Method, apparatus, and non-volatile storage medium for determining fracture toughness of a specimen

Abstract

The present application discloses a method, device and non-volatile storage medium for determining the fracture toughness of a specimen, relating to the field of material testing. Among them, the method includes: determining the stress-plastic strain experimental data of a target specimen and determining a target load; determining a finite element model, and determining the first stress component, the second stress component and the third stress component of the target specimen according to the stress-plastic strain experimental data and the target load; selecting a plurality of points in the target specimen based on the crack tip and determining the distance from each point to the crack tip; determining the mixed-mode crack fracture toughness of the crack tip in the height direction according to the first stress component, the second stress component, the third stress component and the distance from each point to the crack tip. The present application solves the technical problem that in the related art, the fracture toughness performance of materials cannot be accurately determined due to the inability to test the fracture toughness of I-II-III mixed-mode cracks.

Description

Technical Field

[0001] The present application relates to the field of material testing, and in particular, to a method and device for determining the fracture toughness of a specimen and a non-volatile storage medium. Background Art

[0002] Cracks and similar defects are inevitable in any engineering material and structure. They are either inherent in the material itself or caused during processing, manufacturing, construction and use. The existence of these cracks and defects will greatly reduce the bearing capacity of the structure, and when they develop to a certain extent, the structure will completely fail. The study of the expansion law of cracks in metal materials has always been one of the important research topics in engineering. Aluminum alloy materials are widely used in various fields such as navigation, aviation, aerospace, mechanical processing, and production due to their light density, high specific strength and specific stiffness. Especially with the continuous development of the aerospace industry, the demand for aluminum alloys as medium and thick plates, extrusions, free forgings and die forgings for aircraft structural parts is increasing. Due to the low fracture toughness of aluminum alloy materials during application, when there are processing defects, fracture accidents often occur.

[0003] However, the testing of material fracture toughness in related technologies mainly focuses on the research of I, II and I-II composite cracks, and the testing method for the fracture toughness of I-II-III composite cracks has not yet been proposed.

[0004] To address the above-mentioned problems, no effective solution has been proposed yet. Summary of the invention

[0005] The embodiments of the present application provide a method, device and non-volatile storage medium for determining the fracture toughness of a specimen, so as to at least solve the technical problem in the related art that the fracture toughness of a I-II-III composite crack cannot be tested, which leads to the inability to accurately determine the fracture toughness performance of a material.

[0006] According to one aspect of an embodiment of the present application, a method for determining fracture toughness of a sample is provided, comprising: determining stress-plastic strain experimental data of a target sample, and determining a target load of the target sample, wherein the target load is the maximum load at which the target sample is destroyed when a three-point bending test is performed on the target sample, and the target sample contains a prefabricated half crack; determining a finite element model of the target sample, and determining a first stress component, a second stress component, and a third stress component of the target sample based on the stress-plastic strain experimental data and the target load, wherein the first stress component is a stress component in the length direction of the finite element model, and the second stress component is a stress component in the width direction of the finite element model. stress component, the third stress component is the stress component in the height direction of the finite element model; multiple points are selected in the target sample according to the crack tip of the prefabricated half crack, and the distance from each point to the crack tip is determined; the opening fracture toughness data, the sliding fracture toughness data and the tearing fracture toughness data of the target sample are determined according to the first stress component, the second stress component, the third stress component and the distance from each point to the crack tip, and the composite crack fracture toughness at the crack tip in the height direction is determined according to the opening fracture toughness data, the sliding fracture toughness data and the tearing fracture toughness data, wherein the composite crack includes an opening crack, a sliding crack and a tearing crack.

[0007] Optionally, selecting multiple points in the target sample based on the crack tip of the prefabricated half crack includes: selecting a number of first-class points along the height direction at the crack tip; determining the path corresponding to each first-class point, wherein the starting point of the path is the first-class point and the direction of the path is the width direction; and selecting a number of second-class points on each path.

[0008] Optionally, before determining the opening fracture toughness data, sliding fracture toughness data and tearing fracture toughness data of the target sample based on the first stress component, the second stress component, the third stress component and the distance from each point to the crack tip, the sample fracture toughness determination method also includes: determining the stress intensity factor of each second-type point, wherein the stress intensity factor of the second-type point includes the opening fracture toughness parameter, sliding fracture toughness parameter and tearing fracture toughness parameter of the second-type point; and determining the stress intensity factor of the first-type point by extrapolation based on the stress intensity factor of the second-type point corresponding to each first-type point, wherein the stress intensity factor of the first-type point includes the opening fracture toughness parameter, sliding fracture toughness parameter and tearing fracture toughness parameter of the first-type point.

[0009] Optionally, the opening fracture toughness data includes the opening fracture toughness parameters of each point and the position information of each point in the height direction, the slip fracture toughness data includes the slip fracture toughness parameters of each point and the position information of each point in the height direction, and the tearing fracture toughness data includes the tearing fracture toughness parameters of each point and the position information of each point in the height direction.

[0010] Optionally, determining the stress-plastic strain experimental data of the target sample includes: determining the target material type of the target sample; determining the tensile force-displacement experimental data of the target material type, wherein the tensile force-displacement experimental data is data obtained by performing a tensile test on a material of the target material type; determining the engineering stress-strain experimental data of the target material type based on the tensile force-displacement experimental data; and determining the stress-plastic strain experimental data of the target sample based on the engineering stress-strain experimental data.

[0011] Optionally, the coordinate origin of the finite element model is the crack tip, the X-axis direction of the finite element model is the length direction, the Y-axis direction of the finite element model is the width direction, and the Z-axis direction of the finite element model is the height direction.

[0012] Optionally, the crack type of the prefabricated half crack includes an edge deflection crack.

[0013] According to another aspect of an embodiment of the present application, a device for determining fracture toughness of a specimen is also provided, comprising: a first processing module, for determining stress-plastic strain experimental data of a target specimen, and determining a target load of the target specimen, wherein the target load is the maximum load at which the target specimen is destroyed when a three-point bending test is performed on the target specimen, and the target specimen contains a prefabricated half crack; a second processing module, for determining a finite element model of the target specimen, and determining a first stress component, a second stress component, and a third stress component of the target specimen based on the stress-plastic strain experimental data and the target load, wherein the first stress component is a stress component in the length direction of the finite element model, and the second stress component is a stress component in the width direction of the finite element model. stress component, the third stress component is the stress component in the height direction of the finite element model; a third processing module is used to select multiple points in the target sample according to the crack tip of the prefabricated half crack, and determine the distance from each point to the crack tip; a fourth processing module is used to determine the opening fracture toughness data, sliding fracture toughness data and tearing fracture toughness data of the target sample according to the first stress component, the second stress component, the third stress component and the distance from each point to the crack tip, and determine the composite crack fracture toughness of the crack tip in the height direction according to the opening fracture toughness data, the sliding fracture toughness data and the tearing fracture toughness data, wherein the composite crack includes opening cracks, sliding cracks and tearing cracks.

[0014] According to an embodiment of the present application, a non-volatile storage medium is also provided, in which a program is stored, wherein when the program is running, a device where the non-volatile storage medium is located is controlled to execute a method for determining the fracture toughness of a sample.

[0015] According to an embodiment of the present application, there is also provided an electronic device, including: a memory and a processor, the processor being used to run a program stored in the memory, wherein the method for determining the fracture toughness of a specimen is executed when the program is run.

[0016] According to an embodiment of the present application, a computer program product is also provided, including a computer program, which implements the steps of the method for determining the fracture toughness of a specimen when the computer program is executed by a processor.

[0017] In an embodiment of the present application, stress-plastic strain experimental data of a target sample are determined, and a target load of the target sample is determined, wherein the target load is the maximum load at which the target sample is destroyed when a three-point bending test is performed on the target sample, and the target sample contains a prefabricated half crack; a finite element model of the target sample is determined, and a first stress component, a second stress component, and a third stress component of the target sample are determined based on the stress-plastic strain experimental data and the target load, wherein the first stress component is a stress component in the length direction of the finite element model, the second stress component is a stress component in the width direction of the finite element model, and the third stress component is a stress component in the height direction of the finite element model; multiple points are selected in the target sample based on the crack tip of the prefabricated half crack, and the distance from each point to the crack tip is determined; based on the first stress component, the second stress component, the third stress component, and the distance from each point to the crack tip, the distance between the first stress component, the second stress component, the third stress component, and the distance between each point and the crack tip are determined. The opening fracture toughness data, sliding fracture toughness data and tearing fracture toughness data of the target sample are determined according to the distance from the end, and the composite crack fracture toughness of the crack tip in the height direction is determined based on the opening fracture toughness data, sliding fracture toughness data and tearing fracture toughness data, wherein the composite crack includes opening cracks, sliding cracks and tearing cracks. The composite crack fracture toughness of the crack tip in the height direction is determined by determining the opening fracture toughness data, sliding fracture toughness data and tearing fracture toughness data of the target sample, thereby achieving the purpose of determining the I-II-III composite crack fracture toughness of the material, thereby achieving the technical effect of more accurately determining the fracture toughness performance of the material, and further solving the technical problem that the fracture toughness performance of the material cannot be accurately determined due to the inability to test the I-II-III composite crack fracture toughness in the related technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0019] Figure 1 is a structural schematic diagram of a computer terminal (or mobile terminal) provided according to an embodiment of the present application;

[0020] Figure 2 It is a schematic flow chart of a method for determining fracture toughness of a sample provided in an embodiment of the present application;

[0021] Figure 3 is a schematic diagram of a tensile specimen provided according to an embodiment of the present application;

[0022] Figure 4 is a schematic diagram of a tensile specimen size provided according to an embodiment of the present application;

[0023] Figure 5 is a schematic diagram of a load-displacement curve of a tensile test provided in an embodiment of the present application;

[0024] Figure 6 is a schematic diagram of a stress-strain curve of a tensile test provided in an embodiment of the present application;

[0025] FIG. 7 ( a ) is a schematic diagram of the dimensions of a specimen with a prefabricated half crack provided according to an embodiment of the present application;

[0026] FIG7( b ) is a schematic diagram of a sample with a prefabricated half crack provided according to an embodiment of the present application;

[0027] FIG8( a ) is a schematic diagram of an unconventional three-point bending experiment provided according to an embodiment of the present application;

[0028] FIG8( b ) is a schematic diagram of a sample after three-point bending fracturing according to an embodiment of the present application;

[0029] Fig. 9 It is a schematic diagram of a load-displacement curve of an unconventional three-point bending test of a prefabricated half-cracked specimen provided in an embodiment of the present application;

[0030] Fig.10 A schematic diagram of a finite element model provided in an embodiment of the present application;

[0031] Fig.11 A schematic diagram of a first stress component cloud diagram provided in an embodiment of the present application;

[0032] Fig.12 A schematic diagram of a second stress component cloud diagram provided in an embodiment of the present application;

[0033] Fig.13 A schematic diagram of a third stress component cloud diagram provided in an embodiment of the present application;

[0034] Fig.14The embodiment of the present application provides that l=20mm, Z 1 =0, schematic diagram of Kr curve;

[0035] Fig.15 l=20mm, Z provided in the embodiment of the present application 2 =2mm, schematic diagram of Kr curve;

[0036] Fig.16 l=20mm, Z provided in the embodiment of the present application 3 =4mm, schematic diagram of Kr curve;

[0037] Fig.17 l=20mm, Z provided in the embodiment of the present application 4 =6mm, schematic diagram of Kr curve;

[0038] Fig.18 l=20mm, Z provided in the embodiment of the present application 5 = 8mm, schematic diagram of Kr curve;

[0039] Fig.19 l = 20 mm, Z provided in the application example 6 =10mm, schematic diagram of Kr curve;

[0040] Fig. 20 l=20mm, Z provided in the embodiment of the present application 7 =12mm, schematic diagram of Kr curve;

[0041] Fig.21 l=20mm, Z provided in the embodiment of the present application 8 =14mm, schematic diagram of Kr curve;

[0042] Fig. 22 l=20mm, Z provided in the embodiment of the present application 9 =16mm, schematic diagram of Kr curve;

[0043] Fig.23 l=20mm, Z provided in the embodiment of the present application 10 =18mm, schematic diagram of Kr curve;

[0044] Fig.24 l=20mm, Z provided in the embodiment of the present application 11 =20mm, schematic diagram of Kr curve;

[0045] Fig.25 ZK provided in the embodiment of the present applicationI Schematic diagram of the curve;

[0046] Fig.26 ZK provided in the embodiment of the present application II Schematic diagram of the curve;

[0047] Fig. 27 ZK provided in the embodiment of the present application III Schematic diagram of the curve;

[0048] Fig.28 Schematic diagram of a device for determining the fracture toughness of a sample provided in an embodiment of the present application. DETAILED DESCRIPTION

[0049] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present application.

[0050] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0051] Cracks and similar defects are inevitable in any engineering material and structure. They are either inherent in the material itself or caused during processing, manufacturing, construction and use. The existence of these cracks and defects will greatly reduce the bearing capacity of the structure, and when they develop to a certain extent, the structure will completely fail. The study of the expansion law of cracks in metal materials has always been one of the important research topics in engineering. Aluminum alloy materials are widely used in various fields such as navigation, aviation, aerospace, mechanical processing, and production due to their light density, high specific strength and specific stiffness. Especially with the continuous development of the aerospace industry, the demand for aluminum alloys as medium and thick plates, extrusions, free forgings and die forgings for aircraft structural parts is increasing. Due to the low fracture toughness of aluminum alloy materials during application, when there are processing defects, fracture accidents often occur.

[0052] However, the testing of material fracture toughness in related technologies mainly focuses on the research of I, II and I-II composite cracks, and the testing method for the fracture toughness of I-II-III composite cracks has not yet been proposed.

[0053] In order to solve this problem, a relevant solution is provided in the embodiments of the present application, which is described in detail below.

[0054] According to an embodiment of the present application, a method embodiment of a method for determining the fracture toughness of a specimen is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0055] The method embodiments provided in the embodiments of the present application can be executed in a mobile terminal, a computer terminal or a similar computing device. Figure 1 The hardware structure block diagram of a computer terminal (or mobile device) for implementing the method for determining the fracture toughness of a specimen is shown. Figure 1 As shown, the computer terminal 10 (or mobile device 10) may include one or more (102a, 102b, ..., 102n are used to illustrate) processors 102 (the processor 102 may include but is not limited to a processing device such as a microprocessor MCU or a programmable logic device FPGA), a memory 104 for storing data, and a transmission device 106 for communication functions. In addition, it may also include: a display, an input / output interface (I / O interface), a universal serial bus (USB) port (which may be included as one of the ports of the BUS bus), a network interface, a power supply and / or a camera. It can be understood by those skilled in the art that Figure 1 The structure shown is only for illustration and does not limit the structure of the above electronic device. Figure 1 More or fewer components as shown, or with Figure 1 Different configurations are shown.

[0056] It should be noted that the one or more processors 102 and / or other data processing circuits described above may generally be referred to herein as "data processing circuits". The data processing circuits may be embodied in whole or in part as software, hardware, firmware, or any other combination thereof. In addition, the data processing circuit may be a single independent processing module, or may be incorporated in whole or in part into any of the other components in the computer terminal 10 (or mobile device). As involved in the embodiments of the present application, the data processing circuit acts as a processor control (e.g., selection of a variable resistor terminal path connected to an interface).

[0057] The memory 104 can be used to store software programs and modules of application software, such as the program instructions / data storage device corresponding to the method for determining the fracture toughness of a specimen in the embodiment of the present application. The processor 102 executes various functional applications and data processing by running the software programs and modules stored in the memory 104, that is, the above-mentioned method for determining the fracture toughness of a specimen is realized. The memory 104 may include a high-speed random access memory, and may also include a non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some examples, the memory 104 may further include a memory remotely arranged relative to the processor 102, and these remote memories may be connected to the computer terminal 10 via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0058] The transmission device 106 is used to receive or send data via a network. The specific example of the above network may include a wireless network provided by a communication provider of the computer terminal 10. In one example, the transmission device 106 includes a network adapter (Network Interface Controller, NIC), which can be connected to other network devices through a base station so as to communicate with the Internet. In one example, the transmission device 106 can be a radio frequency (RF) module, which is used to communicate with the Internet wirelessly.

[0059] The display may be, for example, a touch screen liquid crystal display (LCD) that enables a user to interact with a user interface of the computer terminal 10 (or mobile device).

[0060] Under the above operating environment, the embodiment of the present application provides a method for determining the fracture toughness of a sample. It should be noted that the specific data mentioned in the embodiment of the present application are only used as examples and do not represent limitations on the present application document. Figure 2 As shown, the method comprises the following steps:

[0061] Step S202, determining stress-plastic strain experimental data of the target sample, and determining the target load of the target sample, wherein the target load is the maximum load when the target sample is destroyed during a three-point bending test, and the target sample contains a prefabricated half crack;

[0062] In the technical solution provided in step S202, the step of determining the stress-plastic strain experimental data of the target sample includes: determining the target material type of the target sample; determining the tensile force-displacement experimental data of the target material type, wherein the tensile force-displacement experimental data is data obtained by performing a tensile test on a material of the target material type; determining the engineering stress-strain experimental data of the target material type based on the tensile force-displacement experimental data; and determining the stress-plastic strain experimental data of the target sample based on the engineering stress-strain experimental data.

[0063] In some embodiments of the present application, when determining the tensile force-displacement experimental data of the target material type, Figure 3 The material shown in the figure is three round bars of the target material type for uniaxial tension testing. The dimensions of the round bar specimens are as follows: Figure 4 As shown in the figure, the load-displacement curve after stretching (that is, the tensile force-displacement experimental data) is as follows Figure 5 After obtaining the load-displacement curve, we can further obtain the following Figure 6 The engineering stress-strain test curve (that is, engineering stress-strain test data) is shown. The engineering stress-strain test curve is then converted into a true stress-true strain curve, and the elastic modulus and true stress-true plastic strain curve (that is, stress-plastic strain test data) of the target material type are obtained.

[0064] Specifically, the calculation formulas for engineering stress and engineering strain are as follows:

[0065]

[0066] In the above formula, F is the tensile load of the testing machine, A is the original cross-sectional area of ​​the round bar specimen, Δl is the deformation of the specimen gauge section, and l is the original length of the specimen gauge. is the engineering stress, For engineering strain.

[0067] The calculation of true stress and true plastic strain is as follows:

[0068]

[0069] In some embodiments of the present application, the crack types of the prefabricated semi-cracks include edge offset cracks. As shown in FIG. 7(a), the size of the target specimen can be L×W×H = 150 mm×50 mm×20 mm, where L is the specimen length, W is the specimen width, and H is the specimen height. The width of the prefabricated semi-crack can be 0.5 mm, and the distance l between the prefabricated semi-crack and the middle position of the specimen satisfies 0 < l < L / 2, for example, l = 20 mm. The physical specimen with the prefabricated semi-crack is shown in FIG. 7(b), and the numbers 4-1 and 4-2 in the figure are the specimen material numbers.

[0070] As an alternative embodiment, as shown in FIG. 8(a), an unconventional three-point bending experiment can be performed on the target specimen containing the prefabricated semi-crack using a three-point bending indenter until the specimen fails, thereby obtaining the target load. As can be seen from FIG. 8(a), the upper and lower surfaces of the target specimen are placed across the two lower indenters of the workbench, and the specimen is placed symmetrically left and right relative to the lower indenters. The span of the lower indenters can be 110 mm. The upper indenter coincides with the central plane of the specimen. After the three-point bending test, the specimen fractured by three-point bending is shown in FIG. 8(b).

[0071] After performing the unconventional three-point bending experiment on the target specimen, the schematic diagram of the load-displacement curve obtained is as Fig. 9 shown. As can be seen from Fig. 9 it, under the above experimental conditions, the maximum load (i.e., the target load) is 79459 N.

[0072] Step S204: Determine the finite element model of the target specimen, and determine the first stress component, the second stress component, and the third stress component of the target specimen based on the stress-plastic strain experimental data and the target load, where the first stress component is the stress component in the length direction of the finite element model, the second stress component is the stress component in the width direction of the finite element model, and the third stress component is the stress component in the height direction of the finite element model;

[0073] In the technical solution provided in step S204, the coordinate origin of the finite element model is the crack tip, the X-axis direction of the finite element model is the length direction, the Y-axis direction of the finite element model is the width direction, and the Z-axis direction of the finite element model is the height direction. The working condition of the finite element model is set to fix the lower indenter and apply the target load on the upper indenter. Specifically, as Fig.10As shown in the figure, the finite element model includes an upper and lower pressure head and a sample with a prefabricated half crack. The upper and lower pressure heads are set as rigid bodies. The material type of the target sample with a prefabricated half crack can be a 7XXX series aluminum alloy material, and its various parameters can be as follows: the elastic model is 70GPa, and the mesh size used near the crack is 0.25mm, and 1mm is used in other positions. In addition, in the finite element model, the prefabricated half crack can be replaced by a slit with a certain width, the crack surface is a free surface, the crack front is a rectangular port, and scanning meshing is used, and a smaller mesh is used around the crack tip.

[0074] As an optional implementation, the elastic modulus also needs to be input into the finite element model to achieve simulation calculation within the elastic range.

[0075] After obtaining the finite element model, the finite element calculation can be performed on the finite element model to obtain the stress component cloud diagram of the model in three directions. Fig.11 The first stress component cloud diagram is shown in Fig.12 The second stress component cloud diagram shown in Fig.13 The third stress component cloud diagram is shown.

[0076] Step S206, selecting a plurality of points in the target sample according to the crack tip of the prefabricated half crack, and determining the distance from each point to the crack tip;

[0077] In the technical solution provided in step S206, the step of selecting multiple points in the target sample according to the crack tip of the prefabricated half crack includes: selecting a number of first-class points along the height direction at the crack tip; determining the path corresponding to each first-class point, wherein the starting point of the path is the first-class point and the direction of the path is the width direction; selecting a number of second-class points on each path. It should be noted that the number of second-class points on different paths can be different, and the number of second-class points on different paths is not less than a preset number. The preset number can be set by yourself, for example, five.

[0078] As an optional implementation, according to the finite element calculation results, 11 first-class points can be selected on average along the Z direction at the crack front, i.e., i=1, 2, ..., 11, and Z i =0mm, 2mm, 4mm, 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, 11 paths are defined along the -Y direction through these 11 points, and 10 second-type nodes are selected near the crack tip on each path, that is, j=1,2,…,10, r ij =0.75mm, 1 mm, 1.25mm, 1. 5mm, 1.75mm, 2mm, 2.25mm, 2.5mm, 2.75mm, 3mm. Among them Zi is the distance of each first-type point relative to the crack tip in the Z direction. ij It is the distance between each second-type point on the path and the crack tip. It should be noted that when selecting the second-type nodes, the present application does not limit the distance between each second-type node and the crack discontinuity, but first determines the selected second-type nodes, and then determines the distance between each second-type node and the crack tip.

[0079] Step S208, determining the opening fracture toughness data, sliding fracture toughness data and tearing fracture toughness data of the target sample based on the first stress component, the second stress component, the third stress component and the distance from each point to the crack tip, and determining the composite crack fracture toughness of the crack tip in the height direction based on the opening fracture toughness data, the sliding fracture toughness data and the tearing fracture toughness data, wherein the composite crack includes an opening crack, a sliding crack and a tearing crack.

[0080] It should be noted that the crack tip is a line segment parallel to the Z axis. In the embodiment of the present application, the stress intensity factors at the crack tip are K I , K II , K III , where K I Corresponding to the opening fracture toughness, K II Corresponding to the slip fracture toughness, K III Corresponding to the tearing fracture toughness. And at different heights of the crack tip, the stress intensity factor K I , K II , K III The values ​​are different.

[0081] In the technical solution provided in step S208, the opening fracture toughness data includes the opening fracture toughness parameters of each point and the position information of each point in the height direction, the slip fracture toughness data includes the slip fracture toughness parameters of each point and the position information of each point in the height direction, and the tearing fracture toughness data includes the tearing fracture toughness parameters of each point and the position information of each point in the height direction.

[0082] As an optional embodiment, before determining the opening fracture toughness data, sliding fracture toughness data and tearing fracture toughness data of the target sample based on the first stress component, the second stress component, the third stress component and the distance from each point to the crack tip, the sample fracture toughness determination method also includes: determining the stress intensity factor of each second-type point, wherein the stress intensity factor of the second-type point includes the opening fracture toughness parameter, sliding fracture toughness parameter and tearing fracture toughness parameter of the second-type point; based on the stress intensity factor of the second-type point corresponding to each first-type point, determining the stress intensity factor of the first-type point by extrapolation, wherein the stress intensity factor of the first-type point includes the opening fracture toughness parameter, sliding fracture toughness parameter and tearing fracture toughness parameter of the first-type point.

[0083] In some embodiments of the present application, the first stress component, the second stress component and the third stress component of the ij point (that is, each second type point) can be obtained according to the stress component cloud map, wherein the first stress component of the ij point is σx, the second stress component of the ij point is τxy, and the third stress component of the ij point is τxz.

[0084] Optionally, the fracture toughness K at different heights of the crack tip of the I-II-III composite crack can be calculated based on the stress components from the component formula of the stress tensor at the crack tip in the three-dimensional crack body under plane strain conditions. IC , K IIC , K IIIC The component formula of the stress tensor at the crack tip is as follows:

[0085]

[0086] Then we can take a point near the crack tip along the -Y direction, that is, θ=0 at this time. Substituting these two conditions into the above formula, we can get the expression of the asymptotic solution of the stress intensity factor at the crack tip:

[0087]

[0088] Then the first stress component, the second stress component and the third stress component at the ij point can be substituted into the above formula to obtain the stress intensity factor K of each ij point: Iij , K IIij , K IIIij .

[0089] The above formula is the expression of the asymptotic solution of the stress intensity factor at the crack tip.

[0090] In some embodiments of the present application, the stress intensity factor of each first-type point at the crack tip, that is, the fracture toughness K, can be obtained at the same height according to the extrapolation method and the stress intensity factor of each second-type point.IiC , K IIiC , K IIIiC The schematic diagram of the fracture toughness K-distance r curve of each first-type point is as follows Figure 14-24 As shown. Among them, Fig.14 The embodiment of the present application provides that l=20mm, Z 1 =0, schematic diagram of Kr curve; Fig.15 l=20mm, Z provided in the embodiment of the present application 2 =2mm, schematic diagram of Kr curve; Fig.16 l=20mm, Z provided in the embodiment of the present application 3 =4mm, schematic diagram of Kr curve; Fig.17 l=20mm, Z provided in the embodiment of the present application 4 =6mm, schematic diagram of Kr curve; Fig.18 l=20mm, Z provided in the embodiment of the present application 5 = 8mm, schematic diagram of Kr curve; Fig.19 l = 20 mm, Z provided in the application example 6 =10mm, schematic diagram of Kr curve; Fig. 20 l=20mm, Z provided in the embodiment of the present application 7 =12mm, schematic diagram of Kr curve; Fig.21 l=20mm, Z provided in the embodiment of the present application 8 =14mm, schematic diagram of Kr curve; Fig. 22 l=20mm, Z provided in the embodiment of the present application 9 =16mm, schematic diagram of Kr curve; Fig.23 l=20mm, Z provided in the embodiment of the present application 10 =18mm, schematic diagram of Kr curve; Fig.24 l=20mm, Z provided in the embodiment of the present application 11 Schematic diagram of Kr curve when =20mm.

[0091] Then, the following can be made based on the Kr curve of each first-class sample point: Fig.25 ZK I Curves, such as Fig.26 ZK II Curves and Fig. 27 ZK III Curve, thereby determining the fracture toughness of the I-II-III complex crack in the height direction at the crack tip.

[0092] The target sample is determined by using stress-plastic strain experimental data and a target load of the target sample, wherein the target load is the maximum load when the target sample is destroyed during a three-point bending test on the target sample, and the target sample contains a prefabricated half crack; the finite element model of the target sample is determined, and the first stress component, the second stress component and the third stress component of the target sample are determined according to the stress-plastic strain experimental data and the target load, wherein the first stress component is the stress component in the length direction of the finite element model, the second stress component is the stress component in the width direction of the finite element model, and the third stress component is the stress component in the height direction of the finite element model; multiple points are selected in the target sample according to the crack tip of the prefabricated half crack, and the distance from each point to the crack tip is determined; the distance from each point to the crack tip is determined according to the first stress component, the second stress component, the third stress component and the distance from each point to the crack tip. The opening fracture toughness data, sliding fracture toughness data and tearing fracture toughness data of the target sample are determined, and the composite crack fracture toughness at the crack tip in the height direction is determined based on the opening fracture toughness data, sliding fracture toughness data and tearing fracture toughness data, wherein the composite crack includes opening cracks, sliding cracks and tearing cracks. By determining the opening fracture toughness data, sliding fracture toughness data and tearing fracture toughness data of the target sample, the composite crack fracture toughness at the crack tip in the height direction is determined, thereby achieving the purpose of determining the I-II-III composite crack fracture toughness of the material, thereby achieving the technical effect of more accurately determining the fracture toughness performance of the material, and further solving the technical problem that the fracture toughness performance of the material cannot be accurately determined due to the inability to test the I-II-III composite crack fracture toughness in the related technology.

[0093] The present application provides a device for determining the fracture toughness of a sample. Fig.28 is a schematic diagram of the structure of the device. Fig.28It can be seen that the device includes: a first processing module 280, which is used to determine the stress-plastic strain experimental data of the target sample, and to determine the target load of the target sample, wherein the target load is the maximum load when the target sample is destroyed when the target sample is subjected to a three-point bending test, and the target sample contains a prefabricated half crack; a second processing module 282, which is used to determine the finite element model of the target sample, and to determine the first stress component, the second stress component and the third stress component of the target sample according to the stress-plastic strain experimental data and the target load, wherein the first stress component is the stress component in the length direction of the finite element model, the second stress component is the stress component in the width direction of the finite element model, and the third stress component is the stress component in the width direction of the finite element model. is the stress component in the height direction of the finite element model; a third processing module 284 is used to select multiple points in the target sample according to the crack tip of the prefabricated half crack, and determine the distance from each point to the crack tip; a fourth processing module 286 is used to determine the opening fracture toughness data, sliding fracture toughness data and tearing fracture toughness data of the target sample according to the first stress component, the second stress component, the third stress component and the distance from each point to the crack tip, and determine the composite crack fracture toughness of the crack tip in the height direction according to the opening fracture toughness data, the sliding fracture toughness data and the tearing fracture toughness data, wherein the composite crack includes an opening crack, a sliding crack and a tearing crack.

[0094] In some embodiments of the present application, the step of the first processing module 280 determining the stress-plastic strain experimental data of the target sample includes: determining the target material type of the target sample; determining the tensile force-displacement experimental data of the target material type, wherein the tensile force-displacement experimental data is data obtained by performing a tensile test on a material of the target material type; determining the engineering stress-strain experimental data of the target material type based on the tensile force-displacement experimental data; and determining the stress-plastic strain experimental data of the target sample based on the engineering stress-strain experimental data.

[0095] In some embodiments of the present application, the crack type of the prefabricated half-crack includes an edge deflection crack.

[0096] In some embodiments of the present application, the coordinate origin of the finite element model is the crack tip, the X-axis direction of the finite element model is the length direction, the Y-axis direction of the finite element model is the width direction, and the Z-axis direction of the finite element model is the height direction.

[0097] In some embodiments of the present application, the step of selecting multiple points in the target sample according to the crack tip of the prefabricated half-crack by the third processing module 284 includes: selecting a number of first-class points along the height direction at the crack tip; determining the path corresponding to each first-class point, wherein the starting point of the path is the first-class point and the direction of the path is the width direction; and selecting a number of second-class points on each path.

[0098] In some embodiments of the present application, the opening fracture toughness data includes the opening fracture toughness parameters of each point and the position information of each point in the height direction, the slip fracture toughness data includes the slip fracture toughness parameters of each point and the position information of each point in the height direction, and the tearing fracture toughness data includes the tearing fracture toughness parameters of each point and the position information of each point in the height direction.

[0099] In some embodiments of the present application, before determining the opening fracture toughness data, sliding fracture toughness data and tearing fracture toughness data of the target sample based on the first stress component, the second stress component, the third stress component and the distance from each point to the crack tip, the sample fracture toughness determination device is also used to: determine the stress intensity factor of each second-type point, wherein the stress intensity factor of the second-type point includes the opening fracture toughness parameter, sliding fracture toughness parameter and tearing fracture toughness parameter of the second-type point; and determine the stress intensity factor of the first-type point by extrapolation based on the stress intensity factor of the second-type point corresponding to each first-type point, wherein the stress intensity factor of the first-type point includes the opening fracture toughness parameter, sliding fracture toughness parameter and tearing fracture toughness parameter of the first-type point.

[0100] It should be noted that the various modules in the above-mentioned specimen fracture toughness determination device can be program modules (for example, a set of program instructions that implement a certain specific function) or hardware modules. For the latter, it can be expressed in the following forms, but is not limited to this: the expression form of each of the above-mentioned modules is a processor, or the functions of each of the above-mentioned modules are implemented by a processor.

[0101] According to an embodiment of the present application, a non-volatile storage medium is further provided, in which a program is stored, wherein when the program is running, the device where the non-volatile storage medium is located is controlled to execute the following method for determining the fracture toughness of a sample: determining stress-plastic strain experimental data of a target sample, and determining a target load of the target sample, wherein the target load is the maximum load when the target sample is destroyed when a three-point bending test is performed on the target sample, and the target sample contains a prefabricated half crack; determining a finite element model of the target sample, and determining a first stress component, a second stress component, and a third stress component of the target sample based on the stress-plastic strain experimental data and the target load, wherein the first stress component is the stress component in the length direction of the finite element model. The second stress component is the stress component in the width direction of the finite element model, and the third stress component is the stress component in the height direction of the finite element model; multiple points are selected in the target sample according to the crack tip of the prefabricated half crack, and the distance from each point to the crack tip is determined; the opening fracture toughness data, the sliding fracture toughness data and the tearing fracture toughness data of the target sample are determined according to the first stress component, the second stress component, the third stress component and the distance from each point to the crack tip, and the composite crack fracture toughness of the crack tip in the height direction is determined according to the opening fracture toughness data, the sliding fracture toughness data and the tearing fracture toughness data, wherein the composite crack includes an opening crack, a sliding crack and a tearing crack.

[0102] According to an embodiment of the present application, an electronic device is also provided, including: a memory and a processor, the processor is used to run a program stored in the memory, wherein the following method for determining the fracture toughness of a sample is executed when the program is running: determining stress-plastic strain experimental data of a target sample, and determining a target load of the target sample, wherein the target load is the maximum load when the target sample is destroyed when a three-point bending test is performed on the target sample, and the target sample contains a prefabricated half crack; determining a finite element model of the target sample, and determining a first stress component, a second stress component, and a third stress component of the target sample based on the stress-plastic strain experimental data and the target load, wherein the first stress component is a stress component in the length direction of the finite element model, and the second stress component is a stress component in the length direction of the finite element model. The second stress component is the stress component in the width direction of the finite element model, and the third stress component is the stress component in the height direction of the finite element model; multiple points are selected in the target sample according to the crack tip of the prefabricated half crack, and the distance from each point to the crack tip is determined; the opening fracture toughness data, sliding fracture toughness data and tearing fracture toughness data of the target sample are determined according to the first stress component, the second stress component, the third stress component and the distance from each point to the crack tip, and the composite crack fracture toughness in the height direction of the crack tip is determined according to the opening fracture toughness data, the sliding fracture toughness data and the tearing fracture toughness data, wherein the composite crack includes opening crack, sliding crack and tearing crack.

[0103] According to an embodiment of the present application, a computer program product is also provided, including a computer program, which implements the following method for determining the fracture toughness of a sample when executed by a processor: determining stress-plastic strain experimental data of a target sample, and determining a target load of the target sample, wherein the target load is the maximum load when the target sample is destroyed when a three-point bending test is performed on the target sample, and the target sample contains a prefabricated half crack; determining a finite element model of the target sample, and determining a first stress component, a second stress component, and a third stress component of the target sample based on the stress-plastic strain experimental data and the target load, wherein the first stress component is a stress component in the length direction of the finite element model, and the second stress component is a stress component in the length direction of the finite element model. The stress component in the width direction of the finite element model, and the third stress component is the stress component in the height direction of the finite element model; multiple points are selected in the target sample according to the crack tip of the prefabricated half crack, and the distance from each point to the crack tip is determined; the opening fracture toughness data, the sliding fracture toughness data and the tearing fracture toughness data of the target sample are determined according to the first stress component, the second stress component, the third stress component and the distance from each point to the crack tip, and the composite crack fracture toughness at the crack tip in the height direction is determined according to the opening fracture toughness data, the sliding fracture toughness data and the tearing fracture toughness data, wherein the composite crack includes an opening crack, a sliding crack and a tearing crack.

[0104] In the above embodiments of the present application, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, please refer to the relevant description of other embodiments.

[0105] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are only schematic. For example, the division of the units can be a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0106] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple units. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0107] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0108] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the relevant technology or all or part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, server or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), mobile hard disk, disk or optical disk, etc. Various media that can store program codes.

[0109] The above is only a preferred implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A method for determining the fracture toughness of a specimen, characterized in that: include: Determine stress-plastic strain experimental data of a target sample, and determine a target load of the target sample, wherein the target load is a maximum load when the target sample is destroyed when a three-point bending test is performed on the target sample, and the target sample contains a prefabricated half crack; Determine a finite element model of the target sample, and determine a first stress component, a second stress component, and a third stress component of the target sample according to the stress-plastic strain experimental data and the target load, wherein the first stress component is a stress component in a length direction of the finite element model, the second stress component is a stress component in a width direction of the finite element model, and the third stress component is a stress component in a height direction of the finite element model; Selecting a plurality of points in the target sample according to the crack tip of the prefabricated half-crack, and determining the distance from each point to the crack tip; The opening fracture toughness data, sliding fracture toughness data and tearing fracture toughness data of the target sample are determined based on the first stress component, the second stress component, the third stress component and the distance from each point to the crack tip, and the I-II-III composite crack fracture toughness of the crack tip in the height direction is determined based on the opening fracture toughness data, sliding fracture toughness data and tearing fracture toughness data, wherein the I-II-III composite crack includes an opening crack, a sliding crack and a tearing crack.

2. The method for determining the fracture toughness of a specimen according to claim 1, characterized in that: Selecting a plurality of points in the target sample according to the crack tip of the prefabricated half-crack includes: Selecting a plurality of first-type points along the height direction at the crack tip; Determine a path corresponding to each of the first-type points, wherein a starting point of the path is the first-type point and a direction of the path is the width direction; A number of second type points are selected on each of the paths.

3. The method for determining the fracture toughness of a specimen according to claim 2, characterized in that: Before determining the opening fracture toughness data, the sliding fracture toughness data and the tearing fracture toughness data of the target sample according to the first stress component, the second stress component, the third stress component and the distance from each point to the crack tip, the sample fracture toughness determination method further includes: Determine the stress intensity factor of each of the second type points, wherein the stress intensity factor of the second type points includes an opening fracture toughness parameter, a sliding fracture toughness parameter, and a tearing fracture toughness parameter of the second type points; According to the stress intensity factor of the second type point corresponding to each first type point, the stress intensity factor of the first type point is determined by extrapolation method, wherein the stress intensity factor of the first type point includes the opening fracture toughness parameter, the sliding fracture toughness parameter and the tearing fracture toughness parameter of the first type point.

4. The method for determining the fracture toughness of a specimen according to claim 1, characterized in that: The opening fracture toughness data includes the opening fracture toughness parameters of each point and the position information of each point in the height direction. The slip fracture toughness data includes the slip fracture toughness parameters of each point and the position information of each point in the height direction. The tearing fracture toughness data includes the tearing fracture toughness parameters of each point and the position information of each point in the height direction.

5. The method for determining the fracture toughness of a specimen according to claim 1, characterized in that: Determine the stress-plastic strain experimental data of the target specimen including: determining a target material type of the target sample; Determining tensile force-displacement experimental data of the target material type, wherein the tensile force-displacement experimental data is data obtained by performing a tensile test on a material of the target material type; Determining engineering stress-strain experimental data of the target material type based on the tensile force-displacement experimental data; The stress-plastic strain experimental data of the target sample is determined based on the engineering stress-strain experimental data.

6. The method for determining the fracture toughness of a specimen according to claim 1, characterized in that: The coordinate origin of the finite element model is the crack tip, the X-axis direction of the finite element model is the length direction, the Y-axis direction of the finite element model is the width direction, and the Z-axis direction of the finite element model is the height direction.

7. The method for determining the fracture toughness of a specimen according to claim 1, characterized in that: The crack types of the prefabricated half cracks include edge deflection cracks.

8. A device for determining fracture toughness of a specimen, characterized in that: include: A first processing module is used to determine stress-plastic strain experimental data of a target sample and determine a target load of the target sample, wherein the target load is a maximum load when the target sample is destroyed when a three-point bending test is performed on the target sample, and the target sample contains a prefabricated half crack; a second processing module, for determining a finite element model of the target sample, and determining a first stress component, a second stress component, and a third stress component of the target sample according to the stress-plastic strain experimental data and the target load, wherein the first stress component is a stress component in a length direction of the finite element model, the second stress component is a stress component in a width direction of the finite element model, and the third stress component is a stress component in a height direction of the finite element model; A third processing module is used to select a plurality of points in the target sample according to the crack tip of the prefabricated half-crack, and determine the distance from each point to the crack tip; The fourth processing module is used to determine the opening fracture toughness data, sliding fracture toughness data and tearing fracture toughness data of the target sample based on the first stress component, the second stress component, the third stress component and the distance from each point to the crack tip, and determine the I-II-III composite crack fracture toughness of the crack tip in the height direction based on the opening fracture toughness data, sliding fracture toughness data and tearing fracture toughness data, wherein the I-II-III composite crack includes opening cracks, sliding cracks and tearing cracks.

9. A non-volatile storage medium, characterized in that: The non-volatile storage medium stores a program, wherein when the program is executed, the device where the non-volatile storage medium is located is controlled to execute the method for determining the fracture toughness of a sample as claimed in any one of claims 1 to 7.

10. An electronic device, characterized in that: include: A memory and a processor, wherein the processor is used to run a program stored in the memory, wherein the method for determining the fracture toughness of a specimen according to any one of claims 1 to 7 is executed when the program is run.

11. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method for determining the fracture toughness of a specimen according to any one of claims 1 to 7 are implemented.

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