JP2020177374A - Method for composite material analysis and computer program for composite material analysis - Google Patents

Abstract

To evaluate fracture properties of composite material using molecular dynamics.SOLUTION: A method for composite material analysis using molecular dynamics comprises: a first step of creating a model for the composite material analysis including a first substance model that models a first substance in composite material and a second substance model that models a second substance in the composite material; a second step of analyzing a response of the model for the analysis when input is given to deform the model for the analysis to at least one of stretching, compressing, and shearing; and a third step of evaluating fracture characteristics of the composite material based on the information on the degree of dissipation of energy that is dissipated from the model for the analysis obtained in the response analysis.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for analyzing a composite material by a molecular dynamics method using a computer, and a computer program for analyzing the composite material.

Conventionally, various numerical analyzes by molecular dynamics have been proposed in order to elucidate the mechanism of fracture of nanostructures of composite materials such as rubber materials.
In numerical analysis by molecular dynamics, for example, when analyzing the destruction of nanostructures due to deformation of a rubber material, it is necessary to break and eliminate the interparticle bonds of polymer particles in the rubber material. On the other hand, a method of analyzing the fracture without eliminating the fracture of the interparticle bond has been proposed (Patent Document 1).
According to the above method, when the interparticle distance of at least a pair of particles bonded by the interparticle bond is equal to or more than the threshold set, the bonding energy and bond of the interparticle bond are obtained when the interparticle distance is less than the threshold. Numerical analysis of the analysis model is performed using a break-coupling operation function that reduces at least one of the forces. Therefore, since the physical disappearance of the interparticle bond due to the fracture can be prevented, it is possible to reproduce the pseudo fracture without physically extinguishing the interparticle bond, and the interparticle fractured during the numerical analysis. It is said that it is possible to identify the fractured part of the bond.

Japanese Unexamined Patent Publication No. 2019-39774

By the way, in order to accelerate the development of rubber materials that improve the wear resistance performance of tires, it is helpful to clarify the mechanism of nanostructure destruction due to deformation of rubber materials. By analyzing the fracture of the nanostructure of the rubber material before and after deformation, it is possible to accelerate the development of materials for improving the fracture strength of the filler-filled rubber used in actual tires.

In the above method, in order to analyze the fracture of the nanostructure due to the deformation of the rubber material, the fractured part of the interparticle bond of the polymer particles in the rubber material can be specified, but the fractured part of the interparticle bond is specified. Even if it can be done, it is not possible to predict the breakage of the entire rubber material. That is, although it is possible to predict the presence or absence of breakage of the interparticle bond of the polymer particles in the nanostructure, it is not possible to evaluate the presence or absence of breakage in the entire rubber material and its breaking characteristics.

Therefore, an object of the present invention is to provide a method for analyzing a composite material and a computer program for analyzing the composite material, which can evaluate the breaking characteristics of the composite material by using the molecular dynamics method.

One aspect of the present invention is a method in which a computer analyzes a composite material by a molecular dynamics method. The method is
The first step of creating an analysis model of a composite material including a first substance model that models the first substance in the composite material and a second substance model that models the second substance in the composite material.
A second step of analyzing the response of the analysis model when an input is given to the analysis model so as to cause the analysis model to deform at least one of expansion, compression, and shear.
It comprises a third step of evaluating the breaking properties of the composite material based on the information about the degree of dissipation of energy dissipated from the analytical model obtained in the response analysis.

In the second step, it is preferable to analyze the relaxation response of the analytical model at the time of stretching by pulling the analytical model and giving the input so as to maintain a constant elongation.

The information regarding the degree of dissipation is at least the ratio of the stress generated by the analysis model and the amount of energy stored in the analysis model to the input energy amount given to the analysis model by giving the input. It is preferable to include one.

The composite material has a structure in which the first substance is used as a base material and the second substance is distributed as particles in the base material.
The information regarding the degree of dissipation is at least one of the stress generated by the first substance model and at least the ratio of the amount of energy stored in the first substance model to the amount of input energy given to the first substance model. Is preferably included.

In the third step, it is preferable that the larger the degree of dissipation, the better the evaluation of the breaking characteristics.

In the third step, it is preferable to calculate the breaking elongation or breaking energy of the composite material as an evaluation of the breaking characteristics.

In the second step, the response analysis is performed a plurality of times by changing the size of the input given to the analysis model.
In the third step, it is preferable to evaluate the breaking characteristics based on the degree of dissipation obtained by the response analysis a plurality of times.

In the first step, at least a plurality of models in which the arrangement of the first substance model and the second substance model are changed are created as the analysis model.
The method for analyzing the composite material further evaluates the breaking characteristics corresponding to each of the analysis models obtained by performing the second step and the third step in each of the analysis models. It is preferable to include a fourth step of integration.

In the second step, input 1 and input 2 under different conditions from the input 1 are separately given as the inputs to be given to the analysis model, and different response analyzes are performed.
In the third step, it is preferable to evaluate the breaking characteristic by integrating the evaluation of the breaking characteristic corresponding to the input 1 and the evaluation of the breaking characteristic corresponding to the input 2.

In the first step, in addition to the analysis model, a modified analysis model in which a part of the analysis model is modified is created for a material in which a part of the composite material is modified.
By performing the second step and the third step using the modified analysis model, a change in the breaking characteristic using the modified analysis model is obtained with respect to the evaluation of the breaking characteristic using the analysis model. , Is preferable.

Furthermore, another aspect of the present invention is a computer program for analyzing a composite material that causes a computer to execute the method for analyzing the composite material.

According to the above-mentioned method for analyzing a composite material and a computer program for analyzing a composite material, the breaking characteristics of the composite material can be evaluated.

It is a figure which shows an example of the flow of the analysis method of the composite material of one Embodiment. It is a conceptual diagram which shows an example of the analysis model of the composite material used in the analysis method of the composite material of one Embodiment. It is a figure which shows an example of the cross-linking chain used in the analysis method of the composite material of one Embodiment. It is a figure explaining an example of the response analysis of the analysis model performed by the analysis method of the composite material of one Embodiment. It is a figure explaining the presence or absence of the determination of the breakage of a composite material used in the analysis method of a composite material of one Embodiment. It is a functional block diagram of the analysis apparatus which performs the analysis method of the composite material of one Embodiment.

Hereinafter, the method for analyzing the composite material and the computer program for analyzing the composite material according to the embodiment of the present invention will be described with reference to the attached figures.

FIG. 1 is a diagram showing an example of a flow of an analysis method for a composite material of one embodiment. The analysis method shown in FIG. 1 is a method for analyzing a composite material by a molecular dynamics method using a computer. That is, the analysis of the composite material is performed by a computer. As shown in FIG. 1, the method for analyzing the composite material includes a step of creating an analysis model of the composite material (ST10) and a step of giving an input to the analysis model and performing a response analysis by molecular dynamics (ST12). It mainly comprises a step (ST14) of evaluating the breaking characteristics of the composite material based on the information on the degree of energy dissipation in the analytical model.

Here, the composite material includes a first substance and a second substance. The first substance is, for example, a polymer (polymer material). The second substance is, for example, filler particles added to the raw material. The composite material preferably has a structure in which the first substance is used as a base material and the second substance is distributed in the base material. In the following description, the case where the first substance is a polymer and the second substance is filler particles will be described as an example. In addition to the forms described below, the form of the composite material may include the form of a blended polymer composed of a plurality of types of polymers as the composite material. For example, a blend polymer having a sea-island structure and a lamella structure can be mentioned. In the case of a sea-island structure, the first substance may be treated as a polymer constituting the sea portion of the sea-island structure, and the second substance may be treated as a polymer constituting the island portion of the sea-island structure. The blended polymer may consist of a crystalline polymer and a non-crystalline polymer. In this case, the first substance may be treated as a non-crystalline polymer, and the second substance may be treated as a crystalline polymer. Further, the form of the composite material may include a form having a hard segment phase and a soft segment phase in one molecule, such as a thermoplastic elastomer. In this case, the first substance can be treated as the soft segment phase and the second substance can be treated as the hard segment phase.

(Creation of model for analysis)
In the step of creating a model for analysis of a composite material, analysis of the composite material including a first substance model that models the first substance in the composite material and a second substance model that models the second substance in the composite material. Create a model for.

FIG. 2 is a conceptual diagram showing an example of a model for analysis of a composite material. As shown in FIG. 2, in the analysis model 1, for example, a particle model is created in a model creation region which is a virtual space having a substantially cubic shape. The model creation area is a three-dimensional space extending in the X-axis, Y-axis, and Z-axis directions orthogonal to each other. The analytical model 1 includes four filler models 11A, 11B, 11C, and 11D modeled by the plurality of filler particles 11a, four polymer models 21 in which the plurality of polymer particles 21a and the binding chain 21b are modeled, and the four polymer models 21. Includes. The filler models 11A, 11B, 11C, and 11D will be described as the filler model 11 when generically described. In the example shown in FIG. 2, the analysis model 1 describes an example in which the four filler models 11A, 11B, 11C, and 11D are modeled, but the number of filler models to be modeled is not limited. The analysis model 1 may include three or less filler models 11 and may include more than four filler models 11. Further, in FIG. 2, only four polymer models 21 are shown, but in the analysis model 1, a plurality of polymer models 21 exist over the entire area within the model creation region. In the example shown in FIG. 2, an example in which the model creation region is a virtual space having a substantially rectangular parallelepiped shape is shown, but any shape such as a spherical shape, an elliptical shape, a rectangular parallelepiped shape, or a polyhedral shape may be used.

The filler model 11 is modeled in a state where a plurality of filler particles 11a are aggregated in a substantially spherical body. Further, the filler models 11 are arranged in a state of being separated from each other at a predetermined interval. The plurality of filler models 11 may be connected to each other by covalent bonds at the outer edges in a state of being mutually aggregated.

The filler particles to be modeled include, for example, carbon black particles, silica particles, alumina particles and the like. The filler particles 11a are models of a collection of a plurality of atoms constituting the filler. Further, a group of filler particles in which a plurality of filler particles 11a are aggregated is formed as filler models 11A, 11B, 11C, 11D.
The relative positions of the filler particles 11a are specified by the bonding chains (not shown) between the plurality of filler particles 11a. This bond chain has a function as a spring in which an equilibrium length and a spring constant, which are bond distances between the filler particles 11a, are defined, and constrains the filler particles 11a. The binding chain defines the relative position of the filler particles 11a and the potential for force to be generated by twisting, bending, or the like. The filler model 11 is defined by numerical data including the mass, volume, diameter and initial coordinates of the filler particles 11a for handling the filler in molecular dynamics, the number of aggregated particles, and the like. The numerical data of the filler model 11 is input to the computer.

Polymers modeled in the polymer model 21 include, for example, rubbers, resins, and elastomers. The polymer particles 21a are models of a collection of atoms of a plurality of polymers. Further, a polymer particle group in which a plurality of polymer particles 21a are linked by a binding chain is formed as a polymer model 21. That is, the polymer model 21 has a structure in which polymer particles 21a, which is an aggregate of a plurality of polymer atoms and a plurality of polymer atoms, are connected to each other by a bonding chain, and the polymer model 21 has a predetermined density in a modeling region. It is arranged in. The coupling chain functions as a spring in which, for example, an equilibrium length and a spring constant are defined. The polymer particles 21a are bound by a binding chain 21b between the plurality of polymer particles 21a, and their relative positions are specified. The bond chain 21b has a function as a spring in which an equilibrium length and a spring constant, which are bond distances between the polymer particles 21a, are defined, and constrains the polymer particles 21a. The binding chain 21b defines the relative position of the polymer particles 21a and the potential for force to be generated by twisting, bending, or the like. FIG. 3 is a diagram showing an example of a crosslinked bond used in the embodiment. As shown in FIG. 3, three polymer models 21 are provided with a crosslinked bond 21c between the polymer particles 21a. The crosslinked bond chain 21c has a function as a spring in which the equilibrium length and the spring constant, which are the bond distances between the polymer particles 21a, are defined, and constrains the polymer particles 21a.
In addition, a modifier that enhances the affinity with the filler is added to the polymer, if necessary. Examples of the modifier include a hydroxyl group, a carbonyl group, a functional group of an atomic group, and the like. Corresponding to this modifier, a particle model modeling the modifier particles and a binding chain (not shown) are arranged between the polymer model 21 and the filler model 11.
The polymer model 21 is defined by numerical data (including mass, volume, diameter, initial coordinates, etc. of the polymer particles 21a) for handling the polymer in molecular dynamics. The numerical data of the polymer model 21 is input to the computer as a parameter.

In the analysis model 1, interaction is applied between the filler particles 11a, the polymer particles 21a, and at least a part of the filler particles 11a and the polymer particles 21a. In some cases, an interaction force may be applied to exchange forces between all the particles. As the interaction between the filler particles 11a and the polymer particles 21a, a chemical interaction (attractive force) may be given, or a physical interaction (bond bond) may be given.
Interactions are imparted by providing the potential described below between the illustrated binding chain 21b, the binding chain containing the crosslinked binding chain 21c, and further the particle model not linked by the binding chain. As a result, a force determined by the interaction acts between the particle models.
In the composite material, the polymer may be composed of a plurality of types of polymers, in which case an interaction may be imparted between the different types of polymer particles 21a in the analytical model 1. The interaction between the filler particles 11a and the polymer particles 21a in this case may be different between the different types of polymer particles 21a.
The interaction between particles is defined by, for example, the Lennard-Jones potential shown in the following equation. At this time, the values of σ and ε in the following equation are adjusted as appropriate. By increasing the upper limit distance (cutoff distance) for calculating the potential, the force acting over a long distance can be adjusted. It is preferable to sequentially reduce the parameters of the interaction between the filler particles 11a and the interaction between the polymer particles 21a until the interaction between the filler particles 11a and the interaction between the polymer particles 21a reaches a constant value. By gradually approaching the σ and ε of the Lennard-Jones potential from a large value to the original value, the particles can approach at a gentle speed that does not lead the molecule to an unnatural state. In addition, by gradually reducing the cutoff distance, the force in the interaction can be adjusted within an appropriate range.

(Response analysis)
The response analysis by molecular dynamics performed by giving an input to the analysis model 1 is an analysis for examining how the response of the analysis model 1 changes with the passage of time. For example, the analysis model 1 is used. This is a response analysis regarding the behavior of the analysis model 1 when an input is given to stretch it. FIG. 4 is a diagram illustrating an example of response analysis of the analysis model 1 performed in one embodiment.
In the example of response analysis shown in FIG. 4, an input is given to the analysis model 1 so as to extend in the vertical direction, and at this time, how the polymer model 21 and the filler models 11A to 11D move with time. Is analyzed in chronological order.
Since each of the polymer model 21 and the filler models 11A to 11D has a mass, they start moving according to the equation of motion by receiving the force caused by the input given to the analysis model 1, but at this time, the interaction It moves while being restricted by movement and binding chains. The temporal response is calculated by calculating such movement at predetermined time intervals.

For example, when the displacement is given in a stepped manner and then the stretched state is maintained as the input given to the analysis model 1, the polymer model 21 and the filler models 11A to 11D move with time and eventually become a certain state. Almost stationary at. When the displacement is given in steps, a large extension speed is given. The displacement is given to the analytical model 1 to achieve, for example, 200%, 300% elongation. Therefore, in the response analysis, the process from each of the polymer model 21 and the filler models 11A to 11D through the movement to the substantially rest can be analyzed in chronological order. The stress generated in the analysis model 1 can be calculated by calculating the forces acting on the polymer model 21 and the filler models 11A to 11D at this time. In addition, the energy stored in the analysis model 1 can be calculated. Further, the amount of energy dissipated from the analysis model 1 can be calculated by subtracting the stored energy from the input energy corresponding to the given input. That is, the stress relaxation process can be calculated.

Such stretching includes stretching of uniaxial deformation or biaxial deformation in the analysis model 1.
Further, the response analysis of the above embodiment is an analysis of stretch deformation, but is not limited to the analysis of stretch deformation. For example, as long as the response analysis is possible, the analysis may be an analysis in which the analysis model 1 is compressed or sheared. Further, the analysis may be a combination of at least two deformations of stretching, compression, and shearing.
Further, the response analysis is not limited to the form of analyzing the relaxation response by giving a stepped input, but by giving an input (displacement) of a triangular wave or a sine wave, the vibration of the analysis model 1 at that time is analyzed ( It may be in the form of repeated extension analysis). In the case of a triangular or sine wave input (displacement), the input frequency is preferably set to correspond to the actual usage of the structure in which the composite is used, and the level of the input. Even the composite material in the actual usage of the actual structure can be set to correspond to the maximum strain in the actual usage of the structure in which the composite material is used, the strain at the crack tip, or the apparent strain. It is preferable from the viewpoint of evaluating the breaking characteristics of.

In the response analysis, the bond chain 21b of the polymer model 21 and the bond chain including the cross-linked bond chain 21c may have a length equal to or longer than a predetermined threshold value for breaking. When the interparticle distance is longer than the threshold, according to one embodiment, as described in the above-mentioned prior art, the binding energy and the binding force of the interparticle bond are obtained when the interparticle distance is less than the threshold. A function for breaking binding operation that lowers at least one of the above may be applied to the binding chain. Further, it is not necessary to apply the above-mentioned function for breaking join calculation.

(Evaluate breaking characteristics)
In the evaluation of the fracture characteristics, the fracture characteristics of the composite material are evaluated based on the information regarding the degree of dissipation of the energy dissipated from the analysis model 1 obtained by the above response analysis. In the above response analysis, the polymer model 21 and the filler models 11A to 11D move so as to reduce the potential of the model total, so that the input energy given to the analysis model 1 by the input is the polymer due to the relaxation response. Dissipate due to movement of model 21 and filler models 11A-11D. The larger the amount of dissipated energy, the smaller the amount of input energy stored in the polymer model 21 and the filler models 11A to 11D, so that it is less likely to cause breakage. Therefore, the fracture characteristics of the composite material can be evaluated based on the information regarding the degree of dissipation of the energy dissipated from the analytical model 1. For example, in the analysis model 1, the superiority or inferiority of the fracture characteristics can be evaluated by comparing the degree of energy dissipation when a part of the model is changed and the degree of energy dissipation before the change. ..

For information on the degree of energy dissipation, in the case of the above-mentioned analysis of relaxation response, the decrease in stress generated by the analysis model 1 or the ratio of the amount of energy stored to the amount of input energy input to the analysis model 1 is used. Including. In the case of vibration analysis, the ratio of hysteresis, stress phase difference with respect to input, loss elastic modulus, and loss elastic modulus to storage elastic modulus is included. Since the stress generated by the analysis model 1 is relaxed by the movement of the polymer model 21 and the filler models 11A to 11D, the stress value decreases with time. The stress may be obtained by calculating the force generated for the polymer model 21 and the filler models 11A to 11D, and since the fracture of the polymer is the main factor in the actual fracture of the composite material, the polymer model 21 It may be obtained by calculating the force generated only for the target.

The evaluation of the breaking property of the composite material may be a relative evaluation regarding the superiority or inferiority of the breaking property of the composite material to be compared, or includes an evaluation based on calculated values such as breaking elongation and breaking energy of the composite material. For the breaking elongation and breaking energy, for example, the magnitude of the elongation of the analysis model 1 is variously changed, the response analysis is performed a plurality of times, and the analysis model 1 is given an input to the analysis model 1. The breaking elongation and breaking energy can be obtained by determining that the fracture occurs when the ratio of the accumulated amount of energy stored in the is passed through a predetermined value.

As described above, according to the above-described embodiment, the response analysis of the analysis model 1 when the input is given so as to deform at least one of the expansion, compression, and shear of the analysis model 1 is performed. Since it is possible to calculate information on the degree of dissipation of energy dissipated from the analysis model 1 obtained by this response analysis, it is possible to evaluate the breaking characteristics of the composite material from the response analysis of the analysis model 1.

In one embodiment, as described above, in ST12, the relaxation response of the analysis model 1 at the time of extension is analyzed by pulling the analysis model 1 and giving an input (displacement) so as to maintain a constant elongation. This is preferable from the viewpoint of evaluating the static breaking characteristics of the composite material because the relaxation process of the composite material can be accurately reproduced by moving the polymer model 21 and the filler models 11A to 11D. In this case, it is possible to know whether the relaxation process is large or small due to a decrease in the stress generated by the analysis model 1 or a decrease in the amount of energy stored in the analysis model 1. When the decrease in stress is small, it means that the relaxation process is small and the degree of dissipation of dissipated energy is small. Therefore, when the response analysis is performed with various elongations, the amount of decrease in the ratio of stress to elongation is predetermined. The elongation when the threshold value of is not exceeded is determined as the breaking elongation. Further, as the degree of dissipation of the dissipated energy becomes smaller, the amount of energy stored in the analysis model 1 increases, so that the amount of energy stored with respect to the amount of input energy given to the analysis model 1 for elongation increases. It is determined that the fracture occurs when the ratio of As shown in FIG. 5, when the ratio of the physical quantity is reduced by the relaxation response, the ratio of the physical quantity calculated from the analysis model 1 to the input is compared with the threshold value, and the composite material is determined whether or not the threshold value is crossed. It is preferable to determine the presence or absence of breakage. Further, as shown in FIG. 5, the presence or absence of fracture of the composite material may be determined by using the slope of the initial change in the ratio of the physical quantity during relaxation. FIG. 5 is a diagram illustrating the presence or absence of determination of breakage of the composite material used in one embodiment.

In this case, the information regarding the degree of energy dissipation is the stress generated by the analysis model 1 and the amount of energy stored in the analysis model 1 with respect to the input energy amount given by giving an input to the analysis model 1. It is preferable to include at least one of the ratios from the viewpoint of evaluating the breaking characteristics with high accuracy by using the relaxation process of the analysis model 1. As described above, stress is a physical quantity that decreases in the relaxation process, so it decreases as the degree of energy dissipation increases. The degree of energy dissipation from the analysis model 1 can be determined by subtracting the ratio of the stored energy amount to the input energy amount corresponding to the input given to the analysis model 1 from 1.

According to one embodiment, when the composite material has a configuration in which particles (second substance) are distributed in the base material (first substance), information on the degree of energy dissipation is at least a model of the base material (first substance). It may include at least one of the stress generated by the 1-material model) and at least the ratio of the amount of energy stored in the (first substance model) base material model to the input energy amount given to the base material model. It is preferable from the viewpoint of accurately evaluating the breaking characteristics. The breakage of the composite material is often the breakage of the base material itself or the peeling from the interface between the base material and the particles. For example, when the rubber material in which the filler is dispersed is broken, the rubber itself, which is the base material, is often broken, or the rubber which is the base material and the filler, which is the particles, are peeled off from the interface.

According to one embodiment, it is preferable that the greater the degree of dissipation of energy dissipated from the analysis model 1, the better the evaluation of the fracture characteristics. Thereby, the superiority or inferiority of the breaking property in a plurality of composite materials can be relatively evaluated.
Further, according to one embodiment, it is preferable to calculate the breaking elongation or breaking energy of the composite material. This makes it possible to numerically evaluate the breaking characteristics of the composite material. In the calculation of breaking elongation or breaking energy, for example, when the ratio of the stored amount of energy stored in the analysis model 1 to the input energy amount given to the analysis model 1 by the input becomes large and exceeds the threshold value, the composite material Is determined to break, and the breaking elongation is obtained from the elongation given to the analysis model 1 at that time. Further, the energy stored in the analysis model 1 at this time is obtained as the breaking energy.

When the response analysis of the analysis model 1 is performed, the response analysis is performed a plurality of times by changing the size of the input given to the analysis model 1, for example, the size of the elongation. When evaluating the fracture characteristics, it is preferable to evaluate the fracture characteristics based on the degree of energy dissipation obtained by a plurality of response analyzes. For example, when the magnitude of the input is the magnitude of elongation, the response analysis is performed multiple times at preset elongation intervals, and the presence or absence of breakage of the composite material is determined based on the degree of energy dissipation obtained by the response analysis. Can be determined.

According to one embodiment, when creating the analysis model 1, at least a plurality of models in which the arrangement of the polymer model 21 and the filler model 11 are changed may be created as the analysis model 1. In this case, in addition to the steps shown in FIG. 1, each of the analysis models 1 corresponds to each of the analysis models 1 obtained by performing the response analysis and the evaluation of the breaking characteristics of the analysis model 1. It is preferable to include a step of integrating the evaluation of breaking characteristics into one. As a result, it is possible to suppress variations in the evaluation of fracture characteristics due to variations in the arrangement of the filler model 11 and the polymer model 21. In order to suppress the variation in evaluation, it is preferable to prepare three or more models and evaluate the fracture characteristics. When the evaluation is numerical, the average value, median value, and mode value may be used to integrate the evaluation of fracture characteristics. When the evaluation of the breaking characteristics is superior or inferior, the ranking may be performed by the average value, the median value, or the most frequent value of the ranking.

Further, according to one embodiment, when the response analysis of the analysis model 1 is performed, the input 1 and the input 2 under different conditions from the input 1 are separately given as the inputs given to the analysis model 1, and the response analyzes different from each other are performed. You may. At this time, the analysis model 1 is common. When evaluating the breaking characteristics, it is preferable to evaluate the breaking characteristics by integrating the evaluation of the breaking characteristics corresponding to the input 1 and the evaluation of the breaking characteristics corresponding to the input 2. This makes it possible to comprehensively evaluate the breaking characteristics.
For example, the evaluation of the fracture characteristics by the vibration analysis and the evaluation of the fracture characteristics by the relaxation process described above may be integrated to give one evaluation. Further, in the case of integration, if the evaluation is a numerical value such as breaking elongation or breaking energy, weighting may be performed to obtain one value.
Different conditions include differences in temperature conditions, differences in static strain and dynamic strain, differences in extension speed, differences in frequency in vibration analysis, and loads (excluding) as long as the response analysis of the analysis model 1 can be calculated under different conditions. Includes differences in load), differences in applied pressure, differences in deformation modes such as uniaxial extension and biaxial extension, and the like.

According to one embodiment, when the analysis model 1 is created, in addition to the analysis model 1, a modified analysis model in which a part of the analysis model is modified is targeted for a material in which a part of the composite material is modified. May be created. In this case, by performing response analysis and evaluation of fracture characteristics using the model for correction analysis, it is possible to obtain the change in fracture characteristics using the model for correction analysis with respect to the evaluation of fracture characteristics using model 1 for analysis. preferable. This makes it possible to search for a composite material having improved breaking characteristics.
Some modifications of the composite material include cross-linking density, cross-linking distribution, cross-linking strength (interaction strength), filler presence / absence, filler distribution and shape, filler body integration rate, filler size, filler. Includes modifications such as the interaction between and the polymer, the type of polymer (eg, change in length, twist, bilateral angle energy), and the structure of the polymer (length, etc.), and the type of polymer in the blended polymer. .. Therefore, in the modified analysis model, various parameters of the model are changed in response to the partial modification of the composite material.

FIG. 6 is a functional block diagram of an analyzer that performs an analysis method for a composite material of one embodiment.
As shown in FIG. 6, the analysis device 50 includes a computer including a processing unit 52 and a storage unit 54. The analyzer 50 is electrically connected to an input operation system 53 and a monitor 55 including a mouse and a keyboard. The input operation system 53 sets data such as information on the polymer and filler for which the analysis model of the composite material is to be created, the type of response analysis, the boundary conditions in the response analysis, and the input conditions given to the analysis model 1. .. These input data are sent to the processing unit 52 or the storage unit 54.

The processing unit 52 includes, for example, a central processing unit (CPU: Central Processing Unit) and a memory. The processing unit 52 reads a computer program from the storage unit 54 and starts it when executing various processes. The computer program executes various processes. For example, the processing unit 52 expands the data related to various processes stored in advance from the storage unit 54 into an area allocated to itself on the memory as needed, and based on the expanded data, a model for analyzing a composite material. Various processes related to the preparation of 1 and the response analysis of the composite material using the analysis model 1 are executed.

The processing unit 52 includes a model creation unit 52a, a condition setting unit 52b, an analysis unit 52c, and an evaluation unit 52d.
The model creation unit 52a creates an analysis model 1 suitable for the molecular dynamics method based on the data stored in the storage unit 54 in advance and various input conditions. When creating an analysis model 1 that models a composite material such as a filler and a polymer as shown in FIG. 2, the model creation unit 52a uses the number of molecules, the molecular weight, the length of the molecular chain, the number of molecular chains, and branching of the filler and the polymer. , Shape, size, and arrangement and setting of components such as the target number of molecules included in the analysis model 1 to be created, and setting of the model such as the number of calculation steps. In addition, the model creation unit 52a sets initial conditions for various calculation parameters such as interactions between the filler particles 11a, between the polymer particles 21a, hydrogen bonds between the filler and polymer particles, and intermolecular forces. In addition, the model creation unit 52a creates the crosslinked chain 21c and the like shown in FIG. 3 as needed.

In the case of the above-mentioned Lennard-Jones potential, the values of σ and ε are set as the calculation parameters for adjusting the interaction between the particles including the interaction between the filler particles 11a and the interaction between the polymer particles 21a.

The condition setting unit 52b sets various conditions used for response analysis such as extension analysis, vibration analysis, and shear analysis. The conditions include, for example, in the case of extension analysis, conditions such as the elongation rate of the analysis model 1, uniaxial extension, biaxial extension, and extension rate.

The analysis unit 52c executes the numerical analysis of the analysis model 1 based on the analysis conditions set by the condition setting unit 52b. Further, the analysis unit 52c acquires a physical quantity by executing a numerical analysis by a molecular dynamics method using the analysis model 1 of the composite material created by the model creation unit 52a. Here, the analysis unit 52c executes deformation analysis such as extension analysis and shear analysis and vibration analysis as numerical analysis. In addition, the analysis unit 52c has executed a predetermined calculation process on the values such as displacements in the polymer particles 21a and the filler particles 11 obtained as a result of the numerical analysis or the obtained values, and the energy stored in the analysis model 1. Physical quantities such as the amount of accumulated energy and the amount of energy dissipated from the analysis model 1 are calculated.

In addition, the analysis unit 52c may acquire various physical quantities such as the motion displacement and the nominal strain obtained by calculating the nominal stress obtained from the result of the numerical analysis. As a result, the state change of the entire analysis model such as the bond length and polymer particle velocity of the polymer molecule of the entire analysis model, the velocity or bond length between the cross-linking points and the free end, and the physical quantity such as orientation, which changes with each analysis time, can be changed. The relationship between the expressed numerical value and distortion can be obtained. Further, the relationship between the pressure or the analysis time and the numerical value representing the state change such as the bond length of the polymer particles 21a and the moving speed of the polymer particles 21a, which changes with each analysis time, may be obtained. Further, the relationship between the temperature or the analysis time and the numerical value representing the state change such as the bond length of the polymer particles 21a and the speed of the polymer particles 21a, which change with each analysis time, may be obtained. This enables a more detailed analysis of changes in the local molecular state of the polymer particles 21a.
The analysis unit 52c stores the analysis result of the analyzed composite material in the storage unit 54.

The evaluation unit 52d evaluates the fracture characteristics of the composite material based on the information regarding the degree of dissipation of the energy dissipated from the analysis model 1 obtained by the numerical solution (response analysis) of the analysis unit 52c. The method for evaluating the breaking characteristics is as described above.

The storage unit 54 can read and write to a non-volatile memory such as a hard disk device, a magneto-optical disk device, a flash memory and a CD-ROM that can only be read, and a RAM (Random Access Memory). Volatile memory, which is a possible recording medium, is appropriately combined.

In the storage unit 54, data for creating an analysis model of the composite material to be analyzed via the input operation system 53, for example, data of fillers such as carbon black, silica, and alumina, rubber, resin, and Data on polymers such as elastomers are stored. Further, the storage unit 54 stores a computer program or the like for realizing a method for analyzing the composite material. This computer program may be capable of realizing the method for analyzing a composite material according to the present embodiment in combination with a computer program already recorded in a computer or a computer system. The term "computer system" as used herein includes hardware such as an OS (Operating System) and peripheral devices.

The monitor 55 is, for example, a display device such as a liquid crystal display device. The monitor 55 displays a setting screen for setting the conditions for executing the above-mentioned numerical solution (response analysis) and the input given to the analysis model 1, and is in the middle of analysis or at the end of analysis in the analysis unit 52c. The state of the analysis model 1 of the above is displayed, and further, the evaluation of the breaking characteristics obtained by the evaluation unit 52 is displayed. The storage unit 54 may be located in another device such as a database server. For example, the analysis device 50 may access the processing unit 52 and the storage unit 54 by communication from a terminal device including the input operation system 53 and the monitor 55.

In this way, the computer program can cause the computer to execute the method of analyzing the composite material.

(Example, comparative example)
In order to confirm the effect of the above embodiment, as a composite material, a model for analysis as shown in FIG. 2 is modeled on a filler-containing rubber material containing rubber as a base material and carboblackon particles as filler particles in the rubber. , A model for analysis was created by modeling a rubber material made of pure rubber that does not contain filler. Lennard-Jones potential was used for the interaction between each binding chain and particles, and the values of σ and ε were appropriately adjusted and added to the analysis model. For the analysis model, three models with various arrangements were created without changing the total number of the filler model 11 and the polymer model 21, and the breaking characteristics were collectively evaluated.

Response analysis of the relaxation response when a displacement that changes stepwise in a stepwise manner is applied to the analysis model by uniaxial extension and extension strain is applied, and the ratio of the energy stored in the analysis model to the input energy is a predetermined threshold value. It is assumed that a break occurs at the time of crossing the above, and the elongation at that time is determined as the break elongation Eb (Example).
Further, when the relaxation response is analyzed by giving the analysis model an extension under the condition of uniaxial extension, a void is generated due to the breakage of the binding chain 21a of the polymer model 21 in the analysis model, and the volume of this void is expanded. Increases as the number increases. The information on the increase in the volume of the void can be used to determine the breakage of the material. Therefore, it is assumed that fracture occurs when the rate of increase of the void volume of the analysis model crosses a predetermined threshold value (becomes equal to or higher than the threshold value), and the elongation at that time is determined as the fracture elongation Eb (comparative example).
In both the examples and the comparative examples, the average value of the break elongation Eb values in the above-mentioned three models was obtained as the evaluation value of the break characteristics of the examples and the comparative examples.

In addition, the breaking elongation Eb of the rubber material to be modeled as an analysis model was measured by an elongation test (measured value). The table below shows the measurement results, the evaluation results in the examples, and the evaluation results in the comparative examples. The evaluation result is represented by an index of the evaluation value of the filler-containing rubber material with the evaluation value of the rubber material made of pure rubber as a reference (index 100). The higher the index, the better the fracture characteristics.

As can be seen from Table 1, the rate of change in the fracture characteristics of the filler-containing rubber material with respect to pure rubber by the response analysis of the relaxation response of the examples is closer to the rate of change in the measured values than the rate of change in the comparative example. Understand. That is, it can be said that the response analysis of the present embodiment accurately evaluates the breaking characteristics of the filler-containing rubber material.

The method for analyzing a composite material and the computer program for analyzing a composite material of the present invention have been described in detail above, but the present invention is not limited to the above-described embodiment, and various types are described within the scope of the gist of the present invention. Of course, it may be improved or changed.

1 Analysis model 11, 11A, 11B, 11C, 11D Filler model 11a Filler particles 21,21A, 21B, 21C Polymer model 21a Polymer particles 21b Bonded chain 21c Crosslinked bonded chain 50 Analytical device 51 Input / output device 52 Processing unit 52a Model creation Unit 52b Condition setting unit 52c Analysis unit 52d Evaluation unit 53 Input operation system 54 Storage unit 55 Monitor

Claims (11)

A method in which a computer analyzes a composite material by a molecular dynamics method, in which a first substance model in which the first substance in the composite material is modeled and a second substance in the composite material are modeled. The first step in creating a model for analysis of composite materials, including a two-material model,
A second step of performing a response analysis of the analysis model when an input is given to the analysis model so as to cause the analysis model to deform at least one of stretching, compression, and shearing.
Analysis of the composite material, comprising: Method. The composite material according to claim 1, wherein in the second step, the relaxation response of the analytical model at the time of stretching is analyzed by pulling the analytical model and giving the input so as to maintain a constant elongation. Analysis method. The information regarding the degree of dissipation is at least the ratio of the stress generated by the analysis model and the amount of energy stored in the analysis model to the amount of input energy given to the analysis model by giving the input. The method for analyzing a composite material according to claim 2, which comprises one of them. The composite material has a structure in which the first substance is used as a base material and the second substance is distributed as particles in the base material.
The information regarding the degree of dissipation is at least one of the stress generated by the first substance model and at least the ratio of the amount of energy stored in the first substance model to the amount of input energy given to the first substance model. The method for analyzing a composite material according to claim 1 or 2, which comprises. The method for analyzing a composite material according to any one of claims 1 to 4, wherein in the third step, the larger the degree of dissipation, the better the evaluation of the breaking characteristics. The method for analyzing a composite material according to any one of claims 1 to 5, wherein in the third step, the breaking elongation or the breaking energy of the composite material is calculated as the evaluation of the breaking characteristics. In the second step, the response analysis is performed a plurality of times by changing the size of the input given to the analysis model.
The method for analyzing a composite material according to any one of claims 1 to 6, wherein in the third step, the breaking characteristics are evaluated based on the degree of dissipation obtained by the response analysis a plurality of times. In the first step, at least a plurality of models in which the arrangement of the first substance model and the second substance model are changed are created as the analysis model.
The method for analyzing the composite material further evaluates the breaking characteristics corresponding to each of the analysis models obtained by performing the second step and the third step in each of the analysis models. The method for analyzing a composite material according to any one of claims 1 to 7, further comprising a fourth step of integrating the composite material. In the second step, the input 1 and the input 2 under different conditions from the input 1 are separately given as the inputs to be given to the analysis model, and different response analyzes are performed.
In the third step, the breaking characteristics are evaluated by integrating the evaluation of the breaking characteristics corresponding to the input 1 and the evaluation of the breaking characteristics corresponding to the input 2, according to claims 1 to 8. The method for analyzing a composite material according to any one of the following items. In the first step, in addition to the analysis model, a modified analysis model in which a part of the analysis model is modified is created for a material in which a part of the composite material is modified.
By performing the second step and the third step using the modified analysis model, a change in the fracture characteristic using the modified analysis model is obtained with respect to the evaluation of the fracture characteristic using the analysis model. , The method for analyzing a composite material according to any one of claims 1 to 9. A computer program for analyzing a composite material, which comprises causing a computer to execute the method for analyzing a composite material according to any one of claims 1 to 10.

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