A method and system for optimizing pore defects in forming composite materials containing multi-volatiles

Abstract

The present invention belongs to the technical field related to composite material curing and molding, and discloses a method and system for optimizing pore defects in the molding of composite materials containing multiple volatiles. The method includes: determining the type of volatiles in the composite material curing process, the material parameters of the volatiles, and the curing kinetic equation of the composite material; calculating the critical curing pressure; obtaining the temperature curve and the curing degree curve during 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 to reach a preset curing degree at the actual curing temperature; thereby determining that when the actual curing pressure is less than or equal to the critical curing pressure, curing is performed below the actual curing temperature, and the actual curing time is greater than the time required to reach the preset curing degree, the composite material has the least pores during the molding process. The present invention solves the problem of being unable to optimize pore defects in the case of multiple volatiles in composite curing and molding.

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, with their high specific strength, corrosion resistance, and fatigue resistance, are widely used in aerospace and other fields. Porosity is a common defect in the composite molding process, affecting properties such as strength and service life, and thus restricting the further development and application of composite materials.

[0003] Currently, the mainstream method for reducing the porosity of composite materials is a trial-and-error approach. This involves conducting orthogonal experiments to analyze the relationship between factors such as pressure, temperature, and vacuum level and the porosity of the resulting composite component. However, this approach has the following limitations: 1) it is time-consuming and energy-intensive; 2) it only targets a single material system, making it difficult to universally apply; and 3) it lacks sufficient understanding of the pore formation process, making it difficult to accurately and quantitatively analyze the relationship between porosity and these factors.

[0004] Porosity control through theoretical modeling and simulation analysis can avoid these issues. However, research on modeling the pore evolution process in composite materials is scarce, and existing pore control theories only consider the influence of water vapor volatile pressure, ignoring 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 response to the above-mentioned defects or improvement needs of the prior art, the present invention provides a method and system for optimizing pore defects in the molding of composite materials containing multiple volatiles, which solves the problem that pore defect optimization cannot be performed when multiple volatiles are present during composite curing molding.

[0006] To achieve the above objectives, according to one aspect of the present invention, a method for optimizing pore defects in the molding of a composite material containing multivolatiles 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 a curing kinetic equation of the composite material;

[0008] A pore equilibrium growth model of a single volatile is constructed, and the 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 process of the composite material is simulated using the curing kinetics equation to obtain a temperature curve and a 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 solidification 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 minimized.

[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 solidification 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 chromatography-mass spectrometry (GC-MS).

[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 compound is as follows:

[0018]

[0019] Where P is the critical pressure; P0 and T0 are the vapor pressure and vapor temperature of the volatile component respectively; ΔH Vap is the steam enthalpy change; RH0 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 iis the critical pressure of the i-th volatile.

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

[0024] According to another aspect of the present invention, a system for optimizing porosity defects during the molding of a composite material containing multi-volatiles is provided. The system includes an actuator for executing the above-mentioned method for optimizing porosity defects during the molding of 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 the forming of 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. This 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 composite material curing simulation to derive the holding time under this temperature condition. When the composite material is cured under the optimized temperature curve, its porosity is minimized, thereby solving the problem of pore defect optimization that cannot be performed in the case of multiple volatiles during composite curing.

[0028] 2. The present invention constructs a pore equilibrium growth model for a single volatile compound and then uses this single growth model to obtain a total pore equilibrium growth model for all volatile compounds. This model can describe the pore growth mechanism of multiple volatile compounds during the composite material molding process and calculate conditions such as the critical pressure and critical temperature that inhibit pore growth, providing a theoretical basis for pore control during composite material molding.

[0029] 3. The present invention proposes a method for coupling a multi-volatile pore equilibrium growth model with composite material curing and molding simulation. The critical temperature for inhibiting pore growth is obtained through a theoretical pore model. This temperature serves as a boundary condition in the simulation model to obtain the corresponding curing degree curve. This method facilitates the close integration of the theoretical pore equilibrium growth model with the actual composite material molding process, providing a new perspective and reasonable reference for the design of composite material curing and molding processes. Compared with the iterative experimentation method based on accumulated experience, this method is less costly and more efficient.

[0030] 4. Based on a theoretical model and molding simulation coupling method, the present invention optimizes the design of the composite material curing molding temperature system curve to address the problem of multi-volatile porosity. The optimized curing process curve can effectively reduce the porosity of the cured product, 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 Schematic diagram of the critical pressure for preventing pore growth with respect to moisture and acetone content constructed according to a preferred embodiment of the present invention;

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

[0034] Figure 4 The optimized composite material molding temperature system curve 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 objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining 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 may 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 containing multiple volatiles is presented, including obtaining the volatility characteristics and gas material parameters of composite components, constructing a pore equilibrium growth model from multiple gas sources, simulating the forming 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 as follows:

[0040] Through DSC testing, the heat released during the composite molding process is obtained, thereby establishing the curing kinetics equation;

[0041] Through gas chromatography-mass spectrometry (GC-MS) testing, the composition and proportion of volatiles in the composite material molding process are obtained, and 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, an epoxy resin was subjected to TGA, DSC, and GC-MS analysis. The main volatile components were identified as water and acetone. Water had an evaporation pressure of 1 atm, an evaporation temperature of 373 K, and an enthalpy change of 75.34 kJ / mol. Acetone had an evaporation pressure of 1 atm, an evaporation temperature of 329 K, and an enthalpy change of 31.3 kJ / mol.

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

[0044] In one embodiment of the present invention, the pore equilibrium growth model is constructed as follows:

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

[0046] C H2O，∞ >C H2O，Bubble

[0047] Where C H2O，∞ is the water concentration in the resin body away from the bubble position, 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, k1 is the parameter obtained from the fitting experiment, P H2O and is the true vapor pressure and saturated vapor pressure at a certain temperature.

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

[0052]

[0053] Among them, RH0 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 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; P0 and T0 are the vapor pressure and vapor temperature of the volatile component; △H Vap is the steam enthalpy change; RH0 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. The pressure criteria of multiple volatiles need to be summed to obtain the criterion model for the common partial pressure of multiple volatiles in the composite material.

[0063] In this embodiment, the volatile substances 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; RH1 and RH2 are 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 2 As shown in the figure, when the process parameters are below the curved surface, pores are less likely to grow. It is understood that higher volatile humidity or lower applied external pressure require lower temperatures to prevent pore growth. It is also understood that when the molding temperature exceeds the standard and the resin is still in a fluid state, pores are more likely to form.

[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: Simulate the curing molding of composite materials based on the resin curing kinetics equation to obtain the molding temperature field distribution and curing degree curve;

[0069] During the curing process of resin-based composite materials, the core parameters for determining pore growth in the aforementioned multi-volatile components are temperature, pressure, and volatile humidity. During curing, the composite material transforms into a glassy state, where pore growth ceases. The critical point for this transition is typically 50% cure. Since molding pressure and volatile humidity are typically fixed process parameters, composite curing simulations are conducted focusing on these parameters to obtain the temperature field distribution and cure curve.

[0070] A composite material model is established in the simulation software, the composite material parameters and curing kinetics equation 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 calculated by 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 determining the molding external pressure and volatile humidity, the critical temperature for inhibiting pore growth is calculated. It can be understood that when the composite molding temperature exceeds this critical temperature, pores are likely to grow.

[0074] It is understood that the critical temperature is used as the first holding platform temperature during composite molding, and the time required to reach 50% cure at this temperature is calculated using composite curing simulation. It is understood that this time is the first holding platform time during composite molding. After reaching 50% cure, the resin has transformed into a rubbery state, pores no longer form, and the temperature can be continued to rise, completing composite molding.

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

[0076] This completes the application of a porosity prediction model for composite materials containing multiple volatile components and the optimization of the composite curing temperature regime. This method optimizes the thermal insulation platform during the first stage of composite molding and prevents porosity formation by adjusting the curing temperature, providing guidance for controlling porosity in composite component molding.

[0077] It will be easily understood by those skilled in the art that the above description is merely 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 scope of protection of the present invention.

Claims

1. A method for optimizing pore defects in the forming of composite materials 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 a curing kinetic equation of the composite material; A pore equilibrium growth model of a single volatile is constructed, and the 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 process of the composite material is simulated using the curing kinetics equation to obtain a temperature curve and a 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 pores in the composite material are the least during molding; The pore equilibrium growth model of the single volatile is as follows: in, is the critical pressure; and are the vapor pressure and vapor temperature of the volatile component, respectively; is the steam enthalpy change; is the relative humidity of volatile components; is the actual temperature; 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 i-th volatile.

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

3. The method for optimizing pore defects in forming a composite material containing multivolatiles according to claim 1 or 2, wherein: The curing kinetics equation is constructed by DSC testing method.

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

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

6. 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 the forming of a composite material containing multi-volatiles according to any one of claims 1 to 5 is implemented.

7. A system for optimizing pore defects in the forming of 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 the forming of a composite material containing multi-volatiles as claimed in any one of claims 1 to 5.

8. 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 the forming of a composite material containing multi-volatiles according to any one of claims 1 to 5 is implemented.

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