Molding analysis method, program, and recording medium

Abstract

This molding analysis method includes performing molding analysis on an intermediate base material during molding, using a metal mold, of a tabular intermediate base material that includes a resin and a reinforcement material. The method comprises a step in which a model having anisotropy between an out-of-plane direction and an in-plane direction orthogonal to the out-of-plane direction is applied as a model of the intermediate base material, and a step in which the viscosity distribution in a cross-sectional direction of a molded article is calculated using each viscosity that corresponds to a flow field. The viscosity distribution indicates, under a boundary condition that there is no flow slide of the intermediate base material on a wall surface of the metal mold, that a low-viscosity layer where the impact of out-of-plane shear viscosity is greater than for a central part of the intermediate base material is automatically formed in the vicinity of the wall surface due to a shear field being generated in the vicinity of the wall surface, and that the intermediate base material in the vicinity of the wall surface functions as a lubrication layer.

Description

Molding analysis method, program, and recording medium

[0001] The present invention relates to a molding analysis method, a program for causing a computer to execute the molding analysis method, and a recording medium on which the program is recorded. In particular, the present invention relates to a molding analysis method for a composite material containing a resin and a reinforcing material.

[0002] Composite materials containing resins and reinforcing materials are known, and are typically processed by molding into articles of predetermined shape.

[0003] The molding of composite materials involves a variety of conditions, such as the temperature of the mold and substrate, the time for dwelling and cooling, the speed and load when compressing the substrate, the arrangement of the substrate in the mold, and the thickness of the substrate. Repeated experiments to find the optimal conditions require a great deal of effort and cost. Therefore, it has been proposed to use computer simulation to analyze the flow of resin during molding of composite materials.

[0004] For example, U.S. Patent Application Publication No. 2019 / 0232535 ​​(Patent Document 1) discloses determining the flow pattern of resin during molding by CAE (computer-aided engineering) using a modified Lipscomb equation.

[0005] U.S. Patent Application Publication No. 2019 / 0232535

[0006] Fiber-reinforced plastics, a type of composite material, have directional fibers contained within the resin. When the fibers are randomly oriented within the resin, the fiber-reinforced plastic exhibits isotropy in the fiber orientation plane. In molding of such fiber-reinforced plastics, the flow in the fiber orientation plane and the flow out of the fiber orientation plane exhibit different behaviors. Therefore, molding analysis of composite materials that have anisotropy in the out-of-plane direction requires a model that takes this anisotropy into account.

[0007] However, a model suitable for the molding analysis of a specific material is not necessarily suitable for the molding analysis of another material. Therefore, to accurately evaluate the flow of composite materials with out-of-plane anisotropy during molding, a molding analysis using a more widely applicable (i.e., general-purpose) model is desired.

[0008] An object of the present invention is to provide a technique for more accurately analyzing the flow of a composite material having anisotropy between the out-of-plane direction and the in-plane direction during molding.

[0009] A molding analysis method according to one aspect of the present invention is a method for performing molding analysis of a plate-shaped intermediate substrate containing a resin and a reinforcing material when molding the intermediate substrate using a mold. The molding analysis method includes the steps of applying a model of the intermediate substrate that has anisotropy between the out-of-plane direction and an in-plane direction perpendicular to the out-of-plane direction, and calculating a viscosity distribution in the cross-sectional direction of the molded product using viscosities corresponding to the flow field. The viscosity distribution shows that under the boundary condition of no flow slippage of the intermediate substrate at the wall surface of the mold, a shear field occurs near the wall surface, automatically forming a low-viscosity layer near the wall surface where the influence of the out-of-plane shear viscosity is greater than that in the center of the intermediate substrate, and the intermediate substrate near the wall surface functions as a lubricating layer.

[0010] This configuration makes it possible to obtain the viscosity distribution in the cross-sectional direction of the composite material after molding. In particular, it is possible to obtain the evaluation result that a lubricant layer is automatically formed near the wall surface of the mold, which was not possible with conventional analysis. Therefore, this configuration makes it possible to accurately analyze the molding of a composite material that has anisotropy between the out-of-plane direction and the in-plane direction.

[0011] In the above configuration, the molding analysis method includes a step in which, as the viscosity ratio, which indicates the strength of anisotropy, increases, the flow velocity near the wall surface of the mold approaches the flow velocity at the center of the molded product, and the flow velocity distribution approaches uniformity in the thickness direction of the molded product.

[0012] According to this configuration, the flow velocity distribution in the thickness direction of the molded product can be obtained with high accuracy. In the above configuration, the molding analysis method includes a step of applying a weighting function that depends on the flow field to the viscosities in the in-plane direction and the out-of-plane direction of the model to calculate an average viscosity, which is an isotropic viscosity.

[0013] According to this configuration, by appropriately selecting the weighting function, it is possible to appropriately represent the deformation state of the intermediate substrate in both the out-of-plane direction and the in-plane direction. Therefore, it is possible to perform forming analysis of the intermediate substrate with high accuracy. Note that the weighting function can be selected arbitrarily.

[0014] In the above configuration, the weighting function is a function obtained based on an orthogonal tensor decomposition of the strain rate tensor related to the deformation of the model.

[0015] According to this configuration, an appropriate weighting function is selected, so that forming analysis of the intermediate base material can be performed with high accuracy.

[0016] In the above configuration, the flow fields are out-of-plane compression, in-plane compression, isotropic compression, out-of-plane shear, and in-plane shear.

[0017] According to this configuration, the flow field is taken into consideration as the deformation state of a model having anisotropy between the out-of-plane direction and the in-plane direction, thereby enabling accurate molding analysis of the intermediate substrate.

[0018] In the above configuration, the viscosity in the in-plane direction of the model is the in-plane viscosity, and the viscosity in the out-of-plane direction of the model includes the out-of-plane normal shear viscosity and the out-of-plane shear viscosity.

[0019] With this configuration, weighting the in-plane viscosity, the out-of-plane normal shear viscosity, and the out-of-plane shear viscosity makes it possible to express the deformation state of a model that has anisotropy between the out-of-plane and in-plane directions, thereby enabling accurate molding analysis of the intermediate substrate.

[0020] In the above-described configuration, the intermediate substrate is a fiber-reinforced plastic that uses fibers as a reinforcing material.

[0021] According to this configuration, molding analysis of fiber reinforced plastics can be performed with high accuracy. A program according to one aspect of the present invention is a program for causing a computer to execute any of the molding analysis methods described above.

[0022] A recording medium according to one aspect of the present invention is a computer-readable recording medium having the above program recorded thereon.

[0023] According to the present invention, it is possible to more accurately analyze the flow of a composite material having anisotropy between the out-of-plane direction and the in-plane direction during molding.

[0024] 1. A diagram showing the deformation state of a material with in-plane isotropy. 2. A diagram outlining an intermediate substrate to be analyzed according to the present embodiment and a manufacturing method thereof. 3. A flowchart showing an example of a manufacturing method for CTT material. 4. A flowchart showing a molding method according to the present embodiment. 5. A diagram showing an example of a configuration capable of implementing a molding analysis method according to the present embodiment. 6. A block diagram showing an example of a hardware configuration of the analysis device shown in FIG. 5. 7. A diagram showing an example of a functional block of the analysis device shown in FIG. 5. 8. A schematic plan view of an experimental material. 9. A schematic diagram of a molding experiment. 10. A diagram showing an analytical model created by a computer to simulate the molding experiments shown in FIGS. 8 and 9. 11. A diagram showing the results of a compression analysis using the model shown in FIG. 10, illustrating the results of examining a constant viscosity independent of shear rate for an isotropic material and a transversely isotropic material. 12. A diagram showing the results of a compression analysis using the model shown in FIG. 10, illustrating an example of application of simulation to a CTT material (viscosity distribution in the cross-sectional direction of the material). 13. A diagram showing the analysis results of a flow velocity distribution corresponding to the viscosity distribution shown in FIG. 11. A diagram showing the analysis results of a flow velocity distribution corresponding to the viscosity distribution shown in FIG. 12. 14. A diagram showing experimental results and simulation results regarding a compression test on a CTT material.

[0025] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the accompanying drawings, in which the same or corresponding parts in the drawings are designated by the same reference numerals and the description thereof will not be repeated.

[0026] 1. Overview A typical example of a composite material having out-of-plane anisotropy is fiber reinforced plastics. In the embodiment of the present invention, chopped carbon fiber tape reinforced thermoplastics (CTT) material, which is a carbon fiber reinforced composite material, is exemplified.

[0027] Chopped carbon fiber tape reinforced thermoplastics (CTT) materials are intermediate substrates made by laminating carbon fiber tapes impregnated with resin. CTT materials are produced by laminating carbon fiber tapes so that the fibers are randomly oriented. Therefore, CTT materials are isotropic in the fiber orientation plane. However, CTT materials are anisotropic in the out-of-plane direction of the tape, i.e., the tape stacking direction.

[0028] In the forming of CTT materials, the flow in the orientation direction (in-plane direction) of the chopped tape and the flow in the stacking direction (out-of-plane direction) of the chopped tape exhibit different behaviors. Therefore, in the forming analysis of CTT materials, it is necessary to construct a model that takes anisotropy into account. In addition, because the stress generated in the stacking direction of CTT materials differs from that in the direction perpendicular to it, it is necessary to perform an analysis that takes into account the anisotropy of the stress tensor.

[0029] In an embodiment of the present invention, a model is used that indirectly considers the anisotropy of stress using a scalar quantity derived from the anisotropic stress tensor, specifically, the equivalent viscosity. Specifically, in an embodiment of the present invention, a generalized stress tensor is introduced to calculate the average viscosity weighted by the flow field. Any weighting can be applied as the weighting by the flow field. In one embodiment of the present invention, weighting based on orthogonal tensor decomposition is used.

[0030] <2. Derivation of the generalized stress tensor> (1) Basis tensor

[0031]

[0032] Figure 1 shows the deformation state of a material with in-plane isotropy. A laminate is considered as a material with in-plane isotropy. As shown in Figures 1(a) to 1(f), there are six types of deformation states for a material with in-plane isotropy: (a) out-of-plane compression, (b) in-plane compression, (c) isotropic expansion, (d) and (e) out-of-plane shear, and (f) in-plane shear.

[0033] In Figure 1, three mutually orthogonal directions are indicated by arrows labeled "1" to "3." The "1st direction" and the direction perpendicular to the 1st direction ("2nd direction") are set as in-plane directions for a material with in-plane isotropy, and the stacking direction of the material (i.e., the out-of-plane direction) is set as the "3rd direction."

[0034] The basis of the symmetric tensor for materials with in-plane isotropy is expressed by equations (2-3) to (2-8). The symbols (a) to (f) before each equation correspond to the symbols (a) to (f) shown in Figure 1. In equations (2-3) to (2-8), R is R=(t1t2n) when the orientation of the material is expressed in the Cartesian coordinate system (t1, t2, n). T is a rotation matrix expressed as follows.

[0035] The subscripts "1" to "3" used in the formulas explained below represent the directions "1" to "3" shown in Figure 1. Furthermore, "⊥" represents the out-of-plane direction, and "||" represents the in-plane direction.

[0036]

[0037] 1 are the stacking directions, the unit vector n in the stacking direction is given by equation (2-9), where R=I.

[0038]

[0039] (2) Strain rate tensor The strain rate tensor D can be decomposed into orthogonal tensors as shown in equation (2-11) by using the relationship in equation (2-10) (taking incompressibility into consideration). In equation (2-11), ε with a dot (·) represents the strain rate.

[0040]

[0041] As shown in equation (2-12), each strain rate is expressed as the inner product of the basis tensor and the strain rate tensor.

[0042]

[0043] (3) Equivalent deformation velocity The equivalent deformation velocity is given by equation (2-13).

[0044]

[0045] (4) Stress tensor When the stress tensor σ is expressed using the basis tensors, it is expressed as in the following equation (2-14). Note that the viscosity parameters are the out-of-plane normal shear viscosity η ⊥ , in-plane viscosity η ∥ , out-of-plane shear viscosity η s and p is the hydrostatic pressure.

[0046]

[0047] Equation (2-14) shows that the stress tensor σ is a stress tensor that takes into account the anisotropy in the out-of-plane direction. In this specification, the stress tensor expressed by equation (2-14) is called a "generalized stress tensor."

[0048] <3. Making viscosity isotropic> The isotropic viscosity is calculated for the generalized stress tensor expressed by equation (2-14). In this specification, the isotropic viscosity is also called "average viscosity."

[0049] In order to consider changing the coefficients and powers of each viscosity parameter depending on the type of flow, in this embodiment, a weighting function dependent on the flow field is defined as given by equation (3-1).

[0050]

[0051] When a weighting function dependent on the flow field is used, the isotropic viscosity is expressed by equation (3-2).

[0052]

[0053] As described above, in this embodiment, the viscosity can be expressed in an isotropic manner by using a generalized stress tensor and a weighting function that changes depending on the flow state. The isotropic viscosity (average viscosity) can be expressed as the sum of the in-plane viscosity (in-plane viscosity) weighted depending on the flow field of the model and the out-of-plane viscosity (out-of-plane normal shear viscosity and out-of-plane shear viscosity) weighted depending on the flow field of the model.

[0054] <4. Molding Analysis Method> In this embodiment, the flow during molding of a composite material that has anisotropy between the out-of-plane direction and the in-plane direction can be analyzed by calculating the isotropic viscosity (average viscosity) using a computer.

[0055] 2 is a diagram illustrating an intermediate substrate to be analyzed according to the present embodiment and a manufacturing method thereof. As shown in FIG. 2, an intermediate substrate 10 contains a resin 12 and fibers 14. The directions indicated by the reference numerals "1" to "3" in FIG. 2 correspond to the directions "1" to "3" shown in FIG. 1, respectively.

[0056] The resin 12 may be a thermoplastic resin, a thermosetting resin, or both. Specific examples of the resin 12 include, but are not limited to, polyolefin resins such as polypropylene, polyester resins, polyamide resins, epoxy resins, unsaturated polyester resins, phenolic resins, diallyl phthalate resins, vinyl ester resins, silicone resins, and polyimide resins.

[0057] Examples of the fibers 14 include those generally used in fiber-reinforced plastics, such as carbon fibers, glass fibers, boron fibers, silicon carbide fibers, alumina fibers, silica fibers, and aromatic polyamide fibers.

[0058] In this embodiment, a CTT material is used as an example of an intermediate substrate. Therefore, an example of a method for manufacturing a CTT material is shown in Figures 2 and 3 as an example of a method for manufacturing an intermediate substrate. Hereinafter, an example of a method for manufacturing a CTT material will be described with reference to Figures 2 and 3.

[0059] Fig. 3 is a flowchart showing an example of a method for manufacturing a CTT material. As shown in Fig. 2 and Fig. 3, first, a continuous fiber prepreg is produced (Step S1). In Step S1, a sheet-like substrate (prepreg tape) is produced by impregnating unidirectionally aligned carbon fibers with a thermoplastic resin (e.g., acid-modified polypropylene).

[0060] Next, the prepreg tape is cut to a predetermined size to produce chopped tape, which is a discontinuous fiber tape (step S2). The dimensions of the chopped tape are not particularly limited, but in one example, the length is 35 mm, the width is 15 mm, and the thickness is 0.1 mm.

[0061] Next, the plurality of chopped tapes are stacked so that the fibers 14 are randomly oriented in the in-plane direction. The stacked plurality of chopped tapes are compressed by heating and pressure (step S3). This integrates the plurality of chopped tapes to produce the plate-shaped intermediate substrate 10.

[0062] As shown in Fig. 2, the fibers 14 are randomly oriented in the in-plane direction. This gives the intermediate substrate 10 (CTT material) isotropy in the in-plane direction and anisotropy in the out-of-plane direction. Because the fibers 14 are oriented in the in-plane direction, the behavior of the intermediate substrate 10 during flow differs between the in-plane direction and the out-of-plane direction.

[0063] Fig. 4 is a flowchart showing a molding method according to this embodiment. As shown in Fig. 4, the intermediate substrate 10 is heated by a heating device such as an infrared heater. Next, the intermediate substrate 10 softened by heat is compressed in a mold. This produces a molded product. Note that Fig. 4 shows stamping molding as an example of a molding method. In stamping molding, the intermediate substrate 10 is pressed by a stamping mold to produce a molded product having a desired shape.

[0064] Fig. 5 is a diagram showing an example of a configuration capable of implementing the molding analysis method according to this embodiment. As shown in Fig. 5, for example, a heating device 22, a molding device 24, and an analysis device 26 may be combined. The heating device 22 is, for example, the infrared heater shown in Fig. 4, and heats the intermediate substrate 10. The molding device 24 includes a mold 25 (for example, the stamping mold shown in Fig. 4), and molds the intermediate substrate 10 softened by heat.

[0065] The analysis device 26 is a device for executing the forming analysis method according to this embodiment, and is realized by executing a program using hardware that conforms to a general-purpose computing architecture. The analysis device 26 performs a forming analysis of the intermediate substrate 10 by executing a simulation.

[0066] Fig. 6 is a block diagram showing an example of the hardware configuration of the analysis device shown in Fig. 5. The analysis device 26 includes a processor 31, a primary storage device 32, a secondary storage device 33, an external device interface 34, an input interface 35, an output interface 36, a communication interface 37, and a bus 38. Elements such as the processor 31 and the primary storage device 32 exchange data, signals, etc. via the bus 38.

[0067] The processor 31 processes programs and data stored in the primary storage device 32. The primary storage device 32 stores programs executed by the processor 31 and data referenced by the processor 31. In some aspects, a dynamic random access memory (DRAM) may be used as the primary storage device 32.

[0068] The secondary storage device 33 stores programs, data, etc. in a nonvolatile manner. In some aspects, a nonvolatile memory such as a hard disk drive (HDD) or a solid state drive (SSD) may be used as the secondary storage device 33. Therefore, the secondary storage device 33 corresponds to a computer-readable recording medium that records a program to be executed by a computer.

[0069] The external device interface 34 is used when connecting an external device to the analysis device 26. The external device interface 34 is, for example, a USB (Universal Serial Bus) interface.

[0070] The input interface 35 is used to connect input devices such as a keyboard 41 and a mouse 42. The input interface 35 accepts user operations and inputs through these input devices.

[0071] The output interface 36 is used to connect an output device such as a display 43 .

[0072] The communication interface 37 is used by the analysis device 26 to communicate with external devices. For example, the communication interface 37 is used for communication of the analysis device 26 via a network. Communication with external devices may be wireless or wired.

[0073] The analysis device 26 may optionally include an optical drive. The optical drive reads a computer-readable program stored in a recording medium (for example, an optical recording medium such as a DVD (Digital Versatile Disc)) that non-transiently stores the program. The program read from the recording medium may be installed in the secondary storage device 33 or the like. Furthermore, various programs executed by the analysis device 26 may be downloaded from a server device or the like on a network and installed in the analysis device 26.

[0074] Fig. 7 is a diagram showing an example of functional blocks of the analysis device shown in Fig. 5. In one aspect, the hardware shown in Fig. 6 executes software that realizes the functions of each functional block, thereby configuring analysis device 26 as shown in Fig. 7. Note that analysis device 26 may further include components other than those shown in Fig. 7.

[0075] 7 , the analysis device 26 includes an input unit 51, an average viscosity calculation unit 52, a viscosity distribution calculation unit 53, a storage unit 54, and an output unit 55. The input unit 51 receives information such as the material properties of the resin and the molding conditions as input. This information includes, for example, the characteristic values ​​of a molded product actually obtained by molding an intermediate base material according to predetermined conditions, and the predetermined molding conditions.

[0076] The average viscosity calculation unit 52 uses a model of the intermediate substrate 10 that has anisotropy between the out-of-plane direction and the in-plane direction perpendicular to the out-of-plane direction, and applies a weighting function dependent on the flow field to the viscosities in the in-plane and out-of-plane directions of the model to calculate the average viscosity, which is an isotropic viscosity. As the weighting function dependent on the flow field, for example, weighting based on orthogonal tensor decomposition is used.

[0077] The viscosity distribution calculation unit 53 performs molding analysis of finite elements of a molded product model that models an actual molded product in accordance with predetermined molding conditions. The viscosity distribution calculation unit 53 calculates an average viscosity for each finite element of the model. The average viscosity is calculated by the average viscosity calculation unit 52. The viscosity distribution calculation unit 53 is a simulation execution unit that performs molding analysis. The average viscosity calculation unit 52 may be included in the viscosity distribution calculation unit 53 as a part of the viscosity distribution calculation unit 53.

[0078] The storage unit 54 stores an analysis program 61 for molding analysis, parameters 62 for molding analysis input by the user to the analysis device 26, etc. The average viscosity calculation unit 52 and viscosity distribution calculation unit 53 read out the analysis program 61 and parameters 62 from the storage unit 54, execute molding analysis of the model, and calculate the average viscosity for each finite element. As a result, the average viscosity calculation unit 52 and viscosity distribution calculation unit 53 calculate the viscosity distribution in the cross-sectional direction of the molded product.

[0079] The output unit 55 outputs, as an analysis result, the viscosity distribution in the cross-sectional direction of the molded product, which is the calculation result of the viscosity distribution calculation unit 53. The analysis result is displayed, for example, on the display 43 (see FIG. 6).

[0080] 5. Example of Molding Analysis An experiment on molding of a CTT material will be described with reference to FIGS. 8 and 9. FIG. 8 is a schematic plan view of the experimental material. FIG. 9 is a schematic diagram of the molding experiment. As shown in FIGS. 8 and 9, a disk-shaped CTT material (corresponding to intermediate substrate 10) with scribed lines was subjected to a compressive load using a compression testing device under conditions of a resin temperature of 220°C and a compression speed of 3 mm / min. Note that scribed lines 11 were formed on the surface of the CTT material to confirm that slippage did not occur on the surface where the CTT material contacts the wall. Viscosity characteristics were evaluated based on the compressive load and the rate of compressive displacement. The values ​​obtained in the experiment were input into a computer, which then executed a program using the input values ​​to perform molding analysis.

[0081] Fig. 10 is a diagram showing an analytical model created by a computer to simulate the molding experiments shown in Figs. 8 and 9. As shown in Fig. 10, the viscosity distribution when a disk-shaped reinforced plastic substrate was subjected to a compressive load was determined by simulation. Although there is no particular limitation on the software used to perform the simulation, in this example, the analytical software 3D TIMON-CompositePRESS (Toray Engineering D Solutions Co., Ltd., "3D TIMON" and "CompositePRESS" are registered trademarks) was used. In the simulation, the average viscosity was calculated for each finite element. The equivalent strain rate was used as the weighting function for calculating the average viscosity.

[0082] Figure 11 is the first diagram showing the results of a compression analysis using the model shown in Figure 10. The analysis models used were an isotropic material and a transversely isotropic material, which is a material with anisotropy between the out-of-plane and in-plane directions. Figure 11 also shows the results of examining constant viscosity independent of shear rate for the isotropic material and the transversely isotropic material. Figure 11(a) shows the viscosity distribution in the cross-sectional direction of the isotropic material, and Figure 11(b) shows the viscosity distribution in the cross-sectional direction of the transversely isotropic material.

[0083] For isotropic materials, the out-of-plane normal shear viscosity η ⊥ , in-plane viscosity η ∥ , out-of-plane shear viscosity η s is the same (η ⊥ =η∥ =η s On the other hand, for transversely isotropic materials, the out-of-plane normal shear viscosity η ⊥ , and in-plane viscosity η ∥ is the same, and the out-of-plane shear viscosity η s is the out-of-plane normal shear viscosity η ⊥ , and in-plane viscosity η ∥ and different (η ⊥ =η ∥ =1E+07Pa・s, η s = 1E+04 Pa s). In this case, a shear field is generated near the wall of the disk, and the influence of the low out-of-plane shear viscosity increases in response to the shear field. The viscosity near the wall becomes significantly lower than that at the center, and a lubricating layer is automatically formed.

[0084] As shown in Figure 11(b), in the case of a transversely isotropic material, a large difference in viscosity occurs between the area near the center of the substrate (disk) and the area near the mold wall. The "lubrication layer" refers to this low-viscosity region. Note that "automatic" means that no changes are made to the boundary conditions (no slip), and no specific region (near the mold wall or center) is specified.

[0085] Figure 12 shows the results of a compression analysis using the model shown in Figure 10, illustrating an example of the application of the simulation to a CTT material (viscosity distribution in the cross-sectional direction of the material). Figure 12(a) shows the viscosity distribution in the cross-sectional direction, calculated for comparison purposes assuming the CTT material to be an isotropic material. Figure 12(b) shows the viscosity distribution in the cross-sectional direction of a CTT material (transversely isotropic material).

[0086] 12(a) and 12(b), it can be seen that with the CTT material (transversely isotropic material), a lubricating layer is more pronounced near the mold wall than with the assumed isotropic material (i.e., the viscosity difference between the center and the vicinity of the mold wall is larger). As a result, when an anisotropic viscosity parameter that takes into account the measured shear rate dependency is used, as with the CTT material, a lubricating layer appears more pronounced in the region near the mold wall during molding.

[0087] Fig. 13 is a diagram showing the analysis results of the flow velocity distribution corresponding to the viscosity distribution shown in Fig. 11. Fig. 14 is a diagram showing the analysis results of the flow velocity distribution corresponding to the viscosity distribution shown in Fig. 12. As can be seen from Figs. 11 to 14, in the molding analysis method according to this embodiment, as the viscosity ratio, which indicates the strength of anisotropy, increases, the flow velocity near the wall surface of the mold approaches the flow velocity at the center of the molded product, and the flow velocity distribution approaches uniformity in the thickness direction of the molded product.

[0088] Figure 15 shows experimental and simulation results for a compression test on a CTT material. It can be seen from Figure 15 that the simulation results for a CTT material (transversely isotropic material) are close to the experimental results. For comparison, the simulation results assuming an isotropic material resulted in a load significantly lower than the experimental value. This shows that, according to this embodiment, highly accurate simulation results can be obtained in forming analysis of a CTT material.

[0089] In the above embodiment, fiber-reinforced plastics are shown as an example of the target material. However, the composite material of the present embodiment is not limited to fiber-reinforced plastics, and may be a composite material in which other types of reinforcing materials are added to a resin as a matrix. Examples of such reinforcing materials include inorganic fillers such as clay and talc.

[0090] In the above embodiment, a transversely isotropic material is exemplified as a material having anisotropy between the out-of-plane direction and the in-plane direction. However, the material having anisotropy between the out-of-plane direction and the in-plane direction is not limited to a transversely isotropic material, and may be, for example, an in-plane isotropic material. The forming analysis method according to this embodiment can also be applied to an in-plane isotropic material.

[0091] Although the embodiments and examples of the present invention have been described, the embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, and it is intended to include all modifications within the meaning and scope of the claims.

[0092] 10 intermediate substrate, 11 scribe line, 12 resin, 14 fiber, 22 heating device, 24 molding device, 25 mold, 26 analysis device, 31 processor, 32 primary storage device, 33 secondary storage device, 34 external device interface, 35 input interface, 36 output interface, 37 communication interface, 38 bus, 41 keyboard, 43 display, 51 input unit, 52 average viscosity calculation unit, 53 viscosity distribution calculation unit, 54 memory unit, 55 output unit, S1 to S3 steps.

Claims

1. A method for performing molding analysis of a plate-shaped intermediate substrate containing a resin and a reinforcing material when molding the intermediate substrate using a mold, comprising: applying, as a model of the intermediate substrate, a model having anisotropy between an out-of-plane direction and an in-plane direction orthogonal to the out-of-plane direction; calculating a viscosity distribution in a cross-sectional direction of a molded product using respective viscosities according to a flow field; The viscosity distribution is such that, under a boundary condition that there is no flow slip of the intermediate substrate on the wall surface of the mold, a shear field is generated near the wall surface, and a low-viscosity layer in which the influence of the out-of-plane shear viscosity is greater than that in the central portion of the intermediate substrate is automatically formed near the wall surface, indicating that the intermediate substrate near the wall surface functions as a lubricating layer. A molding analysis method.

2. The molding analysis method according to claim 1, further comprising a step in which, as the viscosity ratio indicating the strength of anisotropy increases, the flow velocity near the wall surface of the mold approaches the flow velocity at the center of the molded product, and the distribution of the flow velocity approaches uniformity in the thickness direction of the molded product.

3. The molding analysis method according to claim 1, further comprising a step of applying a weight function depending on a flow field to viscosities in the in-plane direction and the out-of-plane direction of the model to calculate an average viscosity which is an isotropized viscosity.

4. The molding analysis method according to claim 3, wherein the weight function is a function obtained based on an orthogonal tensor decomposition of a strain rate tensor related to deformation of the model.

5. The molding analysis method according to claim 1, wherein the flow field is out-of-plane compression, in-plane compression, isotropic compression, out-of-plane shear, or in-plane shear.

6. The viscosity in the in-plane direction of the model is an in-plane viscosity, The viscosity in the out-of-plane direction of the model includes an out-of-plane normal shear viscosity and an out-of-plane shear viscosity. The molding analysis method according to claim 1.

7. The molding analysis method according to claim 1, wherein the intermediate substrate is a fiber-reinforced plastic using fibers as the reinforcing material.

8. A program for causing a computer to execute the molding analysis method according to any one of claims 1 to 7.

9. A computer-readable recording medium recording the program according to claim 8.