity calculation formula to obtain the second minimum value validity calculation result, and then compare the size relationship between the second minimum value validity calculation result and the preset threshold, and so on, until any minimum value validity calculation result is not greater than the preset threshold, and determine the fatigue life data after data screening corresponding to this minimum value validity calculation result as the first valid data; S44. When the first minimum value validity calculation result is not greater than the preset threshold, but the first maximum value validity calculation result is greater than the preset threshold, then after discarding the maximum value corresponding to the first maximum value validity calculation result from the set of fatigue life data, re - determine the maximum value and substitute it into the data validity calculation formula to obtain the second maximum value validity calculation result, and then compare the size relationship between the second maximum value validity calculation result and the preset threshold, and so on, until any maximum value validity calculation result is not greater than the preset threshold, and determine the fatigue life data after data screening corresponding to this maximum value validity calculation result as the first valid data; S45. When both the first maximum value validity calculation result and the first minimum value validity calculation result are greater than the preset threshold, then respectively discard the maximum value corresponding to the first maximum value validity calculation result and the minimum value corresponding to the first minimum value validity calculation result from the set of fatigue life data, re - determine the maximum value and the minimum value and substitute them into the data validity calculation formula to obtain the second maximum value validity calculation result and the second minimum value validity calculation result, and then respectively compare the size relationship between the second maximum value validity calculation result and the preset threshold, and the size relationship between the second minimum value validity calculation result and the preset threshold, and so on, until both the maximum value validity calculation result and the minimum value validity calculation result are not greater than the preset threshold, and determine the fatigue life data after data screening corresponding to this maximum value validity calculation result and this minimum value validity calculation result as the first valid data.

4. The rapid testing and verification method of the S-N curve according to claim 3, characterized in that, The data validity calculation formula is at least where x represents the data number of any one of the fatigue life data, N x represents a single one of the fatigue life data, σ represents the variance of the logarithmic life data obtained by logarithmic operation on each group of the fatigue life data with or without data reduction, and the logarithmic operation at least refers to taking the logarithm to the base 10 of any one of the fatigue life data.

5. The rapid testing and calibration method of the S-N curve according to claim 1, characterized in that The distribution compliance verification includes at least one of log - normal distribution compliance verification, Weibull distribution compliance verification, and exponential distribution compliance verification.

6. The rapid testing and calibration method of the S-N curve according to claim 1, characterized in that The tensile properties of the material include at least the yield strength; The selected interval of the test stress value is at least one of 50% - 60% of the yield strength, 60% - 70% of the yield strength, 50% - 70% of the yield strength, 60% - 80% of the yield strength, and 60% - 90% of the yield strength.

7. The rapid testing and verification method of the S-N curve according to any one of claims 1-6, characterized in that, It at least further includes a curve verification process; the curve verification process at least includes the following steps: S7. Perform tests on the calibration fatigue specimens at at least 6 calibration stress levels based on conventional methods to obtain the preset reliability, the preset confidence level, and the calibration fatigue life data of the calibration fatigue specimens at each calibration stress level; S8. Draw a calibration S-N curve according to the calibration stress level and the corresponding calibration fatigue life data, and then verify the target S-N curve by judging the coincidence degree between the target S-N curve and the calibration S-N curve.

8. A rapid testing and calibration device for S-N curves, characterized in that, It at least includes a rapid test module; the rapid test module at least includes: A processing module, configured to process and process a plurality of fatigue specimens made of the same material, so that multiple characteristic parameters of each processed fatigue specimen meet preset conditions; A stress determination module, at least configured to determine two test stress values of the slant line segments of the target S-N curve corresponding to the material used for the fatigue specimen according to the tensile properties of the material of the fatigue specimen; A grouped test module, configured to divide all fatigue specimens into two groups, perform fatigue life tests with a stress ratio less than 1 on one group of the fatigue specimens at each of the test stress values of the slant line segments, and record the fatigue cycle times of each fatigue specimen to obtain the fatigue life data of the two groups of fatigue specimens; A screening and calculation module, configured to screen out first valid data from the fatigue life data of the two groups according to a preset selection criterion, perform distribution compliance verification on the first valid data to obtain second valid data, and then calculate the preset reliability, the preset confidence level, and the credible logarithmic life and credible fatigue life of the two groups of fatigue specimens at each of the test stress values of the slant line segments based on the second valid data; A formula acquisition module, configured to substitute the credible fatigue life and the test stress values of the slant line segments corresponding to the two groups of fatigue specimens into the S-N curve slant line segment empirical formula to obtain the slant line segment formula of the target S-N curve; A curve drawing module, configured to measure the fatigue limit strength of the material used for the fatigue specimen by the staircase method, and then draw the target S-N curve according to the fatigue limit strength and the slant line segment formula of the target S-N curve.

9. An electronic device, characterized in that, It includes a processor and a memory, and the memory stores computer-readable instructions. When the computer-readable instructions are executed by the processor, the steps in the rapid test and verification method of the S-N curve according to any one of claims 1-7 are run.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the rapid test and verification method of the S-N curve according to any one of claims 1-7.

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