Calculation device, prediction method, and program for predicting mechanical characteristics of composite material

Abstract

To improve a technique for predicting mechanical characteristics of a composite material.SOLUTION: A calculation device for predicting mechanical characteristics of a composite material including a polymer and a filler comprises a control unit. The control unit: acquires mechanical characteristics of a filler agglomerate on the basis of a first simulation model based on a molecular dynamics theory; generates a second simulation model based on a continuum theory including an element having the mechanical characteristics of the filler agglomerate as input physical properties; and predicts the mechanical characteristics of the composite material by the second simulation model.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a calculation device, a prediction method, and a program for predicting the mechanical properties of a composite material such as rubber. [Background technology]

[0002] For example, as shown in Non-Patent Document 1, the filler aggregation structure of rubber observed as an actual image using an electron microscope or the like is modeled, and tensile calculations are being studied to predict physical properties. [Prior art documents] [Patent documents]

[0003] [Non-Patent Document 1] H. Kadowaki et. al “Evaluation of the appropriate size of the finite element representative volume for filled rubber composite analyzes” The Japan Society of Mechanical Engineers, 2016. Summary of the Invention [Problem to be solved by the invention]

[0004] Here, in the method of Non-Patent Document 1, the hierarchy of the filler aggregate structure is modeled as a filler as it is. Specifically, it is possible to obtain the mechanical properties of the interface between the filler and a polymer such as a matrix rubber (hereinafter also referred to as a polymer) based on a molecular dynamics simulation, and perform a finite element analysis using the mechanical properties as an input property. In such a finite element analysis, the filler, polymer, and interface elements in the composite material are each specified and a simulation is performed. In this case, calculations can be performed if the strain is within a range of about 10% (the range of simulation of small deformation). However, when calculating large deformations, the calculations fail and no calculation results can be obtained. This is because the method of Non-Patent Document 1 reproduces the complex structure of the filler, the microstructure such as small gaps between the fillers by each specifying the filler, polymer, and interface elements that constitute the composite material. In the method of Non-Patent Document 1, the positional relationship of these microstructures is constrained, so the calculations fail within the range of simulation of large deformations. In addition, in the method of Non-Patent Document 1, since the microstructure is reproduced, the filler aggregate structure is treated as one elastic body. Therefore, it is not possible to perform calculations that take into account the shape changes inside the filler aggregate structure. Furthermore, the large difference in physical properties between the filler and the polymer was also a factor that caused the calculations to fail.

[0005] As described above, in the conventional methods, the calculation range of strain was limited to about 10% due to the non-uniform structure of the composite material and the large difference in physical properties between the filler and the polymer. In other words, there was room for improvement in the prediction technology for the mechanical properties of composite materials.

[0006] In view of the above circumstances, an object of the present disclosure is to improve prediction techniques for mechanical properties of composite materials. [Means for solving the problem]

[0007] (1) A computing device according to an embodiment of the present disclosure, A calculation device for predicting mechanical properties of a composite material including a polymer and a filler, the calculation device including a control unit, the control unit comprising: The mechanical properties of the filler agglomerates are obtained based on a first simulation model based on molecular dynamics theory; Generate a second simulation model based on a continuum theory including an element having the mechanical properties of the filler agglomerates as input properties; The second simulation model predicts mechanical properties of the composite material.

[0008] (2) A computing device according to an embodiment of the present disclosure is the computing device according to (1), The filler agglomerates include filler and polymer surrounding the filler.

[0009] (3) A computing device according to an embodiment of the present disclosure is the computing device according to (2), The elements having the mechanical properties of the filler agglomerates as input properties are set based on position information of the filler in the composite material and the filler volume fraction of the filler agglomerates set in the first simulation model.

[0010] (4) A computing device according to an embodiment of the present disclosure is the computing device according to any one of (1) to (3), The mechanical property is a stress-strain relationship, a viscoelastic property, a damage fracture property, or a thermal conductivity property.

[0011] (5) A computing device according to an embodiment of the present disclosure is the computing device according to (4), The mechanical properties are determined based on an approximation curve that is fitted within a predetermined strain range from the stress-strain relationship of the filler agglomerates obtained based on the first simulation model.

[0012] (6) A computing device according to an embodiment of the present disclosure is the computing device according to any one of (1) to (4), The first simulation model is a model based on a coarse-grained molecular dynamics simulation or an all-atom simulation.

[0013] (7) A computing device according to an embodiment of the present disclosure is the computing device according to any one of (1) to (5), The second simulation model is a model based on a finite element method, a particle method, or a phase field method.

[0014] (8) A prediction method according to an embodiment of the present disclosure, A method for predicting mechanical properties of a composite material including a polymer and a filler, the method comprising: Obtaining mechanical properties of the filler agglomerates based on a first simulation model based on molecular dynamics theory; generating a second simulation model based on a continuum theory including an element having the mechanical properties of the filler agglomerates as an input property; predicting mechanical properties of the composite material using the second simulation model; and A method for predicting a prediction result.

[0015] (9) A program according to an embodiment of the present disclosure, A program for predicting mechanical properties of a composite material including a polymer and a filler, comprising: Obtaining mechanical properties of the filler agglomerates based on a first simulation model based on molecular dynamics theory; A step of generating a second simulation model based on a continuum theory including an element having the mechanical properties of the filler agglomerates as input properties; predicting mechanical properties of the composite material using the second simulation model; Execute the command. Effect of the Invention

[0016] According to an embodiment of the present disclosure, prediction techniques for mechanical properties of composite materials can be improved. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a block diagram showing a schematic configuration of a computing device according to an embodiment of the present disclosure. [Diagram 2] 1 is a flowchart illustrating an operation of a computing device according to an embodiment of the present disclosure. [Diagram 3] FIG. 13 shows a snapshot of the molecular behavior of filler agglomerates. [Figure 4] 1 is a graph showing the stress-strain relationship obtained by a coarse-grained molecular dynamics simulation. [Diagram 5] FIG. 13 is a schematic diagram showing position information of a filler. [Figure 6] FIG. 13 is a diagram showing a map of principal strains. [Figure 7] FIG. 13 is a graph showing prediction results. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, a material calculation device 10 according to an embodiment of the present disclosure will be described with reference to the drawings.

[0019] In each drawing, the same or corresponding parts are denoted by the same reference numerals. In the description of this embodiment, the description of the same or corresponding parts will be omitted or simplified as appropriate.

[0020] The outline and configuration of a computing device 10 according to this embodiment will be described with reference to FIG.

[0021] The computing device 10 may be any computing device used by a user, including, for example, an industrial instrument, a personal computer, a server computer, a general-purpose electronic device, or a special-purpose electronic device.

[0022] First, an overview of this embodiment will be described, and details will be described later. A calculation device 10 of this embodiment acquires mechanical properties of a filler agglomerate based on a first simulation model based on molecular dynamics theory. The calculation device 10 also generates a second simulation model based on continuum theory, which includes an element in which the mechanical properties of the filler agglomerate are input properties. The calculation device 10 then predicts the mechanical properties of the composite material using the second simulation model.

[0023] In this manner, according to this embodiment, the calculation device 10 acquires the mechanical properties of the filler aggregates based on the first simulation model based on the molecular dynamics theory, and predicts the mechanical properties using the second simulation model based on the continuum theory, which includes an element that uses the mechanical properties as an input property. In this manner, in this embodiment, the hierarchical structure of the filler aggregates is not modeled as a filler as it is, and therefore, it is possible to perform tensile calculation of strain due to large deformation, thereby improving the prediction technology of the mechanical properties of composite materials.

[0024] Here, the filler agglomerate is an agglomerate defined by the filler and its surrounding area (hereinafter also referred to as the filler agglomerate area) assumed for the filler dispersion structure obtained by measurement such as analysis using an electron microscope, etc. In other words, the filler agglomerate is composed of the filler and polymer in the filler agglomerate area of ​​the composite material.

[0025] Here, the mechanical properties of the object to be predicted in this embodiment include stress-strain relationship, viscoelasticity property, damage-fracture property, or heat conduction property. Hereinafter, the mechanical properties of the object to be predicted in this embodiment will be described as being stress-strain relationship, viscoelasticity property, damage-fracture property, or heat conduction property, but the object to be predicted in this disclosure is not limited thereto, and any mechanical property may be the object to be predicted.

[0026] Next, each component of the computing device 10 will be described in detail.

[0027] (Configuration of the computing device 10) As shown in FIG. 1, a computing device 10 includes a control unit 11, a storage unit 12, an input unit 13, and an output unit 14.

[0028] The control unit 11 includes at least one processor, at least one dedicated circuit, or a combination of these. The processor is a general-purpose processor such as a central processing unit (CPU) or a graphics processing unit (GPU), or a dedicated processor specialized for a specific process. The dedicated circuit is, for example, a field-programmable gate array (FPGA) or an application specific integrated circuit (ASIC). The control unit 11 executes processes related to the operation of the computing device 10 while controlling each part of the computing device 10.

[0029] The storage unit 12 includes at least one semiconductor memory, at least one magnetic memory, at least one optical memory, or a combination of at least two of these. The semiconductor memory is, for example, a random access memory (RAM) or a read only memory (ROM). The RAM is, for example, a static random access memory (SRAM) or a dynamic random access memory (DRAM). The ROM is, for example, an electrically erasable programmable read only memory (EEPROM). The storage unit 12 functions as, for example, a main storage device, an auxiliary storage device, or a cache memory. The storage unit 12 stores data used in the operation of the computing device 10 and data obtained by the operation of the computing device 10.

[0030] The input unit 13 includes at least one input interface. The input interface is, for example, a physical key, a capacitive key, a pointing device, or a touch screen integrally provided with a display. The input interface may also be, for example, a microphone that accepts voice input, or a camera that accepts gesture input. The input unit 13 accepts an operation to input data used in the operation of the computing device 10. The input unit 13 may be connected to the computing device 10 as an external input device instead of being provided in the computing device 10. As a connection method, any method such as USB (Universal Serial Bus), HDMI (registered trademark) (High-Definition Multimedia Interface), or Bluetooth (registered trademark) can be used.

[0031] The output unit 14 includes at least one output interface. The output interface is, for example, a speaker that outputs information by voice. The output unit 14 outputs data obtained by the operation of the computing device 10. The output unit 14 may be connected to the computing device 10 as an external output device instead of being provided in the computing device 10. As a connection method, any method such as USB, HDMI (registered trademark), or Bluetooth (registered trademark) can be used.

[0032] The functions of the computing device 10 are realized by executing a program according to this embodiment on a processor corresponding to the computing device 10. That is, the functions of the computing device 10 are realized by software. The program causes a computer to execute the operations of the computing device 10, thereby causing the computer to function as the computing device 10. That is, the computer functions as the computing device 10 by executing the operations of the computing device 10 in accordance with the program.

[0033] In this embodiment, the program can be recorded on a computer-readable recording medium. The computer-readable recording medium includes a non-transitory computer-readable medium, such as a magnetic recording device, an optical disc, a magneto-optical recording medium, or a semiconductor memory. The program is distributed, for example, by selling, transferring, or lending a portable recording medium such as a DVD (digital versatile disc) or a CD-ROM (compact disc read only memory) on which the program is recorded. The program may also be distributed by storing the program in the storage of an external server and transmitting the program from the external server to another computer. The program may also be provided as a program product.

[0034] (Operation of computing device) The operation of the computing device 10 according to the present embodiment will be described with reference to Fig. 2. Fig. 2 is a flowchart showing an example of a prediction method executed by the computing device 10 according to the present embodiment.

[0035] Step S100: The control unit 11 of the computing device 10 acquires the mechanical properties of the filler agglomerates based on a first simulation model. The first simulation model is a model based on molecular dynamics theory. For example, the first simulation model is a model based on coarse-grained molecular dynamics simulation or all-atom simulation. The filler agglomerates include fillers and polymers around the fillers. Any method can be adopted as a method for acquiring the mechanical properties of the filler agglomerates based on the first simulation model.

[0036] Step S200: The control unit 11 generates a second simulation model including elements that use the mechanical properties of the filler agglomerates as input properties. The second simulation model is a model based on the continuum theory. For example, the second simulation model is a model based on the finite element method, the particle method, or the phase field method. The elements that use the mechanical properties of the filler agglomerates as input properties are set based on the position information of the filler in the composite material and the filler volume fraction of the filler agglomerates set in the first simulation model. Any setting method can be adopted. In addition, in the second simulation model, the area other than the filler agglomerates is defined as an element that uses the mechanical properties of the polymer as input.

[0037] Step S300: The control unit 11 predicts the mechanical properties of the composite material using the second simulation model. For example, the control unit 11 performs a simulation calculation simulating a tensile test of the composite material using the second simulation model, and calculates the principal strain occurring in each element of the composite material. Alternatively, the control unit 11 performs a tensile calculation of the composite material using the second simulation model, and predicts the stress-strain relationship of the composite material.

[0038] Step S400: The control unit 11 outputs the prediction result via the output unit 14. The prediction result includes the principal strains occurring in each element of the composite material, the stress-strain relationship of the composite material, and the like.

[0039] As described above, according to this embodiment, the calculation device 10 acquires the mechanical properties of the filler agglomerates based on the first simulation model based on the molecular dynamics theory, and predicts the mechanical properties using the second simulation model based on the continuum theory, which includes an element that uses the mechanical properties as an input property. In this way, in this embodiment, the filler agglomerate structure is not modeled as a filler as it is, and therefore, it is possible to perform tensile calculation of strain due to large deformation, thereby improving the prediction technology of mechanical properties related to composite materials.

[0040] In particular, in this embodiment, the filler aggregates include the filler and the polymer around the filler. Since the filler and the periphery of the filler are treated as one integrated element in this way, the second simulation model in this embodiment is characterized in that it does not faithfully reproduce the complex structure of the filler and the extremely microscopic structure such as the small gaps between the fillers. This makes it possible to prevent the calculation failure of the second simulation caused by the reproduction of such microscopic structures. In addition, the filler and the periphery of the filler are treated as one integrated element, and the mechanical properties of this element are used in the second simulation model. Since the difference in physical properties between this element and the polymer is smaller than the difference in physical properties between the filler and the polymer, it is also possible to suppress the calculation failure caused by the large difference in physical properties between the filler and the polymer. In other words, in this embodiment, the prediction technology of the mechanical properties of the composite material can be improved in that the calculation constraints due to the influence of the non-uniform structure and physical property differences of the composite material can be eliminated.

[0041] (Example) Hereinafter, an example will be described in which the mechanical properties of a composite material are predicted by the method according to the above embodiment. Here, the mechanical properties of the composite material to be predicted are stress-strain relationships. In addition, in this example, a simulation was performed according to the following procedure. (1) A coarse-grained molecular dynamics simulation model (corresponding to the first simulation model described above) of a filler agglomerate (here, containing multiple fillers with volume fractions of 40% and 50%) was created, and a tensile calculation was performed to obtain the stress-strain relationship. (2) A coarse-grained molecular dynamics simulation model of only the cross-linked polymer without filler was created, and tensile calculations were performed to obtain the stress-strain relationship. (3) A scale factor was calculated so that the experimental value of the strain-stress relationship of only the cross-linked polymer containing no filler matched the stress of the coarse-grained molecular dynamics simulation model of only the cross-linked polymer containing no filler. (4) The stress-strain relationship of the coarse-grained simulation model containing multiple fillers was multiplied by the above-mentioned scale factor to calculate the stress-strain relationship related to the filler agglomerates. (5) The stress-strain relationship for the filler agglomerates obtained above was applied to a region defined in an actual TEM or SEM image, etc., around the filler containing the filler so that the effective volume fraction of the filler was 40% (or 50%). (6) A finite element model (corresponding to the second simulation model mentioned above) was constructed by applying the experimental physical properties of the cross-linked polymer without filler to the remaining region. (7) Tensile tests were conducted using a finite element method model. Each step will be explained below.

[0042] The above steps (1)-(4) correspond to step S100. A method for acquiring the mechanical properties of the filler agglomerates based on the first simulation model in steps (1)-(4) will be specifically described. Figure 3 shows a snapshot of the molecular behavior of the filler agglomerates obtained by numerical calculation using the first simulation model.

[0043] Snapshot 300 shows the filler agglomerates in the initial state of the simulation. The filler agglomerates include filler and polymer around the filler. The ratio of the filler and polymer regions was set to a defined volume fraction (here, 40% and 50%). This initial filler agglomerate structure can have various configurations within the defined volume fraction range. This initial configuration can be set according to real data, or sufficient accuracy can be obtained by selecting a representative structure as in the embodiment.

[0044] Snapshots 310 and 320 show the filler agglomerate in an initial state, where it has been stretched above and below the plane of the page as a result of performing tension calculations on the filler agglomerate.

[0045] FIG. 4 is a graph showing the stress-strain relationship obtained by the first simulation model of this embodiment. FIG. 4 shows the stress-strain relationship when the volume fraction of the filler agglomerates is 40% and 50%. Based on the graph showing the stress-strain relationship, the mechanical properties of the filler agglomerates (here, the stress-strain relationship) were obtained. Specifically, for example, the stress-strain relationship of the filler agglomerates was specified by the coefficients of the approximation curves 410, 420 obtained by fitting the plot of the simulation results shown in FIG. 4. In this embodiment, the approximation curves 410, 420 are fitted based on the calculation results obtained in the range of 1-1.5, but the strain range to be fitted is not limited to this. The range to be fitted can be appropriately set based on the range of the target to be predicted by the tensile calculation. In other words, the mechanical properties of the filler agglomerates may be determined based on the approximation curve fitted in a predetermined strain range among the stress-strain relationships of the filler agglomerates obtained based on the first simulation model.

[0046] Here, in this embodiment, the units of strain and stress are not specified at the stage of the first simulation model in the above procedure (1). In other words, in the procedure (1), no adjustment is made to make the simulation consistent with the experimental values. Therefore, it is necessary to adjust the obtained calculation results so that they are consistent with the experimental values. Therefore, the scale factor was calculated by comparing the coarse-grained molecular dynamics simulation of the polymer with the experimental values ​​in the above procedure (2)-(4). Specifically, a tensile calculation was performed by a coarse-grained molecular dynamics simulation of only the polymer to obtain a stress-strain relationship. Based on the simulation results and the stress-strain relationship measured by the experimental values, a scale factor was calculated. In addition, the scale factor was multiplied by the stress-strain relationship obtained in the procedure (1) to calculate the stress-strain relationship after adjustment. Note that if the units of strain and stress are specified in the simulation in the procedure (1) before calculation, it is not necessary to perform a calculation process of the scale factor.

[0047] Next, the steps (5) and (6) will be described. The steps (5) and (6) correspond to step S200 described above. FIG. 5 shows a schematic diagram showing the position information of the filler in this embodiment. In this procedure, elements to be treated as filler agglomerates are set based on the position information of the filler and the volume fraction of the filler agglomerates. Specifically, for example, a spherical region (hereinafter also referred to as a region of a predetermined range) of a predetermined radius centered on the position information of the filler is treated as a filler agglomerate. The predetermined radius is defined by the volume fraction of the filler in the filler agglomerate. In this manner, in the present disclosure, a region of a predetermined range in which the filler and the polymer exist is treated as a filler agglomerate, with the location where the filler exists as the center. In other words, the region of a predetermined range in which the filler and the polymer exist is defined by enlarging (thickening) the location where the filler exists, and the region of the predetermined range is treated as a filler agglomerate. The elements of the region not treated as a filler agglomerate have the mechanical properties of the polymer as input properties.

[0048] In this way, the mechanical properties of all elements in the second simulation model are determined. By treating the predetermined region as a filler agglomerate and regarding the mechanical properties of the filler agglomerate as an element with input physical properties, it is not necessary to take into account the non-uniform structure at the interface between the filler and the polymer, the large difference in physical properties between the filler and the polymer, and the like in the second simulation model.

[0049] The prediction results are calculated and output by the above-mentioned procedure (7). Procedure (7) corresponds to the above-mentioned steps S300 and S400. Fig. 6 is a map of principal strains output based on the principal strain values ​​of each element predicted in this embodiment. As shown in Fig. 6, for example, a map of principal strains is output as the predicted values ​​of the mechanical properties of the composite material.

[0050] Fig. 7 is a graph showing the predicted results of the stress-strain relationship of the composite material. As shown in Fig. 7, in this example, the predicted results of the stress-strain relationship were roughly consistent with the experimental values ​​up to the region of 94% strain.

[0051] Although the present disclosure has been described based on the drawings and embodiments, it should be noted that those skilled in the art can easily make various modifications and corrections based on the present disclosure. Therefore, it should be noted that these modifications and corrections are included in the scope of the present disclosure. For example, the functions included in each means or step can be rearranged so as not to be logically inconsistent, and multiple means or steps can be combined or divided into one.

[0052] For example, in the present embodiment, the volume fraction of the filler agglomerates is described as 40% or 50%, but the volume fraction is not limited to this and can be set appropriately. Specifically, the volume fraction of the filler agglomerates can be determined according to the volume fraction of the filler in the target composite material.

[0053] [Contribution to the United Nations-led Sustainable Development Goals (SDGs)] The SDGs have been proposed to realize a sustainable society. One embodiment of the present invention is considered to be a technology that can contribute to "No. 12_Responsible Consumption and Production" and "No. 13_Concrete measures against climate change." [Explanation of symbols]

[0054] 1 computing device 11 Control section 12 Storage section 13 Input section 14 Output section 300, 310, 320 Snapshots 410, 420 approximate curve

Claims

1. A calculation device for predicting mechanical properties of a composite material including a polymer and a filler, the calculation device including a control unit, the control unit comprising: The mechanical properties of the filler agglomerates are obtained based on a first simulation model based on molecular dynamics theory; Generate a second simulation model based on a continuum theory, the second simulation model including an element having the mechanical properties of the filler agglomerates as input properties; A computing device that predicts mechanical properties of the composite material using the second simulation model.

2. 2. The computing device of claim 1, The filler agglomerates include a filler and a polymer surrounding the filler.

3. 3. A computing device as claimed in claim 2, comprising: A calculation device in which an element having the mechanical properties of the filler agglomerates as input properties is set based on position information of the filler in the composite material and the filler volume fraction of the filler agglomerates set in the first simulation model.

4. 2. The computing device of claim 1, The mechanical property is a stress-strain relationship, a viscoelastic property, a damage fracture property, or a thermal conductivity property.

5. 5. A computing device according to claim 4, comprising: A calculation device, wherein the mechanical properties are determined based on an approximation curve that is fitted within a predetermined strain range to the stress-strain relationship of the filler agglomerate obtained based on the first simulation model.

6. 2. The computing device of claim 1, The first simulation model is a model based on a coarse-grained molecular dynamics simulation or an all-atom simulation.

7. The computing device according to claim 1 , wherein the second simulation model is a model based on a finite element method, a particle method, or a phase field method.

8. A method for predicting mechanical properties of a composite material including a polymer and a filler, the method comprising: Obtaining mechanical properties of the filler agglomerates based on a first simulation model based on molecular dynamics theory; generating a second simulation model based on a continuum theory including an element having the mechanical properties of the filler agglomerates as an input property; predicting mechanical properties of the composite material using the second simulation model; and A method for predicting a prediction result.

9. A program for predicting mechanical properties of a composite material including a polymer and a filler, comprising: Obtaining mechanical properties of the filler agglomerates based on a first simulation model based on molecular dynamics theory; A step of generating a second simulation model based on a continuum theory including an element having the mechanical properties of the filler agglomerates as an input property; predicting mechanical properties of the composite material using the second simulation model; A program that executes the following.

Images