Method and system for optimizing pore defects in forming of composite material containing multiple volatile matters

Abstract

The invention belongs to the related technical field of composite material curing forming, and discloses a pore defect optimization method and system in forming of a composite material containing multiple volatile matters. The method comprises the following steps: determining the types of volatile matters in the curing process of the composite material, material parameters of the volatile matters and a curing kinetic equation of the composite material; calculating critical curing pressure; obtaining a temperature curve and a curing degree curve in the curing process of the composite material; calculating the actual curing temperature of the composite material under the actual curing pressure, and calculating the actual curing time required for reaching the preset curing degree under the actual curing temperature; it is determined that when the actual curing pressure is smaller than or equal to the critical curing pressure, curing is carried out below the actual curing temperature, and when the actual curing time is larger than the time needed for reaching the preset curing degree, pores in the composite material forming process are minimum. According to the invention, the problem that pore defect optimization cannot be carried out under the condition of multiple volatile matters in compound curing molding is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field related to composite material curing and molding, and more specifically, relates to a method and system for optimizing pore defects in the molding of composite materials containing multi-volatiles. Background Art

[0002] Composite materials have the advantages of high specific strength, corrosion resistance, and fatigue resistance, and are widely used in aerospace and other fields. Porosity is a common defect in the composite material molding process, which affects the properties of composite materials such as strength and service life, and restricts the further development and application of composite materials.

[0003] At present, the mainstream method to reduce the porosity of composite materials is the trial and error method, which analyzes the relationship between pressure, temperature, vacuum degree and the porosity of the final composite component by conducting orthogonal tests. However, the above method has the following problems: 1) high time cost and high energy and material consumption; 2) only for a single material system, poor universality; 3) insufficient analysis of the pore formation process, making it difficult to accurately and quantitatively analyze the relationship between porosity and various factors.

[0004] The above problems can be avoided by controlling porosity through theoretical modeling and simulation analysis, but research on modeling the pore evolution process of composite materials is scarce, and the existing pore control theory only considers the influence of water vapor volatile pressure and ignores other volatiles. Therefore, a method for optimizing pore defects in composite materials with multiple gas sources is urgently needed. Summary of the invention

[0005] In view of the above defects or improvement needs of the prior art, the present invention provides a method and system for optimizing pore defects in the forming of composite materials containing multiple volatiles, which solves the problem that pore defect optimization cannot be performed in the case of multiple volatiles in the curing molding of composite materials.

[0006] To achieve the above object, according to one aspect of the present invention, a method for optimizing pore defects in forming a composite material containing multi-volatiles is provided, the method comprising the following steps:

[0007] Determining the types of volatiles during the curing process of the composite material, material parameters of the volatiles and the curing kinetic equation of the composite material;

[0008] A pore equilibrium growth model of a single volatile is constructed, and a total pore equilibrium growth model of the composite material is constructed using the pore equilibrium growth model of the single volatile. The critical curing pressure P is calculated using the material parameters of all volatiles and the total pore equilibrium growth model. 临 ;

[0009] The curing kinetics equation is used to simulate the curing process of the composite material to obtain the temperature curve and curing degree curve during the curing process of the composite material;

[0010] The total pore equilibrium growth model is used to calculate the actual solidification pressure P 实 The actual curing temperature T of the composite material 实 , combining the temperature curve and the curing degree curve to calculate the curing time t required to reach the preset curing degree at the actual curing temperature 实 ;

[0011] Therefore, the optimal conditions for the porosity in composite material molding are determined as follows:

[0012] When the actual curing pressure P 实 Less than or equal to the critical curing pressure P 临 At the actual curing temperature T 实 The curing time is greater than the curing time t required to reach the preset curing degree. 实 When the composite material is formed, the pores are minimal.

[0013] Further preferably, in the condition where the pores in the composite material are optimal, when the actual curing pressure P 实 Greater than the critical curing pressure P 临 When the composite material is formed, the porosity is minimized.

[0014] Further preferably, the curing kinetics equation is constructed by a DSC test method.

[0015] Further preferably, the types of the volatiles and the material parameters of the volatiles are obtained by analyzing the composite material using a gas chromatograph-gas spectrometer.

[0016] Further preferably, the material parameters of the volatiles include vapor enthalpy change, vapor temperature and vapor pressure of the volatiles.

[0017] Further preferably, the pore equilibrium growth model of the single volatile is as follows:

[0018]

[0019] Where P is the critical pressure; P 0 and T 0 are the vapor pressure and vapor temperature of the volatile components; ΔH Vap is the steam enthalpy change; RH 0 is the relative humidity of the volatile components; T is the actual temperature.

[0020] Further preferably, the total pore equilibrium growth model is as follows:

[0021] P 总 =∑P i

[0022] Among them, P总 is the total critical pressure, P i is the critical pressure of the ith volatile.

[0023] According to another aspect of the present invention, a computer-readable storage medium is provided, on which a computer program is stored, and when the computer program is executed by a processor, the method for optimizing pore defects in forming a composite material containing multi-volatiles is implemented as described above.

[0024] According to another aspect of the present invention, a system for optimizing pore defects in forming a composite material containing multi-volatiles is provided. The system includes an actuator for executing the above-mentioned method for optimizing pore defects in forming a composite material containing multi-volatiles.

[0025] According to another aspect of the present invention, a computer program product is provided, comprising a computer program or instructions, which, when executed by a processor, implements the above-mentioned method for optimizing pore defects in forming a composite material containing multi-volatiles.

[0026] In general, the above technical solutions conceived by the present invention have the following beneficial effects compared with the prior art:

[0027] 1. The present invention establishes a pore equilibrium growth model for multiple volatiles, derives the critical temperature condition for inhibiting pore growth under a certain external pressure, and combines it with the composite material curing simulation to obtain the insulation time under the temperature condition. The composite material is cured under the optimized temperature curve, and its porosity is the lowest, thereby solving the problem of pore defect optimization that cannot be performed in the case of multiple volatiles in the composite curing molding.

[0028] 2. The present invention constructs a pore equilibrium growth model of a single volatile, and then uses the single growth model to obtain the total pore equilibrium growth model of all volatiles. It can describe the multi-volatile pore growth mechanism during the composite material molding process, and calculate the critical pressure and critical temperature conditions that inhibit pore growth, providing a theoretical basis for pore control in composite material molding.

[0029] 3. The present invention proposes a method for coupling a multi-volatile pore equilibrium growth model with a composite material curing molding simulation. The critical temperature for inhibiting pore growth is obtained through a pore theoretical model. This temperature is used as a boundary condition of the simulation model to obtain a corresponding curing degree curve. This is beneficial for closely combining the theoretical model of pore equilibrium growth with the actual composite material molding process, providing a new perspective and reasonable reference for the design of composite material curing molding process. Compared with the repeated experimental method based on accumulating experience, this method has lower cost and higher efficiency.

[0030] 4. Based on the theoretical model and the molding simulation coupling method, the present invention optimizes the design of the curing molding temperature system curve of the composite material to address the problem of multi-volatile porosity. Through the optimized curing process curve, the porosity of the cured product can be effectively reduced, thereby achieving high-quality and stable manufacturing of composite material components. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a flow chart of a method for optimizing pore defects in forming a composite material containing multi-volatiles constructed according to a preferred embodiment of the present invention;

[0032] Figure 2 It is a schematic diagram of the critical pressure for preventing pore growth with respect to the moisture and acetone content constructed according to the preferred embodiment of the present invention;

[0033] Figure 3 It is a composite material molding temperature system curve after optimized design when the relative content of water and acetone is 50% constructed according to the preferred embodiment of the present invention;

[0034] Figure 4 The composite material molding temperature system curve after optimized design is constructed according to the preferred embodiment of the present invention when the relative content of water and acetone is 80%. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0036] like Figure 1 As shown, a method for predicting and optimizing pore defects in composite materials with multiple volatiles includes obtaining the volatile characteristics of composite components and gas material parameters, constructing a pore equilibrium growth model from multiple gas sources, simulating the molding and curing temperature field and curing degree of composite components, and optimizing the design of a thermal insulation platform for the composite material temperature system.

[0037] The following steps are involved:

[0038] S1: Use TGA, DSC and gas chromatography-mass spectrometry to measure the volatility characteristics and volatiles of the composite material, and obtain the physical properties of the volatile components and the resin curing kinetic equation;

[0039] In one embodiment of the present invention, the required parameters are obtained in the following manner:

[0040] Through DSC testing, the heat released during the composite material molding process is obtained, so as to establish the curing kinetic equation;

[0041] Through gas chromatography-mass spectrometry (GC-MS) testing, the composition and proportion of volatiles in the composite material molding process are obtained, compared with the preset mass fraction, the main volatiles are identified, and their enthalpy change, evaporation temperature and evaporation pressure are obtained.

[0042] In one embodiment of the present invention, the epoxy resin is tested by TGA, DSC and gas chromatography-mass spectrometry. It is clear that the main volatiles are water and acetone. The evaporation pressure of water is 1 atm, the evaporation temperature is 373K, and the enthalpy change is 75.34 kJ / mol; the evaporation pressure of acetone is 1 atm, the evaporation temperature is 329K, and the enthalpy change is 31.3 kJ / mol.

[0043] S2: Derivation of pore equilibrium growth model based on ideal gas law, diffusion law and Clapeyron equation;

[0044] In one embodiment of the present invention, the pore equilibrium growth model is constructed in the following manner:

[0045] Under high temperature conditions, volatiles evaporate from the composite material to form bubbles. When the internal pressure of the bubble is greater than the external pressure of the resin, the bubble grows steadily, eventually causing pores in the component. Taking water vapor as an example, bubble growth requires conditions, the diffusion law:

[0046] C H2O，∞ >C H2O，Bubble

[0047] In the formula, C H2O，∞ is the water concentration in the resin body far away from the bubble, C H2O，Bubble is the bubble water concentration.

[0048] The concentration of water dissolved in the resin, C, is proportional to the square of the relative humidity RH:

[0049]

[0050] ρ resin is the resin density, k 1 P is the parameter obtained by fitting the experiment. H2O and is the true vapor pressure and saturated vapor pressure at a certain temperature.

[0051] Rearranging the above inequalities, the bubble growth condition is:

[0052]

[0053] Among them, RH 0 is the resin humidity, P H2O is the actual pressure of the bubble at this temperature, is the saturated vapor pressure at this temperature. When the diffusion of water between the bubbles and the resin reaches a state of equilibrium, the resin pressure is approximately equal to the bubble pressure, that is: P H2O ≈P Resin .

[0054] Combining the Clausius-Clapeyron equation and the ideal gas law:

[0055]

[0056] PV=RT

[0057] The pore equilibrium growth model expression is obtained as follows:

[0058]

[0059] Where, P is the critical pressure; P 0 and T 0 is the vapor pressure and vapor temperature of the volatile component; △H Vap is the steam enthalpy change; RH 0 is the relative humidity of the volatile components; T is the actual temperature.

[0060] S3: Substitute the volatile component parameters into the above model to obtain the critical pressure criterion for inhibiting its pore growth;

[0061] Substituting the obtained material parameters into the pore equilibrium growth model, the critical criterion for preventing pore growth can be obtained.

[0062] The above formula only considers the pressure effect of a single volatile component. It is necessary to add the pressure criteria of multiple volatiles to obtain the criterion model of the common partial pressure of multiple volatiles in the composite material.

[0063] In this embodiment, the volatiles considered are water and acetone, and the pressure criterion model for preventing pore growth is:

[0064]

[0065] Where P is the critical pressure for pore formation; T is the actual temperature; RH 1 and RH 2 is the relative humidity of water and acetone.

[0066] In the above formula, when the critical pressure is 1, 3, 5, and 8 atm, the relationship between the temperature for preventing pore growth and the relative humidity of water and acetone can be obtained, such as Figure 2As shown. When the process parameters are below the curved surface, pores are not easy to grow. It is understandable that the higher the humidity of the volatiles or the smaller the applied external pressure, the lower the temperature is required to prevent pore growth. It is understandable that when the molding temperature exceeds the standard and the resin is still in a fluid state, pores are easily formed.

[0067] It can be seen that the modeling method of this embodiment is based on the material system and has a wider range of applicability, providing an effective path for predicting and controlling pore formation in composite material molding.

[0068] S4: Perform composite material curing molding simulation based on the resin curing kinetic equation to obtain the molding temperature field distribution and curing degree curve;

[0069] In the curing process of resin-based composite materials, the core parameters for the pore growth of the above-mentioned multi-volatiles are temperature, pressure, and volatile humidity. When the composite material is cured, it turns into a glassy state, and the pores no longer grow. Generally, 50% curing degree is taken as the critical moment. Molding pressure and volatile humidity are usually fixed process parameters. Therefore, the composite material curing molding simulation is carried out based on temperature and curing degree to obtain the temperature field distribution and curing degree curve.

[0070] A composite material model is established in the simulation software, composite material parameters and curing kinetic equations are input, the temperature system is loaded as boundary conditions, and the heat transfer analysis module is used to obtain the curing degree curve of the composite material under this temperature system.

[0071] S5: Based on the insulation platform temperature that prevents pore growth inferred from the model, combined with the composite material curing molding simulation to calculate the time to reach 50% curing degree at this temperature, the composite material molding temperature system can be optimized to achieve pore control.

[0072] In some embodiments, the pore defect prediction criterion model for composite materials with multiple gas sources can be applied as follows:

[0073] After the molding external pressure and volatile humidity are determined, the critical temperature for inhibiting pore growth is calculated. It can be understood that when the molding temperature of the composite material exceeds the critical temperature, pores are likely to grow.

[0074] It can be understood that the critical temperature is used as the first stage insulation platform temperature of the composite material molding, and the composite material curing molding simulation is used to calculate the time required to reach 50% curing degree at this temperature. It can be understood that this time is used as the first stage insulation platform time of the composite material molding. After reaching 50% curing degree, the resin has been transformed into a rubber state, pores are no longer formed, and the temperature can continue to rise to complete the composite material molding.

[0075] In this example, the external pressure for composite molding is 8 atm. When the relative humidity of water and acetone is 50%, the temperature of the insulation platform can be calculated to be 146°C and the insulation time is 0.8h. When the relative humidity of water and acetone is 80%, the temperature of the insulation platform can be calculated to be 126°C and the insulation time is 1.6h. Therefore, the temperature system curve after the optimization design is as follows: Figure 3 and Figure 4 As shown in the figure, when the applied pressure is smaller or the volatile humidity is higher, the temperature of the insulation platform needs to be lower to prevent the formation of pores; and when the temperature of the insulation platform is lower, a longer insulation time is required to complete the resin curing.

[0076] So far, the application of the pore prediction model for composite materials with multiple volatile components and the optimization of the temperature regime for composite curing molding have been completed. This method can optimize the first insulation platform for composite molding, prevent pore formation by adjusting the curing temperature, and provide guidance for pore control in composite component molding.

[0077] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for optimizing pore defects in forming a composite material containing multi-volatiles, characterized in that: The method comprises the following steps: Determining the types of volatiles during the curing process of the composite material, material parameters of the volatiles and the curing kinetic equation of the composite material; A pore equilibrium growth model of a single volatile is constructed, and a total pore equilibrium growth model of the composite material is constructed using the pore equilibrium growth model of the single volatile. The critical curing pressure P is calculated using the material parameters of all volatiles and the total pore equilibrium growth model. 临 ; The curing kinetics equation is used to simulate the curing process of the composite material to obtain the temperature curve and curing degree curve during the curing process of the composite material; The total pore equilibrium growth model is used to calculate the actual solidification pressure P 实 The actual curing temperature T of the composite material 实 , combining the temperature curve and the curing degree curve to calculate the curing time t required to reach the preset curing degree at the actual curing temperature 实 ; Therefore, the optimal conditions for the porosity in composite material molding are determined as follows: When the actual curing pressure P 实 Less than or equal to the critical solidification pressure P 临 At the actual curing temperature T 实 The actual curing time is greater than the curing time t required to reach the preset curing degree. 实 When the composite material is formed, the pores are minimal.

2. The method for optimizing pore defects in forming a composite material containing multi-volatiles according to claim 1, characterized in that: In the condition of optimal porosity in the composite material molding, when the actual curing pressure P 实 Greater than the critical curing pressure P 临 When the composite material is formed, the porosity is minimized.

3. A method for optimizing pore defects in forming a composite material containing multi-volatiles according to claim 1 or 2, characterized in that: The curing kinetics equation is constructed by DSC testing method.

4. A method for optimizing pore defects in forming a composite material containing multi-volatiles according to claim 1 or 2, characterized in that: The types of the volatiles and the material parameters of the volatiles are obtained by analyzing the composite material using a gas chromatograph-gas spectrometer.

5. The method for optimizing pore defects in forming a composite material containing multi-volatiles according to claim 1 or 2, characterized in that: The material parameters of the volatiles include vapor enthalpy change, vapor temperature and vapor pressure of the volatiles.

6. The method for optimizing pore defects in forming a composite material containing multi-volatiles according to claim 1, characterized in that: The pore equilibrium growth model of the single volatile is as follows: Where P is the critical pressure; P0 and T0 are the vapor pressure and vapor temperature of the volatile components, respectively; ΔH Vap is the steam enthalpy change; RH0 is the relative humidity of the volatile components; T is the actual temperature.

7. The method for optimizing pore defects in forming a composite material containing multi-volatiles according to claim 6, characterized in that: The total pore equilibrium growth model is as follows: P 总 =∑P i Among them, P 总 is the total critical pressure, P i is the critical pressure of the ith volatile.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method for optimizing pore defects in forming a composite material containing multi-volatiles as described in any one of claims 1 to 7 is implemented.

9. A system for optimizing pore defects in forming composite materials containing multi-volatiles, characterized in that: The system comprises an actuator, which is used to execute the method for optimizing pore defects in forming a composite material containing multi-volatiles as described in any one of claims 1-7.

10. A computer program product comprising a computer program or instructions, characterized in that When the computer program or instruction is executed by a processor, the method for optimizing pore defects in forming a composite material containing multi-volatiles as described in any one of claims 1 to 7 is implemented.

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