CN110987621A - Method for establishing three-dimensional fracture model of metal material in complex stress state - Google Patents
Method for establishing three-dimensional fracture model of metal material in complex stress state Download PDFInfo
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Abstract
The invention provides a method for establishing a three-dimensional fracture model of a metal material in a complex stress state, which comprises the steps of designing a first group of samples and a second group of samples, carrying out a quasi-static standard tensile test on the first group of samples by adopting nonlinear tensile force to obtain a true stress-plastic strain curve of the first group of samples, inputting the true stress-plastic strain curve of the first group of samples into material numerical value test models corresponding to various sample types in the second group of samples, and obtaining stress triaxial degree η and normalized Rockwell angle parameter corresponding to various sample types in the second group of samples
(ii) a Carrying out fracture test on various types of samples in the second group of samples by adopting the nonlinear tensile force to obtain critical fracture strain values corresponding to various types of samples in the second group of samples; according to the secondStress triaxial degree η, normalized Rockwell Angle parameter for each sample type in the set of samples
And obtaining a three-dimensional fracture model of the metal material in a complex stress state by using the critical fracture strain value.
Description
Technical Field
The invention belongs to the field of automobile informatization, and particularly relates to a method for establishing a three-dimensional fracture model of a metal material in a complex stress state.
Background
In the research of metal material fracture, a forming limit diagram and a fixed critical fracture strain value are mostly adopted to simulate the fracture failure of the metal material. However, when the forming limit diagram is used to judge the occurrence of cracks, the crack regions are too conservative, and the cracks are often generated too early or too late; and the forming limit diagram can only be used for predicting the cracking condition of the material under the condition of a linear strain path, and in the practical process, the material is accompanied by strong strain path dependence after necking. When the generation condition of the crack is judged by adopting the fixed critical fracture strain value, the influence of the stress state of the material on the critical fracture strain value is not considered. Obviously, the current fracture failure simulation method does not consider the influence of different stress states and nonlinear strain paths on the fracture failure at the same time, and the fracture failure of the metal material in a complex stress state cannot be accurately simulated.
Disclosure of Invention
The invention provides a method for establishing a three-dimensional fracture model of a metal material in a complex stress state, which aims to solve the problem that the fracture failure of the metal material in the complex stress state cannot be accurately simulated because the influence of different stress states and nonlinear strain paths on the fracture failure is not simultaneously considered in the conventional fracture failure simulation method.
According to a first aspect of the embodiments of the present invention, there is provided a method for establishing a three-dimensional fracture model of a metal material in a complex stress state, including:
designing a first group of test samples for a quasi-static standard tensile test and a second group of test samples for a fracture test aiming at metal materials of the same material, wherein the test samples in the second group of test samples comprise multiple types;
performing quasi-static standard tensile test on the first group of samples by adopting nonlinear tensile force to obtain a true stress-plastic strain curve of the first group of samples, inputting the true stress-plastic strain curve of the first group of samples into a material numerical test model corresponding to each sample type in the second group of samples, and obtaining stress triaxial degree η, Rockwell angle parameter ξ and normalized Rockwell angle parameter corresponding to each sample type in the second group of samples
Carrying out fracture test on various types of samples in the second group of samples by adopting the nonlinear tensile force to obtain critical fracture strain values corresponding to various types of samples in the second group of samples;
for each specimen type in the second set of specimens, its three stress axes η, Rockwell Angle parameter ξ, normalized Rockwell Angle parameter
And substituting the critical fracture strain value into the corresponding three-dimensional model to establish a multiple equation set, and calculating five unknown coefficients K, C,
f. n, thereby obtaining the complex stress state of the metal materialA three-dimensional fracture model in a state.
In an alternative implementation, the first set of test specimens comprises a plurality of test specimens, and the performing a quasi-static standard tensile test on the first set of test specimens by using a nonlinear tensile force to obtain a true stress-plastic strain curve of the first set of test specimens comprises:
performing a quasi-static standard tensile test on each sample in the first group of samples by using the nonlinear tensile force to obtain a true stress-plastic strain curve of each sample in the first group of samples;
the central one of the true stress-plastic strain curves of each of the first set of test samples was selected as the true stress-plastic strain curve of the first set of test samples.
In another alternative implementation, each specimen type in the second set of specimens comprises a plurality of specimens of that type; the fracture test of each type of the second group of samples by using the nonlinear tensile force to obtain the critical fracture strain value corresponding to each type of the second group of samples comprises:
and aiming at each sample type in the second group of samples, performing corresponding fracture tests on a plurality of samples of the type by adopting the nonlinear tensile force to obtain critical fracture strain values of the number of the corresponding samples, calculating the average value of the critical fracture strain values of the number of the corresponding samples, and taking the average value as the critical fracture strain value of the sample type in the second group of samples.
In another alternative implementation, the second set of specimens includes five specimen types, a pure shear tensile test specimen, a center hole uniaxial tensile test specimen, an R5 notch tensile test specimen, an R10 notch tensile test specimen, and a cup-shaped specimen, each specimen type including a plurality of specimens of that type.
In another alternative implementation, the failure strain of the three-dimensional fracture model is a function of the triaxial stress degree and the normalized Rockwell angle, as shown below
In the formula, five unknowns are contained, which are K, C,
f. n, calibrating by a plurality of groups of fracture tests, wherein the stress triaxial degree η and the normalized Rockwell angle parameter are used
The stress state of the material is characterized, and the values are all [ -1, 1 [ -1 [ ]]In the formula
Stress triaxial degree:
wherein, p is the hydrostatic pressure,
is Mises equivalent stress, σ1、σ2、σ3First, second and third principal stresses, I1Is a first constant of stress, J2Is a second stress offset invariant;
the Rockwell angle parameter:
in the formula (I), the compound is shown in the specification,
is Mises equivalent stress, J2、J3Respectively a second bias stress offset invariant and a third bias stress offset invariant;
normalized Rockwell angle
In the three-dimensional fracture model, fracture failure of the material is judged by a damage factor D, and when D is 1, fracture occurs, and the calculation formula is shown as follows
In the formula d epsilonpIs the amount of plastic strain buildup,
in the calculation of the damage factor D, the damage accumulation of the nonlinear strain path of the material is considered for the fracture failure strain corresponding to different stress triaxial degrees and normalized Rockwell angles.
In another alternative implementation, a DIC apparatus is used to perform real-time strain measurements to obtain critical fracture strain values corresponding to each sample type in the second set of samples.
The invention has the beneficial effects that:
1. according to the invention, a quasi-static standard tensile test is carried out on a first group of samples by adopting a nonlinear tensile force, and a nonlinear strain path is considered when a true stress-plastic strain curve of the first group of samples is obtained; the method is characterized in that a nonlinear tensile force is adopted during a fracture test, and various types of samples are designed, so that the influence of different stress states on fracture failure is considered; the method considers the influence of different stress states and nonlinear strain paths on the fracture failure, and can accurately simulate the fracture failure of the metal material in a complex stress state;
2. according to the invention, a first group of samples comprises a plurality of samples, quasi-static standard tensile tests are repeatedly carried out on the samples in the first group of samples by adopting the same nonlinear tensile force, after a true stress-plastic strain curve of each sample in the first group of samples is obtained, a centered true stress-plastic strain curve is selected as the true stress-plastic strain curve of the first group of samples, so that the obtained true stress-plastic strain curve of the first group of samples can more accurately reflect the deformation of a metal material;
3. when the fracture test is carried out on various types of samples, the corresponding fracture test is carried out on a plurality of samples of the type (namely, the corresponding fracture test is repeatedly carried out for a plurality of times), the average value of the critical fracture strain values obtained by the repeated tests is obtained, and the average value is used as the critical fracture strain value of the sample of the type, so that the influence of the corresponding fracture sample (namely, the corresponding stress state) on the fracture failure can be further accurately responded.
Drawings
FIG. 1 is a block diagram of a method for establishing a three-dimensional fracture model of a metal material under a complex stress state according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of the structure of the samples in the first set of samples (in mm);
FIG. 3 is a schematic diagram of the structure of five specimen types (in mm) in the second set of specimens;
FIG. 4 is a B-pillar hydrostatic model in three-dimensional fracture model validation;
FIG. 5 is a comparison graph of static pressure numerical simulation and test results of a 22MnB5 high-strength steel B column in three-dimensional fracture model verification.
Detailed Description
In order to make the technical solutions in the embodiments of the present invention better understood and make the above objects, features and advantages of the embodiments of the present invention more comprehensible, the technical solutions in the embodiments of the present invention are described in further detail below with reference to the accompanying drawings.
In the description of the present invention, unless otherwise specified and limited, it is to be noted that the term "connected" is to be interpreted broadly, and may be, for example, a mechanical connection or an electrical connection, or a communication between two elements, or may be a direct connection or an indirect connection through an intermediate medium, and a specific meaning of the term may be understood by those skilled in the art according to specific situations.
Referring to fig. 1, a block diagram of an embodiment of a method for establishing a three-dimensional fracture model of a metal material under a complex stress state according to the present invention is shown. The method may comprise the steps of:
step S101, aiming at metal materials of the same material, designing a first group of samples for quasi-static standard tensile test and a second group of samples for fracture test, wherein the samples in the second group of samples comprise multiple types. In this embodiment, the first set of samples may include a plurality of samples, for example, 3 samples, and the structure of the samples in the first set of samples is shown in fig. 2. The second set of specimens may include five specimen types of pure shear tensile test specimens, center hole uniaxial tensile test specimens, R5 notch tensile test specimens, R10 notch tensile test specimens, and cup test specimens, as shown in fig. 3.
Step S102, performing quasi-static standard tensile test on the first group of samples by adopting nonlinear tensile force to obtain true stress-plastic strain curves of the first group of samples, inputting the true stress-plastic strain curves of the first group of samples into material numerical value test models corresponding to various sample types in the second group of samples to obtain stress triaxial degree η, Rockwell angle parameter ξ and normalized Rockwell angle parameter corresponding to various sample types in the second group of samples
In step S102, performing a quasi-static standard tensile test on the first group of samples by using a nonlinear tensile force to obtain a true stress-plastic strain curve of the first group of samples includes: performing a quasi-static standard tensile test on each sample in the first group of samples by using the nonlinear tensile force to obtain a true stress-plastic strain curve of each sample in the first group of samples; the central one of the true stress-plastic strain curves of each of the first set of test samples was selected as the true stress-plastic strain curve of the first set of test samples. The quasi-static standard tensile test is carried out on the first group of samples by adopting the nonlinear tensile force, the nonlinear strain path is considered when the true stress-plastic strain curve of the first group of samples is obtained, the first group of samples comprises a plurality of samples, the quasi-static standard tensile test is repeatedly carried out on the plurality of samples in the first group of samples by adopting the same nonlinear tensile force, after the true stress-plastic strain curve of each sample in the first group of samples is obtained, the centered true stress-plastic strain curve is selected as the true stress-plastic strain curve of the first group of samples, and the obtained true stress-plastic strain curve of the first group of samples can more accurately reflect the deformation of the metal material. For example, 3 quasi-static standard tensile tests were repeated using the same nonlinear strain tensile force for 3 samples of the structure shown in fig. 2 to obtain 3 true stress-plastic strain curves, and the centered true stress-plastic strain curve was selected from the 3 true stress-plastic strain curves as the true stress-plastic strain curve of the first set of samples. In this embodiment, when performing quasi-static standard tensile test, a Digital Image Correlation (DIC) apparatus may be used to perform real-time strain test, and when stretching the specimen, a non-linear tensile force may be applied to the specimen by loading a constant tensile speed.
In addition, in this embodiment, the samples in the second group of samples include a plurality of types, and each type corresponds to a material numerical test model, after obtaining a true stress-plastic strain curve for representing the deformation of the metal material, the invention inputs the true stress-plastic strain curve into the material numerical test models corresponding to the types of the samples in the second group of samples, so as to obtain the stress triaxial degree η, the lode angle parameter ξ, and the normalized lode angle parameter corresponding to the types of the samples in the second group of samples
Stress triaxial degree η, Rockwell angle parameter ξ and normalized Rockwell angle parameter corresponding to each sample type
All used for representing a stress state of a metal material, stress triaxial degree η, Rockwell angle parameter ξ and normalized Rockwell angle parameter corresponding to various sample types
Can be respectively used for representing various stress states of the metal material. In this embodiment, a numerical model of each test may be established based on the sample size and the test conditions of each type of sample, and the true stress-plastic strain curve of the first set of samples may be input into the MAT _24 material numerical test model of LS _ DYNA.
Step S103, carrying out fracture tests on various types of samples in the second group of samples by adopting the nonlinear tensile force, and carrying out real-time strain tests by adopting digital Image Correlation (digital Image Correlation) equipment to obtain critical fracture strain values corresponding to various types of samples in the second group of samples.
Wherein each specimen type in said second set of specimens comprises a plurality of specimens of that type; in step S103, performing a fracture test on each type of the second group of samples by using the nonlinear tensile force, and obtaining critical fracture strain values corresponding to each type of the second group of samples includes: and aiming at each sample type in the second group of samples, performing corresponding fracture tests on a plurality of samples of the type by adopting the nonlinear tensile force to obtain critical fracture strain values of the number of the corresponding samples, calculating the average value of the critical fracture strain values of the number of the corresponding samples, and taking the average value as the critical fracture strain value of the sample type in the second group of samples. For example, for five sample types shown in fig. 3, each sample type includes 3 samples, and for each sample type, the corresponding fracture test may be repeated 3 times by using the same nonlinear strain tensile force as the quasi-static standard tensile test, so as to obtain 3 critical fracture strain values, and an average value of the 3 critical fracture strain values is obtained as the critical fracture strain value of the sample type. The invention designs various types of samples during the fracture test, and considers the influence of different stress states on the fracture failure, and when the invention is used for the fracture test of various types of samples, the invention carries out corresponding fracture tests on a plurality of samples of the type (namely, repeatedly carries out a plurality of tests on the corresponding fracture test), calculates the average value of critical fracture strain values obtained by the repeated tests, and uses the average value as the critical fracture strain value of the sample of the type, thereby further accurately corresponding the influence of the fracture sample (namely, the corresponding stress state) on the fracture failure.
In this embodiment, when performing quasi-static standard tensile test and fracture test, a digital Image Correlation (digital Image Correlation) device may be used to perform real-time strain test, and when stretching the sample, a non-linear tensile force may be applied to the sample by loading a constant tensile speed. In addition, the second group of specimens includes five specimen types of a pure shear tensile test specimen, a center hole uniaxial tensile test specimen, an R5 notch tensile test specimen, an R10 notch tensile test specimen, and a cup-shaped specimen, each specimen type including a plurality of specimens of this type. Wherein, the unidirectional tensile test, the shear test, the R5 notch tensile test and the R10 notch tensile test are all carried out on a CMT5305 electronic universal tester, and the test rates are respectively 3mm/min, 2.3mm/min, 1.2mm/min and 2.4 mm/min. The perforation test was also carried out on a CMT5305 electronic universal tester, with a punch speed of 1 mm/min. In the test process, a 50mm extensometer is selected for the unidirectional tensile test, and a 25mm extensometer is selected for the shear test, the R5 notch tensile test and the R10 notch tensile test to carry out relative deformation measurement.
Step S104, aiming at each sample type in the second group of samples, the stress triaxial degree η, the Rockwell angle parameter ξ and the normalized Rockwell angle parameter are processed
And substituting the critical fracture strain value into the corresponding three-dimensional model to establish a multiple equation set, and calculating five unknown coefficients K, C,
f. And n, further obtaining a three-dimensional fracture model of the metal material in a complex stress state.
In this example, the failure strain of the three-dimensional fracture model is a function of the triaxial stress degree and the normalized Rockwell angle, as shown below
In the formula, five unknowns are contained, which are K, C,
f. And n, calibrating by a plurality of groups of fracture tests. Wherein three axes are defined by stressη and normalized Rockwell Angle parameter
The stress state of the material is characterized, and the values are all [ -1, 1 [ -1 [ ]]In the formula
Stress triaxial degree:
wherein, p is the hydrostatic pressure,
is Mises equivalent stress, σ1、σ2、σ3First, second and third principal stresses, I1Is a first constant of stress, J2Is a second stress offset invariant;
the Rockwell angle parameter:
in the formula (I), the compound is shown in the specification,
is Mises equivalent stress, J2、J3Respectively a second bias stress offset invariant and a third bias stress offset invariant;
normalized Rockwell angle
In the three-dimensional fracture model, fracture failure of the material is judged by a damage factor D, and when D is 1, fracture occurs, and the calculation formula is as follows:
in the formula d epsilonpIs the amount of plastic strain buildup,
for three axial degrees and returns of different stressesThe failure strain at break corresponding to the normalized lode angle, and the damage accumulation of the nonlinear strain path of the material is considered in the calculation of the damage factor D. After three-dimensional fracture models of the metal material under different stress states and nonlinear strain paths are obtained, determining a fracture curved surface of the metal material under a complex stress state according to the three-dimensional fracture models; or the true stress-plastic strain curve of the metal material and the three-dimensional fracture model in the complex stress state are brought into any working condition model of the metal material for simulation calculation, so that the fracture condition of the metal material is predicted.
According to the embodiment, the quasi-static standard tensile test is carried out on the first group of samples by adopting the nonlinear tensile force, and the nonlinear strain path is considered when the true stress-plastic strain curve of the first group of samples is obtained; the method is characterized in that a nonlinear tensile force is adopted during a fracture test, and various types of samples are designed, so that the influence of different stress states on fracture failure is considered; the method considers the influence of different stress states and nonlinear strain paths on the fracture failure, and can accurately simulate the fracture failure of the metal material in a complex stress state.
The three-dimensional model was verified as follows: in order to verify whether the calibrated 22MnB5 high-strength steel is suitable for the fracture curved surface obtained according to the three-dimensional fracture model, the calibrated 22MnB5 high-strength steel is applied to a B-column static pressure numerical model, a B-column static pressure process is simulated, a crack area of a B column after static pressure is predicted, and a B-column static pressure test is carried out at the same time. The size of the grid of the main deformation area of the B column is 0.5mm, and two ends of the B column are fixed on a tool.
In the simulation process of the 22MnB5 high-strength steel B column, the tools at two ends are restrained, a pressure head presses the B column downwards at the speed of 1.85m/s, the stroke of the pressure head is 100mm, and the whole static pressure process is 0.054 s. An MAT _20 rigid material constitutive model in LS _ DYNA is selected by an indenter and a tool, an MAT _24 isotropic material constitutive model is selected by a B column, and an MMC fracture curved surface of 22MnB5 high-strength steel is input through MAT _ ADD _ EROSION without considering the influence of a strain rate. In the simulation process, the B column grid is selected to be adaptively subdivided, and the minimum grid size is defined to be 0.5 mm. By simulation calculation, the deformation of the 22MnB5 high-strength steel B column after static pressing is shown in the left graph in FIG. 5. As can be seen from the left side, the area of the B-pillar in contact with the indenter deforms the most after hydrostatic pressure, and the maximum plastic strain of the B-pillar is 0.857, as shown by the oval circled area in the figure. Meanwhile, a few units are deleted on the back of the position where the B column deforms most, and microcracks appear.
In the experimental process of the 22MnB5 high-strength steel B column, the B column is in an actual vehicle loading state, the upper end and the lower end of the B column are welded with the mounting plate and then fixed with the test bed through the tool, and the upper end and the lower end of the B column are fully constrained. During the test, the pressure head is adopted to carry out quasi-static loading on the mounting position of the middle door hinge of the B column, the pressing speed of the pressure head is 2mm/s (namely, nonlinear pressure is applied to the B column), and the pressing displacement of the pressure head is 100 mm. The deformation of the 22MnB5 high-strength steel B-pillar is shown in the right diagram of FIG. 5. As can be seen from the right graph, after the static pressure test, the 22MnB5 high-strength steel B columns are greatly deformed at the positions contacted with the indenter, as shown by the oval circled areas in the graph; at the same time, microcracks were present on the back of the B-pillar. As can be seen from fig. 5, after the static pressing, the 22MnB5 high strength steel B columns were largely deformed at the same positions, and as shown by the oval circled areas in fig. 5, microcracks were generated at the same positions on the back surfaces of the B columns. The numerical simulation result and the experimental result have high goodness of fit, which shows that the failure condition of the 22MnB5 high-strength steel can be accurately predicted by the calibrated fracture curved surface.
Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.
It will be understood that the invention is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the invention is to be controlled solely by the appended claims.
Claims (6)
1. A method for establishing a three-dimensional fracture model of a metal material in a complex stress state is characterized by comprising the following steps:
designing a first group of test samples for a quasi-static standard tensile test and a second group of test samples for a fracture test aiming at metal materials of the same material, wherein the test samples in the second group of test samples comprise multiple types;
performing quasi-static standard tensile test on the first group of samples by adopting nonlinear tensile force to obtain a true stress-plastic strain curve of the first group of samples, inputting the true stress-plastic strain curve of the first group of samples into a material numerical test model corresponding to each sample type in the second group of samples, and obtaining stress triaxial degree η, Rockwell angle parameter ξ and normalized Rockwell angle parameter corresponding to each sample type in the second group of samples
Carrying out fracture test on various types of samples in the second group of samples by adopting the nonlinear tensile force to obtain critical fracture strain values corresponding to various types of samples in the second group of samples;
for each specimen type in the second set of specimens, its three stress axes η, Rockwell Angle parameter ξ, normalized Rockwell Angle parameter
And substituting the critical fracture strain value into the corresponding three-dimensional model to establish a multiple equation set, and calculating five unknown coefficients K, C,
f. And n, further obtaining a three-dimensional fracture model of the metal material in a complex stress state.
2. The method for establishing the three-dimensional fracture model of the metal material under the complex stress state according to claim 1, wherein the first group of test samples comprises a plurality of test samples, the quasi-static standard tensile test is performed on the first group of test samples by using the nonlinear tensile force, and the obtaining of the true stress-plastic strain curve of the first group of test samples comprises:
performing a quasi-static standard tensile test on each sample in the first group of samples by using the nonlinear tensile force to obtain a true stress-plastic strain curve of each sample in the first group of samples;
the central one of the true stress-plastic strain curves of each of the first set of test samples was selected as the true stress-plastic strain curve of the first set of test samples.
3. The method for establishing a three-dimensional fracture model of a metallic material under a complex stress state according to claim 1, wherein each specimen type in the second group of specimens comprises a plurality of specimens of the type; the fracture test of each type of the second group of samples by using the nonlinear tensile force to obtain the critical fracture strain value corresponding to each type of the second group of samples comprises:
and aiming at each sample type in the second group of samples, performing corresponding fracture tests on a plurality of samples of the type by adopting the nonlinear tensile force to obtain critical fracture strain values of the number of the corresponding samples, calculating the average value of the critical fracture strain values of the number of the corresponding samples, and taking the average value as the critical fracture strain value of the sample type in the second group of samples.
4. The method for establishing a three-dimensional fracture model of a metal material under a complex stress state according to any one of claims 1 to 3, wherein the second group of samples comprises five sample types of a pure shear tensile test sample, a center hole uniaxial tensile test sample, an R5 notch tensile test sample, an R10 notch tensile test sample and a cup-shaped test sample, and each sample type comprises a plurality of samples of the type.
5. The method for building a three-dimensional fracture model of a metal material in a complex stress state according to claim 1, wherein the failure strain of the three-dimensional fracture model is a function of the triaxial stress degree and the normalized Rockwell angle, as shown below
In the formula, five unknowns are contained, which are K, C,
f. n, calibrating by a plurality of groups of fracture tests, wherein the stress triaxial degree η and the normalized Rockwell angle parameter are used
The stress state of the material is characterized, and the values are all [ -1, 1 [ -1 [ ]]In the formula
Stress triaxial degree:
wherein, p is the hydrostatic pressure,
is Mises equivalent stress, σ1、σ2、σ3First, second and third principal stresses, I1Is a first constant of stress, J2Is a second stress offset invariant;
the Rockwell angle parameter:
in the formula (I), the compound is shown in the specification,
is Mises equivalent stress, J2、J3Respectively a second bias stress offset invariant and a third bias stress offset invariant;
normalized Rockwell angle
In the three-dimensional fracture model, fracture failure of the material is judged by a damage factor D, and when D is 1, fracture occurs, and the calculation formula is as follows:
in the formula d epsilonpIs the amount of plastic strain buildup,
in the calculation of the damage factor D, the damage accumulation of the nonlinear strain path of the material is considered for the fracture failure strain corresponding to different stress triaxial degrees and normalized Rockwell angles.
6. The method for establishing the three-dimensional fracture model of the metal material in the complex stress state according to claim 1, wherein DIC equipment is adopted to perform real-time strain testing, and critical fracture strain values corresponding to various sample types in the second group of samples are obtained.
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| CN112199879A (en) * | 2020-10-22 | 2021-01-08 | 中国石油大学(华东) | Method for establishing and analyzing three-dimensional fracture model of polyethylene under complex stress |
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| CN112067437A (en) * | 2020-08-14 | 2020-12-11 | 南京航空航天大学 | Method for establishing tension-compression asymmetric failure criterion of isotropic material |
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| WO2022181401A1 (en) * | 2021-02-25 | 2022-09-01 | 国立大学法人東京農工大学 | Stress test device, material model identification processing device, material model identification processing network system, material model identification processing method, and material model identification processing program |
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| CN113673030B (en) * | 2021-08-05 | 2023-07-25 | 河钢股份有限公司 | Simulation analysis method for ductile fracture coupling failure of metal material |
| CN113843326A (en) * | 2021-08-11 | 2021-12-28 | 上海交通大学 | Metal plate stamping forming edge cracking prediction method considering trimming quality |
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| CN114526992B (en) * | 2022-01-19 | 2024-07-05 | 北京理工大学重庆创新中心 | Test characterization method for dynamic fracture performance of material under complex stress state |
| CN114509341A (en) * | 2022-02-23 | 2022-05-17 | 北京理工大学重庆创新中心 | Method for measuring stress triaxial degree in material sample tensile fracture test process |
| CN114509341B (en) * | 2022-02-23 | 2023-08-25 | 北京理工大学重庆创新中心 | Method for measuring stress triaxial degree in tensile fracture test process of material sample |
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