Design method and device for multilayer modeling of autoclave mold

Abstract

The invention relates to the technical field of composite autoclave processes, in particular to a design method and device for multi-layer modeling of an autoclave mold. The invention provides a design method and device for multi-layer modeling of an autoclave mold, and the method comprises the steps: constructing a double-layer autoclave simulation process model according to the working conditions of an autoclave and the physical parameters of the autoclave, and setting an autoclave molding process condition simulation field according to the molding process conditions of a composite material, simulating the double-layer autoclave simulation process model to obtain a multi-physical field simulation result and a composite material forming and curing curve; compared with a single shell adopted in the prior art, the double-layer autoclave simulation process model constructed by the invention can better meet the simulation requirements of a complex mold and a composite material hot pressing process, and on the other hand, compared with a single physical field and double-field coupling adopted in the prior art, the double-layer autoclave simulation process model can better meet the simulation requirements of the complex mold and the composite material hot pressing process. And setting an autoclave molding process condition simulation field to be closer to the coupling effect of each physical field in the actual hot pressing process.

Description

Technical Field

[0001] The present invention relates to the technical field of autoclave processes for composite materials, and particularly to a design method and device for multi-layer modeling of autoclave molds. Background Art

[0002] In today's industrial manufacturing field, especially in industries such as aerospace and high-end equipment manufacturing, the demand for high-performance composite components is increasing day by day. As a key device for producing high-quality composite products, the autoclave mold is subjected to the interaction of multiple physical fields such as temperature, pressure, and chemistry during the complex autoclave process. In the past, limited by computing power and simulation technology levels, the temperature field simulation and analysis of autoclave molds adopted a single-shell modeling method, and mostly focused on a single physical field or simple dual-field coupling. For example, when applying the flow field, the convective circulation in the actual structure was not considered; at the same time, only the influence of the temperature field on the thermal deformation of the mold was considered, while the change in the mechanical properties of the mold material caused by pressure changes and the feedback effect of the chemical heat generated during the material curing process on the overall temperature distribution were ignored; this one-sided simulation method led to the fact that in actual production, the molds designed based on the simulation results and the autoclave processes formulated could not adapt to the complex and changing multi-physical field environment. With the continuous emergence of new composite materials, these materials have more complex physical and chemical properties, and higher precision requirements for the autoclave forming process. At the same time, the product structure design is also developing towards lightweight, integrated, and multi-functional directions, which makes the structure of autoclave molds more complex; for example, molds with internal cooling channels and special-shaped structures have more significant coupling effects of various physical fields during the autoclave process.

[0003] On the other hand, the prior art discloses a method and system for simulating the thermal distribution of multiple workpieces loaded into an autoclave (publication number: CN119358357B). Among them, the method includes performing overall three-dimensional modeling to obtain a master model; dividing the geometric model of the multiple workpieces loaded into the autoclave to obtain multiple divided sub-regions; performing three-dimensional modeling on each sub-region to obtain multiple sub-models; performing mesh division on the master model; performing mesh division on the sub-models; importing the mesh-divided master model into a finite element simulation software to obtain the flow field results of the master model; according to the flow field results of the master model, obtaining the velocity vector and static pressure at the division interface of each sub-model; for each sub-model, importing the mesh-divided sub-model and the corresponding velocity vector and static pressure at the sub-model division interface into the finite element simulation software to obtain the flow field results of the sub-model; and then obtaining the temperature field of each sub-model. The solution provided by this invention can greatly reduce the processing difficulty of the overall flow field and temperature field.

[0004] However, the simulation technologies in the existing art cannot meet the simulation requirements of complex molds and the hot pressing process of composite materials. There is an urgent need for a comprehensive and accurate multi-physics field simulation method. In addition, under the general trend of pursuing high-efficiency production and cost control, enterprises expect to optimize the mold design and hot pressing process parameters in advance through accurate simulation analysis at the initial stage of product R & D, so as to reduce the trial-and-error cost and production cycle. However, due to the inability to accurately simulate the multi-physics field coupling effect, the existing autoclave mold simulation means are difficult to achieve this goal. Summary of the Invention

[0005] The object of the present invention is to overcome the problem that the simulation technologies in the existing art cannot meet the simulation requirements of complex molds and the hot pressing process of composite materials, and to provide a design method and device for multi-layer modeling of autoclave molds.

[0006] On the one hand, the present invention provides a design method for multi-layer modeling of autoclave molds, which specifically includes the following steps: S1. Construct a double-layer autoclave simulation process model according to the working conditions of the autoclave and the physical parameters of the autoclave; S2. Set the autoclave forming process condition simulation field according to the forming process conditions of the composite material, and perform simulation on the double-layer autoclave simulation process model to obtain the multi-physics field simulation results and the composite material forming and curing curve.

[0007] Preferably, before the S2, it is also necessary to construct a mold model according to the forming mold parameters of the composite material, and place the mold model in the double-layer autoclave simulation process model for simulation.

[0008] More preferably, before constructing the mold model, it is also necessary to set the modeling parameters of the autoclave and the forming process conditions of the composite material, and establish the temperature change relationship formula of the mold and the boundary condition formula of the mold.

[0009] Preferably, the autoclave forming process condition simulation field in the S2 needs to select the flow field environment according to the Reynolds number.

[0010] More preferably, based on the selected flow field environment, set the fluid inlet of the double-layer autoclave simulation process model at the position of the centrifugal impeller, and set the position of the fluid outlet at the positions of the cooler and the heat exchanger.

[0011] More preferably, according to the selected flow field environment, set the multi-physics field in combination with the working environment of the autoclave. The multi-physics field specifically needs to set the flow field simulation conditions, the solid-fluid heat transfer simulation conditions, and the multi-physics field coupling simulation conditions.

[0012] Further preferably, based on the multi-physical fields, mesh generation is performed on the double autoclave simulation process model and the mold model participating in the simulation, and a solver is set.

[0013] Further preferably, the multi-physical field simulation results of the double autoclave simulation process model and the mold model are obtained, and the results of the solver are processed using a mathematical model calculation module to obtain the composite material forming and curing curve.

[0014] Further preferably, based on the multi-physical field simulation results and the composite material forming and curing curve, an analysis is performed to select the placement position of the mold in the autoclave.

[0015] On the other hand, the present invention provides a design device for multi-layer modeling of an autoclave mold, including at least one processor and a memory communicatively connected to the at least one processor; the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the method described in any one of the above.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Compared with the single shell used in the prior art, the double autoclave simulation process model constructed by the present invention can better meet the simulation requirements of complex molds and the hot pressing process of composite materials. On the other hand, compared with the single physical field and dual-field coupling used in the prior art, the simulation field for setting the autoclave forming process conditions is closer to the coupling effect of each physical field in the actual hot pressing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a flowchart of a design method for multi-layer modeling of an autoclave mold in Embodiment 1.

[0018] Figure 2 It is a schematic diagram of the mold in Embodiment 1.

[0019] Figure 3 It is a schematic diagram of single-shell mold modeling in Embodiment 1.

[0020] Figure 4 It is a schematic diagram of multi-layer mold modeling in Embodiment 1.

[0021] Figure 5 It is a schematic diagram of composite material forming process environment modeling in Embodiment 1.

[0022] Figure 6 It is a schematic diagram of mesh generation in Embodiment 1.

[0023] Figure 7 It is a flowchart of the simulation process of the double autoclave simulation process model in Embodiment 1.

[0024] Figure 8 It is a schematic diagram of a design device for multi-layer modeling of an autoclave mold in Example 2. Specific embodiments

[0025] The present invention will be further described in detail below in conjunction with specific embodiments. However, this should not be construed as limiting the scope of the above-mentioned subject matter of the present invention to the following embodiments. Any technology implemented based on the content of the present invention belongs to the scope of the present invention.

[0026] In the description of the specific embodiments of the present invention, without special instructions, the expression terms indicating the orientation or positional relationship such as "upper", "lower", "left", "right", "center", "inner", "outer", etc. are all based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship when the invention product / device / equipment is usually used and placed. These terms of orientation or positional relationship are only for the convenience of describing the solution of the present invention or simplifying the description in specific embodiments, so as to facilitate technicians to quickly understand the solution, rather than indicating or implying that a specific device / component / element must have a specific orientation or be constructed and operated in a specific positional relationship. Therefore, it should not be construed as a limitation to the present invention.

[0027] In addition, if terms such as "horizontal", "vertical", "hanging", "parallel" appear, it does not mean that the corresponding device / component / element is required to be absolutely horizontal or vertical or hanging or parallel, but can be slightly inclined or have a deviation. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined. Or, it can be simply understood that the corresponding device / component / element is arranged in the directions of "horizontal", "vertical", "hanging", "parallel", etc., and can have an error / deviation of ±10% relative to the corresponding direction setting, more preferably within ±8%, more preferably within ±6%, more preferably within ±5%, more preferably within ±4%. As long as the corresponding device / component / element is within the error / deviation range, it can still play its role in the solution of the present invention.

[0028] In addition, the expressions such as "first", "second", "third", etc. in the terms are only used to distinguish the description of the same or similar components, and should not be construed as emphasizing or implying the relative importance of specific components.

[0029] In addition, in the description of the embodiments of the present invention, "several", "multiple", "a number of" represent at least 2. It can be any situation such as 2, 3, 4, 5, 6, 7, 8, 9, etc., and even can be more than 9.

[0030] In addition, in the description of the technical solution of the present invention, unless otherwise clearly specified / defined / restricted, when the terms "set", "installed", "connected", "linked", "provided with", "laid", "arranged" appear, they should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection. It can be connection means commonly used in the art such as welding, riveting, bolting, and threaded connection. Such a connection can be a mechanical connection, an electrical connection, or a communication connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components.

[0031] Embodiment 1 This embodiment proposes a design method for multi-layer modeling of an autoclave mold. The flowchart is as Figure 1 shown, and specifically includes the following steps: Step 1: Query the autoclave model and the process conditions of composite material hot pressing and forming, and set the autoclave modeling parameters and the process conditions of composite material forming. The schematic diagram of the mold is as Figure 2 shown.

[0032] Step 2: Establish the mold temperature change relationship formula and the mold boundary condition formula; The mold temperature change relationship formula is:

[0033] The mold boundary condition formula is:

[0034] In each relationship formula and formula: the effective diameter of the autoclave , the fluid density , the specific heat of the fluid , the thermal conductivity of the fluid the viscosity coefficient of the fluid , the thermal conductivity of the mold .

[0035] Step 3: Establish the mold model and the double-layer autoclave model according to the autoclave model and the process conditions of composite material forming, and at the same time simplify the model to eliminate chamfers, redundancy, and fill small holes; compared with the single-shell mold modeling (the schematic diagram is as Figure 3 shown) adopted by the traditional modeling method, the multi-layer mold modeling (the schematic diagram is as Figure 4 shown) adopted by the present invention can better adapt to the simulation of multi-physical fields, and at the same time the multi-layer mold modeling can also better realize the simulation of complex structure molds.

[0036] Among them, the model simplification specifically includes: removing unnecessary details, removing geometric features that have a minimal impact on the analysis results, such as tiny chamfers and small holes; at the same time, for small holes whose size is very small relative to the overall size of the part and whose influence on stress concentration can be ignored in this analysis, fill the small holes; check whether the model has geometric defects and repair the defects that may cause mesh generation failure or inaccurate analysis results.

[0037] Step 4: According to the autoclave composite material forming process, set the simulation field environment in combination with the actual working conditions of the autoclave. The schematic diagram of the composite material forming process environment modeling is as Figure 5 shown.

[0038] Step 5: Select a laminar flow simulation field or a turbulent flow simulation field according to the Reynolds number and the fluid flow situation. In this embodiment, a turbulent flow simulation field is selected, and the fluid inlet of the double-layer autoclave simulation process model is set at the position of the centrifugal impeller, and the position of the fluid outlet is set at the positions of the cooler and the heat exchanger.

[0039] Reynolds number formula:

[0040] In the formula: is the Reynolds number, a dimensionless number used to judge whether the flow is laminar or turbulent; is the fluid density; is the characteristic velocity of the fluid; is the characteristic length; is the fluid viscosity; is the kinematic viscosity.

[0041] Step 6: Set the multi-physical fields according to the actual working conditions of the autoclave and the requirements of the composite material forming process, and set the flow field simulation conditions, solid-fluid heat transfer simulation conditions, and multi-physical field coupling simulation conditions respectively. In this embodiment, turbulent flow simulation, solid-fluid heat transfer simulation, and non-isothermal fluid flow are selected.

[0042] Step 7: Set the steady-state and transient simulation field conditions respectively according to the simulation field formula, specifically including: Conjugate heat transfer steady-state formula:

[0043]

[0044] In the formula: is the density; is the specific heat capacity at constant pressure of the fluid; is the fluid velocity, indicating the distance the fluid moves per unit time; is the gradient of the heat flux density; is the internal heat source; is the heat conduction term; is the thermal conductivity; is the temperature gradient; is the heat flux density.

[0045] Steady-state conjugate heat transfer fluid formula:

[0046]

[0047]

[0048] In the formula: is the fluid density; is the specific heat capacity at constant pressure of the fluid; is the fluid velocity; is the temperature gradient; is the gradient of the heat flux density; is the internal heat source; is the phase change heat source; is the volume diffusion heat source; is the heat flux density; is the thermal conductivity; is the temperature; is the pressure; is the gas constant; Turbulent steady-state simulation field formula:

[0049]

[0050]

[0051]

[0052]

[0053]

[0054]

[0055]

[0056] In the formula: is the fluid density; is the fluid velocity; is the gradient operator; is the unit tensor; is the stress tensor; is the body force; is the dynamic viscosity; is the turbulent viscosity; is the velocity gradient tensor; is the transpose of the velocity gradient tensor; k is the turbulent kinetic energy; is the generation rate of turbulent kinetic energy; is the turbulent dissipation rate; is the Prandtl number of turbulent kinetic energy; is the Prandtl number of turbulent dissipation rate; and are model constants; is a model constant.

[0057] Conjugate heat transfer transient formula: [[ID=2T3]]

[0058]

[0059] In the formula: is the density; is the specific heat capacity; is the rate of change of temperature with time; is the fluid velocity; is the temperature gradient; is the heat flux density gradient; is the internal heat source; is the external heat source; is the thermal conductivity; is the heat flux density.

[0060] Conjugate heat transfer fluid transient formula:

[0061]

[0062]

[0063] In the formula: is the density; is the specific heat capacity; is the rate of change of temperature with time; is the fluid velocity; is the temperature gradient; is the heat flux density gradient; is the internal heat source; is the latent heat of phase change; is the heat caused by volume change; is the thermal conductivity; is the absolute pressure of the fluid; is the gas constant; is the temperature.

[0064] The heat source formula is:

[0065]

[0066] Wherein: is the total heat of the heat source; is the heat source intensity per unit volume; is the total power of the heat source; is the volume of the heat source.

[0067] Turbulent transient simulation field formula:

[0068]

[0069]

[0070]

[0071]

[0072]

[0073]

[0074]

[0075] Wherein: is the fluid density; is the fluid velocity; is the gradient operator; is the unit tensor; is the stress tensor; is the body force; is the dynamic viscosity; is the turbulent viscosity; is the turbulent kinetic energy; is the turbulent dissipation rate; is the Prandtl number of the turbulent kinetic energy; is the Prandtl number of the turbulent dissipation rate; is the production rate of the turbulent kinetic energy; and are model constants; is a model constant.

[0076] Step 8. Initial conditions and boundary conditions also need to be set in the multi-physics field setting, specifically including: Boundary condition formula: The boundary thermal insulation formula is:

[0077] Wherein: is the heat flux density in the boundary thermal insulation formula.

[0078] The heat source formula is:

[0079]

[0080] In the formula: is the total heat of the heat source; is the heat source intensity per unit volume; is the total power of the heat source; is the volume of the heat source.

[0081] Autoclave turbulent wall formula:

[0082]

[0083]

[0084]

[0085] In the formula: is the component of the fluid velocity in the wall normal direction; is the turbulent diffusion coefficient; is the fluid density; is the friction velocity; is the dimensionless velocity; is the component of the fluid velocity in the wall tangential direction; is the component of the turbulent kinetic energy gradient in the wall normal direction; is the turbulent dissipation rate; is the turbulent model constant; is the turbulent kinetic energy; is the turbulent diffusion coefficient; is the wall distance; is the dynamic viscosity of the fluid.

[0086] Turbulent flow continuity formula:

[0087]

[0088] In the formula: is the source point velocity; is the end point velocity; is the difference between the pressure and permeability at the end point; is the source point permeability; is the end point permeability; is the turbulent dissipation rate at the source point; is the turbulent dissipation rate at the end point.

[0089] Turbulent inlet formula:

[0090]

[0091]

[0092] Where: is the fluid velocity; is the reference speed; is the normal vector; is the reference speed; is the turbulent kinetic energy; is the turbulence length scale; is the turbulence model constant; is the turbulent dissipation rate; is the turbulent kinetic energy.

[0093] Turbulent outlet formula:

[0094]

[0095]

[0096] Where: For pressure; is the characteristic length; is a constant; is the normal vector; is the outlet pressure; is the reference pressure; is the tangent vector; For strain; is the gradient operator.

[0097] Transient formula for non-isothermal flow:

[0098] Where: is the transient heat flux density of non-isothermal flow; is the stress tensor; is the gradient operator; is the fluid velocity.

[0099] Step 9: Use finite element analysis method to simulate the system, divide the mesh according to the mold parameters, and set the solver at the same time. The mesh division diagram is as follows: Figure 6 shown.

[0100] The solver settings specifically include: setting the transient solver and the steady-state solver. When the autoclave has reached the set temperature and remains stable, and physical quantities such as the internal temperature field, flow field, and stress field do not change with time, the production information can be obtained by using the steady-state solver; during the heating process of the autoclave, from the initial temperature to the set temperature, physical quantities such as temperature, pressure, and structural deformation change with time, and the changes at different time points can be obtained by using the transient solver; during the solving process, the steady-state solving result can be used as the initial value of the transient state.

[0101] Step 10: Analyze the results according to the solver results to obtain the multi-physical field simulation results of the mold model and the double-layer autoclave simulation process model. In summary, the flow chart of the simulation process of the double-layer autoclave simulation process model is as Figure 7 shown; The obtained simulation results can be combined to change the placement direction of the mold model, and the above operations are repeated for the mold models in different placement directions to evaluate and obtain the optimal placement direction of the mold model.

[0102] The multi-physical field simulation method of the autoclave is applicable to various types of autoclaves.

[0103] The mathematical model calculation module can fit the relational expression into a curve to obtain the composite material forming and curing curve, and display the curve on the display.

[0104] Embodiment 2 As Figure 8 shown, a design device for multi-layer modeling of an autoclave mold includes at least one processor and a memory communicatively connected to the at least one processor; the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the design method of multi-layer modeling of an autoclave mold described in the foregoing embodiment. The input / output interface may include a display, a keyboard, a mouse, and a USB interface for inputting and outputting data; the power supply is used to provide electrical energy for the electronic device.

[0105] Those skilled in the art can understand that all or part of the steps of implementing the above method embodiments can be completed by hardware related to program instructions. The foregoing program can be stored in a computer-readable storage medium. When the program is executed, it executes the steps including the above method embodiments; and the foregoing storage medium includes: mobile storage devices, read-only memories (ROMs), magnetic disks, or optical discs and other various media that can store program codes.

[0106] When the above integrated units of the present invention are implemented in the form of software functional units and sold or used as independent products, they can also be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the embodiments of the present invention essentially or the part that contributes to the prior art can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the methods described in the various embodiments of the present invention. The foregoing storage medium includes: various media such as removable storage devices, ROMs, magnetic disks, or optical discs that can store program codes.

Claims

1. A design method for multi-layer modeling of autoclave molds, characterized in that Including: S1. Construct a double-layer autoclave simulation process model according to the working conditions of the autoclave and the physical parameters of the autoclave. S2. Set the autoclave forming process condition simulation field according to the forming process conditions of the composite material, and simulate the double-layer autoclave simulation process model to obtain the multi-physical field simulation results and the composite material forming and curing curve.

2. The design method of multi-layer modeling of an autoclave mold according to claim 1, characterized in that, Before S2, it is also necessary to construct a mold model according to the forming die parameters of the composite material, and place the mold model in the double-layer autoclave simulation process model for simulation.

3. A design method for multi-layer modeling of an autoclave mold according to claim 2, characterized in that Before constructing the mold model, it is also necessary to set the modeling parameters of the autoclave and the forming process conditions of the composite material, and establish the temperature change relationship formula of the mold and the boundary condition formula of the mold.

4. The design method for multi-layer modeling of an autoclave mold according to claim 1, characterized in that, The autoclave forming process condition simulation field in S2 needs to select the flow field environment according to the Reynolds number.

5. A design method for multi-layer modeling of an autoclave mold according to claim 4, characterized in that, Based on the selected flow field environment, set the fluid inlet of the double-layer autoclave simulation process model at the position of the centrifugal impeller, and set the position of the fluid outlet at the positions of the cooler and the heat exchanger.

6. The design method of multi-layer modeling of an autoclave mold according to claim 4, characterized in that, According to the selected flow field environment, set the multi-physical field in combination with the working environment of the autoclave. The multi-physical field specifically needs to set the flow field simulation conditions, the solid-fluid heat transfer simulation conditions, and the multi-physical field coupling simulation conditions.

7. A design method for multi-layer modeling of an autoclave mold according to claim 6, characterized in that, Based on the multi-physical field, perform mesh division on the double-layer autoclave simulation process model and the mold model participating in the simulation, and set the solver.

8. A design method for multi-layer modeling of an autoclave mold according to claim 7, characterized in that, Analyze the results of the solver to obtain the multi-physical field simulation results of the double-layer autoclave simulation process model and the mold model, and use the mathematical model calculation module to process the results of the solver to obtain the composite material forming and curing curve.

9. A design method for multi-layer modeling of an autoclave mold according to claim 8, characterized in that Based on the multi-physical field simulation results and the composite material forming and curing curve for analysis, select the placement position of the mold in the autoclave.

10. A design device for multi-layer modeling of an autoclave mold, characterized in that, Including at least one processor and a memory communicatively connected to the at least one processor; the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the method according to any one of claims 1 to 9.

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