JP2020095494A - Simulation device, simulation method, and program - Google Patents

Abstract

To model a region after a die exit and shorten a calculation time, in a simulation device.SOLUTION: A simulation device 100 simulates a flow of a rubber 1 ejected from a die flow channel 12. The simulation device 100 comprises: an input unit 140 which inputs information; a recording unit 160 which records information; and a first analysis unit 120 and a second analysis unit 130 which perform analysis on the basis of the data input via the input unit 140 or the data read from the recording unit 160. The first analysis unit 120 includes: a die flow channel model creation unit 121; a die flow channel FEM modeling unit 122; a first analysis condition definition unit 123; and a preliminary calculation unit 124. The second analysis unit 130 includes: an extrusion flow channel model creation unit 131; a total FEM modeling unit 132; a second analysis condition definition unit 133; and a main calculation unit 134.SELECTED DRAWING: Figure 3

Description

The present invention relates to a simulation method, a simulation method, and a program.

If a problem occurs during the extrusion process of polymeric materials such as rubber, use simulation to identify the cause of the problem and check if there is a problem with the polymeric material flow in the die channel (pipe). It is effective to do. For example, Patent Document 1 discloses a simulation method of acquiring an optimum flow path shape by simulating a fluid flow in a pipeline.

JP, 2015-210776, A

By the way, it is known that when a polymer material is extruded into the atmosphere from an exit of a die, a die swell phenomenon (or a ballast effect) occurs in which a cross section of an extrudate becomes larger than a cross section of an exit of the die. In order to confirm the flow of polymer material in the die channel by simulation, it is important to reproduce the analytical model in a state close to the actual one. Therefore, it is preferable to reproduce the die swell phenomenon by modeling the area after the exit of the die in addition to the model of the die flow path.

In Patent Document 1, the die flow path is modeled to calculate the flow velocity distribution at the outlet, but there is no detailed reference to the die swell phenomenon. When an analysis model that also models the area after the die exit is created so as to simply reproduce the die swell phenomenon and the simulation is executed, the speed and stress change rapidly at the die exit. Therefore, the calculation result may diverge and the analysis may not be completed.

It is an object of the present invention to model a region after exit of a die and prevent divergence of calculation results in a simulation device, a simulation method, and a program.

A first aspect of the present invention is a simulation device for simulating a flow of a fluid extruded from a die flow path, which comprises an input unit for inputting information, a storage unit for recording information, and the input unit. A first analysis unit and a second analysis unit that perform analysis based on input data or data read from the storage unit, wherein the first analysis unit reproduces the die flow channel. A die channel model creating section for creating a model, a die channel FEM modeling section for creating a die channel FEM model by dividing the die channel model into a finite number of elements for analysis, and the die channel A simulation calculation of a fluid flow is performed for a first analysis condition definition unit that defines an analysis condition in the FEM model and the die flow channel FEM model in which the analysis condition is defined by the first analysis condition definition unit, and the die flow is calculated. And a preliminary calculation unit that performs preliminary calculation for acquiring the parameter of the fluid at the outlet of the channel model, and the second analysis unit creates an extrusion channel model connected downstream from the outlet of the die channel model. In the whole FEM model; and the whole FEM model, which divides the die flow path model and the extrusion flow path model into a finite number of elements for analysis to create a whole FEM model. A second analysis condition defining unit that defines an analysis condition, and in particular, defines a boundary condition to be continuous at the outlet of the die flow channel model based on a parameter acquired by the preliminary calculation; There is provided a simulation device including a main calculation unit that performs a simulation calculation of a fluid flow with respect to the entire FEM model whose analysis condition is defined by the condition definition unit.

According to this configuration, the flow channel model including not only the die flow channel model that models the die flow channel but also the extrusion flow channel model that models the area after the exit of the die is used, and the analysis considering the die swell phenomenon is performed. It can be performed. At this time, preliminary calculation is executed by the first analysis unit, and parameters such as the stress component of the fluid at the outlet of the die channel are acquired in advance. Then, the second analysis unit defines the boundary condition to be continuous at the exit of the die channel model based on the parameters obtained by the preliminary calculation, and then executes the overall analysis. Therefore, it is possible to prevent a rapid change in values such as velocity and stress in the flow path model, prevent divergence of calculation results, and perform stable analysis.

The analysis conditions defined by the second analysis condition definition unit include the internal stress of the fluid and the shear stress on the wall surface, and in the extrusion flow channel model, a predetermined distance downstream from the outlet of the die flow channel model. Up to the region as an interpolation region, the internal stress is interpolated in the interpolation region so as to be atmospheric pressure in the most downstream region of the interpolation region, and the shear stress becomes zero in the most downstream region of the interpolation region. May be interpolated in the interpolation area.

According to this configuration, it is possible to prevent a sudden change in the value by interpolating the boundary condition of the interpolation area. In detail, originally, the internal stress, shear stress, and velocity component change abruptly at the exit of the die flow path. However, such abrupt changes may cause solution vibrations and the analysis may not be stable. Therefore, by providing an interpolation area and interpolating the above parameters so as not to be discontinuous, it is possible to prevent a sudden change in the value due to a change in the boundary condition.

The interpolation of the internal stress and the shear stress in the interpolation region may be linear interpolation.

According to this method, since the linear interpolation is adopted as the interpolation method, the setting is simple and the calculation cost can be reduced.

The interpolation of the internal stress and the shear stress in the interpolation region may be high-order interpolation.

According to this configuration, since high-order interpolation is used as the interpolation method, it is possible to perform interpolation with a higher degree of freedom than linear interpolation.

The interpolation region may have a length such that at least three elements of the die flow channel FEM model are included in the fluid flow direction.

According to this configuration, when the extrusion flow channel model is divided into a finite number of elements for analysis, at least three elements are provided in the interpolation region in the fluid flow direction. Since the analysis points are set between the elements, at least two analysis points are provided in the interpolation area. Therefore, it is possible to perform highly accurate analysis using a plurality of analysis points.

A second aspect of the present invention is a simulation method for simulating a flow of a fluid extruded from a die channel, which is based on data input via an input unit or data read from a storage unit. 1 analysis and 2nd analysis are performed, The said 1st analysis produces the die-channel model which reproduced the said die-channel, The said die-channel model is a finite number of for analysis. A die flow channel FEM model is created by dividing the elements into elements, analysis conditions in the die flow channel FEM model are defined, and a fluid flow simulation operation is performed on the die flow channel FEM model in which the analysis conditions are defined. Comprising performing preliminary calculations to obtain parameters of the fluid at the outlet of the die channel model, the second analysis creates an extrusion channel model connected downstream from the outlet of the die channel model. , The die flow channel model and the extrusion flow channel model are divided into a finite number of elements for analysis to create an overall FEM model, and the analysis conditions in the overall FEM model are defined, and in particular obtained by the preliminary calculation. A simulation method, comprising defining a boundary condition to be continuous at the outlet of the die flow channel model based on the parameters described above, and performing a simulation calculation of a fluid flow with respect to the entire FEM model in which analysis conditions are defined. I will provide a.

The analysis condition defined in the second analysis includes the internal stress of the fluid and the shear stress on the wall surface, and in the extrusion channel model, a region from the outlet of the die channel model to a predetermined distance downstream. As the interpolation area, the internal stress is interpolated in the interpolation area so that the atmospheric pressure is obtained in the most downstream area of the interpolation area, and the shear stress is zero in the most downstream area of the interpolation area. Interpolation may be performed in the interpolation area.

The interpolation of the internal stress and the shear stress in the interpolation region may be linear interpolation.

The interpolation of the internal stress and the shear stress in the interpolation region may be high-order interpolation.

The interpolation region may have a length such that at least three elements of the die flow channel FEM model are included in the fluid flow direction.

A third aspect of the present invention provides a program that causes a computer to execute the simulation method when loaded into a control unit of the computer.

According to the present invention, the boundary condition of the flow path model is defined to be continuous in the simulation device, the simulation method, and the program, so that the area after the exit of the die is modeled and the dispersion of the calculation result is prevented. it can.

FIG. 3 is a perspective view showing rubber extruded from a die. A flow path model that reproduces the rubber flow path in Fig. 1. The block diagram of the simulation device concerning one embodiment of the present invention. The block diagram which shows the 1st analysis part of the simulation apparatus of FIG. The block diagram which shows the 2nd analysis part of the simulation apparatus of FIG. The side view of a flow path model. The side view of a FEM model. A graph showing the relationship between internal stress and position. The graph which shows the relationship between a shear stress and a position. The flowchart which shows the process performed by a simulation device. The graph which shows the internal stress in a modification, and the relationship of a position. The graph which shows the relationship between a shear stress and a position in a modification.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

The simulation device of the present embodiment analyzes the flow of rubber (an example of a fluid) that is a material for a tire of an automobile or the like. However, the following description is an exemplification, and the simulation device can be used for analyzing various fluid flows other than the analysis of the rubber flow.

Referring to FIG. 1, a rubber 1 is extruded from an outlet 11 of a die 10 that forms a die flow passage 12 inside after mixing a plurality of kinds of materials by a kneader (not shown), and is used in accordance with each part of a tire. Molded in various thicknesses and widths. In this embodiment, since the outlet 11 of the die 10 has a rectangular shape, the rubber 1 to be extruded has a substantially rectangular cross-sectional shape. However, to be precise, the rubber 1 expands when it exits the outlet 11 of the die 10 due to the die swell phenomenon, and the rectangular shape is not maintained. In this embodiment, the flow of the rubber 1 extruded from the die flow path 12 is analyzed, but the flow path model 20 (see FIG. 2) imitating the flow of the rubber 1 in which the die swell phenomenon is taken into consideration is used for the analysis. .. In the following description, for simplicity of illustration and description, it is assumed that only the upper portion of the rubber 1 expands in the thickness direction due to the die swell phenomenon, but the rubber 1 originally expands isotropically.

FIG. 2 is a perspective view showing an example of the flow path model 20 used in the analysis. The flow path model 20 of FIG. 2 imitates the flow of the rubber 1 of FIG. The flow channel model 20 has a die flow channel model 21 and an extrusion flow channel model 22.

The die flow channel model 21 is a reproduction of the die flow channel 12 (see FIG. 1). The die channel model 21 is an area on the upstream side of the channel model 20. In this embodiment, the cross section of the die flow path 12 perpendicular to the flow direction of the rubber 1 (see the arrow in FIG. 1) is rectangular. The thickness of the die flow channel model 21 is, for example, about 3 to 40 mm. However, the cross-sectional shape of the die flow channel model 21 is not limited to the rectangular shape, and may be various shapes such as a triangular shape, a rhombic shape, or a trapezoidal shape. Therefore, the thickness of the die flow path model 21 is not necessarily 3 mm or more, and when there is an acute angle portion, a value such as 1 mm can be partially taken.

The extrusion channel model 22 is an area on the downstream side of the channel model 20. The extrusion channel model 22 is an area outside the die 10 (see FIG. 1). Therefore, the thickness of the extrusion flow channel model 22 is set larger than that of the die flow channel model 21 in order to reproduce the die swell phenomenon, and is about 3 to 80 mm, for example. In detail, the thickness of the extrusion channel model 22 gradually increases toward the downstream side until the internal stress of the rubber 1 and the atmospheric pressure reach an equilibrium state, as described later. Further, as described above, there may be a portion having a thickness of, for example, about 1 mm depending on the sectional shape. The length of the extrusion channel model 22 is, for example, about 1 to 100 mm.

An interpolation area 22a is set in the extrusion channel model 22. The interpolation region 22a is a region on the upstream side of the extrusion flow channel model 22, that is, a region from a portion connected to the die flow channel model 21 to a predetermined distance downstream. The length of the interpolation area 22a is set to, for example, 10 mm or less. In the interpolation area 22a, the boundary condition is set so that the calculation does not diverge, and the details will be described later.

FIG. 3 is a block diagram of the simulation apparatus 100 of this embodiment. The simulation apparatus 100 includes a control unit (processor) 110, an input unit 140 for inputting information, a display unit 150 for displaying information, and a storage unit 160 for recording information.

The control unit 110 performs arithmetic processing and control of the entire device. The input unit 140 is a unit that generates or receives input data for the simulation apparatus 100, and is configured by, for example, a keyboard, a mouse, a touch panel, or the like. The display unit 150 is a unit that displays the processing result and the like by the control unit 110, and is configured by, for example, a liquid crystal display, an organic EL display, a plasma display, or the like. The storage unit 160 stores parameter data and the like necessary for a program running on the control unit 110. The control unit 110, the input unit 140, the display unit 150, and the storage unit 160 are connected to each other. The simulation device 100 is configured by an information processing device such as a desktop personal computer, a notebook computer, a workstation, or a tablet terminal.

The control unit 110 includes a first analysis unit 120 for executing preliminary calculation (first analysis) and a second analysis unit 130 for executing main calculation (second analysis). The first analysis unit 120 and the second analysis unit 130 each perform analysis based on the data input via the input unit 140 or the data read from the storage unit 160. The first analysis unit 120 and the second analysis unit 130 are realized by cooperation between the control unit 110 as a processor which is a hardware resource and a program which is software stored in the storage unit 160.

With reference to FIG. 4, the first analysis unit 120 includes a die flow channel model creation unit 121, a die flow channel FEM modeling unit 122, a first analysis condition definition unit 123, and a preliminary calculation unit 124. .

The die flow channel model creation unit 121 creates a die flow channel model 21 (see FIG. 2) that reproduces the die flow channel 12 (see FIG. 1). The die flow channel FEM modeling unit 122 divides the die flow channel model 21 into a finite number of elements for analysis to create a die flow channel FEM model 21A (see FIG. 7 described later). The first analysis condition definition unit 123 defines analysis conditions in the die flow channel FEM model 21A. For example, the analysis conditions include conditions such as the mass flow rate and the volume flow rate of the rubber 1 at the inlet of the die 10, the presence or absence of slippage on the wall surface inside the die 10, and the material properties of the flowing rubber 1 as inflow conditions. The preliminary calculation unit 124 performs a simulation calculation of the fluid flow of the die flow channel FEM model 21A for which the analysis conditions are defined by the first analysis condition definition unit 123, and the flow of the rubber 1 at the outlet 21a of the die flow channel model 21. Perform preliminary calculations to obtain parameters for For example, the parameters relating to the flow of the rubber 1 include the internal stress of the rubber 1 and the shear stress on the wall surface of the die flow path 12 (FIG. 1).

The first analysis unit 120 analyzes the flow of the rubber 1 only in the die channel model 21 as a preliminary calculation. Thereby, the internal stress, the shear stress, etc. of the rubber 1 at the outlet 21a of the die flow channel model 21 are obtained.

With reference to FIG. 5, the second analysis unit 130 includes an extrusion channel model creation unit 131, an overall FEM modeling unit 132, a second analysis condition definition unit 133, and a main calculation unit 134.

The extrusion flow channel model creation unit 131 creates an extrusion flow channel model 22 (see FIG. 2) connected downstream from the outlet 21a of the die flow channel model 21. The entire FEM modeling unit 132 divides the flow channel model 20 including the die flow channel model 21 and the extrusion flow channel model 22 into a finite number of elements for analysis to divide the die flow channel FEM model 21A and the extrusion flow channel FEM model 22A. An entire FEM model 20A including (see FIG. 7 described later) is created. The second analysis condition definition unit 133 defines the analysis conditions in the entire FEM model 20A, and in particular does not become discontinuous between the die flow channel model 21 and the extrusion flow channel model 22 based on the parameters acquired by preliminary calculation. The boundary conditions are defined as described below. The main calculation unit 134 performs a simulation calculation of the flow of the rubber 1 for the entire FEM model 20A for which the analysis conditions are defined by the second analysis condition definition unit 133.

FIG. 6 is a side view of the schematic flow path model 20. FIG. 7 is a side view of the schematic entire FEM model 20A. In both figures, the left side shows the upstream side and the right side shows the downstream side in the figures. The position x1 indicates the position of the outlet 21a of the die flow channel model 21. The position x2 indicates a position downstream of the outlet 21a of the die flow path model 21 by a predetermined distance, and is a position specified by the user for setting analysis conditions. The area between the positions x1 and x2 corresponds to the above-described interpolation area 22a.

In the present embodiment, the length of the interpolation area 22a is such that three elements of the die channel FEM model 21A are included. Specifically, in the example of FIG. 7, three elements for analysis are provided in the interpolation area 22a. As a result, two analysis points (indicated by black circles in the figure) are provided in the interpolation area 22a in the flow direction A (see arrow A). Preferably, the length of the interpolation area 22a is such that at least three elements of the die flow channel FEM model 21A are included, that is, four or more elements may be provided in the interpolation area 22a. Accordingly, in the flow direction A, three or more analysis points are provided in the interpolation area 22a.

Referring to FIGS. 6 and 7, in the preliminary calculation by the first analysis unit 120, the analysis is performed by the die flow path model 21 up to the position x1. Next, in the main calculation by the second analysis unit 130, the analysis is performed by the flow channel model 20 including the extrusion flow channel model 22 after the position x1.

In the present embodiment, the second analysis unit 130 defines the boundary condition based on the internal stress of the rubber 1 and the shear stress on the wall surface of the die flow channel 12 acquired by the preliminary calculation unit.

FIG. 8 is a graph showing the relationship between the internal stress σ in the direction perpendicular to the flow direction of the rubber 1 and the position x in the flow direction. The horizontal axis represents the position x in the flow direction, and the vertical axis represents the internal stress σ. The internal stress σ is linearly interpolated in the interpolation region 22a (see FIG. 7) so that the internal pressure σ becomes the atmospheric pressure P at a predetermined distance downstream (position x2) from the outlet 21a (position x1) of the die flow path model 21. In the downstream region after the position x2, the internal stress σ and the atmospheric pressure P are in equilibrium.

FIG. 9 is a graph showing the relationship between the shear stress τ and the position x in the flow direction. The horizontal axis represents the position x in the flow direction, and the vertical axis represents the shear stress τ. The shear stress τ is linearly interpolated in the interpolation region 22a (see FIG. 7) so that it becomes zero at a predetermined distance downstream (position x2) from the outlet 21a (position x1) of the die flow channel model 21. In the downstream region after the position x2, the shear stress τ is zero.

FIG. 10 is a flowchart showing the processing executed by the simulation device 100.

Referring to FIG. 10, when the process is started (step S1), first, the die flow channel model creation unit 121 creates the die flow path model 21 (see FIG. 6) (step S2). Next, the created die channel model 21 is divided into elements for analysis by the die channel FEM modeling unit 122, and the die channel FEM model 21A (see FIG. 7) is created (step S3). Next, the analysis conditions are defined for the die flow channel FEM model 21A by the first analysis condition definition unit 123 (step S4). Then, the preliminary calculation unit 124 executes the preliminary calculation for the die flow channel FEM model 21A (step S5). As a result of the preliminary calculation, the internal stress of the rubber 1 at the outlet 21a of the die flow path model 21 and the like are obtained. Next, the extrusion flow channel model creation unit 131 creates the extrusion flow channel model 22 (see FIG. 6) (step S6). In this embodiment, the die flow channel model 21 and the extrusion flow channel model 22 constitute the entire flow channel model 20. Then, the overall FEM modeling unit 132 divides the flow channel model 20 into elements for analysis, and an overall FEM model 20A (see FIG. 7) including the die flow channel FEM model 21A and the extrusion flow channel FEM model 22A is created (see FIG. 7). Step S7). Next, the analysis conditions are defined for the entire FEM model 20A by the second analysis condition definition unit 133 (step S8). Then, the main calculation unit 134 analyzes the entire FEM model 20A (step S9). The analysis is executed until the calculation result converges (step S10), and when the calculation result does not converge, the condition is reset as necessary (step S11) and the analysis is performed (step S9). When the analysis is completed (step S10), the result is output to the display unit 150 (step S12), and the process ends (step S13). The results output to the display unit 150 are, for example, the velocity component and pressure value of the flow of the rubber 1 in each part of the flow path model 20. Therefore, the user can confirm the flow in the die flow channel model 21 that cannot be visually recognized from the outside through the display unit 150.

The simulation device 100 of the present embodiment has the following advantageous effects.

Referring to FIGS. 1 and 2, a flow channel model 20 including not only a die flow channel model 21 that models the die flow channel 12 but also an extrusion flow channel model 22 that models a region after the outlet 11 of the die 10 is used. However, it is possible to perform an analysis considering the die swell phenomenon. Referring also to FIG. 3, at this time, preliminary calculation is executed by the first analysis unit 120, and parameters such as the internal stress of the rubber 1 at the outlet 11 of the die channel 12 are acquired in advance. Then, the second analysis unit 130 defines the boundary condition to be continuous at the outlet 21a of the die flow channel model 21 based on the parameters obtained by the preliminary calculation, and then executes the overall analysis. Therefore, in the flow path model 20, it is possible to prevent rapid changes in values such as speed and stress, prevent divergence of calculation results, and perform stable analysis.

By interpolating the boundary conditions of the interpolation area 22a with reference to FIGS. 1, 2, 6 and 7, it is possible to prevent a sudden change in the value. Referring to FIGS. 8 and 9 together, in detail, originally, the internal stress σ and the shear stress τ suddenly change when they go out from the outlet 11 of the die flow channel 12. Further, although not shown, similarly, the velocity component also rapidly changes when it goes out from the outlet 11 of the die flow channel 12. However, such abrupt changes may cause solution vibrations and the analysis may not be stable. Therefore, by providing the interpolation area 22a and interpolating the above parameters in the interpolation area 22a so as not to be discontinuous, it is possible to prevent a rapid change in the value due to a change in the boundary condition. In particular, since linear interpolation is used as the interpolation method, the setting is simple and the calculation cost can be reduced.

Referring to FIG. 7, when the extrusion flow channel model 22 is divided into a finite number of elements for analysis, at least three elements are provided in the fluid flow direction A in the interpolation area 22a. Since the analysis points are set between the elements, at least two analysis points are provided in the interpolation area 22a. Therefore, it is possible to perform highly accurate analysis using a plurality of analysis points.

(Modification)
11 and 12 correspond to FIGS. 8 and 9 and show modification examples of the interpolation method in the interpolation area 22a. As shown in FIGS. 11 and 12, the interpolation method in the interpolation area 22a may be quadratic interpolation other than the linear interpolation shown in FIGS.

In this modification, an example of quadratic interpolation is shown in FIGS. That is, the respective parameters σ and τ of the interpolation area at the positions x1 to x2 are interpolated by the quadratic function. According to this modified example, as described above, the interpolation area is provided, and interpolation is performed in the interpolation area 22a so that the above parameters are gradually changed, whereby a rapid change in the value due to a change in the boundary condition can be prevented. In particular, since high-order interpolation is used as the interpolation method, it is possible to perform interpolation with a higher degree of freedom than linear interpolation. As the higher-order interpolation, cubic or higher-order interpolation may be adopted, or spline interpolation may be adopted.

Although specific embodiments of the present invention and modifications thereof have been described above, the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 rubber 10 die 11 exit 12 die flow path 20 flow path model 20A whole FEM model 21 die flow path model 21a exit 21A die flow path FEM model 22 extrusion flow path model 22A extrusion flow path FEM model 22a interpolation area 100 simulation device 110 control Department (processor)
120 1st analysis part 121 Die channel model creation part 122 Die channel FEM modeling part 123 1st analysis condition definition part 124 Preliminary calculation part 130 2nd analysis part 131 Extrusion channel model creation part 132 Whole FEM modeling part 133 2nd Analysis condition definition unit 134 Main calculation unit 140 Input unit 150 Display unit 160 Storage unit

Claims (11)

A simulation device for simulating the flow of fluid extruded from a die flow path,
An input unit for inputting information, a storage unit for recording information, and a first analysis unit and a second analysis unit for performing analysis based on data input via the input unit or data read from the storage unit. Section and
The first analysis unit,
A die channel model creating unit for creating a die channel model that reproduces the die channel,
A die channel FEM modeling unit that divides the die channel model into a finite number of elements for analysis to create a die channel FEM model;
A first analysis condition definition unit that defines an analysis condition in the die channel FEM model;
A simulation calculation of a fluid flow is performed on the die flow channel FEM model for which the analysis conditions are defined by the first analysis condition definition unit, and preliminary calculation is performed to obtain the parameters of the fluid at the outlet of the die flow channel model. Including the preliminary calculation section,
The second analysis unit,
An extrusion flow channel model creating unit that creates an extrusion flow channel model connected downstream from the outlet of the die flow channel model,
An overall FEM modeling unit that divides the die channel model and the extrusion channel model into a finite number of elements for analysis to create an overall FEM model,
A second analysis condition definition unit that defines an analysis condition in the overall FEM model, and in particular defines a boundary condition to be continuous at the outlet of the die flow channel model based on a parameter acquired by the preliminary calculation. ,
And a main calculation unit that performs a simulation calculation of a fluid flow with respect to the entire FEM model for which analysis conditions are defined by the second analysis condition definition unit. The analysis condition defined by the second analysis condition definition unit includes the internal stress of the fluid and the shear stress on the wall surface,
In the extrusion flow path model, the area from the outlet of the die flow path model to a predetermined distance downstream is an interpolation area,
The internal stress is interpolated in the interpolation area so as to become atmospheric pressure in the most downstream of the interpolation area,
The simulation device according to claim 1, wherein the shear stress is interpolated in the interpolation region so as to be zero in the most downstream of the interpolation region. The simulation apparatus according to claim 2, wherein the interpolation of the internal stress and the shear stress in the interpolation region is linear interpolation. The simulation device according to claim 2, wherein the interpolation of the internal stress and the shear stress in the interpolation region is high-order interpolation. The simulation apparatus according to any one of claims 2 to 4, wherein the interpolation region has a length in which at least three elements of the die flow channel FEM model are included in the flow direction of the fluid. A simulation method for simulating the flow of fluid extruded from a die channel,
Performing a first analysis and a second analysis based on data input via the input unit or data read from the storage unit,
The first analysis is
Create a die channel model that reproduces the die channel,
A die channel FEM model is created by dividing the die channel model into a finite number of elements for analysis,
Defining the analysis conditions in the die channel FEM model,
Performing a simulation calculation of a fluid flow with respect to the die channel FEM model in which analysis conditions are defined, and performing a preliminary calculation for obtaining a parameter of the fluid at an outlet of the die channel model,
The second analysis is
Create an extrusion channel model that is connected downstream from the outlet of the die channel model,
The die channel model and the extrusion channel model are divided into a finite number of elements for analysis to create an entire FEM model,
Defining analysis conditions in the overall FEM model, in particular defining boundary conditions to be continuous at the outlet of the die channel model based on the parameters obtained by the preliminary calculation;
A simulation method, comprising performing a simulation calculation of a fluid flow for the entire FEM model in which analysis conditions are defined. The analysis conditions defined in the second analysis include the internal stress of the fluid and the shear stress on the wall surface,
In the extrusion flow path model, the area from the outlet of the die flow path model to a predetermined distance downstream is an interpolation area,
The internal stress is interpolated in the interpolation area so as to become atmospheric pressure in the most downstream of the interpolation area,
The simulation method according to claim 6, wherein the shear stress is interpolated in the interpolation region so as to be zero in the most downstream of the interpolation region. The simulation method according to claim 7, wherein the interpolation of the internal stress and the shear stress in the interpolation region is linear interpolation. The simulation method according to claim 7, wherein the interpolation of the internal stress and the shear stress in the interpolation region is high-order interpolation. The simulation method according to any one of claims 7 to 9, wherein the interpolation region has a length in which at least three elements of the die flow channel FEM model are included in the fluid flow direction. A program that, when loaded into a control unit of a computer, causes the computer to execute the simulation method according to any one of claims 6 to 10.

Images