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

[Technical Field]

[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 stored. In particular, the present invention relates to a molding analysis method for composite materials including resin and reinforcing materials. [Background technology]

[0002] Composite materials containing resins and reinforcing materials are known. Such composite materials are generally processed into products with a predetermined shape by molding.

[0003] In the molding of composite materials, various conditions are involved, including mold and substrate temperatures, holding pressure and cooling times, compression speed and load, substrate placement within the mold, and substrate thickness. Repeated experiments to find the optimal conditions require considerable time and cost. Therefore, it has been proposed to analyze the resin flow during composite material molding using computer simulations.

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

[0005] [Patent Document 1] U.S. Patent Application Publication No. 2019 / 0232535 [Overview of the Initiative] [Problems that the invention aims to solve]

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

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

[0008] The objective of the present invention is to provide a technique for more accurately analyzing the flow of composite materials having anisotropy between the out-of-plane and in-plane directions during molding. [Means for solving the problem]

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

[0010] This configuration allows for obtaining the viscosity distribution in the cross-sectional direction of the molded composite material. In particular, it is possible to obtain evaluation results that could not be obtained with conventional analyses, such as the automatic formation of a lubricating layer near the mold wall. Therefore, this configuration enables accurate molding analysis of composite materials that exhibit anisotropy between the out-of-plane and in-plane directions.

[0011] In the above configuration, the molding analysis method includes a step in which, as the viscosity ratio indicating the strength of anisotropy increases, the flow velocity near the mold wall 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] This configuration allows for accurate determination of the flow velocity distribution in the thickness direction of the molded product. In the above configuration, the molding analysis method includes the step of applying a flow field-dependent weighting function to the viscosity in the in-plane and out-of-plane directions of the model to calculate the average viscosity, which is the isotropized viscosity.

[0013] With this configuration, by appropriately selecting the weighting function, the deformation states of the intermediate material in both the out-of-plane and in-plane directions can be appropriately represented. Therefore, the molding analysis of the intermediate material can be performed with high accuracy. Note that the weighting function can be selected arbitrarily.

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

[0015] This configuration allows for the selection of an appropriate weighting function, enabling accurate molding analysis of intermediate materials.

[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 above flow field is considered as the deformation state of a model having anisotropy between the out-of-plane direction and the in-plane direction. Thereby, the forming analysis of the intermediate substrate can be performed with high accuracy.

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

[0019] According to this configuration, by weighting the in-plane viscosity, the out-of-plane normal shear viscosity, and the out-of-plane shear viscosity, the deformation state of a model having anisotropy between the out-of-plane direction and the in-plane direction can be expressed. Therefore, the forming analysis of the intermediate substrate can be performed with high accuracy.

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

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

[0022] A recording medium according to an aspect of the present invention is a computer-readable recording medium on which the above program is recorded.

Advantages of the Invention

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

Brief Description of the Drawings

[0024] [Figure 1] It is a diagram showing the deformation state of a substance having in-plane isotropy. [Figure 2] It is a diagram schematically explaining the intermediate substrate to be analyzed according to the present embodiment and its manufacturing method. [Figure 3]This is a flowchart showing an example of a manufacturing method for CTT material. [Figure 4] This is a flowchart showing the molding method according to this embodiment. [Figure 5] This figure shows an example of a configuration that enables the implementation of the molding analysis method according to this embodiment. [Figure 6] Figure 5 is a block diagram showing an example of the hardware configuration of the analysis device. [Figure 7] Figure 5 shows an example of the functional block of the analysis device. [Figure 8] This is a schematic plan view of the experimental materials. [Figure 9] This is a schematic diagram of the molding experiment. [Figure 10] Figures 8 and 9 show the computer-generated analysis model used to simulate the molding experiments. [Figure 11] Figure 10 shows the results of a compression analysis using the model shown, illustrating the results of examining a constant viscosity independent of shear rate for isotropic and transversely isotropic materials. [Figure 12] Figure 10 shows the results of a compression analysis using the model shown, illustrating an example of applying the simulation to a CTT material (viscosity distribution in the cross-sectional direction of the material). [Figure 13] This figure shows the analysis results of the flow velocity distribution corresponding to the viscosity distribution shown in Figure 11. [Figure 14] This figure shows the analysis results of the flow velocity distribution corresponding to the viscosity distribution shown in Figure 12. [Figure 15] This figure shows experimental and simulation results regarding compression tests on CTT material. [Modes for carrying out the invention]

[0025] Embodiments of the present invention will be described in detail with reference to the drawings. Note that identical or corresponding parts in the drawings are denoted by the same reference numerals, and their descriptions will not be repeated.

[0026] <1. Overview> A typical example of a composite material with out-of-plane anisotropy is fiber-reinforced plastic. In the embodiments of the present invention, CTT (Chopped carbon fiber Tape reinforced Thermoplastics), which is a carbon fiber reinforced composite material, is used as an example.

[0027] CTT (Chopped carbon fiber tape reinforced thermoplastics) material is an intermediate material made by laminating carbon fiber tapes impregnated with resin. CTT material is manufactured by laminating carbon fiber tapes so that the fibers are randomly oriented. Therefore, CTT material is isotropic within the orientation plane of the fibers. On the other hand, CTT material is anisotropic in the out-of-plane direction of the tape, i.e., in the lamination direction of the tape.

[0028] In the molding of CTT material, the flow in the orientation direction (in-plane direction) and the flow in the stacking direction (out-of-plane direction) of the chopped tape exhibit different behaviors. Therefore, in the molding analysis of CTT material, it is necessary to construct a model that takes anisotropy into account. Furthermore, since the stress generated in the stacking direction of the CTT material differs from that in the direction perpendicular to it, the molding analysis of CTT material must be performed considering the anisotropy of the stress tensor.

[0029] In embodiments of the present invention, a model is used that indirectly considers stress anisotropy using a scalar quantity derived from an anisotropic stress tensor, specifically equivalent viscosity. Specifically, in embodiments 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) Base Tensor

[0031]

number

[0032] Figure 1 shows the deformation states 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 (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), (e) out-of-plane shear, and (f) in-plane shear.

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

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

[0035] In the formulas described below, the subscripts "1" to "3" represent the directions "1" to "3" shown in Figure 1, respectively. Additionally, "⊥" represents the out-of-plane direction, and "||" represents the in-plane direction.

[0036]

number

[0037] Since the "three directions" shown in Figure 1 are the stacking directions, the unit vector n in the stacking direction is given by equation (2-9). In this case, R = I.

[0038]

number

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

[0040]

number

[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]

number

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

[0044]

number

[0045] (4) Stress tensor When the stress tensor σ is expressed using the base tensor, the stress tensor σ is expressed as shown in equation (2-14) below. 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]

number

[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 represented by equation (2-14) is called the "generalized stress tensor".

[0048] <3. Viscosity Isotropization> For the generalized stress tensor represented by equation (2-14), the isotropic viscosity is determined. In this specification, the isotropic viscosity is also referred to as the "average viscosity".

[0049] In order to consider changing the coefficients and powers of each viscosity parameter according to the flow shape, this embodiment defines a flow field-dependent weighting function, as given by equation (3-1).

[0050]

number

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

[0052]

number

[0053] As described above, in this embodiment, viscosity can be expressed in an isotropic form by using a generalized stress tensor and a weighting function that changes according to the flow state. The isotropic viscosity (average viscosity) can be expressed as the sum of the 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, by calculating the isotropic viscosity (average viscosity) using a computer, it is possible to analyze the flow during molding of a composite material that has anisotropy between the out-of-plane and in-plane directions.

[0055] Figure 2 is a schematic diagram illustrating the intermediate substrate subject to analysis according to this embodiment and its manufacturing method. As shown in Figure 2, the intermediate substrate 10 contains resin 12 and fibers 14. The directions indicated by reference numerals "1" to "3" in Figure 2 correspond to the directions "1" to "3" shown in Figure 1, respectively.

[0056] The resin 12 may be a thermoplastic resin or a thermosetting resin, or both may be used. Specific examples of the resin 12 include polyolefin resins such as polypropylene, polyester resins, polyamide resins, epoxy resins, unsaturated polyester resins, phenolic resins, diallyl phthalate resins, vinyl ester resins, silicone resins, polyimide resins, and the like.

[0057] Examples of fibers 14 include those commonly 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, CTT material is used as an example of an intermediate substrate. Therefore, Figures 2 and 3 show an example of a method for manufacturing the intermediate substrate, specifically an example of a method for manufacturing CTT material. The example of a method for manufacturing CTT material will be described below with reference to Figures 2 and 3.

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

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

[0061] Next, multiple chopped tapes are laminated. At this time, the multiple chopped tapes are laminated so that the fibers 14 are randomly oriented in the in-plane direction. The laminated multiple chopped tapes are compressed by heating and pressurizing (step S3). As a result, the multiple chopped tapes are integrated to produce a plate-shaped intermediate material 10.

[0062] As schematically shown in Figure 2, the fibers 14 are randomly oriented in the in-plane direction. As a result, the intermediate material 10 (CTT material) is isotropic in the in-plane direction and anisotropic in the out-of-plane direction. Due to the orientation of the fibers 14 in the in-plane direction, the behavior of the intermediate material 10 during flow differs between the in-plane and out-of-plane directions.

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

[0064] Figure 5 shows an example of a configuration that enables the implementation of the molding analysis method according to this embodiment. As shown in Figure 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 Figure 4, which heats the intermediate substrate 10. The molding device 24 includes a mold 25 (for example, the stamping mold shown in Figure 4) and molds the intermediate substrate 10 that has been softened by heat.

[0065] The analysis device 26 is a device for executing the molding 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 molding analysis of the intermediate substrate 10 by executing a simulation.

[0066] Figure 6 is a block diagram showing an example of the hardware configuration of the analysis device shown in Figure 5. The analysis device 26 comprises 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. The processor 31 and the primary storage device 32, among other elements, exchange data, signals, etc., through 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 that are referenced. In some cases, DRAM (Dynamic Random Access Memory) may be used as the primary storage device 32.

[0068] The secondary storage device 33 stores programs and data in a non-volatile manner. In certain situations, non-volatile memory such as an HDD (Hard Disk Drive) or SSD (Solid State Drive) may be used as the secondary storage device 33. Therefore, the secondary storage device 33 corresponds to a computer-readable recording medium that stores programs executed by the computer.

[0069] The external device interface 34 is used when connecting external devices to the analysis device 26, etc. 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 user input 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 for the analysis device 26 to communicate with external devices. For example, the communication interface 37 is used for communication of the analysis device 26 over a network. Communication with external devices may be via wireless or wired communication.

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

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

[0075] Referring to Figure 7, the analysis device 26 comprises 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 molding conditions as input. This information includes, for example, the characteristic values ​​of a molded product actually obtained by molding an intermediate substrate 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 flow field-dependent weighting function to the viscosity in the in-plane and out-of-plane directions of the model to calculate the average viscosity, which is the isotropized viscosity. As the flow field-dependent weighting function, for example, weighting based on orthogonal tensor decomposition is used.

[0077] The viscosity distribution calculation unit 53 performs a molding analysis of the finite elements of a molded product model that models an actual molded product, corresponding to predetermined molding conditions. The viscosity distribution calculation unit 53 calculates the average viscosity for each finite element of the above 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 part of the viscosity distribution calculation unit 53.

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

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

[0080] <5. Example of molding analysis> The molding experiment of the CTT material will be explained with reference to Figures 8 and 9. Figure 8 is a schematic plan view of the experimental material. Figure 9 is a schematic diagram of the molding experiment. As shown in Figures 8 and 9, a disc-shaped CTT material (corresponding to the intermediate material 10) with scribed lines is compressed using a compression test apparatus under the conditions of resin temperature: 220°C and compression speed: 3 mm / min. In order to confirm that no slippage occurs on the surface of the CTT material that is in contact with the wall, scribed lines 11 are formed on the surface of the CTT material, and the viscosity characteristics are evaluated from the compression load and the rate of compression displacement. The values ​​obtained in the experiment are input into a computer, and the computer performs molding analysis by executing a program using these input values.

[0081] Figure 10 shows an analysis model created by a computer to simulate the molding experiment shown in Figures 8 and 9. As shown in Figure 10, the viscosity distribution of a disc-shaped reinforced plastic substrate under compressive load was determined by simulation. While there are no particular limitations on the software used to perform the simulation, in this example, the analysis 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 for each finite element was calculated. The equivalent strain rate was used as the weighting function for calculating the average viscosity.

[0082] Figure 11 is the first figure showing the results of a compression analysis using the model shown in Figure 10. The analysis models used were isotropic material and transverse isotropic material, which exhibits anisotropy between the out-of-plane and in-plane directions. Figure 11 also shows the results of examining a constant viscosity independent of shear rate for both isotropic and transverse isotropic materials. Figure 11(a) shows the viscosity distribution in the cross-sectional direction for the isotropic material, and Figure 11(b) shows the viscosity distribution in the cross-sectional direction for the transverse 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 = 1E+04 Pa·s). On the other hand, for the transversely isotropic material, the out-of-plane normal shear viscosity η ⊥ , and the in-plane viscosity η ∥ are made the same, and the out-of-plane shear viscosity η s is made different from the out-of-plane normal shear viscosity η ⊥ , and the in-plane viscosity η ∥ (η ⊥ = η ∥ = 1E+07 Pa·s, η s = 1E+04 Pa·s). In this case, since a shear field occurs near the wall surface of the disk, the influence of the low-viscosity out-of-plane shear viscosity increases according to the shear field, and the viscosity becomes significantly lower near the wall surface than at the center, resulting in the automatic generation of a lubricating layer.

[0084] As shown in Fig. 11(b), in the case of the transversely isotropic material, a large viscosity difference occurs between the portion near the center of the base material (disk) and the portion near the mold wall surface of the base material (disk). The "lubricating layer" refers to this low-viscosity region. Note that "automatically" means not changing the boundary conditions (no-slip, and not specifying a specific region (near the mold wall surface or the center)).

[0085] Fig. 12 is a diagram showing the results of a compression analysis using the model shown in Fig. 10, and is a diagram showing an application example of the simulation to the CTT material (viscosity distribution in the cross-sectional direction of the material). Fig. 12(a) is a diagram showing the viscosity distribution in the cross-sectional direction obtained by assuming the CTT material as an isotropic material for comparison. Fig. 12(b) is a diagram showing the viscosity distribution in the cross-sectional direction of the CTT material (transversely isotropic material).

[0086] As can be seen from the comparison of Figures 12(a) and 12(b), in the case of CTT material (transverse isotropic material), a lubricating layer is significantly formed near the mold wall compared to the assumed isotropic material (i.e., the viscosity difference between the center and the vicinity of the mold wall is large). As a result, when using anisotropic viscosity parameters that take into account the measured shear rate dependence, as in the case of CTT material, a lubricating layer appears more prominently in the region near the mold wall during molding.

[0087] Figure 13 shows the analysis results of the flow velocity distribution corresponding to the viscosity distribution shown in Figure 11. Figure 14 shows the analysis results of the flow velocity distribution corresponding to the viscosity distribution shown in Figure 12. As can be seen from Figures 11 to 14, the molding analysis method according to this embodiment shows that as the viscosity ratio, which indicates the strength of anisotropy, increases, the flow velocity near the mold wall 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 the experimental and simulation results for a compression test on CTT material. From Figure 15, it can be seen that the simulation results for CTT material (transverse isotropic material) are close to the experimental results. For comparison, the simulation results when isotropic material was assumed resulted in a significantly lower load than the experimental value. From this, it can be seen that according to this embodiment, highly accurate simulation results can be obtained in the molding analysis of CTT material.

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

[0090] Furthermore, in the above embodiment, transverse isotropic material was given as an example of a material having anisotropy between the out-of-plane direction and the in-plane direction. However, a material having anisotropy between the out-of-plane direction and the in-plane direction is not limited to transverse isotropic material; for example, it may be in-plane isotropic material. The molding analysis method according to this embodiment can also be applied to in-plane isotropic material.

[0091] While embodiments and examples of the present invention have been described, the embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims, and all modifications within the meaning and scope of equivalents of the claims are intended to be included. [Explanation of Symbols]

[0092] 10 Intermediate material, 11 Scribing line, 12 Resin, 14 Fiber, 22 Heating device, 24 Molding device, 25 Mold, 26 Analysis device, 31 Processor, 32 Primary memory, 33 Secondary memory, 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 Storage unit, 55 Output unit, S1~S3 steps.

Claims

1. A method for performing a molding analysis of an intermediate substrate when molding a plate-shaped intermediate substrate containing resin and reinforcing material using a mold, The step of applying a model to the intermediate substrate that has anisotropy between the out-of-plane direction and the in-plane direction perpendicular to the out-of-plane direction, The process includes the step of calculating the viscosity distribution in the cross-sectional direction of a molded product using various viscosities corresponding to the flow field. The viscosity distribution indicates that, under boundary conditions where there is no flow slippage of the intermediate material at the wall surface of the mold, a shear field is generated near the wall surface, causing a low-viscosity layer to be automatically formed near the wall surface where the influence of out-of-plane shear viscosity is greater than in the central part of the intermediate material, and thus the intermediate material near the wall surface functions as a lubricating layer.

2. The molding analysis method according to claim 1, comprising the step that 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 the step of applying a flow field-dependent weighting function to the viscosity in the in-plane and out-of-plane directions of the model to calculate the 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 the orthogonal tensor decomposition of the strain rate tensor relating to the 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, and in-plane shear.

6. The viscosity in the in-plane direction of the aforementioned model is the in-plane viscosity, The molding analysis method according to claim 1, wherein 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.

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

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

9. A computer-readable recording medium having the program described in claim 8 recorded on it.

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