A rapid prediction method for curing deformation of resin-based composite components

Abstract

The present application relates to a kind of resin-based composite material member curing deformation fast prediction method, comprising the following steps: first modeling forming mould;Then the composite material member is simulated thermally-chemically, temperature load is applied to forming mould profile in stages: in the temperature distribution on the forming mould profile is uniform in the heat preservation stage, and in the heating stage and the temperature stage, then the temperature field of heating stage and temperature stage is obtained according to measured data;Finally, the composite material member after thermal-chemical simulation is analyzed thermally-mechanically, and the stress, strain and deformation of the composite material member are obtained.The present application simplifies simulation process, reduces simulation steps, improves prediction efficiency, can improve solving efficiency under the premise of ensuring prediction accuracy, provides basis for mould design and compensation.

Description

TECHNICAL FIELD

[0001] The application relates to a resin-based composite material component curing deformation rapid prediction method and belongs to the technical field of resin curing. BACKGROUND

[0002] At present, a hot press tank device is mainly used in the field of aviation and aerospace to cure and form resin-based composite material components. In the hot press tank curing and forming process of the composite material components, due to the temperature distribution change in the tank and the heat release effect of the resin curing reaction, temperature gradient distribution and residual stress inevitably occur in the components, resulting in component deformation and natural defects.

[0003] In order to improve the forming precision of the hot press tank curing process and reduce the structural deformation of the components, numerical simulation means are currently used to predict the forming precision of the composite material, so as to provide a basis for the design and compensation of the forming mold.

[0004] At present, the numerical simulation method is used to predict the curing deformation of the composite material, and a sequential coupling mode of flow field-thermochemistry-thermodynamics is usually used to simulate the curing and forming process. The hot press tank flow field analysis, composite material thermal-chemical analysis and thermal-mechanical analysis are sequentially performed, and finally the stress, strain and deformation of the composite material component are obtained. Among them, the flow analysis is to obtain the temperature distribution of the forming mold in the whole curing process. However, in the actual production process, the placement and state of the forming mold in the hot press tank cannot realize the same conditions as the numerical simulation, and the structure of the general frame type forming mold is relatively complex, which makes the simulation pre-processing work of the mold temperature field very large, accounting for more than 70% of the whole simulation calculation amount. Considering the derivation and import of the forming mold temperature field in the simulation process, the calculation time will also increase. Therefore, the analysis process of the numerical simulation using the sequential coupling mode is relatively complex and low in efficiency, and the time is long, and the simulation result cannot be quickly obtained.

[0005] In order to facilitate the verification of the curing effect of the resin-based composite material component during the mold design, how to quickly simulate the curing deformation of the resin-based composite material component becomes a problem to be solved. SUMMARY

[0006] The technical problem to be solved by the application is to provide a resin-based composite material component curing deformation prediction method which improves the efficiency on the premise of ensuring the prediction precision.

[0007] In order to solve the above technical problems, the technical scheme provided by the application is as follows: a resin-based composite material component curing deformation rapid prediction method, comprising the following steps:

[0008] Step one, modeling the forming mold, constructing the bottom surface of the composite component through the mold surface, and setting the ply information and material parameters of the composite component, and obtaining the composite component model through meshing.

[0009] Step two, thermal-chemical simulation of the composite component, during the thermal-chemical simulation, the mold surface and the bottom surface of the composite component adopt face-face contact, and the temperature load is applied to the forming mold surface in stages: in the holding stage, the temperature distribution on the forming mold surface is uniform, the temperature load applied to the forming mold surface is consistent with the temperature corresponding to the curing process curve, and 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 forming mold.

[0010] The method for obtaining the temperature field of the heating stage and the cooling stage according to the measured data is as follows: when curing and forming are carried out in the autoclave using the same curing process curve, 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 curve of each point on the forming mold surface in the heating stage and the cooling stage is calculated by interpolation.

[0011] Step three, thermal-mechanical analysis of the composite component after thermal-chemical simulation, to obtain the stress, strain and deformation of the composite component, and to complete the rapid prediction of the curing deformation of the resin-based composite component. The thermal-mechanical analysis process is prior art, which can be referred to relevant literature and will not be repeated here.

[0012] The present application aims at the defect that the temperature field simulation of the forming mold in the curing forming process is large in workload in the prior art, which usually adopts the sequential coupling mode of flow field-thermal chemistry-thermal mechanics, after the finite element model of the forming mold and the composite component is established, the simulation process only includes two steps of thermal-chemical analysis and thermal-mechanical analysis, wherein the temperature field applied to the forming mold is simplified in the thermal-chemical analysis, in the holding stage, the temperature distribution on the forming mold surface is uniform, and 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 surface is interpolated to give the mold an accurate temperature field, so as to calculate the temperature field of the composite component in the curing process, which is used to replace the flow field analysis in the autoclave in the prior art, thereby simplifying the simulation process, reducing the simulation steps, improving the prediction efficiency, and improving the solving efficiency under the premise of ensuring the prediction accuracy, providing basis for mold design and compensation.

[0013] In addition, the present application considers that the profile of the forming die directly contacts the bottom surface of the composite component, and the temperature of the profile of the forming die directly acts on the bottom surface of the composite component, which has a great influence on the curing and deformation of the composite component. Therefore, the frame type die used in the composite forming manufacturing is simplified, and only the die profile is reserved for calculation, so that the calculation time is effectively reduced, and the prediction efficiency is further improved. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 FIG. 1 is a schematic view of a forming die in an embodiment of the present application.

[0015] Figure 2 FIG. 2 is a schematic view of a composite component in an embodiment of the present application.

[0016] Figure 3 FIG. 3 is a schematic view of constraints during thermal-mechanical analysis.

[0017] Figure 4 FIG. 4 is a schematic view of the curing deformation result. DETAILED DESCRIPTION

[0018] The present application shows a resin-based composite component curing deformation fast prediction method to improve the simulation efficiency of the curing deformation of the composite component, which can provide support for the mold design of the composite material.

[0019] The resin-based composite component curing deformation fast prediction method of the present embodiment comprises the following steps:

[0020] Step one, modeling the forming die, constructing the bottom surface of the composite component through the die profile, and setting the ply information and material parameters of the composite component, and obtaining the composite component model through grid division; wherein the ply information includes the thickness, ply angle, material properties and laying area of each ply,

[0021] The material parameters include composite thermal performance parameters: mass density, specific heat, thermal conductivity, composite curing kinetics parameters: reaction order, activation energy and reaction frequency, thermal-mechanical related parameters of the matrix: Young's modulus, Poisson's ratio, thermal expansion coefficient, chemical induced shrinkage coefficient, gel point, thermal-mechanical related parameters of the fiber: Young's modulus, Poisson's ratio, thermal expansion coefficient and fiber volume fraction.

[0022] In order to simplify the calculation, as an embodiment, when modeling the forming die, the frame structure at the bottom of the forming die is removed, and only the die profile part is reserved.

[0023] The material of the forming die used in the present embodiment is A3 steel, and the main material parameters are shown in Table 1, and the grid division result of the forming die is shown in Figure 1 ​

[0024] Table 1 Material parameters of the mold

[0025]

[0026] Preferably, when building the model of the 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, 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 region by region; after all the 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 is an Ω-shaped component with a thickness of 1.6 mm, and there are eight symmetrically arranged plies, which are [0 / 45 / 0 / 45 / 45 / 0 / 45 / 0] respectively, and each ply has a thickness of 0.2 mm. The material used for the Ω-shaped composite component is ZT7H / 5429 composite material, and the material parameters of the composite material are shown in Tables 2-5, and the three-dimensional grid model of the composite component is shown in Figure 2 .

[0027] Table 2 Equivalent thermal performance parameters of the composite material

[0028]

[0029] Table 3 Curing kinetics parameters of the composite material

[0030]

[0031] Table 4 Thermo-mechanically related matrix material parameters

[0032]

[0033] Table 5 Thermo-mechanically related fiber material parameters

[0034]

[0035] Step two, define the boundary conditions on the forming mold model and the composite component model, and perform thermo-chemical simulation on the composite component. First, set the boundary conditions (in this embodiment, the boundary conditions include the initial temperature of the forming mold and the composite component, which is 20℃).

[0036] During the thermo-chemical simulation process, the mold surface and the bottom surface of the composite component adopt face-to-face contact, therefore, this embodiment applies temperature load to the forming mold surface in stages: in the holding stage, the temperature distribution on the forming mold surface is uniform, and the temperature load applied on the forming mold surface is consistent with the temperature corresponding to the curing process curve; while 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 forming mold.

[0037] The method for obtaining the temperature field of the heating stage and the cooling stage according to the measured data is as follows: when curing and forming are performed in the autoclave using the same curing process curve, the temperature change curves of the air inlet and the air outlet of the autoclave are measured by the thermocouples arranged in the autoclave, the temperature change curves of each point on the mold surface in the heating stage and the cooling stage are calculated by interpolation (preferably linear interpolation), that is, the temperature values of each point on the mold surface are calculated according to the distances of the points on the mold surface to the air inlet and the air outlet of the autoclave by interpolation, so as to create the temperature field of the entire mold surface, and finally the temperature field is applied to the mold surface as a temperature load. 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, and therefore linear interpolation can be used for calculation.

[0038] It should be noted that when the temperature change curves of the air inlet and the air outlet of the autoclave are measured by the thermocouples arranged in the autoclave, curing and forming can be performed using the same curing process curve, and the shape of the autoclave and the shape of the forming mold are not considered. Historical data of the autoclave can be used, or separate experiments can be performed for measurement. The applicant's experiments show that what is needed in the present application is the temperature difference between the windward end and the leeward end of the forming mold, and the shape of the autoclave and the shape of the forming mold have little effect on the simulation results, which can be ignored.

[0039] Preferably, in addition to measuring the temperature change curves of the air inlet and the air outlet of the autoclave, the temperature change curves of the middle part of the autoclave are also measured by the thermocouples, and the temperature change curves of each point on the mold surface in the heating stage and the cooling stage are calculated by the temperature change curves of the air inlet, the air outlet and the middle part of the autoclave.

[0040] Specifically, the curing process used by the composite component in this embodiment includes three stages: first, the temperature is raised to 150℃ at a rate of 2℃ / min, then the temperature is continuously raised to 180℃ at a rate of 1℃ / min after holding for 60min, then the temperature is raised to 200℃ at a rate of 1℃ / min after holding for 120min, and finally the temperature is naturally lowered to room temperature after holding for 300min, and then the autoclave is taken out.

[0041] Step three, performing thermal-mechanical analysis on the composite component after thermal-chemical simulation to obtain the stress, strain and deformation of the composite component, and completing the rapid prediction of the curing deformation of the resin-based composite component.

[0042] The thermal-mechanical analysis process is known in the art, including defining the contact and constraint of the mold and the component, mapping the results of the thermal-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, etc. Please refer to the relevant literature for details.

[0043] In order to make the composite component deform during the demolding deformation stage, but not to appear translation or overturning, preferably, the stiffness displacement of the composite component is limited. As shown in Figure 3 , three points on the same plane are selected, the stiffness displacement of the three directions is fixed at point A, the stiffness displacement of the Y and Z directions is fixed at point B, and the stiffness displacement of the Z direction is fixed at point C. The freedom of all other nodes is released during demolding.

[0044] The computer configuration for fast prediction in this embodiment is Intel Core i5-10400 CPU with 32 GB memory. In terms of prediction time, the total calculation time of 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. Compared with the prior art, the preset efficiency of this embodiment is increased by 75%, which is much higher than the method of the prior art. Considering that the grid division and other preprocessing steps during mold temperature field analysis also require a certain amount of time, the calculation efficiency of the prediction method of this embodiment is actually higher. The specific solidification deformation simulation results of this embodiment are shown in Figure 4 , the solidification deformation of the composite component is 5.96 mm, the actual test solidification deformation is 5.71 mm, the error between the simulation results and the test results is 4.03%, and the prediction accuracy can meet the requirements of mold design.

Claims

1. A method for rapidly predicting the curing deformation of a resin-based composite material component, comprising the following steps: Step 1: Remove the frame structure at the bottom of the forming mold, retain only the mold surface, model the forming mold, construct the bottom surface of the composite component through the mold surface, set the layup information and material parameters of the composite component, and obtain the composite component model through meshing; wherein the layup information includes the thickness, layup angle, material properties and layup area of ​​each ply; When constructing a composite component model, after setting the layup information of the composite component, the boundary line of each layup 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 multiple regions, and the two-dimensional grid of the layup is divided into each region; After all plies are laid up to generate a 2D mesh, the 3D mesh model of the composite component is obtained by stretching the 2D mesh; 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 mold surface in stages: in the insulation stage, the temperature distribution on the mold surface is uniform, and the temperature load applied to the mold surface is consistent with the temperature corresponding to the curing process curve; in the heating stage and the cooling stage, the temperature fields of the heating stage and the cooling stage are obtained based on the measured data and applied to the mold; The method for obtaining the temperature fields in the heating and cooling stages based on measured data is as follows: when performing curing molding in an autoclave using the same curing process curve, the temperature change curves at the air inlet and outlet of the autoclave are measured by thermocouples arranged in the autoclave, and the temperature change curves of each point on the molding die surface in the heating and cooling stages are calculated by interpolation; Step 3: Limit the rigid body displacement of the composite component. Select three points on the same plane of the composite component. The first point needs to fix the rigidity displacement in three directions. The second point is in the X direction of the first point. Only the rigidity 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. Only the rigidity 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. Thermo-mechanical analysis is performed on the composite material components after thermo-chemical simulation to obtain the stress, strain and deformation of the composite material components.

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 2, when the temperature fields in the heating stage and the cooling stage are obtained according to the measured data, linear interpolation is used for the interpolation.

3. The method for rapidly predicting 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 based on 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 also measured by a thermocouple. The temperature change curves of each point on the molding surface in the heating and cooling stages are calculated based on the temperature change curves of the autoclave at the air inlet, outlet and middle.

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