A method and system for simulation of large plastic deformation of composite materials

Abstract

The present disclosure relates to a method and system for simulating large plastic deformation of composite materials. Obtain the mechanical curve parameters of the composite material under multiple test types, and perform fitting processing on each mechanical curve parameter to obtain equivalent curve parameters; perform simulation and standardization processing on the equivalent curve parameters, and determine whether the accuracy of the equivalent curve parameters meets the standard; in response to determining that the accuracy of the equivalent curve parameters meets the standard, determine damage initiation parameters and damage evolution parameters based on damage test parameters of the composite material under stress triaxiality, and perform simulation verification processing on the composite material based on the equivalent curve parameters, the damage initiation parameters and the damage evolution parameters. By introducing the ductile damage initiation and plastic displacement controlled damage evolution criterion, and coupling with the material card, not only the post-peak slow descent and platform segment response of the composite material and its gradual damage evolution characteristics are more reasonably represented, but also the simulation prediction consistency and engineering applicability under complex load scenarios such as large deformation or collision are improved.

Description

Technical Field

[0001] The embodiments in this specification belong to the field of simulation analysis technology for specific composite materials, and in particular relate to a simulation method and system for large plastic deformation of composite materials. Background Technology

[0002] With the continuous advancement of automotive lightweighting technology, composite materials are increasingly widely used in automotive structures and components due to their advantages such as high specific strength and strong designability. Among them, composite materials with typical mechanical response characteristics, such as polypropylene plus ethylene propylene diene monomer (PP+EPDM_TD10), exhibit a slow decreasing trend in load after reaching the peak load capacity under tensile load, gradually tending towards a stable plateau. Their high ductility and energy absorption capacity are particularly important for the overall vehicle collision safety performance.

[0003] LS-DYNA, as the most widely used solver in the field of vehicle collision simulation, commonly employs MAT_24 or MAT_187 material cards to provide equivalent representations of composite materials in current vehicle collision and large deformation simulation analyses. However, these material cards still have shortcomings in characterizing damage initiation, damage evolution, and post-peak response under large plastic strain conditions. They struggle to continuously and accurately depict the mechanical response process of composite materials under complex stress paths, thus weakening the simulation and prediction capabilities of the ductile energy absorption characteristics and failure modes of composite materials to some extent. Consequently, they fail to meet the demands for refined material behavior descriptions and improved accuracy in vehicle simulations. Summary of the Invention

[0004] The embodiments of this disclosure present a method and system for simulating large plastic deformation of composite materials.

[0005] In a first aspect of this disclosure, a method for simulating large plastic deformation of composite materials is provided. The method includes acquiring mechanical curve parameters of the composite material under various test types and fitting these mechanical curve parameters to obtain equivalent curve parameters. The method further includes performing simulation benchmarking on all equivalent curve parameters and determining whether the accuracy of all equivalent curve parameters meets the standards based on the simulation benchmarking results. In response to determining that the accuracy of all equivalent curve parameters meets the standards, the method further includes determining damage initiation parameters and damage evolution parameters based on damage test parameters of the composite material under multiple stress triaxialities. Furthermore, the method includes performing simulation verification processing on the composite material based on all equivalent curve parameters, damage initiation parameters, and damage evolution parameters.

[0006] In a second aspect of this disclosure, a simulation system for large plastic deformation of composite materials is provided. The system includes a fitting module configured to acquire mechanical curve parameters of the composite material under various test types and to fit these mechanical curve parameters to obtain equivalent curve parameters. The system also includes a simulation benchmarking module configured to perform simulation benchmarking on all equivalent curve parameters and determine whether the accuracy of all equivalent curve parameters meets the standards based on the simulation benchmarking results. The system further includes a damage parameter determination module configured to, in response to determining that the accuracy of all equivalent curve parameters meets the standards, determine damage initiation parameters and damage evolution parameters based on damage test parameters of the composite material under multiple stress triaxialities. Furthermore, the system includes a simulation verification module configured to perform simulation verification processing on the composite material based on all equivalent curve parameters, damage initiation parameters, and damage evolution parameters.

[0007] In a third aspect of this disclosure, a computer program product is provided, comprising a computer program that is executed by a processor to implement the method according to the first aspect.

[0008] In a fourth aspect of this disclosure, a machine-readable storage medium is provided. The machine-readable storage medium stores machine-executable instructions, which are executed by a processor to implement the method provided according to a first aspect of this disclosure.

[0009] It should be understood that the description in the Summary of the Invention section is not intended to limit the key or essential features of the embodiments of this disclosure, nor is it intended to restrict the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description

[0010] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. In the drawings, the same or similar reference numerals denote the same or similar elements, wherein:

[0011] Figure 1 A schematic diagram of an example environment in which some embodiments of this disclosure may be implemented is shown;

[0012] Figure 2 A flowchart illustrating a method for simulating large plastic deformation of composite materials according to some embodiments of this disclosure is shown;

[0013] Figure 3 A schematic diagram of a true stress-plastic strain curve is shown for some embodiments of this disclosure;

[0014] Figure 4 A schematic diagram of a damage variable curve is shown, representing some embodiments of the present disclosure.

[0015] Figure 5 A block diagram of a simulation system for large plastic deformation of composite materials, according to some embodiments of this disclosure, is shown; and

[0016] Figure 6 A block diagram of an electronic device that can implement several embodiments of the present disclosure is shown. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0018] The terms “comprising” and “having”, and any variations thereof, in this specification, claims, and the foregoing drawings are intended to cover a non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus. Depending on the context, the word “if” as it applies herein may be interpreted as “when”, “when”, “in response to determination”, or “in response to detection”.

[0019] As mentioned above, LS-DYNA is the most widely used solver in the field of whole-vehicle collision simulation. In current whole-vehicle collision and large deformation simulation analysis, for the large deformation simulation modeling of composite materials such as polypropylene plus ethylene propylene diene monomer (PP+EPDM_TD10) which represent typical mechanical response characteristics, engineering often refers to the calibration approach of metallic or isotropic materials. That is, the MAT_24 material card or MAT_187 material card is commonly used to make equivalent representations of composite materials. Specifically, the constant strain failure criterion built into the MAT_24 material card can be used, or the simplified failure model of the MAT_187 material card can be used. Alternatively, the GISSMO failure model can be used to describe failure and damage.

[0020] However, these material cards still have shortcomings in characterizing damage initiation, damage evolution, and post-peak response under large plastic strain conditions, specifically the following technical problems:

[0021] Damage initiation criteria mismatch: The damage initiation / failure criteria of the constant strain failure criterion in the MAT_24 material card or the simplified failure model of the MAT_187 material card are mostly based on the assumption of metal or equivalent isotropic material, which is difficult to be consistent with the ductile damage initiation mechanism of composite materials under large strain conditions mentioned above, resulting in large prediction deviations in damage initiation time, crack initiation location and crack initiation threshold.

[0022] Uncontrollable post-peak softening and plateau response: As mentioned above, after the composite material reaches its peak load-bearing capacity, the existing model has limited ability to characterize the slow decline after the peak and the load-bearing characteristics of the plateau segment. The shape of the post-peak curve is sensitive to parameter settings and lacks a stable and controllable evolution law, which can easily lead to problems such as premature failure, sudden stress drop, or difficulty in reproducing the plateau segment, thereby affecting the simulation consistency and repeatability of the energy absorption process.

[0023] Insufficient sensitivity to multiaxial loading and strain paths: Under complex stress conditions (such as tension-compression coupling, shear involvement, and different stress triaxiality conditions), existing models do not adequately characterize the response to changes in loading paths and stress states, making it difficult to accurately reflect the differences in damage accumulation and evolution of composite materials under multiaxial conditions, thus limiting the prediction accuracy of material mechanical response and failure modes under complex vehicle load scenarios.

[0024] In summary, existing technologies are unable to continuously and accurately characterize the mechanical response process of composite materials under complex stress paths, which to some extent weakens the simulation and prediction capabilities of the ductile energy absorption characteristics and failure modes of composite materials, and thus makes it difficult to meet the needs for refined material behavior description and improved vehicle simulation accuracy.

[0025] Therefore, embodiments of this disclosure propose a simulation method for large plastic deformation of composite materials. The method includes acquiring mechanical curve parameters of the composite material under various test types, and fitting these mechanical curve parameters to obtain equivalent curve parameters. The method also includes performing simulation benchmarking on all equivalent curve parameters, and determining whether the accuracy of all equivalent curve parameters meets the standards based on the simulation benchmarking results. In response to determining that the accuracy of all equivalent curve parameters meets the standards, the method further includes determining damage initiation parameters and damage evolution parameters based on damage test parameters of the composite material under multiple stress triaxialities. Furthermore, the method includes performing simulation verification processing on the composite material based on all equivalent curve parameters, damage initiation parameters, and damage evolution parameters.

[0026] In this way, the damage evolution criteria controlled by DIEM ductile damage initiation and plastic displacement can be introduced and coupled with the MAT_187 material card to achieve a continuous description of the composite material under large plastic deformation conditions of "elastoplasticity - damage initiation - damage evolution - fracture failure". This not only more reasonably characterizes the post-peak slack and plateau response of composite materials and their gradual damage evolution characteristics, but also improves the consistency of simulation prediction and engineering applicability under complex load scenarios such as large deformation or collision.

[0027] Figure 1 Schematic diagrams are shown illustrating example environments in which some embodiments of this disclosure can be implemented. For example... Figure 1 As shown, the example environment 100 may include a sample preparation test platform 101. This platform 101 is used to conduct various standard mechanical tests on the composite material, such as polypropylene plus ethylene propylene diene monomer (PP+EPDM_TD10), which represents a composite material with typical mechanical response characteristics, after the tester has prepared it, and to obtain the mechanical curve parameters of the composite material under various test types. Specifically, the various standard mechanical test types include uniaxial tensile testing, uniaxial compression testing, shear testing (i.e., V-notch shear testing), and a plastic Poisson's ratio test to determine the plastic Poisson's ratio of the composite material. The mechanical curve parameters of the composite material under uniaxial tensile testing can be a stress-displacement curve or a converted engineering stress-strain curve; the mechanical curve parameters of the composite material under uniaxial compression testing can be a stress-displacement curve or a converted compressive stress-strain curve; and the mechanical curve parameters of the composite material under shear testing can be a stress-displacement curve or a converted shear stress-strain curve. Of course, in the embodiments of this disclosure, the various standard mechanical test types can also be biaxial tensile tests, tensile tests with different notch radii, or uniaxial tensile tests under different strain rates (the corresponding mechanical curve parameters can also be determined directly based on the high-speed coefficient of the uniaxial tensile test, and / or the corresponding uniaxial compression mechanical curve parameters can be determined based on the high-speed coefficient, and / or the corresponding shear mechanical curve parameters can be determined based on the high-speed coefficient). The mechanical test processes of the various types mentioned above are well known to those skilled in the art, and will not be elaborated here.

[0028] Example environment 100 may also include processing terminal 102, which establishes a communication connection with sample preparation test platform 101 to obtain mechanical curve parameters of composite material under various test types, and performs fitting processing on the mechanical curve parameters corresponding to various test types to obtain equivalent curve parameters, that is, the hardening curve describing the elastoplastic behavior of composite material in the MAT_187 material card. Here, taking uniaxial tensile, uniaxial compression, and shear tests as examples of various standard mechanical test types, the mechanical curve parameters corresponding to the uniaxial tensile test can be piecewise fitted (using the Swift hardening equation) to construct the corresponding equivalent curve parameters (monotonically increasing throughout). Considering that the composite material is isotropic, the equivalent curve parameters corresponding to the uniaxial compression test can be determined based on the equivalent curve parameters corresponding to the uniaxial tensile test (e.g., it is recommended to process the equivalent curve parameters corresponding to the uniaxial tensile test based on a scaling factor to obtain the equivalent curve parameters corresponding to the uniaxial compression test). The mechanical curve parameters corresponding to the shear test can be saturated constitutive fitted (e.g., using the saturated hardening equation of the Voce constitutive model). These mechanical curve parameters corresponding to the shear test can be the actual shear stress-strain curve obtained through non-contact measurement to construct the corresponding equivalent curve parameters.

[0029] Furthermore, the processing terminal 102 can perform simulation benchmarking on all equivalent curve parameters and determine whether the accuracy of all equivalent curve parameters meets the standards based on the simulation benchmarking results. Here, simulation benchmarking can be understood as using LS-DYNA to build a model, performing simulation processing by setting a MAT_187 material card containing one or more equivalent curve parameters, and determining whether the matching degree between the simulation processing results and the corresponding mechanical curve parameters meets the standards. For example, by inputting the equivalent curve parameters corresponding to the uniaxial tensile test, it can be determined whether the matching degree between the simulation processing results (i.e., stress-displacement curve or converted engineering stress-strain curve) output by LS-DYNA corresponding to the uniaxial tensile test and the mechanical curve parameters corresponding to the uniaxial tensile test meets the standard; and / or, by inputting the equivalent curve parameters corresponding to the uniaxial tensile test and the equivalent curve parameters corresponding to the shear test, it can be determined whether the matching degree between the simulation processing results (i.e., stress-displacement curve or converted shear stress-strain curve) output by LS-DYNA corresponding to the uniaxial tensile test and the shear test meets the standard.

[0030] Furthermore, in response to ensuring the accuracy of all equivalent curve parameters, the processing terminal 102 can determine the damage initiation parameters and damage evolution parameters based on the damage test parameters of the composite material under multiple stress triaxialities. Here, the damage test parameters of the composite material under multiple stress triaxialities can be understood as the mechanical curve parameters (such as stress-displacement curves) collected by the sample preparation test platform 101 for tensile tests of the composite material with different notch radii, corresponding to each notch radius tensile test. Each mechanical curve parameter has a corresponding stress triaxiality and a crack initiation plastic strain value determined by the simulation processing results output by LS-DYNA.

[0031] It is understandable that by observing the damage test parameters under multiple stress triaxiality conditions, it can be concluded that the composite material exhibits ductile damage characteristics that are sensitive to stress triaxiality (for example, in the damage test parameters under stress triaxiality of about 0.33, it can be seen that the composite material has obvious necking before fracture and fibrous filamentation on the fracture surface, which is a typical ductile fracture phenomenon). Therefore, in the simulation process of LS-DYNA, the ductile damage initiation criterion and the damage evolution criterion controlled by plastic displacement in the DIEM failure material card (i.e., the DIEM failure model) can be activated, and the parameters of the DIEM material card can be calibrated by determining the damage initiation parameters and damage evolution parameters, thereby realizing the coupled modeling with the MAT_187 material card.

[0032] The damage initiation parameters can be determined by all stress triaxialities and the corresponding initiation plastic strain values, for example, as curves or tables plotted from all stress triaxialities and the corresponding initiation plastic strain values; the damage evolution parameters can be determined by all stress triaxialities and the corresponding plastic displacement values, which have corresponding evolution parameters (which can be adjusted based on the simulation results output by LS-DYNA), for example, as tables plotted from all stress triaxialities and the corresponding evolution parameters.

[0033] Furthermore, the processing terminal 102 can also perform simulation verification processing on composite materials based on all equivalent curve parameters, damage initiation parameters, and damage evolution parameters. Here, the processing terminal 102 can configure and package all equivalent curve parameters, damage initiation parameters, and damage evolution parameters to obtain a standardized MAT_187+DIEM material card file. Then, by establishing a subsystem test simulation model, the MAT_187+DIEM material card file is used for simulation verification processing, such as benchmarking macroscopic stress-displacement curves and local deformation modes. The verified MAT_187+DIEM material card file can be finally applied to the whole vehicle collision simulation model to be benchmarked with the actual vehicle test results, completing the final engineering verification.

[0034] Here, the MAT_187+DIEM material card file can consist of a MAT_187 material card, a DIEM material card, and historical configuration parameters. The MAT_187 material card specifically includes key characters starting with *MAT_187, all equivalent curve parameters, basic parameters of the composite material (such as basic density, elastic modulus, and elastic Poisson's ratio), and a switch character to activate the DIEM material card. The DIEM material card specifically includes damage initiation parameters and damage evolution parameters. The historical configuration parameters specifically include internal variable parameters of the composite material (such as characters corresponding to equivalent plastic strain, characters corresponding to the DIEM damage variable D, and characters corresponding to the DIEM damage initiation indicator WD), and are not limited to these.

[0035] Of course, in the embodiments of this disclosure, before performing simulation verification on the MAT_187+DIEM material card file, the grid size effect can be calibrated using LS-DYNA to ensure that the MAT_187+DIEM material card file has robustness and accuracy under different grid scales and loading rates.

[0036] In this way, the damage evolution criteria controlled by DIEM ductile damage initiation and plastic displacement can be introduced and coupled with the MAT_187 material card to achieve a continuous description of the composite material under large plastic deformation conditions of "elastoplasticity - damage initiation - damage evolution - fracture failure". This not only more reasonably characterizes the post-peak slack and plateau response of composite materials and their gradual damage evolution characteristics, but also improves the consistency of simulation prediction and engineering applicability under complex load scenarios such as large deformation or collision.

[0037] It should be understood that the architecture and functionality in example environment 100 are described for illustrative purposes only and do not imply any limitation on the scope of this disclosure. Embodiments of this disclosure can also be applied to other environments with different architectures and / or functionalities.

[0038] Figure 2 A flowchart illustrating a method for simulating large plastic deformation of composite materials according to some embodiments of this disclosure is shown. Method 200 may, for example, be derived from... Figure 1 The processing terminal in the example environment shown executes. For example... Figure 2 As shown in box 202, method 200 can obtain the mechanical curve parameters of the composite material under various test types, and perform fitting processing on each mechanical curve parameter to obtain equivalent curve parameters. Here, the processing terminal connects with... Figure 1The sample preparation test platform in the example environment shown establishes a communication connection to acquire the mechanical curve parameters of polypropylene plus ethylene propylene diene monomer (PP+EPDM_TD10), a composite material representing typical mechanical response characteristics, under various test types. These various test types can specifically include uniaxial tensile testing, uniaxial compression testing, shear testing (i.e., V-notch shear testing), and plastic Poisson's ratio testing to determine the plastic Poisson's ratio of the composite material. The mechanical curve parameters can be the stress-displacement curve or the converted stress-strain curve corresponding to each test type. Of course, in the embodiments of this disclosure, the various test types can also be biaxial tensile testing, tensile testing with different notch radii, or uniaxial tensile testing at different strain rates (the corresponding mechanical curve parameters can also be determined directly based on the high-speed coefficient of the uniaxial tensile test, and / or based on the high-speed coefficient to determine the corresponding uniaxial compression mechanical curve parameters, and / or based on the high-speed coefficient to determine the corresponding shear mechanical curve parameters). The mechanical test processes mentioned above are well known to those skilled in the art and will not be elaborated upon here.

[0039] Understandably, taking uniaxial tensile, uniaxial compression, and shear tests as examples, the mechanical curve parameters corresponding to the uniaxial tensile test can be piecewise fitted (using the Swift hardening equation) to construct the corresponding equivalent curve parameters (monotonically increasing throughout). Considering the isotropic nature of the composite material, the equivalent curve parameters corresponding to the uniaxial compression test can be determined based on the equivalent curve parameters corresponding to the uniaxial tensile test (e.g., by processing the equivalent curve parameters corresponding to the uniaxial tensile test using a scaling factor). The mechanical curve parameters corresponding to the shear test can be saturated constitutive fitted (e.g., using the saturated hardening equation of the Voce constitutive model), and these mechanical curve parameters can be the actual shear stress-strain curves obtained through non-contact methods to construct the corresponding equivalent curve parameters.

[0040] In some implementations, when fitting the mechanical curve parameters to obtain equivalent curve parameters, taking the fitting of the mechanical curve parameters corresponding to the uniaxial tensile test as an example, the mechanical curve parameters corresponding to the uniaxial tensile test can be transformed to obtain multiple sets of first strain-stress values. Here, when the mechanical curve parameter is a stress-displacement curve, the engineering strain value corresponding to each displacement value can be determined based on multiple displacement values ​​and the original gauge length value (known parameter) in the stress-displacement curve, referring to the strain calculation equation shown below:

[0041]

[0042] In the above formula, This represents the engineering strain value. denoted as , where is the difference between each displacement value in the stress-displacement curve and the initial displacement value, and L is the original gauge length value.

[0043] Furthermore, based on the stress values ​​corresponding to each displacement value in the stress-displacement curve and the original cross-sectional area (known parameters), the engineering stress value corresponding to each displacement value can be determined by referring to the stress calculation equation shown below:

[0044]

[0045] In the above formula, F represents the engineering stress value, F represents each stress value in the stress-displacement curve, and A represents the original cross-sectional area.

[0046] It is understandable that the engineering strain value and engineering stress value corresponding to each displacement value in the stress-displacement curve can be determined as a set of first strain-stress values.

[0047] Subsequently, based on the first strain stress values ​​of each group and the plastic Poisson's ratio of the composite material, the true stress plastic strain value is determined. Here, the plastic Poisson's ratio of the composite material can be obtained by performing a plastic Poisson's ratio test on the composite material using the aforementioned specimen preparation test platform. The corresponding true strain value can be determined based on the engineering strain value in each group of first strain stress values, referring to the true strain calculation equation shown below:

[0048]

[0049] In the above formula, This is the true strain value. This represents the engineering strain value.

[0050] Furthermore, the corresponding true stress value can be determined based on the engineering strain value, engineering stress value, and plastic Poisson's ratio of the composite material in each group of first strain stress values, referring to the true stress calculation equation shown below:

[0051]

[0052] In the above formula, This is the true stress value. This represents the engineering strain value. ν is the engineering stress value, and v is the plastic Poisson's ratio of the composite material.

[0053] After determining the true stress values, the corresponding plastic strain values ​​can also be determined based on the true strain values, the corresponding true stress values, and the elastic modulus of the composite material (which can be determined based on the initial slope in the stress-displacement curve), referring to the plastic strain value calculation equation shown below:

[0054]

[0055] In the above formula, This is the plastic strain value. This is the true strain value. is the true stress value, and E is the elastic modulus of the composite material.

[0056] It is understood that the true stress value and plastic strain value corresponding to the engineering strain value in each group of first strain stress values ​​can be determined as the true stress plastic strain value. Of course, in order to ensure the accuracy and effectiveness of all true stress plastic strain values, the embodiments of this disclosure can also perform smoothing processing (such as moving average method) on all true stress plastic strain values, and truncate and remove the initial slip segment (such as the part of true stress plastic strain value corresponding to the displacement value less than the preset displacement threshold) and the force drop segment after fracture (such as the part of true stress plastic strain value corresponding to the displacement value that suddenly drops to 0) in all the smoothed true stress plastic strain values.

[0057] Subsequently, three curve intervals were determined based on all true stress plastic strain values, and all true stress plastic strain values ​​corresponding to all curve intervals were fitted to obtain equivalent curve parameters. In one example, taking a three-segment curve interval as the first, middle, and final segment, the processing terminal can construct a true stress-plastic strain curve based on all true stress-plastic strain values ​​and identify four key feature points from this curve. The first key feature point can be the initial yield point determined in the true stress-plastic strain curve based on the 0.2% plastic strain offset method. The second key feature point can be the point after the peak in the true stress-plastic strain curve, corresponding to a true stress value 4% after the maximum true stress value. The third key feature point can be the end point of the plateau segment in the true stress-plastic strain curve, estimated to be the point where the curve begins to flatten after the peak (e.g., the point corresponding to a plastic strain value of 0.15 after the peak). The fourth key feature point can be the starting point of the tail segment in the true stress-plastic strain curve, corresponding to a larger plastic strain value after the end of the plateau segment (e.g., the point corresponding to a set plastic strain value). It is understandable that the first section of the curve contains multiple true stress-plastic strain value points (i.e., true stress-plastic strain values) in the true stress-plastic strain curve, with the starting point being the first key feature point and the ending point being the second key feature point; the middle section of the curve contains multiple true stress-plastic strain value points (i.e., true stress-plastic strain values) in the true stress-plastic strain curve, with the starting point being the second key feature point and the ending point being the third key feature point; the final section of the curve contains multiple true stress-plastic strain value points (i.e., true stress-plastic strain values) in the true stress-plastic strain curve, with the starting point being the third key feature point and the ending point being the fourth key feature point.

[0058] Next, the first hardening equation is fitted based on all true stress-plastic strain values ​​corresponding to the first curve segment interval to obtain the parameters of the first curve segment. Here, all true stress-plastic strain values ​​corresponding to the first curve segment interval can be substituted into the first hardening equation shown below (e.g., the Swift hardening equation), and the material parameters in the first hardening equation can be solved by fitting using the least squares method:

[0059]

[0060] In the above formula, This is the true stress value. K represents the plastic strain value. and The parameters are the material parameters to be solved. It can be understood that the parameters of the first curve segment are the first hardening equation obtained by substituting the material parameters.

[0061] Next, the first hardening equation is fitted based on all true stress plastic strain values ​​corresponding to the middle section of the curve to obtain the middle section curve parameters; the slope of the middle section curve parameters is lower than a preset slope threshold. Here, all true stress plastic strain values ​​corresponding to the middle section curve interval can be substituted into the first hardening equation shown above, and the least squares method can be used for fitting to solve for the material parameters in the first hardening equation. The first hardening equation with the solved material parameters is then determined as the middle section curve parameters.

[0062] Understandably, the parameters of the middle section curve correspond to the plateau period of the softening segment of the engineering stress. In essence, it is a slightly rising curve equation (that is, the curve slope is very small, and it needs to be lower than the preset slope threshold) to replace the falling segment and plateau segment of the original curve. This not only ensures numerical stability, but also ensures that the energy absorption is comparable to the original curve. It also avoids numerical instability caused by localization / distortion / negative slope that is prone to occur in the softening segment.

[0063] Next, initial curve parameters are constructed based on the mid-section curve parameters. Based on the simulation results of the composite material under these initial curve parameters, the initial curve parameters are adjusted to obtain the final curve parameters. Here, the initial curve parameters can be constructed to be completely identical to the mid-section curve parameters, or with a curve slope slightly higher than the mid-section curve parameters. A model is then built using LS-DYNA. Simulation processing is performed by setting the MAT_187 material card, which includes the first, mid, and initial curve parameters, and the initial curve parameters are adjusted based on the simulation results. Understandably, if the simulation results indicate that the element undergoes severe distortion when it reaches a large strain value, the initial curve parameters can be appropriately increased in slope to increase the stress at the end and enhance the element's resistance to distortion. In addition, after adjusting the initial curve parameters, a MAT_187 material card containing the first curve parameters, the middle curve parameters, and the adjusted initial curve parameters can be set up to perform simulation again. This process can be iterated several times until severe distortion no longer occurs. At this point, the final curve parameters can be the final adjusted initial curve parameters.

[0064] Of course, embodiments of this disclosure can also adjust the parameters of the middle section curve by adjusting the range corresponding to the middle section curve range when the simulation results indicate that the unit has severe distortion when it reaches a large strain value, and refer to the above to further determine the parameters of the final section curve until severe distortion no longer occurs, and are not limited to this.

[0065] Please see Figure 3 A schematic diagram of a true stress-plastic strain curve according to some embodiments of the present disclosure is shown. Figure 3 As shown, point A in the true stress-plastic strain curve 300 is the first key feature point (i.e., the initial yield point) mentioned above, point B is the second key feature point (i.e., the point after the peak) mentioned above, point C is the third key feature point (i.e., the end point of the plateau segment) mentioned above, and point D is the fourth key feature point (i.e., the start point of the tail segment) mentioned above.

[0066] Next, the parameters of the first, middle, and final curve segments are determined as equivalent curve parameters. Here, the equivalent curve parameters can be understood as three smoothly connected, monotonically increasing true stress-plastic strain curves that can completely replace the softening segment that may exist in the original experimental curve, but are equivalent to the original curve in terms of energy (area under the curve), thus ensuring the stability of the simulation results.

[0067] In some implementations, when fitting the mechanical curve parameters to obtain equivalent curve parameters, taking the fitting of the mechanical curve parameters corresponding to the shear test as an example, the mechanical curve parameters corresponding to the shear test can be transformed to obtain multiple sets of second strain-stress values. Here, each set of second strain-stress values ​​includes the engineering strain value and engineering stress value corresponding to each displacement value in the stress-displacement curve. The determination process can be found above and will not be elaborated further here.

[0068] Subsequently, true stress and true strain values ​​are determined based on the second strain stress values ​​of each group and the plastic Poisson's ratio of the composite material. Here, each group of true stress and true strain values ​​includes the true stress value and true strain value corresponding to the engineering strain value in the second strain stress values. The determination process can be found above, and will not be elaborated further here. Of course, the embodiments of this disclosure can also directly obtain the true shear stress-strain curve corresponding to the shear test by non-contact measurement, and are not limited to this.

[0069] Next, the second hardening equation is fitted based on all true stress and true strain values ​​to obtain the equivalent curve parameters. Here, refer to the above method of converting each true stress and true strain value into the corresponding true stress and plastic strain value, and substituting all true stress and plastic strain values ​​into the second hardening equation shown below (e.g., the Voce hardening equation). The material parameters in the second hardening equation are then solved using the least squares method for fitting.

[0070]

[0071] In the above formula, This is the true stress value. This is the plastic strain value. , and Let be the material parameters to be solved. It can be understood that the equivalent curve parameters are the second hardening equation obtained by substituting the material parameters.

[0072] Of course, embodiments of this disclosure can also determine equivalent curve parameters corresponding to the biaxial tensile test, such as by fitting the mechanical curve parameters corresponding to the biaxial tensile test (see the fitting process corresponding to the uniaxial tensile test), or by fitting the mechanical curve parameters corresponding to the uniaxial tensile test and the Mises yield criterion when no biaxial tensile test is performed on the composite material, to obtain equivalent curve parameters corresponding to the biaxial tensile test, and are not limited thereto. It should be noted that all the equivalent curve parameters mentioned above should preferably satisfy the plasticity law in the corresponding test to effectively ensure the validity and reliability of the data.

[0073] In box 204, method 200 can perform simulation benchmarking on all equivalent curve parameters and determine whether the accuracy of all equivalent curve parameters meets the standard based on the simulation benchmarking results. Here, simulation benchmarking can be understood as using LS-DYNA to build a model, performing simulation processing by setting a MAT_187 material card containing one or more equivalent curve parameters, and determining whether the matching degree between the simulation processing results and the corresponding mechanical curve parameters meets the standard.

[0074] In some implementations, when the processing terminal performs simulation benchmarking on all equivalent curve parameters and determines whether the accuracy of all equivalent curve parameters meets the standard based on the simulation benchmarking results, it specifically determines whether the first matching degree between the first simulation result of the composite material under the equivalent curve parameters corresponding to the uniaxial tensile test and the mechanical curve parameters corresponding to the uniaxial tensile test meets the standard. Here, after establishing the model using LS-DYNA, a MAT_187 material card containing the equivalent curve parameters corresponding to the uniaxial tensile test can be set for tensile simulation processing. The first matching degree is determined by comparing the overall curve trend matching degree (i.e., the first simulation result, or the stress-strain curve) obtained from the simulation processing with the mechanical curve parameters corresponding to the uniaxial tensile test (i.e., the first matching degree, which may also include elastic modulus error and / or yield strength error, etc.).

[0075] It is understandable that when the overall curve trend matching degree exceeds the preset matching degree threshold (which may also include the elastic modulus error being less than the preset error threshold, and / or the yield strength error being less than the preset error threshold), it indicates that the simulation processing result is highly consistent with the experimental result, and thus the first matching degree can be determined to be up to standard; otherwise, it indicates that the simulation processing result is not highly consistent with the experimental result, and the equivalent curve parameters corresponding to the uniaxial tensile test can be re-determined by referring to the above.

[0076] Subsequently, in response to determining that the first degree of matching meets the standard, based on the second simulation results of the composite material under the equivalent curve parameters corresponding to the uniaxial tensile test and the equivalent curve parameters corresponding to the uniaxial compression test, it is determined whether the second degree of matching between the second simulation results and the mechanical curve parameters corresponding to the uniaxial compression test meets the standard. Here, after establishing the model using LS-DYNA, a MAT_187 material card containing the equivalent curve parameters corresponding to the uniaxial tensile test and the equivalent curve parameters corresponding to the uniaxial compression test can be set for compression simulation processing. By comparing the overall curve trend matching degree (i.e., the second simulation result, or the stress-strain curve) obtained from the simulation processing with the mechanical curve parameters corresponding to the uniaxial compression test (i.e., the second degree of matching, which may also include stiffness matching degree and / or yield strength error, etc.), it is determined whether the second degree of matching meets the standard.

[0077] It is understandable that when the overall curve trend matching degree exceeds the preset matching degree threshold (which may also include stiffness matching degree greater than the preset matching degree threshold, and / or yield strength error less than the preset error threshold), it indicates that the simulation processing result is highly consistent with the experimental result, and thus the second matching degree can be determined to be up to standard; otherwise, it indicates that the simulation processing result is not highly consistent with the experimental result, and the equivalent curve parameters corresponding to the uniaxial compression test can be re-determined by referring to the above.

[0078] Subsequently, in response to confirming that the second degree of matching is satisfactory, based on the third simulation results of the composite material under the equivalent curve parameters corresponding to the uniaxial tensile test and the equivalent curve parameters corresponding to the shear test, it is determined whether the third degree of matching between the third simulation results and the mechanical curve parameters corresponding to the shear test is satisfactory. Here, after establishing the model using LS-DYNA, a MAT_187 material card containing the equivalent curve parameters corresponding to the uniaxial tensile test and the equivalent curve parameters corresponding to the shear test can be set for shear simulation processing. The satisfaction of the third degree of matching is determined by comparing the overall curve trend matching degree (i.e., the third simulation result, or the stress-strain curve) obtained from the simulation processing with the mechanical curve parameters corresponding to the shear test.

[0079] It is understandable that when the overall curve trend matching degree exceeds the preset matching degree threshold, it indicates that the simulation processing result is highly consistent with the experimental result, and thus the third matching degree can be determined to be up to standard; otherwise, it indicates that the simulation processing result is not highly consistent with the experimental result, and the equivalent curve parameters corresponding to the shear test can be re-determined by referring to the above.

[0080] Subsequently, in response to determining that the third matching degree meets the standard, based on the fourth simulation results of the composite material under the equivalent curve parameters corresponding to the uniaxial tensile test, the equivalent curve parameters corresponding to the uniaxial compression test, and the equivalent curve parameters corresponding to the shear test, it is determined whether the fourth matching degree between the fourth simulation results and the mechanical curve parameters corresponding to the complex working condition test meets the standard. Here, the complex working condition test is any at least one of the following: uniaxial tensile test, uniaxial compression test, shear test, central hole tensile test, three-point bend test, and punching test. As in the embodiments of this disclosure, the simulation benchmarking processing corresponding to the uniaxial tensile test, uniaxial compression test, shear test, central hole tensile test, three-point bend test, and punching test are performed sequentially to ensure that the MAT_187 material card itself can accurately reproduce the basic elastoplastic behavior of the material under various stress states before the introduction of the complex DIEM failure model.

[0081] In one example, taking the central hole tensile test as an example, a plate model (with a hole in the middle, and the mesh size can be set to be consistent with the whole vehicle model) can be built using LS-DYNA. Then, the MAT_187 material card containing the equivalent curve parameters corresponding to the uniaxial tensile test, the equivalent curve parameters corresponding to the uniaxial compression test, and the equivalent curve parameters corresponding to the shear test can be set to perform tensile simulation processing. By comparing the stress-displacement curve (i.e., the fourth simulation processing result, or stress-strain curve) obtained from the simulation processing results with the overall curve trend matching degree (i.e., the fourth matching degree, which may also include peak error and / or strain distribution error, etc.) between the composite material under the central hole tensile test, it is determined whether the fourth matching degree meets the standard.

[0082] Understandably, when the overall curve trend matching degree exceeds the preset matching degree threshold (which may also include peak error less than the preset matching degree threshold, and / or strain distribution error less than the preset error threshold), it indicates that the simulation results are highly consistent with the experimental results, thus confirming that the fourth matching degree has met the standard. Furthermore, after the matching degree of all complex working condition tests has met the standard, it can be confirmed that the accuracy of all equivalent curve parameters has met the standard. Otherwise, it indicates that the simulation results are not highly consistent with the experimental results, and the equivalent curve parameters corresponding to the uniaxial tensile test, and / or the uniaxial compression test, and / or the shear test can be re-determined by referring to the above.

[0083] In box 206, method 200 can determine damage initiation parameters and damage evolution parameters based on damage test parameters of the composite material under multiple stress triaxialities, in response to ensuring the accuracy of all equivalent curve parameters. Here, the damage test parameters of the composite material under multiple stress triaxialities can be understood as the mechanical curve parameters (such as stress-displacement curves) collected from tensile tests of different notch radii (i.e., notched round bar tensile tests, which may also include smooth round bar tensile tests, shear tests, and / or compression tests) conducted on the composite material by a specimen preparation test platform, corresponding to tensile tests of each notch radius. Each mechanical curve parameter has a corresponding stress triaxiality and a crack initiation plastic strain value determined using simulation processing results output by LS-DYNA.

[0084] It is understandable that by observing the damage test parameters under multiple stress triaxiality conditions, it can be concluded that the composite material exhibits ductile damage characteristics that are sensitive to stress triaxiality (for example, in the damage test parameters under stress triaxiality of about 0.33, it can be seen that the composite material has obvious necking before fracture and fibrous filamentation on the fracture surface, which is a typical ductile fracture phenomenon). Therefore, in the simulation process of LS-DYNA, the ductile damage initiation criterion and the damage evolution criterion controlled by plastic displacement in the DIEM failure material card (i.e., the DIEM failure model) can be activated, and the parameters of the DIEM material card can be calibrated by determining the damage initiation parameters and damage evolution parameters, thereby realizing the coupled modeling with the MAT_187 material card.

[0085] In some implementations, when the processing terminal determines the damage initiation parameters and damage evolution parameters based on the damage test parameters of the composite material under multiple stress triaxialities, specifically, it acquires the damage test parameters of the composite material under multiple stress triaxialities and determines the fracture simulation parameters of the composite material under all equivalent curve parameters and each stress triaxiality. Here, when determining the fracture simulation parameters of the composite material under all equivalent curve parameters and each stress triaxiality, LS-DYNA can be used to establish a finite element model corresponding to each stress triaxiality (e.g., when the stress triaxiality is approximately 0.33, a smooth circular bar model is established). Then, a MAT_187 material card containing equivalent curve parameters corresponding to uniaxial tensile tests, uniaxial compression tests, and shear tests is set for simulation processing to obtain the corresponding stress-displacement curves (i.e., fracture simulation parameters, which can also be stress-strain curves).

[0086] Subsequently, based on the damage test parameters and fracture simulation parameters corresponding to each stress triaxiality, the initiation plastic strain value is determined. Here, the fracture displacement value (i.e., the displacement value when fracture occurs during the test) can be identified from the damage test parameters corresponding to each stress triaxiality. Then, based on the fracture displacement value, the stress value corresponding to the fracture displacement value is determined in the corresponding fracture simulation parameters. Based on the fracture displacement value and the corresponding stress value, the plastic strain value (i.e., the initiation plastic strain value, also known as the equivalent plastic strain value) is obtained by referring to the above process for determining the plastic strain value.

[0087] Subsequently, damage initiation parameters are determined based on all stress triaxialities and all initiation plastic strain values. Here, after obtaining the initiation plastic strain value corresponding to each stress triaxiality, the curve plotted based on all stress triaxialities and all initiation plastic strain values ​​can be determined as the damage initiation parameters. Of course, embodiments of this disclosure can also determine the damage initiation parameters by including a table of multiple stress triaxialities, strain rates corresponding to each stress triaxiality, and initiation plastic strain values ​​when the damage test parameters correspond to the aforementioned tensile tests with different notch radii at different loading rates (i.e., notched round bar tensile tests, and may also include smooth round bar tensile tests, shear tests, and / or compression tests), without further elaboration here.

[0088] Next, based on the damage initiation parameters and all damage test parameters, the damage evolution parameters are determined. In one example, the plastic displacement value can be determined based on the plastic strain value at each initiation point in the damage initiation parameters and the preset size parameters, and the initial evolution parameters can be constructed based on all plastic displacement values. Here, the product of the plastic strain value at each initiation point in the damage initiation parameters and the preset size parameters (i.e., the known model element size) can be used as the corresponding plastic displacement value, and the initial evolution parameters, including the relationship between the damage variable and all plastic displacement values, can be constructed by defining the relationship between the damage variable and each plastic displacement value. It can be understood that the damage variable ranges from 0 to 1 (i.e., from never being damaged to complete failure). It is usually assumed that the damage variable grows linearly from 0 to 1, then the relationship between the damage variable and each plastic displacement value can be a linear proportion, that is, the damage variable is the product of the plastic displacement value and a certain linear proportion value (also called the failure value, which needs to be set by the user); for example, when the plastic displacement value is defined as 0.1, the damage variable is 1, then the linear proportion value at this time can be determined to be 10.

[0089] Next, the evolution simulation parameters of the composite material under all equivalent curve parameters, damage initiation parameters, initial evolution parameters, preset damage variable parameters, and various stress triaxialities are determined. Here, LS-DYNA can be used to establish a finite element model corresponding to each stress triaxiality (e.g., when the stress triaxiality is approximately 0.33, a smooth circular bar model is established). Then, MAT_187 material cards (DIEM material cards need to be activated) containing equivalent curve parameters corresponding to uniaxial tensile tests, uniaxial compression tests, and shear tests are set, along with DIEM material cards containing damage initiation parameters, initial evolution parameters, and preset damage variable parameters, to perform simulation processing and obtain the corresponding stress-displacement curves (i.e., evolution simulation parameters, which can also be stress-strain curves). Specifically, the DITYP of the DIEM material card can be set to 0, P1 to the damage initiation parameter, P5 to the mesh size effect (i.e., the preset damage variable parameter), and Q1 to the initial evolution parameter. The settings of DITYP, P1, and P5 correspond to the ductile damage initiation criterion, while the settings of DITYP and Q1 correspond to the damage evolution criterion controlled by plastic displacement.

[0090] Next, based on all evolution simulation parameters and all damage test parameters, the initial evolution parameters are adjusted to obtain the damage evolution parameters. Here, after determining the evolution simulation parameters corresponding to each stress triaxiality, the evolution simulation parameters and the corresponding damage test parameters can be compared. Based on the comparison results, the corresponding linear scale values ​​set in the initial evolution parameters can be adjusted. Simulation processing can be performed again based on the adjusted initial evolution parameters. This process is iterated several times until the comparison results meet the accuracy requirements, and the finally adjusted initial evolution parameters are determined as the damage evolution parameters. For example, if the comparison result shows a simulation decrease that is too steep, it indicates that the damage evolution is too fast, and the corresponding linear scale value can be increased; if the comparison result shows a simulation decrease that is too gradual, it indicates that the damage evolution is too slow, and the corresponding linear scale value can be decreased. The process of judging the comparison results is a well-known technique in the art and will not be elaborated further here.

[0091] It is understandable that the damage evolution parameters can be a table drawn from the stress triaxiality and the evolution parameters corresponding to each stress triaxiality. The evolution parameters corresponding to each stress triaxiality are either the set linear scaling values ​​or the adjusted linear scaling values.

[0092] Furthermore, when using LS-DYNA for simulation, the damage state of the element can be output by setting *DEFINE_MATERIAL_HISTORIES, such as the damage initiation indicator WD and damage variable D, and a damage variable curve can be plotted based on the damage initiation indicator WD and damage variable D. It is understood that by observing whether the moment when WD is 1 in the damage variable curve corresponds to the moment of microcrack initiation in the test for obtaining damage test parameters, it can be determined whether the aforementioned damage initiation parameters need to be adjusted. For example, if the moment when WD is 1 in the damage variable curve is much smaller than the moment of microcrack initiation in the test (i.e., the error between the two is large), it indicates that the aforementioned damage initiation parameters may be generally too early, and therefore need to be adjusted. Of course, embodiments of this disclosure can also determine whether the aforementioned damage initiation parameters need to be adjusted by observing the crack initiation location and / or crack propagation path in the damage cloud map, but this will not be elaborated further here.

[0093] Please see Figure 4 The diagram illustrates a damage variable curve according to some embodiments of the present disclosure. Figure 4 As shown, the damage variable curve 400 includes the time variation curve of the damage initiation indicator WD and the time variation curve of the damage variable D; wherein, when the damage initiation indicator WD is 0 and the damage variable D is 0, it indicates that the pure elastoplastic stage is in progress; when the damage initiation indicator WD jumps from 0 to 1 and the damage variable D starts to increase from 0, it indicates that the damage is in progress; when the damage initiation indicator WD is 1 and the damage variable is 1, it indicates that the element is removed (i.e., a crack is formed).

[0094] In box 208, method 200 can perform simulation verification processing on composite materials based on all equivalent curve parameters, damage initiation parameters, and damage evolution parameters. Here, the processing terminal can configure and package all equivalent curve parameters, damage initiation parameters, and damage evolution parameters to obtain a standardized MAT_187+DIEM material card file. Then, by establishing a subsystem test simulation model, the MAT_187+DIEM material card file is used for simulation verification processing. For example, it can be benchmarked against the macroscopic stress-displacement curve and the local deformation mode. The MAT_187+DIEM material card file that has passed verification (e.g., the stress-displacement curve and deformation mode are highly consistent with the test results) can be finally applied to the whole vehicle collision simulation model (e.g., the C-NCAP frontal 40% offset collision model) to be benchmarked against the actual vehicle test results, thus completing the final engineering verification.

[0095] Here, the MAT_187+DIEM material card file can consist of a MAT_187 material card, a DIEM material card, and historical configuration parameters. The MAT_187 material card specifically includes key characters starting with *MAT_187, all equivalent curve parameters, basic parameters of the composite material (such as basic density, elastic modulus, and elastic Poisson's ratio), and a switch character to activate the DIEM material card. The DIEM material card specifically includes damage initiation parameters and damage evolution parameters. The historical configuration parameters specifically include internal variable parameters of the composite material (such as characters corresponding to equivalent plastic strain, characters corresponding to the DIEM damage variable D, and characters corresponding to the DIEM damage initiation indicator WD), and are not limited to these.

[0096] Of course, in the embodiments of this disclosure, before performing simulation verification on the MAT_187+DIEM material card file, the grid size effect can be calibrated using LS-DYNA to ensure that the MAT_187+DIEM material card file has robustness and accuracy under different grid scales and loading rates.

[0097] Figure 5 A block diagram of a simulation system for large plastic deformation of composite materials according to some embodiments of the present disclosure is shown. The various embodiments in this specification are described in a progressive manner, with reference to each other for similar or identical parts. Each embodiment focuses on describing the differences from other embodiments. In particular, the apparatus embodiments are basically similar to the method embodiments, so the description is relatively simple, and relevant parts can be referred to the description of the method embodiments. Figure 5 As shown, the large plastic deformation simulation system 500 for composite materials may include a fitting processing module 502, configured to acquire mechanical curve parameters of the composite material under various test types, and perform fitting processing on each mechanical curve parameter to obtain equivalent curve parameters. The large plastic deformation simulation system 500 for composite materials also includes a simulation benchmarking module 504, configured to perform simulation benchmarking processing on all equivalent curve parameters, and determine whether the accuracy of all equivalent curve parameters meets the standards based on the simulation benchmarking processing results. The large plastic deformation simulation system 500 for composite materials also includes a damage parameter determination module 506, configured to determine damage initiation parameters and damage evolution parameters based on damage test parameters of the composite material under multiple stress triaxialities in response to determining that the accuracy of all equivalent curve parameters meets the standards. Furthermore, the large plastic deformation simulation system 500 for composite materials also includes a simulation verification module 508, configured to perform simulation verification processing on the composite material based on all equivalent curve parameters, damage initiation parameters, and damage evolution parameters.

[0098] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this specification are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in or transmitted through a computer-readable storage medium. The computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium accessible to a computer or a data storage device such as a server or data center that integrates one or more available media. The available media may be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., Digital Versatile Discs (DVDs)), or semiconductor media (e.g., Solid State Disks (SSDs)).

[0099] Figure 6 Block diagrams of electronic devices that can implement various embodiments of the present disclosure are shown. For example... Figure 6 As shown, the electronic device 600 includes a processor 601, which can perform various appropriate actions and processes based on computer program instructions loaded into random access memory (RAM) 603 according to computer program instructions stored in read-only memory (ROM) 602. The RAM 603 may also store various programs and data required for the operation of the electronic device 600. The processor 601, ROM 602, and RAM 603 are interconnected via a bus 604. An input / output (I / O) interface 605 is also connected to the bus 604.

[0100] The various processes and procedures described above, such as method 200, can be executed by processor 601. For example, in some embodiments, method 200 may be implemented as a software program tangibly contained in a machine-readable medium. In some embodiments, part or all of the software program may be loaded into and / or installed onto electronic device 600 via ROM 602. When the software program is loaded into RAM 603 and executed by processor 601, one or more actions of method 200 described above may be performed.

[0101] The functions described above in this document can be performed at least in part by one or more hardware logic components. For example, exemplary types of hardware logic components that can be used, without limitation, include: field programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), systems-on-a-chip (SoCs), payload programmable logic devices (CPLDs), and so on.

[0102] The program code used to implement the methods of this disclosure may be written in any combination of one or more programming languages. This program code may be provided to a processor or controller of a general-purpose computer, special-purpose computer, or other programmable data processing apparatus, such that when executed by the processor or controller, the program code causes the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code may be executed entirely on a machine, partially on a machine, as a standalone software package partially on a machine and partially on a remote machine, or entirely on a remote machine or server.

[0103] This disclosure can be a method, apparatus, system, and / or program product. The program product may include a machine-readable storage medium on which machine-readable program instructions for performing various aspects of this disclosure are loaded. The machine-readable program instructions described herein can be downloaded from the machine-readable storage medium to various computing / processing devices, or downloaded via a network, such as the Internet, a local area network, a wide area network, and / or a wireless network, to an external computer or external storage device. The network may include copper transmission cables, fiber optic transmissions, wireless transmissions, routers, firewalls, switches, gateway computers, and / or edge servers. A network adapter card or network interface in each computing / processing device receives the machine-readable program instructions from the network and forwards them to the machine-readable storage medium in the respective computing / processing device.

[0104] Machine program instructions used to perform the operations of this disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, state setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Smalltalk, C++, etc., and conventional procedural programming languages ​​such as the "C" language or similar programming languages. Machine-readable program instructions may be executed entirely on a user's computer, partially on a user's computer, as a standalone software package, partially on a user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving a remote computer, the remote computer may be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or may be connected to an external computer (e.g., via the Internet using an Internet service provider). In some embodiments, electronic circuitry, such as programmable logic circuitry, field-programmable gate arrays (FPGAs), or programmable logic arrays (PLAs), is personalized by utilizing state information from the machine-readable program instructions to implement various aspects of this disclosure.

[0105] In the context of this disclosure, a machine-readable medium can be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, apparatus, or device. A machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. Machine-readable media can be, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing. Furthermore, although operations are depicted in a specific order, this should be understood as requiring that such operations be performed in the specific order shown or in sequential order, or requiring that all illustrated operations be performed to achieve the desired result. In certain environments, multitasking and parallel processing may be advantageous. Similarly, while several specific implementation details are included in the foregoing discussion, these should not be construed as limiting the scope of this disclosure. Certain features described in the context of individual embodiments may also be implemented in combination in a single implementation. Conversely, various features described in the context of a single implementation may also be implemented individually or in any suitable sub-combination in multiple implementations.

[0106] Although the subject matter has been described using language specific to structural features and / or methodological logic, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or actions described above. Rather, the specific features and actions described above are merely illustrative examples of implementing the claims.

Claims

1. A method for simulating large plastic deformation of composite materials, characterized in that, include: The mechanical curve parameters of the composite material under various test types are obtained, and the mechanical curve parameters are fitted to obtain equivalent curve parameters. Simulation benchmarking is performed on all the equivalent curve parameters, and the accuracy of all the equivalent curve parameters is determined based on the simulation benchmarking results. In response to ensuring that the accuracy of all the equivalent curve parameters is met, damage initiation parameters and damage evolution parameters are determined based on damage test parameters of the composite material under multiple stress triaxialities; and The composite material is subjected to simulation verification based on all the equivalent curve parameters, the damage initiation parameters, and the damage evolution parameters.

2. The method according to claim 1, characterized in that, The process of fitting the mechanical curve parameters to obtain equivalent curve parameters includes: The mechanical curve parameters corresponding to the uniaxial tensile test are converted to obtain multiple sets of first strain stress values. Based on the first strain stress value of each group and the plastic Poisson's ratio of the composite material, the true stress plastic strain value is determined; and Based on all the true stress plastic strain values, three curve intervals are determined, and the true stress plastic strain values ​​corresponding to all the curve intervals are fitted to obtain equivalent curve parameters.

3. The method according to claim 2, characterized in that, The three curve segments are divided into the first curve segment, the middle curve segment, and the last curve segment; The process of fitting all the true stress-plastic strain values ​​corresponding to all the curve intervals to obtain equivalent curve parameters includes: The first hardening equation is fitted based on all the true stress plastic strain values ​​corresponding to the first segment curve interval to obtain the first segment curve parameters. The first hardening equation is fitted based on all the true stress plastic strain values ​​corresponding to the middle section curve interval to obtain the middle section curve parameters; the slope of the middle section curve parameters is lower than a preset slope threshold. Initial curve parameters are constructed based on the mid-section curve parameters, and the initial curve parameters are adjusted based on the simulation results of the composite material under the initial curve parameters to obtain the final section curve parameters; and The parameters of the first segment curve, the parameters of the middle segment curve, and the parameters of the last segment curve are determined as equivalent curve parameters.

4. The method according to claim 3, characterized in that, The fitting process for each of the mechanical curve parameters to obtain equivalent curve parameters further includes: The mechanical curve parameters corresponding to the shear test are converted to obtain multiple sets of second strain-stress values. Based on the second strain stress values ​​of each group and the plastic Poisson's ratio of the composite material, the true stress and true strain values ​​are determined; and The second hardening equation is fitted based on all the stated true stress and true strain values ​​to obtain the equivalent curve parameters.

5. The method according to any one of claims 1-4, characterized in that, The step of performing simulation calibration on all the equivalent curve parameters and determining whether the accuracy of all the equivalent curve parameters meets the standard based on the simulation calibration results includes: Based on the first simulation results of the composite material under the equivalent curve parameters corresponding to the uniaxial tensile test, determine whether the first matching degree between the first simulation results and the mechanical curve parameters corresponding to the uniaxial tensile test meets the standard. In response to determining that the first matching degree meets the standard, based on the second simulation results of the composite material under the equivalent curve parameters corresponding to the uniaxial tensile test and the equivalent curve parameters corresponding to the uniaxial compression test, it is determined whether the second matching degree between the second simulation results and the mechanical curve parameters corresponding to the uniaxial compression test meets the standard; In response to determining that the second degree of matching meets the standard, based on the third simulation results of the composite material under the equivalent curve parameters corresponding to the uniaxial tensile test and the equivalent curve parameters corresponding to the shear test, it is determined whether the third degree of matching between the third simulation results and the mechanical curve parameters corresponding to the shear test meets the standard; and In response to determining that the third matching degree meets the standard, based on the fourth simulation results of the composite material under the equivalent curve parameters corresponding to the uniaxial tensile test, the equivalent curve parameters corresponding to the uniaxial compression test, and the equivalent curve parameters corresponding to the shear test, it is determined whether the fourth matching degree between the fourth simulation results and the mechanical curve parameters corresponding to the complex working condition test meets the standard; the complex working condition test is any at least one of the uniaxial tensile test, the uniaxial compression test, the shear test, the central hole tensile test, the three-point bending test, and the punching test.

6. The method according to claim 1, characterized in that, The determination of damage initiation parameters and damage evolution parameters based on damage test parameters of the composite material under multiple stress triaxialities includes: Damage test parameters of the composite material under multiple stress triaxialities are obtained, and fracture simulation parameters of the composite material under all equivalent curve parameters and each stress triaxiality are determined. Based on the damage test parameters and fracture simulation parameters corresponding to each of the stress triaxialities, the crack initiation plastic strain value is determined; Based on all the aforementioned stress triaxiality and all the aforementioned crack initiation plastic strain values, damage initiation parameters are determined; and Based on the damage initiation parameters and all the damage test parameters, the damage evolution parameters are determined.

7. The method according to claim 6, characterized in that, The determination of damage evolution parameters based on the damage initiation parameters and all the damage test parameters includes: Based on the crack initiation plastic strain value and the preset size parameter in the damage initiation parameters, the plastic displacement value is determined, and the initial evolution parameters are constructed based on all the plastic displacement values. Determine the evolution simulation parameters of the composite material under all the equivalent curve parameters, the damage initiation parameters, the initial evolution parameters, the preset damage variable parameters, and each of the stress triaxialities; and Based on all the evolution simulation parameters and all the damage test parameters, the initial evolution parameters are adjusted to obtain the damage evolution parameters.

8. A simulation system for large plastic deformation of composite materials, characterized in that, include: The fitting processing module is configured to acquire the mechanical curve parameters of the composite material under various test types, and to perform fitting processing on each of the mechanical curve parameters to obtain equivalent curve parameters. The simulation benchmarking module is configured to perform simulation benchmarking processing on all the equivalent curve parameters, and determine whether the accuracy of all the equivalent curve parameters meets the standard based on the simulation benchmarking processing results; The damage parameter determination module is configured to determine damage initiation parameters and damage evolution parameters based on damage test parameters of the composite material under multiple stress triaxialities in response to the accuracy of determining all the equivalent curve parameters. as well as The simulation verification module is configured to perform simulation verification processing on the composite material based on all the equivalent curve parameters, the damage initiation parameters, and the damage evolution parameters.

9. A computer-readable storage medium having a computer program stored thereon, the computer-readable storage medium storing instructions that, when executed on a computer or processor, cause the computer or processor to perform the steps of the method as claimed in any one of claims 1-7.

10. An electronic device, characterized in that, include: One or more processors, and A memory associated with the one or more processors, the memory being used to store program instructions that, when read and executed by the one or more processors, perform the steps of the method according to any one of claims 1-7.

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