Method, apparatus, machine-readable storage medium, and computing device for determining fracture toughness

Abstract

Embodiments of the present application provide a kind of fracture toughness determination method, device, machine readable storage medium and computing device, belong to mechanical property testing technical field.The method comprises: obtaining the load-crack nozzle opening displacement curve when target material carries out CTOD test;Each coordinate point on load-crack nozzle opening displacement curve is regularized to obtain J-R resistance curve;The toughness tear amount of target material is obtained, and the offset line is determined based on toughness tear amount;Determine the first CTOD value based on the intersection point corresponding to target J integral of offset line and J-R resistance curve;Linear fitting is carried out based on the first CTOD value and toughness tear amount to obtain fitting straight line;The apparent fracture toughness value of target material is determined based on fitting straight line.From the definition of apparent fracture toughness, the accuracy of fracture toughness calculation for different materials is improved.And by quantitative calculation apparent fracture toughness, provide reference basis for accurate material selection, damage tolerance design and life assessment.

Description

Technical Field

[0001] This invention relates to the field of mechanical property testing technology, and more specifically to a method, apparatus, machine-readable storage medium, and computing device for determining fracture toughness. Background Technology

[0002] Apparent fracture toughness refers to the toughness corresponding to the transformation process from crack blunting to having a macroscopic sharp defect, that is, the material resistance when there is no crack propagation. It can be directly measured from a specimen that produces a limited amount of toughness propagation at the crack tip. However, in actual experiments, on the one hand, it is difficult to directly observe and measure when the apparent fracture toughness is small, and on the other hand, crack propagation may cause deflection, making it impossible to accurately determine the original crack tip, and thus CTOD (Crack Tip Opening Displacement) cannot be measured.

[0003] Currently, most calculations of apparent fracture toughness are derived from fracture toughness values ​​measured on standard specimens, converted using conversion factors. For example, a conversion factor of 1.5-2.5 is needed for specimens tested under high constraint using the standard CTOD test, while a conversion factor of 1.7-1.8 is needed for specimens tested under shallow notch (Single Edge Notched Beam) conditions. Alternatively, the resistance curve obtained from the SENT (Single Edge Notched Tension) test is used to measure characteristic crack propagation. However, these calculation methods lack the relevant procedures based on the definition of apparent fracture toughness, making the calculation results prone to significant errors. Furthermore, apparent fracture toughness often varies for different materials, and calculations using only conversion factors cannot guarantee accuracy. Summary of the Invention

[0004] To address the aforementioned shortcomings in the prior art, the purpose of this application is to provide a method, apparatus, machine-readable storage medium, and computing device for determining fracture toughness.

[0005] To achieve the above objectives, the first aspect of this application provides a method for determining fracture toughness, comprising:

[0006] Obtain the load-crack opening displacement curve of the target material during CTOD testing;

[0007] The coordinate points on the load-crack opening displacement curve are regularized to obtain the JR resistance curve;

[0008] Obtain the toughness tear value of the target material and determine the offset line based on the toughness tear value;

[0009] The first CTOD value is determined based on the target J integral corresponding to the intersection of the bias line and the JR resistance curve;

[0010] A linear fit was performed based on the first CTOD value and the toughness tear amount to obtain the fitted straight line;

[0011] The apparent fracture toughness value of the target material is determined based on the fitted straight line.

[0012] In this embodiment of the application, a linear fitting is performed based on the first CTOD value and the toughness tear amount to obtain a fitted straight line, including:

[0013] A linear fit was performed with the first CTOD value as the x-axis and the toughness tear amount as the y-axis to obtain the fitted straight line.

[0014] In this embodiment of the application, determining the apparent fracture toughness value of the target material based on a fitted straight line includes:

[0015] The apparent fracture toughness value of the target material is determined based on the intersection of the fitted straight line and the horizontal axis.

[0016] In this embodiment of the application, before the step of obtaining the load-crack opening displacement curve of the target material during CTOD testing, the method further includes:

[0017] Obtain the load-crack opening displacement curves of the material under test under different temperatures during CTOD tests.

[0018] The second CTOD value corresponding to each temperature is determined based on the load-crack opening displacement curves.

[0019] Based on the correspondence between each second CTOD value and each temperature, the ductile-brittle transition curve is determined;

[0020] The materials to be tested corresponding to the upper plateau interval and the transition interval in the ductile-brittle transition curve are selected as the target materials.

[0021] In this embodiment of the application, each coordinate point on the load-crack opening displacement curve is regularized to obtain the JR resistance curve, including:

[0022] Obtain the dimensional information, mechanical property parameters, and initial crack length of the target material;

[0023] Based on dimensional information, mechanical performance indicators, and initial crack length, the J integral of each coordinate point on the load-crack opening displacement curve is determined.

[0024] The first standardized coordinates corresponding to each coordinate point are determined based on each J integral;

[0025] Fitting coordinates are selected from each of the first standardized coordinates based on preset fitting conditions;

[0026] The fitting function is determined based on each fitting coordinate.

[0027] Determining the target crack length based on a fitted function;

[0028] The corrected J-integral is determined based on the target crack length;

[0029] The Jr resistance curve is determined based on the target crack length and the modified J integral.

[0030] In this embodiment of the application, determining the target crack length based on a fitting function includes:

[0031] Select the first standardized coordinate point as the second coordinate point, where the corresponding crack opening displacement is greater than or equal to the preset length range.

[0032] The second standardized coordinates corresponding to the second coordinate point are determined based on the initial crack length;

[0033] Determine the first load value corresponding to the second standardized coordinates and the second load value corresponding to the second coordinate point in the fitting function;

[0034] The target crack length is determined based on the first load value, the second load value, and the preset load range.

[0035] In this embodiment of the application, determining the target crack length based on a first load value, a second load value, and a preset load range includes:

[0036] Determine the error between the first load value and the second load value;

[0037] If the error is not within the second preset range, the initial crack length is corrected;

[0038] The first load value is re-determined based on the corrected initial crack length until the error is within the second preset range, and the corrected initial crack length is taken as the target crack length.

[0039] A second aspect of this application provides a fracture toughness determination apparatus, comprising:

[0040] The curve acquisition module is used to acquire the load-crack opening displacement curve of the target material during CTOD testing.

[0041] The regularization module is used to regularize each coordinate point on the load-crack opening displacement curve to obtain the JR resistance curve.

[0042] The offset line determination module is used to obtain the toughness tear amount of the target material and determine the offset line based on the toughness tear amount;

[0043] The CTOD value determination module is used to determine the first CTOD value based on the target J integral corresponding to the intersection of the bias line and the JR resistance curve;

[0044] The linear fitting module is used to perform linear fitting based on the first CTOD value and the toughness tear amount to obtain a fitted straight line;

[0045] The fracture toughness calculation module is used to determine the apparent fracture toughness value of the target material based on the fitted straight line.

[0046] A third aspect of this application provides a machine-readable storage medium storing instructions that cause a machine to perform the fracture toughness determination method as described in the above embodiments.

[0047] A fourth aspect of this application provides a computing device, including: a memory, a processor, and a program stored in the memory and executable on the processor, the program being configured to implement the fracture toughness determination method as described in the above embodiments.

[0048] The above technical solution obtains the load-crack opening displacement curve of the target material during CTOD testing; regularizes each coordinate point on the load-crack opening displacement curve to obtain the JR resistance curve; obtains the toughness tear amount of the target material and determines the offset line based on the toughness tear amount; determines the first CTOD value based on the target J integral corresponding to the intersection of the offset line and the JR resistance curve; performs linear fitting between the first CTOD value and the toughness tear amount to obtain a fitted straight line; and determines the apparent fracture toughness value of the target material based on the fitted straight line. Starting from the definition of apparent fracture toughness, the accuracy of fracture toughness calculation results for different materials is improved. Furthermore, the quantitative calculation of the apparent fracture toughness of materials provides a reference for accurate material selection, damage tolerance design, and equipment life assessment.

[0049] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0050] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings:

[0051] Figure 1 The schematic diagram illustrates a process flow diagram of a method for determining fracture toughness according to an embodiment of this application;

[0052] Figure 2 This illustration schematically shows the toughness tearing amount of a target material fracture surface according to an embodiment of the present application;

[0053] Figure 3 A schematic diagram of a JR drag curve according to an embodiment of this application is shown.

[0054] Figure 4 A schematic diagram of a fitted straight line according to an embodiment of this application is shown.

[0055] Figure 5 A schematic diagram of a ductile-brittle transition curve according to an embodiment of this application is shown.

[0056] Figure 6 The schematic diagram illustrates a structural schematic of a fracture toughness determination device according to an embodiment of this application. Detailed Implementation

[0057] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for illustration and explanation of the embodiments of this application and are not intended to limit the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0058] It should be noted that if the embodiments of this application involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0059] Furthermore, if the embodiments of this application involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0060] Figure 1 The illustration schematically shows a flowchart of a method for determining fracture toughness according to an embodiment of this application. Figure 1 As shown in the embodiments of this application, a method for determining fracture toughness is provided, which may include the following steps:

[0061] Step 100: Obtain the load-crack opening displacement curve of the target material during the CTOD test;

[0062] In this embodiment, it should be noted that the target material can be X80 pipeline steel. X80 pipeline steel is the mainstream grade used in natural gas pipeline engineering in recent years. It belongs to the high-strength steel grade in the American Petroleum Institute (API) standards. Its widespread use allows pipelines to operate under conditions of large diameter and small wall thickness, increasing pipeline medium pressure, improving transportation efficiency, reducing steel usage, and effectively reducing construction and operating costs. During long-term service, pipelines traverse vast areas, and long-distance transportation pipelines inevitably pass through complex environments such as earthquake zones, fault shifts, landslides, and permafrost. The pipelines are subjected to complex loads, and the media transported by pressure pipelines are often flammable, explosive, or toxic and corrosive substances. This makes pipeline safety a top priority; pipeline failure can lead to catastrophic consequences affecting personnel, property, and the environment. Fracture toughness is a comprehensive reflection of a material's strength and toughness, used to characterize a material's ability to resist crack instability and propagation. It plays an important role in assessing the structural integrity of in-service equipment and estimating its service life.

[0063] The CTOD test is a standard test method for evaluating the fracture toughness of materials. For steel, the CTOD test typically uses a single-sided slotted bend (SENB) specimen and applies a three-point bend load. During loading, the loading force and crack tip opening displacement are recorded simultaneously. Generally, steel has good toughness; under load, the crack tip undergoes a process from elastic deformation to plastic deformation until the crack width reaches a critical value. At this point, the crack begins to propagate unstably, forming a new surface and releasing energy. This can lead to partial or complete failure of the material or part, which is considered the most dangerous type of failure in engineering. The purpose of the CTOD test is to calculate the critical value for crack tip opening during unstable crack propagation. During the CTOD test, data is displayed and recorded as a load-crack tip opening displacement curve. Different types of materials may produce load-crack tip opening displacement curves of different shapes.

[0064] Step 200: Regularize each coordinate point on the load-crack opening displacement curve to obtain the JR resistance curve;

[0065] It should be noted that the curve showing the change in the J-integral resistance value of a material with the crack propagation amount Δa is called the JR resistance curve. In most ductile materials, after crack initiation, the singularity at the crack tip is much weaker than before crack initiation. For the crack to continue propagating, the load needs to be continuously increased. The crack undergoes a stable propagation process before finally reaching unstable propagation and fracturing. The JR resistance curve can describe this phenomenon and can relatively completely show the material's ability to resist crack propagation.

[0066] Specifically, in one embodiment, each coordinate point on the load-crack opening displacement curve is regularized to obtain the JR resistance curve, including:

[0067] Obtain the dimensional information, mechanical property parameters, and initial crack length of the target material;

[0068] Based on dimensional information, mechanical performance indicators, and initial crack length, the J integral of each coordinate point on the load-crack opening displacement curve is determined.

[0069] The first standardized coordinates corresponding to each coordinate point are determined based on each J integral;

[0070] Fitting coordinates are selected from each of the first standardized coordinates based on preset fitting conditions;

[0071] The fitting function is determined based on each fitting coordinate.

[0072] Determining the target crack length based on a fitted function;

[0073] The corrected J-integral is determined based on the target crack length;

[0074] The Jr resistance curve is determined based on the target crack length and the modified J integral.

[0075] It should be noted that the dimensional information of the target material includes its width, thickness, net thickness, and span; the mechanical properties include its yield strength, elastic modulus, and Poisson's ratio. The initial and final crack lengths of the target material are obtained. After regularizing each coordinate point on the load-crack opening displacement curve, the standardized load and standardized crack opening displacement corresponding to each coordinate point are obtained. Specifically, the point P with the maximum load on the load-crack opening displacement curve is... max The coordinates of the previous point (P) i V i After regularization, the standardized load P is obtained. Ni and standardized crack opening displacement v p ′ li The processing steps include:

[0076]

[0077]

[0078] Among them, P Ni The normalized load at the i-th coordinate point is represented by W; the width of the target material is represented by B; and the thickness of the target material is represented by η. pl Calculate the parametric factor for the plasticity component of the J integral; a bi v represents the passivation crack correction length corresponding to the i-th coordinate point; p ′ li v represents the normalized crack opening displacement corresponding to the i-th coordinate point; pli It is the displacement of the opening of the plastic crack mouth; C i This represents the crack length 'a' corresponding to the current i-th coordinate point. i The linear compliance of the specimen under elastic load.

[0079] Specifically, Among them, a o Indicates the initial crack length; σ Y σ represents the effective yield strength of the target material. Y =1 / 2(σ ys +σ uts ), where σ ys σ represents the yield strength of the target material. uts Indicates the tensile strength of the specimen; J i Let J represent the integral corresponding to the i-th coordinate point.

[0080] J pl This represents the plastic part of the J-integral. Among them, A pl A is the area of ​​the plastic portion of the load-crack opening displacement curve. pl η is calculated from the load-crack opening displacement curve. pl Indicates the calculation parameters of the plastic part of the J integral; B N B represents the net thickness of the target material. When the target material has no side grooves, B represents the net thickness of the target material. N =B; b o =Wa o .

[0081] Specifically, η pl The following formula is used to calculate the plastic component of J integral based on the crack opening displacement:

[0082] η pl =3.667-2.199(a) o / W)+0.437(a o / W) 2 .

[0083] Specifically, in, Among them, K i J represents the stress intensity factor; oli The plastic component of the J integral corresponding to the i-th coordinate point is represented; E represents the elastic modulus of the target material; v represents the Poisson's ratio of the target material; B N B represents the net thickness of the target material. When the target material does not have side grooves, B N =B; S represents the span;

[0084] in, Among them, a i Indicates the target crack length; when regularizing the coordinates of the points corresponding to the maximum load value on the load-crack opening displacement curve, a i Take the final crack length a f When performing regularization on coordinate points other than those corresponding to the maximum load point, a i Take the initial crack length a o .

[0085] It should be noted that the preset fitting conditions include conditions for filtering the first standardized coordinates. Based on the preset fitting conditions, the first standardized coordinates used for data fitting are selected as the fitting coordinates. Specifically, the maximum load point P on the load-crack opening displacement curve is used as the fitting coordinate. max Tangents are drawn from the first standardized coordinates corresponding to the regularization to the remaining first standardized coordinates. Points with a crack opening displacement less than or equal to 0.001 corresponding to the first standardized coordinates, as well as points to the right of the tangent, are excluded. The remaining first standardized coordinates are used as fitting coordinates for data fitting to obtain a fitting function. Preset fitting conditions also include that the deviation between the load value at the maximum load point determined by the fitting function and the load value at the maximum load point on the load-crack opening displacement curve should be less than 1% of the load value at the maximum load point on the load-crack opening displacement curve; and that at least 10 sets of data points corresponding to the fitting function should be evenly distributed between the coordinate point with a crack opening displacement equal to 0.001 and the tangent point corresponding to the fitting coordinates. It is understood that the preset fitting conditions can be adaptively adjusted based on actual application requirements. Specifically, the fitting function includes:

[0086]

[0087] Among them, P N This represents the loading values ​​in the fitted function; v p ′ l denoted by , where represents the crack opening displacement in the fitted function; a, b, c, and d represent the coefficients of the fitted function.

[0088] After determining the fitting function, the first standardized coordinates are regularized. Based on the fitting function and the regularized first standardized coordinates, the crack length is continuously adjusted to determine the final target crack length. Then, based on the target crack length, the J-integral (corrected J-integral) is determined for each second coordinate point. The crack propagation amount is determined by subtracting the initial crack length from the target crack length. This crack propagation amount is then correlated with the corrected J-integral to obtain the JR drag curve. Specifically, the crack propagation amount Δa is substituted into the following formula to calculate the corrected J-integral:

[0089]

[0090] Where J represents the corrected J integral; J e / 0 J represents the uncorrected elastic component of the integral; p / 0 This represents the uncorrected plastic portion of the J-integral; for the SENB specimen, α is 1; Δa represents the crack propagation amount; b o =Wa o Where W represents the width of the target material; a o This indicates the initial crack length.

[0091] Specifically, determining the target crack length based on the fitted function includes:

[0092] Select the first standardized coordinate point as the second coordinate point, where the corresponding crack opening displacement is greater than or equal to the preset length range.

[0093] The second standardized coordinates corresponding to the second coordinate point are determined based on the initial crack length.

[0094] Determine the first load value corresponding to the second standardized coordinates and the second load value corresponding to the second coordinate point in the fitting function;

[0095] The target crack length is determined based on the first load value, the second load value, and the preset load range.

[0096] In this embodiment, it should be noted that since the crack propagation amount cannot be accurately confirmed during the CTOD test, in this embodiment, the first standardized coordinates corresponding to the crack opening displacement being greater than or equal to a preset length range are selected as the second coordinate points. Let a i Take the initial crack length a o The second coordinate point is regularized to obtain the second standardized coordinates. The first load value corresponding to the second standardized coordinates and the second load value corresponding to the second coordinate point in the fitting function are determined. A preset load range is used to limit the difference between the first and second load values.

[0097] Specifically, the target crack length is determined based on the first load value, the second load value, and the preset load range, including:

[0098] Determine the error between the first load value and the second load value;

[0099] If the error is not within the second preset range, the initial crack length is corrected;

[0100] The first load value is re-determined based on the corrected initial crack length until the error is within the second preset range, and the corrected initial crack length is taken as the target crack length.

[0101] Calculate the difference between the first load value and the second load value, i.e., the error between them; determine if this error is within a second preset range; if it is, directly use the initial crack length as the target crack length; if it is not within the second preset range, correct the initial crack length, with the correction step size set based on accuracy requirements, for example, 0.001 mm. Based on the corrected initial crack length, re-regularize the second coordinate point to obtain new second standardized coordinates, thus obtaining the first load value corresponding to the second standardized coordinates. Continue this process until the error between the first and second load values ​​is within the second preset range, then use the corrected initial crack length as the target crack length.

[0102] By pre-setting the load range, the calculation progress of the target crack length is improved, errors are reduced, and the accuracy of judging the apparent fracture toughness of the material is improved.

[0103] Step 300: Obtain the toughness tear value of the target material and determine the offset line based on the toughness tear value;

[0104] Step 400: Determine the first CTOD value based on the target J integral corresponding to the intersection of the bias line and the JR resistance curve;

[0105] It should be noted that the ductile tear strength can be obtained by taking a fracture image of the target material using an optical microscope, and then measuring this fracture image. (Reference) Figure 2 , Figure 2 This includes a schematic diagram of the ductile tear amount at the fracture surface of the target material in one embodiment. (Reference) Figure 3 In this embodiment, the toughness tearing amount of the target material is used instead of 0.22 mm as the offset line of the JR drag curve. The corrected J integral corresponding to the intersection of the offset line and the JR drag curve is used as the target J integral, and the first CTOD value is determined based on this target J integral. The apparent fracture toughness value of the target material can be determined by correlating the first CTOD value with the toughness tearing amount, thereby characterizing the fracture toughness of the target material. Specifically, the formula for calculating the first CTOD value is:

[0106]

[0107] Where, δ i Indicates the first CTOD value; J1 represents the target J integral; σ Y Indicates the effective yield strength of the target material;

[0108]

[0109] Where, A0 = 3.18 - 0.22 * (a i / W); A1 = 4.32 - 2.23 * (a i / W);

[0110] A2 = 4.44 - 2.29 * (a i / W); A3 = 2.05 - 1.06 * (a i / W); where a i W represents the target crack length; W represents the width of the target material.

[0111] Step 500: Perform linear fitting based on the first CTOD value and the toughness tear amount to obtain the fitted straight line;

[0112] Step 600: Determine the apparent fracture toughness value of the target material based on the fitted straight line.

[0113] In this embodiment, it should be noted that the load-crack opening displacement curves of the target material differ under different temperature conditions; that is, the first CTOD value and toughness tear amount differ at different temperatures. Experiments were conducted under multiple different temperature conditions to obtain multiple first CTOD values ​​and toughness tear amounts. All the first CTOD values ​​and toughness tear amounts were linearly fitted using the equation y = bx + c to obtain a fitted straight line. At this point, the linear relationship between the first CTOD value and toughness tear amount of the target material has been fully obtained, and the corresponding apparent fracture toughness of the target material can be calculated.

[0114] In one embodiment, determining the apparent fracture toughness value of the target material based on a fitted straight line includes:

[0115] The apparent fracture toughness value of the target material is determined based on the intersection of the fitted straight line and the horizontal axis.

[0116] It should be noted that, in this embodiment, the intersection of the fitted straight line and the horizontal axis can characterize the apparent fracture toughness value of the target material.

[0117] In this embodiment, the load-crack opening displacement curve of the target material during a CTOD test is obtained; each coordinate point on the load-crack opening displacement curve is regularized to obtain the JR resistance curve; the toughness tear amount of the target material is obtained, and an offset line is determined based on the toughness tear amount; the first CTOD value is determined based on the target J integral corresponding to the intersection of the offset line and the JR resistance curve; a linear fit is performed between the first CTOD value and the toughness tear amount to obtain a fitted straight line; and the apparent fracture toughness value of the target material is determined based on the fitted straight line. Starting from the definition of apparent fracture toughness, the accuracy of the fracture toughness calculation results for different materials is improved. Furthermore, the quantitative calculation of the apparent fracture toughness of the material provides a reference for accurate material selection, damage tolerance design, and equipment life assessment.

[0118] In one embodiment, a linear fit is performed based on the first CTOD value and the toughness tear amount to obtain a fitted straight line, including:

[0119] A linear fit was performed with the first CTOD value as the x-axis and the toughness tear amount as the y-axis to obtain the fitted straight line.

[0120] In this embodiment, it should be noted that after determining the first CTOD value and the toughness tear amount, based on the correspondence between the first CTOD value and the toughness tear amount, all the first CTOD values ​​and toughness tear amounts are linearly fitted according to y = bx + c to obtain a fitted straight line. (Reference) Figure 4 In one embodiment, taking X80 pipeline steel as an example, the fitted straight line is obtained as y = 2.4792x - 0.2625, R 2 =0.9928.

[0121] In this embodiment, the effectiveness of calculating the fracture toughness of materials is improved by linearly fitting the CTOD value with the toughness tear amount.

[0122] In one embodiment, before the step of obtaining the load-crack opening displacement curve of the target material during CTOD testing, the method further includes:

[0123] Obtain the load-crack opening displacement curves of the material under test under different temperatures during CTOD tests.

[0124] The second CTOD value corresponding to each temperature is determined based on the load-crack opening displacement curves.

[0125] Based on the correspondence between each second CTOD value and each temperature, the ductile-brittle transition curve is determined;

[0126] The materials to be tested corresponding to the upper plateau interval and the transition interval in the ductile-brittle transition curve are selected as the target materials.

[0127] In this embodiment, it should be noted that, to improve the accuracy and effectiveness of the material fracture toughness calculation, samples with larger ductile-brittle transition values ​​are selected for calculation. Specifically, load-crack opening displacement curves of the test material at different temperatures are obtained, and a second CTOD value corresponding to each temperature is determined for each load-crack opening displacement curve. It is understood that the method of determining CTOD values ​​based on load-crack opening displacement curves is well-known to those skilled in the art and will not be elaborated upon here. After determining the second CTOD value of the test material at each temperature, a ductile-brittle transition curve is generated based on the correspondence between each second CTOD value and each temperature. (Reference) Figure 5 In the ductile-brittle transition curve, at higher temperatures, the impact absorption energy changes slowly with temperature, known as the upper plateau region; when the temperature decreases to a very narrow range, the impact absorption energy decreases sharply with decreasing temperature, known as the transition region; when the temperature decreases further, the impact absorption energy changes slowly with temperature again, known as the lower plateau region. In this embodiment, to ensure effective ductile tearing, the test materials corresponding to the upper plateau region and the transition region are selected as the target materials. Furthermore, to meet the experimental requirements, the initial crack length 'a' of the target material is... o It should satisfy 0.45≤a0 / W≤0.70, and the final crack length a of the target material should be... f The crack length should not exceed 4 mm and the initial crack length a o 15%.

[0128] In this embodiment, the effectiveness and accuracy of calculating the fracture toughness of the material are improved by screening the target material. Furthermore, this embodiment can significantly reduce sample preparation and testing costs by using small-sample tests.

[0129] refer to Figure 6 This application embodiment also provides a fracture toughness determining device 1000, comprising:

[0130] The curve acquisition module 1001 is used to acquire the load-crack opening displacement curve of the target material during CTOD testing.

[0131] The regularization processing module 1002 is used to regularize each coordinate point on the load-crack opening displacement curve to obtain the JR resistance curve.

[0132] The offset line determination module 1003 is used to obtain the toughness tear amount of the target material and determine the offset line based on the toughness tear amount;

[0133] The CTOD value determination module 1004 is used to determine the first CTOD value based on the target J integral corresponding to the intersection of the bias line and the JR resistance curve.

[0134] The linear fitting module 1005 is used to perform linear fitting based on the first CTOD value and the toughness tear amount to obtain a fitted straight line;

[0135] Fracture toughness calculation module 1006 is used to determine the apparent fracture toughness value of the target material based on the fitted straight line.

[0136] The fracture toughness determination device 1000 includes a processor and a memory. The curve acquisition module 1001, regularization processing module 1002, offset line determination module 1003, CTOD value determination module 1004, linear fitting module 1005, and fracture toughness calculation module 1006 are all stored in the memory as program units. The processor executes the program units stored in the memory to realize the corresponding functions.

[0137] The processor contains a kernel, which retrieves the corresponding program unit from memory. One or more kernels can be configured, and the fracture toughness of the material is determined by adjusting the kernel parameters.

[0138] The memory may include non-permanent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM, and the memory includes at least one memory chip.

[0139] The fracture toughness determination device provided in this application embodiment can respectively achieve… Figure 1 The various processes of the fracture toughness determination method in the embodiments of the method are the same and can achieve the same technical effect. To avoid repetition, they will not be described again here.

[0140] This application also provides a machine-readable storage medium storing instructions that cause a machine to execute the fracture toughness determination method according to the above embodiments.

[0141] This application also provides a computing device, including: a memory, a processor, and a program stored in the memory and executable on the processor, the program being configured to implement the fracture toughness determination method as described in the above embodiments.

[0142] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0143] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0144] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0145] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0146] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0147] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0148] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0149] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0150] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A method for determining fracture toughness, characterized in that, include: Obtain the load-crack opening displacement curve of the target material during CTOD testing; The coordinate points on the load-crack opening displacement curve are regularized to obtain the JR resistance curve; The toughness tear value of the target material is obtained, and an offset line is determined based on the toughness tear value, wherein the toughness tear value is used as the value of the offset line. The first CTOD value is determined based on the target J integral corresponding to the intersection of the bias line and the JR resistance curve; A linear fit is performed based on the first CTOD value and the toughness tear amount to obtain a fitted straight line; The apparent fracture toughness value of the target material is determined based on the fitted straight line; The step of performing a linear fit based on the first CTOD value and the toughness tear amount to obtain a fitted straight line includes: Obtain the first CTOD value and the toughness tear amount under multiple sets of different temperature conditions; A linear fitting is obtained by performing a linear fit between multiple sets of the first CTOD values ​​and the toughness tear amount.

2. The method for determining fracture toughness according to claim 1, characterized in that, The step of performing a linear fit based on the first CTOD value and the toughness tear amount to obtain a fitted straight line includes: A linear fit is performed with the first CTOD value as the abscissa and the toughness tear amount as the ordinate to obtain a fitted straight line.

3. The method for determining fracture toughness according to claim 2, characterized in that, Determining the apparent fracture toughness value of the target material based on the fitted straight line includes: The apparent fracture toughness value of the target material is determined based on the intersection of the fitted straight line and the horizontal axis.

4. The method for determining fracture toughness according to claim 1, characterized in that, Before the step of obtaining the load-crack opening displacement curve of the target material during CTOD testing, the method further includes: Obtain the load-crack opening displacement curves of the material under test under different temperatures during CTOD tests. The second CTOD value corresponding to each temperature is determined based on each of the load-crack opening displacement curves. Based on the correspondence between each of the second CTOD values ​​and each of the temperatures, the ductile-brittle transition curves are determined; The materials to be tested corresponding to the upper plateau interval and the transition interval in the ductile-brittle transition curve are selected as the target materials.

5. The method for determining fracture toughness according to claim 1, characterized in that, The process of regularizing each coordinate point on the load-crack opening displacement curve to obtain the JR resistance curve includes: Obtain the dimensional information, mechanical property indicators, and initial crack length of the target material; Based on the dimensional information, the mechanical performance indicators, and the initial crack length, determine the J integral of each coordinate point on the load-crack opening displacement curve; The first standardized coordinates corresponding to each coordinate point are determined based on each of the J integrals; Based on preset fitting conditions, fit coordinates are selected from each of the first standardized coordinates; The fitting function is determined based on each of the fitting coordinates; The target crack length is determined based on the fitted function; The corrected J integral is determined based on the target crack length; The Jr resistance curve is determined based on the target crack length and the modified J integral.

6. The method for determining fracture toughness according to claim 5, characterized in that, Determining the target crack length based on the fitted function includes: Select the first standardized coordinate point as the second coordinate point, where the corresponding crack opening displacement is greater than or equal to the preset length range. The second standardized coordinates corresponding to the second coordinate point are determined based on the initial crack length. Determine the first load value corresponding to the second standardized coordinate and the second load value corresponding to the second coordinate point in the fitting function; The target crack length is determined based on the first load value, the second load value, and the preset load range.

7. The method for determining fracture toughness according to claim 6, characterized in that, Determining the target crack length based on the first load value, the second load value, and a preset load range includes: Determine the error between the first load value and the second load value; If the error is not within the second preset range, the initial crack length is corrected; The first load value is re-determined based on the corrected initial crack length until the error is within the second preset range, and the corrected initial crack length is taken as the target crack length.

8. A device for determining fracture toughness, characterized in that, include: The curve acquisition module is used to acquire the load-crack opening displacement curve of the target material during CTOD testing. The regularization processing module is used to regularize each coordinate point on the load-crack opening displacement curve to obtain the JR resistance curve. The offset line determination module is used to obtain the toughness tear amount of the target material and determine the offset line based on the toughness tear amount, wherein the toughness tear amount is used as the value of the offset line. The CTOD value determination module is used to determine the first CTOD value based on the target J integral corresponding to the intersection of the bias line and the JR resistance curve; The linear fitting module is used to perform linear fitting based on the first CTOD value and the toughness tear amount to obtain a fitted straight line; A fracture toughness calculation module is used to determine the apparent fracture toughness value of the target material based on the fitted straight line. The linear fitting module is also used for: Obtain the first CTOD value and the toughness tear amount under multiple sets of different temperature conditions; A linear fitting is obtained by performing a linear fit between multiple sets of the first CTOD values ​​and the toughness tear amount.

9. A machine-readable storage medium, characterized in that, The machine-readable storage medium stores instructions for causing the machine to perform the fracture toughness determination method according to any one of claims 1 to 7.

10. A computing device, characterized in that, include: A memory, a processor, and a program stored in the memory and executable on the processor, the program being configured to implement the fracture toughness determination method according to any one of claims 1 to 7.

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