Rapid prediction method for curing deformation of resin-based composite material component

Abstract

The invention relates to a rapid prediction method for curing deformation of a resin-based composite material component. The method comprises the following steps: firstly, modeling a forming mold; secondly, thermal-chemical simulation is conducted on the composite material component, and temperature loads are applied to the molded surface of the forming mold in stages: in the heat preservation stage, the temperature distribution on the molded surface of the forming mold is uniform, and in the temperature rising stage and the temperature lowering stage, temperature fields of the temperature rising stage and the temperature lowering stage are obtained according to actual measurement data; and finally, carrying out thermo-mechanical analysis on the composite material component subjected to thermo-chemical simulation to obtain the stress, strain and deformation of the composite material component. According to the method, the simulation process is simplified, the simulation steps are reduced, the prediction efficiency is improved, the solving efficiency can be improved on the premise of ensuring the prediction precision, and a basis is provided for mold design and compensation.

Description

Technical Field

[0001] The invention relates to a method for quickly predicting curing deformation of a resin-based composite material component, and belongs to the technical field of resin curing. Background Art

[0002] At present, the aerospace field mainly uses autoclave equipment to cure and mold resin-based composite components. During the curing and molding process of composite components in the autoclave, due to the changes in temperature distribution in the tank and the exothermic effect of the resin curing reaction, temperature gradient distribution and residual stress will inevitably be generated inside the component, resulting in component deformation and natural defects.

[0003] In order to improve the molding accuracy of the autoclave curing process and reduce the structural deformation of the components, numerical simulation methods are now often used to predict the molding accuracy of composite materials, thereby providing a basis for the design and compensation of the molding mold.

[0004] At present, the numerical simulation method is used to predict the curing deformation of composite materials. The sequential coupling method of flow field, thermochemistry and thermodynamics is usually used to simulate the curing molding process. The autoclave flow field analysis, composite material thermo-chemical analysis and thermo-mechanical analysis are carried out in sequence to finally obtain the stress, strain and deformation results of the composite material components. Among them, the process analysis is to obtain the temperature distribution of the molding die during the entire curing process. However, in the actual production process, the placement and state of the molding die in the autoclave cannot achieve the same conditions as the numerical simulation, and the structure of the general frame molding die is relatively complex, which makes the simulation pre-processing workload of the mold temperature field very large, accounting for more than 70% of the total simulation calculation. Considering the export and import of the molding die temperature field during the simulation process, the calculation time will also increase. Therefore, the analysis process of numerical simulation using the sequential coupling method is relatively complex and inefficient, and it takes a long time and cannot quickly obtain simulation results.

[0005] In order to facilitate the verification of the curing effect of resin-based composite components during mold design, how to quickly simulate the curing deformation of resin-based composite components has become an urgent problem to be solved. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a method for predicting the curing deformation of a resin-based composite material component which improves efficiency while ensuring prediction accuracy.

[0007] In order to solve the above technical problems, the technical solution proposed by the present invention is: a method for quickly predicting the curing deformation of a resin-based composite material component, comprising the following steps: Step 1: Model the forming mold, construct the bottom surface of the composite component through the mold surface, set the ply information and material parameters of the composite component, and obtain the composite component model through mesh division; wherein the ply information includes the thickness, ply angle, material properties and covering area of ​​each layer.

[0008] Step 2, performing a thermal-chemical simulation on the composite component. During the thermal-chemical simulation, the mold surface and the bottom surface of the composite component are in surface-to-surface contact, and a temperature load is applied to the molding mold surface in stages: in the heat preservation stage, the temperature distribution on the molding mold surface is uniform, and the temperature load applied to the molding mold surface is consistent with the temperature corresponding to the curing process curve, and in the heating stage and the cooling stage, the temperature fields in the heating stage and the cooling stage are obtained according to the measured data and applied to the molding mold; The method for obtaining the temperature field in the heating stage and the cooling stage according to the measured data is as follows: when the same curing process curve is used in the autoclave for curing molding, the temperature change curves of the air inlet and the air outlet of the autoclave are measured by the thermocouple arranged in the autoclave, and the temperature change curves of each point on the molding die surface in the heating stage and the cooling stage are calculated by interpolation; Step 3: Perform a thermo-mechanical analysis on the composite material component after the thermo-chemical simulation to obtain the stress, strain and deformation of the composite material component, and complete the rapid prediction of the curing deformation of the resin-based composite material component. The thermo-mechanical analysis process is an existing technology, and relevant literature can be referred to, and no further description is given.

[0009] The present invention aims at the defect that the workload of simulating the temperature field of the forming mold during the curing molding process is large, which is usually simulated by the sequential coupling mode of flow field, thermochemistry and thermodynamics in the prior art. After the finite element model of the forming mold and the composite material component is established, the simulation process only includes two major steps: thermal-chemical analysis and thermal-mechanical analysis. Among them, when performing the thermal-chemical analysis, the temperature field applied to the forming mold is simplified. In the insulation stage, the temperature distribution on the molding surface of the forming mold is uniform. In the heating stage and the cooling stage, the required temperature field is calculated according to the measured data. Considering the non-uniformity of the mold temperature, the temperature of the mold is interpolated and an accurate temperature field is given to the mold. Therefore, the temperature field of the composite material component during the curing process is calculated to replace the flow field analysis in the autoclave in the prior art, thereby simplifying the simulation process, reducing the simulation steps, and improving the prediction efficiency. The solution efficiency can be improved under the premise of ensuring the prediction accuracy, and a basis for mold design and compensation is provided.

[0010] In addition, the present invention takes into account that the molding surface of the molding die is in direct contact with the bottom surface of the composite material component, and the temperature of the molding surface of the molding die directly acts on the bottom surface of the composite material component, which has a great influence on the curing and deformation of the composite material component. Therefore, the present invention simplifies the frame mold used in the molding and manufacturing of composite materials, and only retains the mold surface to participate in the calculation, thereby effectively reducing the calculation time and further improving the prediction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Schematic diagram of a molding die in an embodiment of the present invention.

[0012] Figure 2 Schematic diagram of a composite material component in an embodiment of the present invention.

[0013] Figure 3 Schematic diagram of constraints during thermo-mechanical analysis.

[0014] Figure 4 Schematic diagram of curing deformation results. DETAILED DESCRIPTION

[0015] The present invention shows a method for quickly predicting the curing deformation of a resin-based composite material component, so as to improve the simulation efficiency of the curing deformation of the composite material component and provide support for the mold design of the composite material.

[0016] The method for rapidly predicting the curing deformation of a resin-based composite material component of this embodiment includes the following steps: Step 1: Model the forming mold, construct the bottom surface of the composite component through the mold surface, set the ply information and material parameters of the composite component, and obtain the composite component model through mesh division; wherein the ply information includes the thickness, ply angle, material properties and paving area of ​​each layer, The material parameters include thermal performance parameters of composite materials: mass density, specific heat, thermal conductivity, composite material curing kinetic parameters: reaction order, activation energy and reaction frequency, matrix thermo-mechanical related parameters: Young's modulus, Poisson's ratio, thermal expansion coefficient, chemically induced shrinkage coefficient, gel point, fiber thermo-mechanical related parameters: Young's modulus, Poisson's ratio, thermal expansion coefficient and fiber volume fraction.

[0017] In order to simplify the calculation, as an implementation method, when modeling the forming mold, the frame structure at the bottom of the forming mold is removed, and only the mold surface portion is retained.

[0018] The material of the forming mold used in this embodiment is A3 steel. The main material parameters are shown in Table 1. The mesh division results of the forming mold are shown in Table 1. Figure 1 shown.

[0019] Table 1 Material parameters of the mold

[0020] Preferably, when constructing a model of a composite component, after setting the ply information of the composite component, the boundary line of each ply is projected onto the bottom surface of the composite component, and the projection of the boundary line on the bottom surface divides the bottom surface into multiple regions, and the two-dimensional grid of the ply is divided into regions; after all plies generate two-dimensional grids, the three-dimensional grid model of the composite component is obtained by stretching the two-dimensional grid. In this embodiment, the composite component adopts an Ω-shaped component with a thickness of 1.6 mm, and there are eight symmetrically arranged plies, namely [0 / 45 / 0 / 45 / 45 / 0 / 45 / 0], and each layer is 0.2 mm thick. The material used for the Ω-shaped composite component is ZT7H / 5429 composite material. The material parameters of the composite material are shown in Tables 2-5. The three-dimensional grid model of the composite component is shown in Tables 2-5. Figure 2 shown.

[0021] Table 2 Equivalent thermal performance parameters of composite materials

[0022] Table 3 Curing kinetic parameters of composite materials

[0023] Table 4 Thermo-mechanical related matrix material parameters

[0024] Table 5 Thermo-mechanical related fiber material parameters

[0025] Step 2: Define boundary conditions on the molding die model and the composite component model, perform thermal-chemical simulation on the composite component, and first set the boundary conditions (in this embodiment, the boundary conditions include that the initial temperature of the molding die and the composite component is 20°C).

[0026] During the thermal-chemical simulation process, the mold surface and the bottom surface of the composite material component are in surface-to-surface contact. Therefore, in this embodiment, the temperature load is applied to the molding mold surface in stages: in the insulation stage, the temperature distribution on the molding mold surface is uniform, and the temperature load applied to the molding mold surface is consistent with the temperature corresponding to the curing process curve; in the heating stage and the cooling stage, the temperature field of the heating stage and the cooling stage is obtained according to the measured data and applied to the molding mold.

[0027] The method for obtaining the temperature field in the heating stage and the cooling stage according to the measured data is as follows: when the same curing process curve is used in the autoclave for curing molding, the temperature change curve of the air inlet and outlet of the autoclave is measured by the thermocouple arranged in the autoclave, and the temperature change curve of each point on the molding mold surface in the heating stage and the cooling stage is calculated by interpolation (preferably linear interpolation), that is, the temperature value of each point on the mold surface is calculated according to the distance between the point on the mold surface and the air inlet and outlet of the autoclave, so as to create the temperature field of the entire mold surface, and finally apply this temperature field as a temperature load to the mold surface. This is because in the heating stage and the cooling stage, the air temperature in the actual autoclave is unevenly distributed, and there is a certain temperature difference between the windward end and the leeward end of the mold. The above method simulates this temperature difference. In order to simplify the calculation, it is assumed that the temperature distribution from the windward end to the leeward end of the mold is linear, so linear interpolation can be used for calculation.

[0028] It should be noted that when the temperature change curves of the air inlet and outlet of the autoclave are measured by the thermocouple arranged in the autoclave, it is sufficient to use the same curing process curve for curing and molding, and the shape of the autoclave and the shape of the molding mold are not considered. The historical data of the autoclave can be used, or a separate experiment can be conducted for measurement. The applicant's experiment shows that what is needed in this application is the temperature difference between the windward end and the leeward end of the molding mold, and the shape of the autoclave and the shape of the molding mold have little effect on the simulation results and can be ignored.

[0029] Preferably, in addition to measuring the temperature change curves of the autoclave at the air inlet and outlet, the temperature change curve of the middle part of the autoclave is also measured by a thermocouple, and the temperature change curves of each point on the molding surface of the molding die in the heating stage and the cooling stage are calculated by the temperature change curves of the autoclave at the air inlet, the air outlet and the middle part.

[0030] Specifically in this embodiment, the curing process used for the composite material component includes three stages. First, the temperature is raised to 150°C at a rate of 2°C / min, and kept warm for 60 minutes. Then, the temperature is raised to 180°C at a rate of 1°C / min, and kept warm for 120 minutes. Then, the temperature is raised to 200°C at a rate of 1°C / min, and kept warm for 300 minutes. Finally, the component is naturally cooled to room temperature before being taken out of the tank.

[0031] Step 3: Perform thermo-mechanical analysis on the composite material component after thermo-chemical simulation to obtain the stress, strain and deformation of the composite material component, and complete the rapid prediction of the curing deformation of the resin-based composite material component.

[0032] The thermo-mechanical analysis process is an existing technology, which includes defining the contact and constraints between the mold and the component, mapping the results of the thermo-chemical analysis to the grid of the composite component in a chained manner, obtaining the mechanical properties of each unit by combining the characteristic parameters of the unit, calculating the deformation of the composite component and other results, etc., and reference may be made to relevant literature, which will not be elaborated here.

[0033] In order to allow the composite material component to undergo solidification deformation without translation or flipping during the demoulding deformation stage, it is preferred to limit the stiffness displacement of the composite material component. Figure 3 As shown, three points on the same plane are selected, point A fixes the stiffness displacement in three directions, point B fixes the stiffness displacement in Y and Z directions, point C fixes the stiffness displacement in Z direction, and the degrees of freedom of all other nodes are released during demolding.

[0034] The computer configuration for the rapid prediction in this embodiment is Intel Core i5-10400 CPU and 32GB memory. In terms of prediction time, the total calculation time using the sequential coupling calculation method of the prior art is 2.4 hours, while the total calculation time of this embodiment is 0.58 hours. By comparison, the preset efficiency of this embodiment is improved by 75%, which is much higher than the method of the prior art. Considering that the pre-processing steps such as meshing during mold temperature field analysis still take a certain amount of time, the calculation efficiency of the prediction method of this embodiment is actually higher. For the specific curing deformation simulation results of this embodiment, see Figure 4 The curing deformation of the composite material component is 5.96 mm, and the curing deformation of the actual test is 5.71 mm. The error between the simulation result and the test result is 4.03%. The prediction accuracy can meet the requirements of mold design.

Claims

1. A method for quickly predicting the curing deformation of a resin-based composite material component, comprising the following steps: Step 1: Modeling the forming mold, constructing the bottom surface of the composite component through the mold surface, setting the ply information and material parameters of the composite component, and obtaining the composite component model through meshing; wherein the ply information includes the thickness, ply angle, material properties and paving area of ​​each layer; Step 2, performing a thermal-chemical simulation on the composite component. During the thermal-chemical simulation, the mold surface and the bottom surface of the composite component are in surface-to-surface contact, and a temperature load is applied to the molding mold surface in stages: in the heat preservation stage, the temperature distribution on the molding mold surface is uniform, and the temperature load applied to the molding mold surface is consistent with the temperature corresponding to the curing process curve, and in the heating stage and the cooling stage, the temperature fields in the heating stage and the cooling stage are obtained according to the measured data and applied to the molding mold; The method for obtaining the temperature field in the heating stage and the cooling stage according to the measured data is as follows: when the same curing process curve is used in the autoclave for curing molding, the temperature change curves of the air inlet and the air outlet of the autoclave are measured by the thermocouple arranged in the autoclave, and the temperature change curves of each point on the molding die surface in the heating stage and the cooling stage are calculated by interpolation; Step 3: Perform a thermo-mechanical analysis on the composite material component after the thermo-chemical simulation to obtain the stress, strain and deformation of the composite material component.

2. The method for rapidly predicting the curing deformation of a resin-based composite material component according to claim 1, comprising the following steps: In step 1, when modeling the forming mold, the frame structure at the bottom of the forming mold is removed, and only the mold surface part is retained.

3. The method for rapidly predicting curing deformation of a resin-based composite material component according to claim 1, comprising the following steps: In step 1, when constructing the composite component model, after setting the ply information of the composite component, the boundary line of each ply is projected onto the bottom surface of the composite component, the projection of the boundary line on the bottom surface divides the bottom surface into a plurality of regions, and the two-dimensional grid of the ply is divided into the regions; After all plies generate 2D meshes, the 3D mesh model of the composite component is obtained by stretching the 2D meshes.

4. The method for rapidly predicting the curing deformation of a resin-based composite material component according to claim 1, comprising the following steps: In step three, the rigid body displacement of the composite component is restricted, and three points of the composite component on the same plane are selected. The first point needs to fix the stiffness displacement in three directions, the second point is in the X direction of the first point, and only the stiffness displacement in the Y and Z directions needs to be fixed while allowing expansion in the X direction. The third point is in the Y direction of the second point, and only the stiffness displacement in the Z direction needs to be fixed while allowing expansion in the Y direction. The degrees of freedom of all other nodes are released during demoulding.

5. The method for rapidly predicting curing deformation of a resin-based composite material component according to claim 1, comprising the following steps: In step 2, when the temperature fields in the heating stage and the cooling stage are obtained according to the measured data, the interpolation adopts linear interpolation.

6. The method for rapidly predicting the curing deformation of a resin-based composite material component according to claim 1, comprising the following steps: When obtaining the temperature field in the heating and cooling stages according to the measured data, in addition to measuring the temperature change curves of the autoclave at the air inlet and outlet, the temperature change curve in the middle of the autoclave is measured by a thermocouple, and the temperature change curves of each point on the molding surface in the heating and cooling stages are calculated through the temperature change curves of the autoclave at the air inlet, outlet and middle.

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