Data analysis apparatus and data analysis method

Abstract

This application relates to a data analysis device and a data analysis method. The data analysis device includes: a controller configured to: perform calculations based on impact simulation data of a target step using a finite element method (FEM) main program to obtain target strain parameters and target stress parameters; transmit the target strain parameters and target stress parameters to a custom subroutine; extract the maximum principal strain and maximum shear strain from the target strain parameters using the custom subroutine; determine the current target state of the porous foam material based on the maximum principal strain, where the target state is either tensile or compressive; obtain the initial stress corresponding to the target step from the target stress parameters; update the initial stress based on the maximum principal strain, maximum shear strain, and the elastic matrix, hardening matrix, and rate-sensitive matrix corresponding to the target state; and output the updated initial stress to the FEM main program so that the FEM main program can perform the next iterative calculation.

Description

Technical Field

[0001] This application relates to electronic digital data processing technology. More specifically, it relates to a data analysis device and a data analysis method. Background Technology

[0002] Existing finite element analysis for porous foam materials (such as expanded polystyrene (EPS)) mainly uses isotropic constitutive models. Due to the assumption of tension-compression symmetry, this model cannot simulate the fracture phenomenon of porous foam materials with tension-compression asymmetry. Consequently, when porous foam materials fracture under impact, there is a large gap between simulation and experiment. Summary of the Invention

[0003] To solve the above-mentioned technical problems, or at least partially solve them, embodiments of this application provide a data analysis device and a data analysis method.

[0004] In a first aspect, embodiments of this application provide a data analysis device, including: a controller configured to: construct a finite element analysis model based on the collaborative simulation of porous foam materials using a finite element main program and a custom subroutine; input the basic parameters of the porous foam material obtained from experiments into the finite element analysis model to perform impact simulation, and perform multi-step iterative calculations through the finite element main program and the custom subroutine during the impact simulation, outputting analysis results; and determine the fracture strength of the porous foam material after impact based on the analysis results; wherein, for the iterative calculation of the target step in the multi-step iterative calculation, the controller is specifically configured to: perform calculations based on the impact simulation data of the target step using the finite element main program to obtain target strain parameters and target stress parameters, and output the target... The strain parameters and the target stress parameters are transmitted to the custom subroutine; the custom subroutine extracts the maximum principal strain and maximum shear strain from the target strain parameters; the target state of the porous foam material is determined based on the maximum principal strain. When the maximum principal strain is positive, the target state is tensile; when the maximum principal strain is negative, the target state is compressive; the initial stress corresponding to the target step is obtained from the target stress parameters; the initial stress is updated based on the maximum principal strain, the maximum shear strain, the elastic matrix, the hardening matrix, and the rate-sensitive matrix corresponding to the target state; the updated initial stress is output to the finite element main program so that the finite element main program can perform the next iterative calculation.

[0005] In this embodiment of the application, by setting whether the target step is in a tensile or compressive state during multi-step iterative calculations through the finite element main program and custom subroutines during the impact simulation, and then updating the stress based on the different elastic matrix, hardening matrix and rate-sensitive matrix corresponding to different states, the traditional model's assumption of tension-compression symmetry is broken. This can simulate the fracture phenomenon of porous foam materials with tension-compression asymmetry, and thus reduce the gap between simulation and experiment when porous foam materials fracture under impact.

[0006] In some embodiments of this application, the controller is further configured to: extract equivalent plastic strain and equivalent plastic strain increment from the target strain parameter through the custom subroutine; update the hardening matrix according to the equivalent plastic strain and the hardening function corresponding to the target state; update the rate-sensitive matrix according to the equivalent plastic strain increment and the rate-sensitive function corresponding to the target state; specifically, the controller is configured to: update the initial stress through the custom subroutine based on the maximum principal strain, the maximum shear strain, and the elastic matrix corresponding to the target state, the updated hardening matrix, and the updated rate-sensitive matrix.

[0007] In this embodiment of the application, by updating the hardening matrix and the rate-sensitive matrix based on the equivalent plastic strain and the equivalent plastic strain increment respectively through the custom subroutine, the hardening matrix and the rate-sensitive matrix can be determined more accurately, and thus the stress update can be performed more accurately.

[0008] In some embodiments of this application, the controller is further configured to: perform stiffness degradation on the elastic modulus through the custom subroutine when the target state is a tensile state; update the elastic matrix based on the stiffened elastic modulus and the elastic function corresponding to the target state; specifically, the controller is configured to: update the initial stress through the custom subroutine based on the maximum principal strain, the maximum shear strain, the updated elastic matrix, the hardening matrix corresponding to the target state, and the rate-sensitive matrix corresponding to the target state.

[0009] In this embodiment of the application, when the target state is a tensile state, the custom subroutine updates the elastic matrix based on the stiffness degradation of the elastic modulus, which can more accurately determine the elastic matrix and thus more accurately update the stress.

[0010] In some embodiments of this application, the controller is specifically configured to: determine the equivalent stress through the custom subroutine based on the initial stress, the maximum principal strain, the maximum shear strain, and the elastic matrix, hardening matrix, and rate-sensitive matrix corresponding to the target state; and update the initial stress if the equivalent stress is less than or equal to the yield strength.

[0011] In this embodiment of the application, the equivalent stress is calculated by the custom subroutine, and then the initial stress is updated when the equivalent stress is less than or equal to the yield strength (i.e., in the elastic strain stage), so that the stress update can be performed more accurately.

[0012] In some embodiments of this application, the controller is further configured to update the yield strength by a custom subroutine based on the hardening function corresponding to the target state and the rate-sensitive function corresponding to the target state before updating the initial stress when the equivalent stress is less than or equal to the yield strength.

[0013] In this embodiment, by updating the yield strength at the target step based on the hardening function corresponding to the target state and the rate-sensitive function corresponding to the target state, a more accurate yield strength can be obtained, and thus the stress can be updated more accurately.

[0014] In some embodiments of this application, the controller is specifically configured to: update the initial stress through the custom subroutine when the equivalent stress is greater than the yield strength; solve for the plastic strain increment based on Newton's iteration method; update the plastic strain based on the plastic strain increment; and output the updated initial stress, the updated plastic strain increment, and the updated plastic strain to the finite element main program so that the finite element main program can perform the next iterative calculation.

[0015] In this embodiment, when the equivalent stress is greater than the yield strength (i.e., in the plastic strain stage), the custom subroutine updates the stress, plastic strain increment, and plastic strain. This allows for accurate updates of the stress, plastic strain increment, and plastic strain, thereby improving the accuracy of the finite element analysis model and enabling better prediction of the fracture strength of porous foam materials after impact.

[0016] In some embodiments of this application, the controller is further configured to: update the damage variable based on the maximum principal strain and the maximum shear strain through the custom subroutine when the equivalent stress is greater than the yield strength; and output the updated damage variable to the finite element main program so that the finite element main program can perform the next iterative calculation.

[0017] In this embodiment, the custom subroutine updates the damage variables based on the maximum principal strain and the maximum shear strain when the equivalent stress is greater than the yield strength. This allows for better iterative analysis based on the damage variables, improving the accuracy of the finite element analysis model and enabling better prediction of the fracture strength of porous foam materials after impact.

[0018] In some embodiments of this application, the controller is specifically configured to: determine the damage increment based on the sum of the maximum principal strain and the maximum shear strain through the custom subroutine when the sum of the maximum principal strain and the maximum shear strain is greater than the damage strain threshold, the sum of the maximum principal strain and the maximum shear strain is greater than the sum of the maximum principal strain and the maximum shear strain in the previous calculation process, and the damage variable in the previous calculation process is less than the damage threshold; and update the damage variable based on the damage increment.

[0019] In this embodiment, the damage increment can be determined more accurately by driving the material damage evolution based on both plastic strain and shear strain, thereby determining the damage variable more accurately. This can improve the analytical accuracy of the finite element analysis model and better predict the fracture strength of porous foam materials after impact.

[0020] In some embodiments of this application, the basic parameters of the porous foam material obtained by the experiment specifically include: the elastic modulus, Poisson's ratio, hardening function, rate-sensitive function and initial yield stress of the corresponding porous foam material sample under tensile state, the elastic modulus, Poisson's ratio, hardening function, rate-sensitive function and initial yield stress under compressive state, and the damage strain threshold, based on uniaxial compression, uniaxial tension and shear experiments.

[0021] In this embodiment, a finite element analysis model based on tension-compression asymmetry can be used to simulate and analyze porous foam materials to determine their fracture strength after impact. The basic parameters of the porous foam material obtained from the experiment may also include other parameters, which are not limited here.

[0022] Secondly, embodiments of this application provide a data analysis method, including: constructing a finite element analysis model for simulating porous foam materials based on the collaboration of a finite element main program and a custom subroutine; inputting the basic parameters of the porous foam material obtained from experiments into the finite element analysis model to perform impact simulation, and performing multi-step iterative calculations through the finite element main program and the custom subroutine during the impact simulation, and outputting analysis results; determining the fracture strength of the porous foam material after impact based on the analysis results; wherein, the iterative calculation for the target step in the multi-step iterative calculation includes: calculating the target strain parameters and target stress parameters based on the impact simulation data of the target step through the finite element main program, and inputting the target strain parameters and target stress parameters into the target model. The parameters are transmitted to the custom subroutine; the custom subroutine extracts the maximum principal strain and maximum shear strain from the target strain parameters; the target state of the porous foam material is determined based on the maximum principal strain. When the maximum principal strain is positive, the target state is tensile; when the maximum principal strain is negative, the target state is compressive; the initial stress corresponding to the target step is obtained from the target stress parameters; the initial stress is updated based on the maximum principal strain, the maximum shear strain, the elastic matrix corresponding to the target state, the hardening matrix corresponding to the target state, and the rate-sensitive matrix corresponding to the target state; the updated initial stress is output to the finite element main program so that the finite element main program can perform the next iterative calculation.

[0023] Thirdly, embodiments of this application provide a computer-readable storage medium, including: storing a computer program on the computer-readable storage medium, wherein when the computer program is executed by a processor, it implements the data analysis method as shown in the second aspect.

[0024] Fourthly, embodiments of this application provide a computer program product, including: when the computer program product is run on a computer, causing the computer to implement the data analysis method as shown in the second aspect. Attached Figure Description

[0025] To more clearly illustrate the implementation methods in the embodiments of this application or related technologies, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings.

[0026] Figure 1 A hardware configuration block diagram of a data analysis device 100 according to some embodiments is shown; Figure 2 One of the flowcharts of a data analysis method according to some embodiments is shown; Figure 3A second schematic flowchart of a data analysis method according to some embodiments is shown; Figure 4 The third schematic diagram of a data analysis method according to some embodiments is shown; Figure 5 A fourth schematic flowchart of a data analysis method according to some embodiments is shown; Figure 6 Fifth of a series of flowcharts illustrating a data analysis method according to some embodiments; Figure 7 A flowchart of a data analysis method according to some embodiments is shown as diagram six; Figure 8 A flowchart of a data analysis method according to some embodiments is shown as diagram seven; Figure 9 Eighth schematic flowchart of a data analysis method according to some embodiments is shown; Figure 10 A flowchart of a data analysis method according to some embodiments is shown as diagram number nine. Detailed Implementation

[0027] To make the objectives and implementation methods of this application clearer, the exemplary implementation methods of this application will be clearly and completely described below with reference to the accompanying drawings of the exemplary embodiments of this application. Obviously, the exemplary embodiments described are only some embodiments of this application, and not all embodiments.

[0028] It should be noted that the brief descriptions of terms in this application are only for the convenience of understanding the embodiments described below, and are not intended to limit the embodiments of this application. Unless otherwise stated, these terms should be understood in their ordinary and common meaning.

[0029] The terms "first," "second," "third," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar or related objects or entities, and do not necessarily imply a specific order or sequence, unless otherwise specified. It should be understood that such terms are interchangeable where appropriate.

[0030] The terms “comprising” and “having”, and any variations thereof, are intended to cover but not exclude inclusion, for example, a product or device that includes a range of components is not necessarily limited to all of the components that are clearly listed, but may include other components that are not clearly listed or that are inherent to such product or device.

[0031] In some embodiments of this application, the data analysis device may be a terminal device, a server device, a server cluster, a data platform composed of multiple server devices or multiple server clusters, or other feasible devices. The specific device can be determined according to the actual situation and is not limited here.

[0032] In this embodiment, the porous foam material possesses properties such as tensile-compression asymmetry, rate-sensitive plasticity, anisotropic porosity, strain-driven damage, crushability, a yield plateau, and high energy absorption. Porous foam materials may include EPS, expanded polypropylene (EPP), expanded polyethylene (EPE), polyurethane foam (PU), polyvinyl chloride (PVC), polymethacrylamide (PMI), aluminum foam, and glass foam, etc., and are not limited thereto.

[0033] EPS is a man-made ultralight material with low thermal conductivity, good impact toughness, good chemical stability, moisture resistance, good durability, sound absorption, and energy absorption. As a packaging and thermal insulation material, it is widely used in various industrial production fields around the world.

[0034] Existing finite element analysis of porous foam materials mainly employs isotropic constitutive models, such as the Deshpande-Fleck model, which cannot simulate the fracture phenomenon of porous foam materials. When the packaging fractures due to impact, the simulation and experiment show a significant discrepancy. This model has three major limitations: First, the symmetry assumption is limited; traditional models (such as Von Mises) assume that tensile / compression behavior is the same, failing to characterize materials with asymmetric tension and compression. Second, the damage model is simplistic; classical damage criteria (such as Johnson-Cook) do not distinguish between tensile / shear failure mechanisms. Third, the hardening function is simplified; isotropic hardening does not consider the differences in tension and compression paths and the rate effect of the corresponding paths.

[0035] The data analysis device provided in this application can have various implementation forms, such as a television, smart television, laser projection device, monitor, electronic bulletin board, electronic table, mobile phone, tablet computer, laptop computer, handheld computer, vehicle electronic device, etc.

[0036] like Figure 1 As shown, the data analysis device 100 may include at least one of the following: a tuner 110, a communicator 120, a detector 130, an external device interface 140, a controller 150, a display 160, an audio output interface 170, a user interface 180, an external memory, and a power supply.

[0037] In some embodiments, the controller includes a processor, a video processor, an audio processor, a graphics processor, RAM, ROM, and a first interface to an nth interface for input / output.

[0038] The display 160 includes a display screen assembly for presenting images, a driving assembly for driving image display, a component for receiving image signals from the controller output, and a user interface for displaying video content, image content, menu control interface, and user control UI.

[0039] The display 160 may be a liquid crystal display, an OLED display, or a projection display, and may also be a projection device and a projection screen.

[0040] The communicator 120 is a component used to communicate with external devices or servers according to various communication protocol types. For example, the communicator may include at least one of the following: a Wi-Fi module, a Bluetooth module, a wired Ethernet module, other network communication protocol chips or near-field communication protocol chips, and an infrared receiver. The data analysis device 100 can establish the transmission and reception of control signals and data signals with external control devices or servers through the communicator 120.

[0041] User interface 180 can be used to receive control signals from control devices (such as infrared remote controllers). It can also be used to directly receive user input operation commands and convert the operation commands into commands that the data analysis device 100 can recognize and respond to; in this case, it can be called a user input interface.

[0042] Detector 130 is used to acquire signals from the external environment or to interact with the external environment. For example, detector 130 includes a light receiver, a sensor for acquiring ambient light intensity; or, detector 130 includes an image acquisition device, such as a camera, which can be used to acquire external environmental scenes, user attributes, or user interaction gestures; or, detector 130 includes a sound acquisition device, such as a microphone, for receiving external sounds. The external device interface 140 may include, but is not limited to, one or more of the following: High Definition Multimedia Interface (HDMI), analog or high-definition component input interface (component), composite video input interface (CVBS), USB input interface (USB), RGB port, etc. It may also be a composite input / output interface formed by multiple interfaces mentioned above.

[0043] The tuner / demodulator 110 receives broadcast television signals via wired or wireless means, and demodulates audio and video signals, such as EPG data signals, from multiple wireless or wired broadcast television signals.

[0044] In some embodiments, the controller 150 and the tuner 110 may be located in different separate devices, that is, the tuner 110 may also be located in an external device of the main device where the controller 150 is located, such as an external set-top box.

[0045] The controller 150 controls the operation of the data analysis device and responds to user operations through various software control programs stored in memory (internal or external memory). The controller 150 controls the overall operation of the data analysis device 100. For example, in response to receiving a user command to select a UI object to display on the display 160, the controller 150 can perform operations related to the object selected by the user command.

[0046] In some embodiments, the controller includes at least one of a central processing unit (CPU), a video processor, an audio processor, a graphics processing unit (GPU), and random access memory (RAM), read-only memory (ROM), a first to an nth interface for input / output, a communication bus, etc.

[0047] RAM, also known as main memory, is an internal memory that directly exchanges data with the controller. It can be read and written at any time (except during refresh) and is very fast, typically serving as temporary data storage for the operating system or other running programs. Its biggest difference from ROM is data volatility; data stored in RAM is lost when power is off. RAM is used in computers and digital systems to temporarily store programs, data, and intermediate results. ROM operates in a non-destructive read-only manner, allowing only reading and not writing. Once information is written, it is fixed and will not be lost even if power is cut off; therefore, it is also called fixed-function memory.

[0048] Users can input commands through a graphical user interface (GUI) displayed on the monitor 160, and the user input interface receives the user input commands through the GUI. Alternatively, users can input commands by entering specific sounds or gestures, and the user input interface receives the user input commands by recognizing the sounds or gestures through sensors.

[0049] A "user interface" is the medium through which an application or operating system interacts and exchanges information with the user. It converts information from its internal form to a form that the user can accept. A common form of user interface is the graphical user interface (GUI), which refers to a user interface related to computer operation displayed graphically. It can be an icon, window, control, or other interface element displayed on the screen of a data analysis device. Controls can include visual interface elements such as icons, buttons, menus, tabs, text boxes, dialog boxes, status bars, navigation bars, and widgets.

[0050] In some embodiments of this application, a data analysis device is provided, including: a controller configured to: construct a finite element analysis model for simulating porous foam materials based on the collaboration of a finite element main program and a custom subroutine; input the basic parameters of the porous foam material obtained from experiments into the finite element analysis model to perform impact simulation, and perform multi-step iterative calculations through the finite element main program and the custom subroutine during the impact simulation, and output the analysis results; and determine the fracture strength of the porous foam material after impact based on the analysis results.

[0051] The finite element main program can be the Abaqus / Explicit main program, and the custom subroutine can be the VUMAT subroutine. The finite element main program and the custom main program can also be other programs, which are not limited here.

[0052] To perform simulation analysis on porous foam materials, it is necessary to mesh the porous foam material, with each endpoint of the mesh being a mesh point. The simulation analysis involves calculating the stress, strain, and other data, as well as damage variables, at each mesh point. In this embodiment, during the impact simulation, the finite element main program and a custom subroutine perform multi-step iterative calculations on the stress and strain data at each mesh point.

[0053] The basic parameters of the porous foam material obtained in the experiment are based on the tension-compression asymmetry and are obtained by conducting uniaxial compression, uniaxial tension and shear experiments at different strain rates. The specific parameters can be determined according to the actual situation and are not limited here.

[0054] Among them, multi-step iterative calculation can be a multi-step iterative calculation with a target number of steps. In this case, the analysis result is output when the number of iterations reaches the target number of steps. Multi-step iterative calculation can also be a multi-step iterative calculation with a target time. In this case, the analysis result is output when the total iteration time reaches the target time. The specific method can be determined according to the actual situation and is not limited here.

[0055] It is understood that the embodiments of this application predict the fracture strength, i.e., the damage status, of porous foam materials after impact simulation based on the analysis results. Therefore, in the case where porous foam materials exhibit damage after impact, their properties can be improved, such as by improving their structure (e.g., setting a gradient density) or by adding fiber reinforcement.

[0056] Specifically, for the iterative calculation of the target step in the multi-step iterative calculation, the controller is configured to: calculate the target strain parameters and target stress parameters based on the impact simulation data of the target step through the finite element main program, and transmit the target strain parameters and target stress parameters to the custom subroutine; The target step can be any step in a multi-step iteration or a partial step in a multi-step iteration. The specific step can be determined according to the actual situation and is not limited here.

[0057] For example, the target step does not include the initial step (i.e., the first step), in which the purely elastic stress is updated only by the finite element master program.

[0058] Among them, due to the tension-compression asymmetry of porous foam materials, the elastic function under tension is different from that under compression, the hardening function under tension is different from that under compression, and the rate-sensitive function under tension is different from that under compression.

[0059] For example, suppose the hardening function is expressed as , This represents the equivalent plastic strain. The values ​​of parameters a, b, c, and d differ for the tensile and compressive states.

[0060] For example, suppose the rate sensitivity function is expressed as , This is the equivalent initial yield plastic strain increment. This represents the equivalent plastic strain increment. The value of parameter m differs for tensile and compressive states.

[0061] Wherein, plastic strain is a multi-degree-of-freedom (e.g., 6 degrees of freedom) tensor, and equivalent plastic strain is a scalar calculated based on plastic strain; similarly, plastic strain increment is a multi-degree-of-freedom (e.g., 6 degrees of freedom) tensor, and equivalent plastic strain increment is a scalar calculated based on plastic strain increment. The specific calculation process is not limited here.

[0062] In multi-step iterative calculations, there are usually two stages: elastic strain and plastic strain. When the equivalent stress is less than the yield strength, the calculation is in the elastic strain stage, and when the equivalent stress is greater than the yield strength, the calculation is in the plastic strain stage.

[0063] During the elastic strain stage, the plastic strain and plastic strain increment are typically zero. Therefore, the hardening function and rate-sensitive function are fixed values ​​for the corresponding state, and consequently, the hardening matrix and rate-sensitive matrix for that state also remain unchanged. In other words, during the elastic strain stage, the hardening matrix and rate-sensitive matrix are only related to the current target state of the porous foam material and are independent of other factors.

[0064] During the elastic strain stage, since the elastic matrix is ​​only related to the elastic modulus and Poisson's ratio, and the elastic modulus under tension is different from that under compression, and the Poisson's ratio under tension is different from that under compression, the elastic matrix during the elastic strain stage is only related to the target state of the porous foam material and is not related to anything else.

[0065] During the plastic strain stage, the plastic strain and the plastic strain increment are usually not zero. The hardening function is related to the equivalent plastic strain, and the rate-sensitive function is related to the equivalent plastic strain increment. Therefore, it is necessary to update the hardening matrix based on the equivalent plastic strain and the hardening function corresponding to the target state; and update the rate-sensitive matrix based on the equivalent plastic strain increment and the rate-sensitive function corresponding to the target state.

[0066] During the plastic strain stage, and when under tension, damage variables may occur. Under the influence of these damage variables, the elastic modulus will undergo stiffness degradation, which can be determined using the formula EC = E * (1 - damage). Here, EC represents the elastic stiffness, i.e., the elastic modulus after stiffness degradation, E is the initial elastic modulus, and damage represents the damage variable.

[0067] Specifically, for the iterative calculation of the target step in this multi-step iterative calculation, the controller is configured to: extract the maximum principal strain and maximum shear strain from the target strain parameters through the custom subroutine; determine the current target state of the porous foam material based on the maximum principal strain; when the maximum principal strain is positive, the target state is tensile; when the maximum principal strain is negative, the target state is compressive; obtain the initial stress corresponding to the target step from the target stress parameters; update the initial stress based on the maximum principal strain, the maximum shear strain, the elastic matrix corresponding to the target state, the hardening matrix corresponding to the target state, and the rate-sensitive matrix corresponding to the target state; and output the updated initial stress to the finite element main program so that the finite element main program can perform the next iterative calculation.

[0068] The process of extracting the maximum principal strain and maximum shear strain from the target strain parameters can be found in relevant procedures and will not be elaborated here.

[0069] In some embodiments of this application, the maximum value of the principal strain maxval(PE) and the minimum value of the principal strain minval(PE) can be extracted from the target strain parameters. The larger of the absolute values ​​of maxval(PE) and minval(PE) is determined as the maximum principal strain maxPENew. When the value of maxPENew is positive, it is determined that the porous foam material is currently in a tensile state. When the value of maxPENew is negative, it is determined that the porous foam material is currently in a compressive state. maxPENew is then used for subsequent calculations.

[0070] In some embodiments of this application, the maximum value maxval(SE) and the minimum value minval(SE) of the shear strain can be extracted from the target strain parameters. The one with the larger absolute value of maxval(SE) and the one with the smaller absolute value of minval(SE) is determined as the maximum shear strain maxSENew for subsequent calculations.

[0071] The elastic matrix corresponding to the target state can be either the elastic matrix corresponding to the target state in the elastic strain stage or the updated elastic matrix corresponding to the target state in the plastic strain stage; the hardening matrix corresponding to the target state can be either the hardening matrix corresponding to the target state in the elastic strain stage or the updated hardening matrix corresponding to the target state in the plastic strain stage; and the rate-sensitive matrix corresponding to the target state can be either the rate-sensitive matrix corresponding to the target state in the elastic strain stage or the updated rate-sensitive matrix corresponding to the target state in the plastic strain stage.

[0072] In some embodiments of this application, the elastic matrix, hardening matrix, and rate-sensitive matrix may be updated in both the elastic strain stage and the plastic strain stage without distinguishing between them. It is understood that in the elastic strain stage, the updated elastic matrix, hardening matrix, and rate-sensitive matrix may exist without change compared to before the update; in the plastic strain stage, the updated elastic matrix may change or remain unchanged (unchanged when the damage variable is 0), and the updated hardening matrix and rate-sensitive matrix may change compared to before the update.

[0073] It is understandable that if the state in the previous step is the same as the target step, and both the equivalent plastic strain and the equivalent plastic strain increment are 0, then the hardening matrix and the rate-sensitive matrix are not updated; if the state in the previous step is different from the target step, but both the equivalent plastic strain and the equivalent plastic strain increment are 0, then the hardening matrix and the rate-sensitive matrix are updated (because the different states cause changes in the hardening function and the rate-sensitive function, which in turn cause changes in the corresponding matrices); regardless of whether the state in the previous step is the same as the target step, but the equivalent plastic strain and the equivalent plastic strain increment are not 0, then the hardening matrix and the rate-sensitive matrix are updated (because the equivalent plastic strain and the equivalent plastic strain increment are not 0, causing changes in the hardening function and the rate-sensitive function, which in turn cause changes in the corresponding matrices).

[0074] The specific process of updating the initial stress based on the maximum principal strain, the maximum shear strain, the elastic matrix corresponding to the target state, the hardening matrix corresponding to the target state, and the rate-sensitive matrix corresponding to the target state is not limited in the embodiments of this application.

[0075] For example, the stress extracted from the stress parameters passed from the main program is used as the initial stress of the target step, and the test stress is calculated based on the initial stress, strain increment and elastic matrix. If the material is in the elastic stage, the final stress of the current step is the test stress. If the material yields and enters the plastic stage, the test stress is plastically corrected, and the final stress of the current step is the corrected stress. The final stress of the current step (the updated stress) is sent back to the main program as the initial stress of the next iteration.

[0076] It should be noted that after the target step calculation, this custom subroutine can also return other parameters to the finite element main program, such as at least one of plastic strain, plastic strain increment, elastic matrix, hardening matrix, and rate-sensitive matrix, and may also include other parameters, which can be determined according to the actual situation and are not limited here.

[0077] In this embodiment of the application, by setting whether the target step is in a tensile or compressive state during multi-step iterative calculations through the finite element main program and custom subroutines during the impact simulation, and then updating the stress based on the different elastic matrix, hardening matrix and rate-sensitive matrix corresponding to different states, the traditional model's assumption of tension-compression symmetry is broken. This can simulate the fracture phenomenon of porous foam materials with tension-compression asymmetry, and thus reduce the gap between simulation and experiment when porous foam materials fracture under impact.

[0078] In some embodiments of this application, the controller is further configured to: extract equivalent plastic strain and equivalent plastic strain increment from the target strain parameter through the custom subroutine; update the hardening matrix according to the equivalent plastic strain and the hardening function corresponding to the target state; update the rate-sensitive matrix according to the equivalent plastic strain increment and the rate-sensitive function corresponding to the target state; specifically, the controller is configured to: update the initial stress through the custom subroutine based on the maximum principal strain, the maximum shear strain, and the elastic matrix corresponding to the target state, the updated hardening matrix, and the updated rate-sensitive matrix.

[0079] The process of obtaining the equivalent plastic strain and the equivalent plastic strain increment from the target strain parameter can be referred to in relevant procedures, and will not be elaborated here.

[0080] In this embodiment of the application, by updating the hardening matrix and the rate-sensitive matrix based on the equivalent plastic strain and the equivalent plastic strain increment respectively through the custom subroutine, the hardening matrix and the rate-sensitive matrix can be determined more accurately, and thus the stress update can be performed more accurately.

[0081] In some embodiments of this application, the controller is specifically configured to: perform stiffness degradation on the elastic modulus when the target state is a tensile state through the custom subroutine; update the elastic matrix based on the stiffened elastic modulus and the elastic function corresponding to the target state; the controller is specifically configured to: update the initial stress based on the maximum principal strain, the maximum shear strain, the updated elastic matrix, the hardening matrix corresponding to the target state, and the rate-sensitive matrix corresponding to the target state through the custom subroutine.

[0082] It is understandable that, based on the results of tension and compression, the elastic matrix is ​​calculated. When the material is in a tensile state, the elastic matrix needs to consider the stiffness degradation caused by damage variables. However, when in a compressive state, the elastic stiffness remains unchanged.

[0083] In this embodiment of the application, when the target state is a tensile state, the custom subroutine updates the elastic matrix based on the stiffness degradation of the elastic modulus, which can more accurately determine the elastic matrix and thus more accurately update the stress.

[0084] In some embodiments of this application, the controller is specifically configured to: determine the equivalent stress through the custom subroutine based on the initial stress, the maximum principal strain, the maximum shear strain, and the elastic matrix, hardening matrix, and rate-sensitive matrix corresponding to the target state; and update the initial stress if the equivalent stress is less than or equal to the yield strength.

[0085] The process of determining the equivalent stress based on the initial stress, the maximum principal strain, the maximum shear strain, the elastic matrix corresponding to the target state, the hardening matrix corresponding to the target state, and the rate-sensitive matrix corresponding to the target state can be referred to in relevant procedures, and will not be elaborated here.

[0086] For example, the dimensionless isotropic yield matrix Q and its inverse matrix Qinv can be used to realize the mutual conversion between stress space and isotropic equivalent space, providing a coordinate transformation basis for yield judgment and plastic flow calculation, that is, converting the real stress into equivalent stress; the isotropic hardening matrix H is used to characterize the strain hardening effect caused by the accumulation of equivalent plastic strain, determine the current hardened yield strength of the material, that is, calculate the yield strength after the current hardening; the rate correlation matrix K is used to characterize the dynamic strengthening effect caused by strain rate, correct the yield strength under high-speed impact, that is, consider the influence of strain rate on yield strength, and correct the equivalent yield surface under dynamic loading; the inverse matrix of the above matrices is used in the plastic return mapping algorithm to solve the plastic strain increment and complete the stress correction; the corresponding partial derivatives are used to construct the stress-strain Jacobian matrix to improve the numerical stability of iterative calculation.

[0087] The yield strength can be determined as a fixed value or a variable value based on the actual situation. That is, whether to implement the updated target step yield strength is determined based on the actual situation. No limitation is made here.

[0088] In this embodiment of the application, the equivalent stress is calculated by the custom subroutine, and then the initial stress is updated when the equivalent stress is less than or equal to the yield strength (i.e., in the elastic strain stage), so that the stress update can be performed more accurately.

[0089] In some embodiments of this application, the controller is further configured to update the yield strength by a custom subroutine based on the hardening function corresponding to the target state and the rate-sensitive function corresponding to the target state before updating the initial stress when the equivalent stress is less than or equal to the yield strength.

[0090] The process of updating the yield strength based on the hardening function and the rate-sensitive function corresponding to the target state can be found in the relevant process and will not be elaborated here.

[0091] In this embodiment, by updating the yield strength at the target step based on the hardening function corresponding to the target state and the rate-sensitive function corresponding to the target state, a more accurate yield strength can be obtained, and thus the stress can be updated more accurately.

[0092] In some embodiments of this application, the controller is specifically configured to: update the initial stress through the custom subroutine when the equivalent stress is greater than the yield strength; solve for the plastic strain increment based on Newton's iteration method; update the plastic strain based on the plastic strain increment; and output the updated initial stress, the updated plastic strain increment, and the updated plastic strain to the finite element main program so that the finite element main program can perform the next iterative calculation.

[0093] Among them, the equivalent stress being greater than the yield strength indicates yielding, which is in the plastic strain stage.

[0094] The process of solving the plastic strain increment based on Newton's iteration method can be found in the relevant process, and will not be elaborated here.

[0095] Wherein, plastic strain is equal to the sum of the plastic strain calculated in the previous step and the plastic strain increment.

[0096] In this embodiment, when the equivalent stress is greater than the yield strength (i.e., in the plastic strain stage), the custom subroutine updates the stress, plastic strain increment, and plastic strain. This allows for accurate updates of the stress, plastic strain increment, and plastic strain, thereby improving the accuracy of the finite element analysis model and enabling better prediction of the fracture strength of porous foam materials after impact.

[0097] In some embodiments of this application, the controller is further configured to: update the damage variable based on the maximum principal strain and the maximum shear strain through the custom subroutine when the equivalent stress is greater than the yield strength; and output the updated damage variable to the finite element main program so that the finite element main program can perform the next iterative calculation.

[0098] The process of updating the damage variable based on the maximum principal strain and the maximum shear strain can be found in relevant techniques, which will not be elaborated here.

[0099] In this embodiment, the custom subroutine updates the damage variables based on the maximum principal strain and the maximum shear strain when the equivalent stress is greater than the yield strength. This allows for better iterative analysis based on the damage variables, improving the accuracy of the finite element analysis model and enabling better prediction of the fracture strength of porous foam materials after impact.

[0100] It is understandable that yielding comes first, followed by damage; yielding is the beginning of plastic deformation, while damage is the degradation of stiffness and deterioration of material; it is possible to yield without damage, or to yield and gradually cause damage; for porous foam materials, under tension → yielding will cause damage → stiffness degradation, under compression → only yielding, no damage (or very small damage that can be ignored).

[0101] In some embodiments of this application, the custom subroutine can determine the damage increment based on the sum of the maximum principal strain and the maximum shear strain when at least one of the following conditions is met: the sum of the maximum principal strain and the maximum shear strain is greater than the damage strain threshold; the sum of the maximum principal strain and the maximum shear strain is greater than the sum of the maximum principal strain and the maximum shear strain in the previous calculation process; and the damage variable in the previous calculation process is less than the damage threshold. Then, the damage variable is updated based on the damage increment.

[0102] In some embodiments of this application, the controller is specifically configured to: determine the damage increment based on the sum of the maximum principal strain and the maximum shear strain through the custom subroutine when the sum of the maximum principal strain and the maximum shear strain is greater than the damage strain threshold, the sum of the maximum principal strain and the maximum shear strain is greater than the sum of the maximum principal strain and the maximum shear strain in the previous calculation process, and the damage variable in the previous calculation process is less than the damage threshold; and update the damage variable based on the damage increment.

[0103] The damage strain threshold can be determined based on experimental data and is not specified here.

[0104] The damage threshold can be determined based on the actual situation, and is not limited here.

[0105] For example, the formula for calculating the damage increment can be: ,in, The strain increment is (i.e., maxPENew + maxSENew - (maxPEOld + maxSEOld)). The characteristic length of the unit (considering size effects) This represents the characteristic length of material damage. Different mesh points correspond to different charLengths, which are calculated automatically by the software; we only need to extract them. Characteristic length normalization mitigates mesh sensitivity. The damage variable equals the sum of the strain and damage increment calculated by the finite element main program.

[0106] In this embodiment, the damage increment can be determined more accurately by driving the material damage evolution based on both plastic strain and shear strain, thereby determining the damage variable more accurately. This can improve the analytical accuracy of the finite element analysis model and better predict the fracture strength of porous foam materials after impact.

[0107] In some embodiments of this application, the basic parameters of the porous foam material obtained by the experiment may specifically include: the elastic modulus, Poisson's ratio, hardening function, rate-sensitive function, and initial yield stress of the corresponding porous foam material sample under tensile conditions, and the elastic modulus, Poisson's ratio, hardening function, rate-sensitive function, and initial yield stress under compressive conditions, as well as the damage strain threshold, obtained based on uniaxial compression, uniaxial tension, and shear experiments. Thus, the porous foam material can be simulated and analyzed based on a finite element analysis model of tension-compression asymmetry to determine the fracture strength of the porous foam material after impact. The basic parameters of the porous foam material obtained by the experiment may also include other parameters, which are not limited here.

[0108] It is understandable that the following treatment is applied to address the tension-compression asymmetry: a) Separate elastic moduli, independently defining tensile (ETe) and compressive elastic moduli (ECo); b) Separate yield strength from hardening, independently define tensile (Y0T) and compressive initial yield stress (Y0C), tensile matHT and compressive hardening function matH; c) Rate sensitivity separation: different rate sensitivity coefficient matrices (matKT and matK) are used for tension and compression.

[0109] For example, by conducting uniaxial compression, uniaxial tension, and shear experiments at different strain rates, the elastic modulus, Poisson's ratio, and dimensionless hardening function fitting functions of the corresponding porous foam material samples are obtained. The rate-related sensitivity matrix k is determined, and the damage initiation strain is defined experimentally.

[0110] In this embodiment, stress and strain data are read at each step, and tensor format data passed through the VUMAT interface is converted into matrix format. The maximum principal strain and maximum shear strain at each step are calculated, and the sign of the maximum principal strain data determines whether the material is under tension or compression (positive for tension). Different functions and parameters are called to calculate different states. Based on the determination results, the elastic matrices under tension and compression conditions are calculated, including tensile damage state variables. The dimensionless isotropic yield matrix Q and its inverse Qinv are calculated. The isotropic hardening matrix H and rate correlation matrix K, along with their inverses and partial derivatives, are calculated. Both the yield matrix and the hardening matrix are isotropic. However, they differ under tension and compression conditions.

[0111] This application's embodiments employ a dual-mechanism damage triggering approach: tensile damage + shear damage, controlled by the maximum principal strain (maxPE) and maximum shear strain (maxSE). A stiffness degradation strategy is used, where stiffness degradation occurs only in the tensile direction, while remaining unchanged in the compressive direction. The plastic hardening function considers tension-compression asymmetry and rate effects to achieve anisotropic hardening of the material and its correction.

[0112] For example, by performing finite element analysis on EPS materials based on the method provided in the embodiments of this application, a high-accuracy prediction of the fracture damage behavior during the impact process of EPS packaging can be achieved. For instance, the consistency between the impact simulation and experimental results of the whole machine with packaging reaches 87.1%, and the consistency between the experimental and simulation results of the standard EPS sample reaches 92.53%.

[0113] To illustrate this solution in more detail, the following will use examples to illustrate it. Figures 2 to 10 To explain, it is understandable that Figures 2 to 10The steps involved may include more or fewer steps in actual implementation, and the order of these steps may also differ, as long as the data analysis method provided in the embodiments of this application can be achieved. The executing entity of the data analysis method can be a data analysis device, or a functional module or functional entity within the data analysis device that can implement the data analysis method; no limitation is made here. Furthermore, the specific description of the data analysis method provided in the embodiments of this application can be found in the relevant description of the aforementioned data analysis device, and the same or similar technical effects can be achieved; further details are omitted here.

[0114] Figure 2 The flowchart illustrates the steps of implementing a data analysis method according to one or more embodiments of this application. The data analysis method may include the following steps S201 to S203.

[0115] S201. Construct a finite element analysis model for the simulation of porous foam materials based on the collaboration of the finite element main program and custom subroutines.

[0116] S202. Input the basic parameters of the porous foam material obtained from the experiment into the finite element analysis model to perform impact simulation. During the impact simulation, perform multi-step iterative calculations through the finite element main program and custom subroutines, and output the analysis results.

[0117] S203. Based on the analysis results, determine the fracture strength of the porous foam material after impact.

[0118] Among them, such as Figure 3 As shown, the iterative calculation of the target step in the multi-step iterative calculation for S202 above includes the following S301 to S307.

[0119] S301. The target strain parameters and target stress parameters are obtained by calculating the impact simulation data of the target step using the finite element main program.

[0120] S302. The target strain parameters and target stress parameters are transferred to the custom subroutine through the finite element main program.

[0121] S303. Extract the maximum principal strain and maximum shear strain from the target strain parameters through this custom subroutine.

[0122] S304. The target state of the porous foam material is determined by the custom subroutine based on the maximum principal strain.

[0123] Specifically, when the maximum principal strain is positive, the target state is a tensile state; when the maximum principal strain is negative, the target state is a compressive state.

[0124] S305. Obtain the initial stress corresponding to the target step from the target stress parameter through this custom subroutine.

[0125] S306. The initial stress is updated by the custom subroutine based on the maximum principal strain, the maximum shear strain, the elastic matrix corresponding to the target state, the hardening matrix corresponding to the target state, and the rate-sensitive matrix corresponding to the target state.

[0126] S307. The updated initial stress is output to the finite element main program through the custom subroutine so that the finite element main program can perform the next iterative calculation.

[0127] In some embodiments of this application, combined with Figure 3 ,like Figure 4 As shown, before S306, the above-mentioned S202 may also include the following S308 to S310, and the above-mentioned S306 can be specifically implemented by the following S306a.

[0128] S308. Extract the equivalent plastic strain and equivalent plastic strain increment from the target strain parameter through this custom subroutine.

[0129] S309. The hardening matrix is ​​updated by the custom subroutine based on the equivalent plastic strain and the hardening function corresponding to the target state.

[0130] S310. The rate sensitivity matrix is ​​updated by the custom subroutine based on the equivalent plastic strain increment and the rate sensitivity function corresponding to the target state.

[0131] S306a. The initial stress is updated by the custom subroutine based on the maximum principal strain, the maximum shear strain, the elastic matrix corresponding to the target state, the updated hardening matrix, and the updated rate-sensitive matrix.

[0132] In some embodiments of this application, combined with Figure 3 ,like Figure 5 As shown, before S306, the above-mentioned S202 may also include the following S311 to S312, and the above-mentioned S306 can be specifically implemented by the following S306b.

[0133] S311. Using this custom subroutine, when the target state is under tension, the elastic modulus is stiffened.

[0134] S312. The custom subroutine updates the elastic matrix based on the elastic modulus after stiffness degradation and the elastic function corresponding to the target state.

[0135] S306b: The initial stress is updated by the custom subroutine based on the maximum principal strain, the maximum shear strain, the updated elastic matrix, the hardening matrix corresponding to the target state, and the rate-sensitive matrix corresponding to the target state.

[0136] In some embodiments of this application, combined with Figure 3 ,like Figure 6 As shown, the above S306 can be specifically implemented through the following S306c and S306d.

[0137] S306c: The equivalent stress is determined by the custom subroutine based on the initial stress, the maximum principal strain, the maximum shear strain, the elastic matrix corresponding to the target state, the hardening matrix corresponding to the target state, and the rate-sensitive matrix corresponding to the target state.

[0138] S306d: This custom subroutine updates the initial stress when the equivalent stress is less than or equal to the yield strength.

[0139] In some embodiments of this application, combined with Figure 6 ,like Figure 7 As shown, before S306d, the above-mentioned S306 may also include the following S306e.

[0140] S306e. If the equivalent stress is less than or equal to the yield strength, before updating the initial stress, the yield strength is updated by the custom subroutine based on the hardening function corresponding to the target state and the rate-sensitive function corresponding to the target state.

[0141] In some embodiments of this application, combined with Figure 7 ,like Figure 8 As shown, after S306c, the above-mentioned S306 may also include the following S306f to S306h, and the above-mentioned S307 can be specifically implemented by the following S307a.

[0142] S306f: This custom subroutine updates the initial stress when the equivalent stress is greater than the yield strength.

[0143] S306g uses this custom subroutine to solve for the plastic strain increment based on Newton's iteration method.

[0144] S306h, Update the plastic strain based on the plastic strain increment through this custom subroutine.

[0145] S307a. The updated initial stress, the updated plastic strain increment, and the updated plastic strain are output to the finite element main program through the custom subroutine, so that the finite element main program can perform the next iterative calculation.

[0146] In some embodiments of this application, in combination with Figure 8 ,like Figure 9 As shown, after S306f, the above-mentioned S202 may also include S313 to S314 as described below.

[0147] S313. Using this custom subroutine, when the equivalent stress is greater than the yield strength, update the damage variable based on the maximum principal strain and the maximum shear strain.

[0148] S314. The updated damage variable is output to the finite element main program through this custom subroutine so that the finite element main program can perform the next iterative calculation.

[0149] The updated initial stress, the updated plastic strain increment, the updated plastic strain, and the updated damage variable can be output to the finite element program separately, or synchronously, or other parameters can be output, which is not limited here.

[0150] In some embodiments of this application, in combination with Figure 9 ,like Figure 10 As shown, the above-mentioned S313 can be implemented by the following S313a and S313b.

[0151] S313a. Under the condition that the sum of the maximum principal strain and the maximum shear strain is greater than the damage strain threshold, the sum of the maximum principal strain and the maximum shear strain is greater than the sum of the maximum principal strain and the maximum shear strain in the previous calculation process, and the damage variable in the previous calculation process is less than the damage threshold, the damage increment is determined based on the sum of the maximum principal strain and the maximum shear strain.

[0152] S313b: Update the damage variable based on the damage increment using this custom subroutine.

[0153] In some embodiments of this application, the basic parameters of the porous foam material obtained by the experiment specifically include: the elastic modulus, Poisson's ratio, hardening function, rate-sensitive function and initial yield stress of the corresponding porous foam material sample under tensile state, the elastic modulus, Poisson's ratio, hardening function, rate-sensitive function and initial yield stress under compressive state, and the damage strain threshold, based on uniaxial compression, uniaxial tension and shear experiments.

[0154] The present invention also provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, it implements the various processes of the above-described data analysis method and achieves the same technical effect. To avoid repetition, it will not be described again here.

[0155] The computer-readable storage medium can be a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk, etc.

[0156] The present invention provides a computer program product, comprising: when the computer program product is run on a computer, causing the computer to implement the above-described data analysis method.

[0157] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0158] For ease of explanation, the above description has been provided in conjunction with specific embodiments. However, the above exemplary discussion is not intended to be exhaustive or to limit the embodiments to the specific forms disclosed above. Various modifications and variations can be obtained based on the above teachings. The selection and description of the above embodiments are for the purpose of better explaining the principles and practical applications, thereby enabling those skilled in the art to better utilize the described embodiments and various different variations of embodiments suitable for specific use considerations.

Claims

1. A data analysis device, characterized in that, include: The controller is configured to: construct a finite element analysis model for simulating porous foam-like materials based on the collaboration of the finite element main program and custom subroutines; The basic parameters of the porous foam material obtained from the experiment are input into the finite element analysis model to perform impact simulation. During the impact simulation, the finite element main program and the user-defined subroutine are used to perform multi-step iterative calculations and output the analysis results. The fracture strength of the porous foam material after impact was determined based on the analysis results. Specifically, for the iterative calculation of the target step in the multi-step iterative calculation, the controller is configured as follows: The target strain parameters and target stress parameters are obtained by the finite element main program based on the impact simulation data of the target step, and the target strain parameters and target stress parameters are transmitted to the custom subroutine. The maximum principal strain and maximum shear strain are extracted from the target strain parameters through the custom subroutine. The target state of the porous foam material is determined based on the maximum principal strain. When the maximum principal strain is positive, the target state is a tensile state; when the maximum principal strain is negative, the target state is a compressive state. The initial stress corresponding to the target step is obtained from the target stress parameters; The initial stress is updated based on the maximum principal strain, the maximum shear strain, the elastic matrix corresponding to the target state, the hardening matrix corresponding to the target state, and the rate-sensitive matrix corresponding to the target state. The updated initial stress is output to the finite element program so that the finite element program can perform the next iterative calculation.

2. The data analysis device according to claim 1, characterized in that, The controller is also configured to: The equivalent plastic strain and equivalent plastic strain increment are extracted from the target strain parameter by the custom subroutine. Update the hardening matrix based on the equivalent plastic strain and the hardening function corresponding to the target state; Update the rate sensitivity matrix based on the equivalent plastic strain increment and the rate sensitivity function corresponding to the target state; The controller is specifically configured as follows: The initial stress is updated by the custom subroutine based on the maximum principal strain, the maximum shear strain, and the elastic matrix, the updated hardening matrix, and the updated rate-sensitive matrix corresponding to the target state.

3. The data analysis device according to claim 1, characterized in that, The controller is also configured to: The custom subroutine performs stiffness degradation on the elastic modulus when the target state is a tensile state. The elastic matrix is ​​updated based on the elastic modulus after stiffness degradation and the elastic function corresponding to the target state. The controller is specifically configured as follows: The custom subroutine updates the initial stress based on the maximum principal strain, the maximum shear strain, the updated elastic matrix, the hardening matrix corresponding to the target state, and the rate-sensitive matrix corresponding to the target state.

4. The data analysis device according to any one of claims 1-3, characterized in that, The controller is specifically configured as follows: The equivalent stress is determined by the custom subroutine based on the initial stress, the maximum principal strain, the maximum shear strain, and the elastic matrix, hardening matrix, and rate-sensitive matrix corresponding to the target state. If the equivalent stress is less than or equal to the yield strength, the initial stress is updated.

5. The data analysis device according to claim 4, characterized in that, The controller is also configured to: If the equivalent stress is less than or equal to the yield strength, before updating the initial stress, the yield strength is updated by the custom subroutine based on the hardening function corresponding to the target state and the rate-sensitive function corresponding to the target state.

6. The data analysis device according to claim 4, characterized in that, The controller is specifically configured as follows: The custom subroutine updates the initial stress when the equivalent stress is greater than the yield strength; Solving for the plastic strain increment based on Newton's iterative method; Update the plastic strain based on the aforementioned plastic strain increment; The updated initial stress, the updated plastic strain increment, and the updated plastic strain are output to the finite element program so that the finite element program can perform the next iterative calculation.

7. The data analysis device according to claim 6, characterized in that, The controller is also configured to: The custom subroutine updates the damage variables based on the maximum principal strain and the maximum shear strain when the equivalent stress is greater than the yield strength. The updated damage variables are output to the finite element main program so that the finite element main program can perform the next iterative calculation.

8. The data analysis device according to claim 7, characterized in that, The controller is specifically configured as follows: The custom subroutine determines the damage increment based on the sum of the maximum principal strain and the maximum shear strain when the sum of the maximum principal strain and the maximum shear strain is greater than the damage strain threshold, the sum of the maximum principal strain and the maximum shear strain is greater than the sum of the maximum principal strain and the maximum shear strain in the previous calculation process, and the damage variable in the previous calculation process is less than the damage threshold. Update the damage variable based on the damage increment.

9. The data analysis device according to any one of claims 1-3, characterized in that, The basic parameters of the porous foam materials obtained from the experiment specifically include: the elastic modulus, Poisson's ratio, hardening function, rate-sensitive function and initial yield stress of the corresponding porous foam material samples under tensile conditions, based on uniaxial compression, uniaxial tension and shear experiments; the elastic modulus, Poisson's ratio, hardening function, rate-sensitive function and initial yield stress under compressive conditions; and the damage strain threshold.

10. A data analysis method, characterized in that, include: A finite element analysis model for simulating porous foam materials based on the collaboration of a finite element main program and custom subroutines is constructed. The basic parameters of the porous foam material obtained from the experiment are input into the finite element analysis model to perform impact simulation. During the impact simulation, the finite element main program and the user-defined subroutine are used to perform multi-step iterative calculations and output the analysis results. The fracture strength of the porous foam material after impact was determined based on the analysis results. The iterative calculation for the target step in the multi-step iterative calculation includes: The target strain parameters and target stress parameters are obtained by the finite element main program based on the impact simulation data of the target step, and the target strain parameters and target stress parameters are transmitted to the custom subroutine. The maximum principal strain and maximum shear strain are extracted from the target strain parameters through the custom subroutine. The target state of the porous foam material is determined based on the maximum principal strain. When the maximum principal strain is positive, the target state is a tensile state; when the maximum principal strain is negative, the target state is a compressive state. The initial stress corresponding to the target step is obtained from the target stress parameters; The initial stress is updated based on the maximum principal strain, the maximum shear strain, the elastic matrix corresponding to the target state, the hardening matrix corresponding to the target state, and the rate-sensitive matrix corresponding to the target state. The updated initial stress is output to the finite element program so that the finite element program can perform the next iterative calculation.

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