A method for testing r-angle out-of-tolerance of a prepreg member

Abstract

This disclosure provides a method for testing the radius (R) deviation of prepreg components. The method includes: determining the viscosity-related value of the resin under test within a preset temperature range; determining the target R-angle deviation of the prepreg component under test based on the mapping relationship between the viscosity-related value and the R-angle deviation, and the viscosity-related value itself; wherein the prepreg component under test is prepared from the resin under test. In this method, a mapping relationship is established between the viscosity-related value of the resin under test and the R-angle deviation of the prepreg component. Therefore, during the testing process, only the viscosity-related value of the resin used to prepare the prepreg component needs to be tested within a preset temperature range to quickly predict the target R-angle deviation of the prepreg component, avoiding the inefficient operation of measuring the R-angle at each point on the prepreg component. Furthermore, it can provide guidance and reminders to operators, allowing for timely adjustments to the prepreg component's production process or resin component formulation.

Description

Technical Field

[0001] This disclosure relates to the field of composite materials, and in particular to a method for testing the R-angle deviation of prepreg components. Background Technology

[0002] The application of prepregs in aircraft is gradually increasing, and some aircraft even have their main load-bearing structures entirely made of prepregs. However, the manufacturing process characteristics of prepreg-molded parts can lead to variations in thickness across different structures, and significant differences can impact safety. A typical example is out-of-tolerance thickness of the radius (R) corner of parts.

[0003] Currently, the thickness deviation of prepregs during the molding process is defined using the term "flowability." Flowability refers to the degree to which the resin flows due to high temperature during the curing process, before the resin components rise from room temperature to the gel point temperature. Summary of the Invention

[0004] To address the problems existing in related technologies, this disclosure provides a method for testing the R-angle deviation of prepreg components, the testing method comprising: Determine the viscosity-related values ​​of the resin under test within the preset temperature range; Based on the mapping relationship between viscosity correlation value and R-angle deviation, and the viscosity correlation value, the target R-angle deviation of the prepreg component to be tested is determined; The prepreg component to be tested is made from the resin to be tested.

[0005] In some embodiments of this disclosure, determining the viscosity-related value of the resin to be tested within a preset temperature range includes: Obtain the viscosity-temperature relationship curve of the resin under test within a preset temperature range; Based on the viscosity-temperature relationship curve, the viscosity-related value is determined according to the viscosity value corresponding to each temperature point.

[0006] In some embodiments of this disclosure, the viscosity-temperature relationship curve is used to determine the viscosity-related value based on the viscosity value corresponding to each temperature point, including: Based on the viscosity-temperature relationship curve, the viscosity-related value is determined by integral method based on the viscosity value corresponding to each temperature point.

[0007] In some embodiments of this disclosure, the testing method further includes: Provide a preset type of sample resin, and obtain the sample viscosity-temperature relationship curve of each sample resin within the preset temperature range; Based on the sample viscosity-temperature relationship curve, determine the sample viscosity correlation value of the sample resin within the preset temperature range.

[0008] In some embodiments of this disclosure, the testing method further includes: The R-angle of each sample prepreg component was found to be out of tolerance; the sample prepreg components were prepared from the sample resins. Based on the viscosity correlation values ​​and R-angle deviations of each sample, a mapping relationship between the viscosity correlation values ​​and R-angle deviations is established.

[0009] In some embodiments of this disclosure, the testing method further includes: Sample prepreg is prepared using the sample resin and fiber; The sample prepreg is laid in a preset number of layers according to a preset rule, and then hot-pressed and cured to obtain the sample prepreg component.

[0010] In some embodiments of this disclosure, the preset temperature range is 100~180℃.

[0011] In some embodiments of this disclosure, the R-angle deviation includes positive R-angle deviation and negative R-angle deviation; The mapping relationship between the viscosity correlation value and the R-angle deviation includes the mapping relationship between the first viscosity correlation value and the positive R-angle deviation, and the correlation relationship between the second viscosity correlation value and the negative R-angle deviation.

[0012] In some embodiments of this disclosure, the mapping relationship between the first viscosity-related value and the deviation of the positive radius (R-angle) is expressed by the following formula:

[0013] in, x 1 represents the first viscosity-related value. y 1 indicates that the positive radius (R) is out of tolerance. <0, >0; The mapping relationship between the second viscosity correlation value and the deviation of the negative radius (R-angle) is expressed by the following formula:

[0014] in, x 2 represents the second viscosity-related value. y 2 indicates that the negative radius (R) is out of tolerance. >0, <0.

[0015] In some embodiments of this disclosure, the radius of the positive R-angle is R5~R9, and the radius of the negative R-angle is R7~R11.

[0016] The beneficial effects of this disclosure include, but are not limited to: In the method for testing the radius (R) deviation of prepreg components provided by this disclosure, a mapping relationship is established between the viscosity correlation value of the resin to be tested and the R-angle deviation of the prepreg component. Therefore, during the testing process, only the viscosity correlation value of the resin used to prepare the prepreg component needs to be tested within a preset temperature range to quickly predict the target R-angle deviation of the prepreg component, avoiding the inefficient operation of measuring the R-angle point by point on prepreg components with complex shapes. Furthermore, since the target R-angle deviation of the prepreg component can be predicted directly based on the viscosity correlation value of the resin to be tested, if the predicted target R-angle deviation exceeds the specified value, it can provide guidance and reminders to operators. For example, operators can adjust the production process of the prepreg component or the formulation of the resin components in a timely manner, without needing to wait until the prepreg component is fully cured before measuring the R-angle deviation.

[0017] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present disclosure and, together with the description, serve to explain the principles of these embodiments. In these drawings, similar reference numerals are used to denote similar elements. The drawings described below are some embodiments of the present disclosure, but not all embodiments. Other drawings will be readily available to those skilled in the art based on these drawings without inventive effort.

[0019] Figure 1 A flowchart of a method for testing the R-angle deviation of a prepreg component according to an exemplary embodiment of this disclosure; Figure 2 Flowchart of a method for testing the R-angle deviation of a prepreg component, which is another exemplary embodiment of this disclosure; Figure 3 This is a graph showing the change in viscosity of the resin component with temperature in an exemplary embodiment of this disclosure. Figure 4a This is a graph showing the correlation between the deviation of the positive radius (R-angle) and the viscosity at 85°C in an exemplary embodiment of this disclosure. Figure 4b This is a graph showing the correlation between the deviation of the negative radius (R-angle) and the viscosity at 85°C in an exemplary embodiment of this disclosure. Figure 5 A viscosity-temperature relationship graph of an exemplary embodiment of this disclosure; Figure 6 Flowchart of a method for testing the R-angle deviation of a prepreg component, which is another exemplary embodiment of this disclosure; Figure 7Flowchart of a method for testing the R-angle deviation of a prepreg component, which is another exemplary embodiment of this disclosure; Figure 8 Flowchart of a method for testing the R-angle deviation of a prepreg component, which is another exemplary embodiment of this disclosure; Figure 9 This is a schematic diagram illustrating the mapping relationship between a first viscosity-related value and the deviation of the positive radius (R-angle) in an exemplary embodiment of this disclosure. Figure 10 This is a schematic diagram illustrating the mapping relationship between the second viscosity-related value and the deviation of the negative radius (R-angle) in an exemplary embodiment of this disclosure. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this disclosure clearer, the technical solutions of this disclosure will be clearly and completely described below in conjunction with the embodiments of this disclosure. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this disclosure can be arbitrarily combined with each other.

[0021] There are two main types of methods for characterizing the flowability of prepregs in related technologies. The first type is direct characterization: using prepregs to manufacture typical parts, the flowability is directly characterized by deviations in the radius (R) thickness of the parts. The second type is indirect characterization: using the national standard GB / T 32788.2-2016 "Test Methods for Prepreg Performance Part 2: Determination of Resin Flowability" to characterize uncured prepregs with the extruded resin weight after hot pressing as a reference index. However, the first type of direct characterization method has low feasibility in practical applications, especially when large-scale resin flowability verification is required in resin formulation development. This necessitates a large amount of resin for prepreg production, typical part placement, curing, and testing, significantly increasing material, equipment, and personnel costs and expanding the workflow. The second type of indirect characterization method, based on practical experience, can only serve as a batch-to-batch stability control indicator for prepregs with different resin systems or formulations. It fails to demonstrate correlation for prepregs with different resin systems or formulations, thus lacking universality.

[0022] Based on this, this disclosure provides a method for testing the radius (R) deviation of prepreg components. In this method, a mapping relationship is established between the viscosity correlation value of the resin to be tested and the R-angle deviation of the prepreg component. Therefore, during the testing process, only the viscosity correlation value of the resin used to prepare the prepreg component needs to be tested within a preset temperature range to quickly predict the target R-angle deviation of the prepreg component, avoiding the inefficient operation of measuring the R-angle point by point on prepreg components with complex shapes. Furthermore, since the target R-angle deviation of the prepreg component can be directly predicted based on the viscosity correlation value of the resin, if the predicted R-angle deviation exceeds the specified value, it can provide guidance and reminders to operators. For example, operators can adjust the production process of the prepreg component or the formulation of the resin components in a timely manner, without needing to wait until the prepreg component is fully cured before measuring the R-angle deviation.

[0023] An exemplary embodiment of this disclosure provides a method for testing the R-angle deviation of a prepreg component, such as... Figure 1 As shown, the test method includes: S100. Determine the viscosity-related value of the resin to be tested within a preset temperature range. The prepreg component to be tested is made from the resin to be tested.

[0024] S200. Based on the mapping relationship between viscosity correlation value and R-angle deviation, and the viscosity correlation value, determine the target R-angle deviation of the prepreg component to be tested.

[0025] The quality of the R-angle forming of prepreg components is related to the fluidity of the resin components in the prepreg during the curing process. The viscosity index of the resin components characterizes the relative mobility of the resin components at a certain temperature and is related to the fluidity of the resin components.

[0026] The R-angle deviation testing method for prepreg components provided in this embodiment establishes a mapping relationship between the viscosity correlation value of the resin under test and the R-angle deviation of the prepreg component under test. Therefore, during the testing process, only the viscosity correlation value of the resin used to prepare the prepreg component under test within a preset temperature range needs to be tested to quickly predict the target R-angle deviation of the prepreg component under test, avoiding the inefficient operation of measuring the R-angle at each point on a prepreg component with a complex shape. In addition, since the target R-angle deviation of the prepreg component under test can be predicted directly from the viscosity correlation value of the resin under test, if the predicted R-angle deviation exceeds the specified value, it can provide guidance and reminders to operators. For example, operators can adjust the production process of the prepreg component or the formulation of the resin components in a timely manner, without having to wait until the prepreg component under test is fully cured before measuring the R-angle deviation.

[0027] In an exemplary embodiment, in step S100, the viscosity-related value of the resin to be tested within a preset temperature range is determined, such as... Figure 2As shown, it includes: S110. Obtain the viscosity-temperature relationship curve of the resin to be tested within the preset temperature range.

[0028] S120. Based on the viscosity-temperature relationship curve, determine the viscosity-related values ​​according to the viscosity value corresponding to each temperature point.

[0029] The curing of prepregs typically occurs over a wide temperature range, and during the curing process, the viscosity of the resin components undergoes complex changes, for example... Figure 3 The curve shown illustrates the change in viscosity of the resin component as temperature increases, initially decreasing and then increasing. Figure 3 In the viscosity-temperature curve, the horizontal axis represents temperature in °C, and the vertical axis represents viscosity in Pa·s. However, using only the viscosity at one or a few temperature points in the viscosity-temperature curve to characterize the flowability of the prepreg (or resin component) is not realistic, because the prepreg (or resin component) exhibits flow behavior at every temperature point within the curing temperature range.

[0030] In this embodiment, the viscosity-temperature relationship curve of the resin to be tested within a preset temperature range is obtained for preparing the prepreg component to be tested. Based on the viscosity-temperature relationship curve and the viscosity value corresponding to each temperature point, all viscosity values ​​within the preset temperature range are integrated to characterize the flowability of the prepreg (or resin component) as a whole index, and the viscosity correlation value is determined. This can comprehensively reflect the rheological characteristics of the resin to be tested at different temperatures and its contribution to the molding of the prepreg component to be tested, making the obtained viscosity correlation value and the established mapping relationship between the viscosity correlation value and the R-angle deviation more accurate and reliable.

[0031] In an exemplary embodiment, step S120, based on the viscosity-temperature relationship curve and the viscosity value corresponding to each temperature point, determines a viscosity-related value, including: Based on the viscosity-temperature relationship curve, viscosity-related values ​​are determined by integral method based on the viscosity value corresponding to each temperature point.

[0032] As mentioned above, characterizing the flowability of prepreg (or resin component) using only the viscosity at one or a few temperature points in the viscosity-temperature curve is unrealistic, as the prepreg (or resin component) exhibits flow behavior at every temperature point within the curing temperature range. In this embodiment, based on the viscosity-temperature curve, a viscosity correlation value is determined by integrating the viscosity value corresponding to each temperature point. This comprehensively reflects the rheological characteristics of the resin under test at different temperatures and its contribution to the molding of the prepreg component, making the obtained viscosity correlation value and the established mapping relationship between the viscosity correlation value and the R-angle deviation more accurate and reliable.

[0033] In the prepreg production process, viscosity-temperature curves are generally used to obtain viscosity values ​​related to production temperature parameters, and to determine the temperature range for coating and impregnation processes. A common example is viscosity at 85℃. A set of prepregs is produced using resins with significantly different viscosity-temperature curves. Typical parts are then manufactured from this set of prepregs. Finally, the radius (R) corner thickness of typical parts prepared from different resins is measured to determine any deviations in R-corner thickness. A correlation analysis is then performed between the 85℃ viscosity of this set of resins and the inner and outer R-corners of the parts. Figure 4a and Figure 4b As shown. Among them, Figure 4a In the figure, the vertical axis represents the deviation of the positive radius (R-angle), in percentage, and the horizontal axis represents the viscosity at 85℃, in Pa·s. Figure 4b Neutralization, the vertical axis represents the deviation of the negative radius (R-angle), in percentage, and the horizontal axis represents the viscosity at 85℃, in Pa·s. Figure 4a and Figure 4b It can be seen that the correlation between the excess tolerance of the positive and negative radius (R-angle) and the viscosity at 85℃ is poor. Around the same viscosity value, the R-angle excess varies greatly; even around the same R-angle excess value, different degrees of viscosity are observed. Therefore, simply using the resin viscosity at a certain temperature point as a characterizing index of the prepreg's flowability is ineffective.

[0034] In the curing of prepregs, taking a common high-temperature epoxy resin system as an example, the curing process generally involves raising the temperature from room temperature to 180°C at a certain rate, and then holding it at that temperature for a certain time for curing. For example, through... Figure 3 The viscosity-temperature relationship curve of the resin component shows that the viscosity of the resin component generally decreases gradually from room temperature to 180℃. This indicates that the viscosity of the resin component varies considerably at each temperature point from room temperature to 180℃. Different viscosities indicate different flow states of the resin at different temperature points; theoretically, the lower the viscosity, the faster the resin flows. Furthermore, identifying the low viscosity range of the resin component allows for a more accurate correlation with the flowability of the prepreg.

[0035] The viscosity-temperature curve obtained from viscosity testing instruments uses a logarithmic ordinate, which cannot accurately reflect the actual viscosity trend. To improve this, the raw data from the viscosity-temperature curve obtained from a viscosity testing instrument, such as a rotational rheometer, can be exported and plotted using a conventional coordinate system. Figure 5 As shown. Figure 5 The horizontal axis represents temperature in °C, and the vertical axis represents viscosity in Pa·s. From Figure 5 As can be seen from the curve, the viscosity-temperature relationship of the resin component, as shown on the conventional coordinate axis, reveals the following trend in the viscosity of the resin component with temperature: from room temperature to 180℃, the viscosity of the resin component decreases logarithmically, as follows... Figure 5The conventional reference viscosity region 10, shown near 80°C, eventually plateaus at a relatively low viscosity around 100°C, forming the low viscosity region 20, until 180°C and above. Therefore, the viscosity in this 100~180°C range is closer to characterizing the flowability of the prepreg.

[0036] In one exemplary embodiment, the preset temperature range is 100~180°C.

[0037] As mentioned above, the viscosity of the resin component exhibits a stable range within the temperature range of 100~180℃. Below 100℃, the resin component has not yet fully flowed, while above 180℃, the resin component has typically begun to solidify, resulting in higher viscosity. Therefore, in this embodiment, the preset temperature range is defined as 100~180℃. This means that within this preset temperature range, the viscosity-related value of the resin to be tested is determined, and a mapping relationship between the viscosity-related value and the R-angle deviation is established. This allows for a more accurate characterization of the prepreg's flowability, enabling more precise prediction of the target R-angle deviation of the prepreg component under test.

[0038] In one exemplary embodiment, such as Figure 6 As shown, the test method for R-angle deviation of prepreg components also includes: S300: Provides a preset type of sample resin and obtains the sample viscosity-temperature relationship curve of each sample resin within a preset temperature range.

[0039] S400. Based on the sample viscosity-temperature relationship curve, determine the sample viscosity correlation value of the sample resin within the preset temperature range.

[0040] In this embodiment, to establish the mapping relationship between viscosity correlation values ​​and R-angle deviation, a preset type of sample resin is first selected. Following the same method as obtaining the viscosity-temperature relationship curve of the resin under test within a preset temperature range, the viscosity-temperature relationship curves of each sample resin within the preset temperature range are obtained. Based on each sample viscosity-temperature relationship curve, the sample viscosity correlation value of each sample resin within the preset temperature range is determined by integration. For example, the preset types of sample resin can be 8 to 30, in order to establish a mapping relationship between viscosity correlation values ​​and R-angle deviation covering a wide range of viscosity correlation values.

[0041] In one exemplary embodiment, such as Figure 7 As shown, the test method for R-angle deviation of prepreg components also includes: S500, Test the sample R-angle deviation of each sample prepreg component. The sample prepreg components are made from the sample resin.

[0042] S600. Based on the viscosity correlation values ​​and R-angle deviations of each sample, establish a mapping relationship between viscosity correlation values ​​and R-angle deviations.

[0043] In this embodiment, sample prepreg components are prepared from each sample resin according to the preparation method of the prepreg component to be tested. A magnetic thickness gauge is used to test the radius (R-angle) deviation of each sample prepreg component. Based on the viscosity correlation value and the R-angle deviation of each sample, a mapping relationship between the viscosity correlation value and the R-angle deviation can be established. For example, the viscosity correlation value and the R-angle deviation of each sample can be fitted to establish a mapping relationship. Through this mapping relationship, in subsequent R-angle deviation testing of prepreg components, only the viscosity correlation value of the resin used to prepare the prepreg component needs to be tested within a preset temperature range to quickly predict the R-angle deviation of the prepreg component to be tested, thus achieving quantitative prediction of the R-angle deviation of the prepreg component to be tested.

[0044] In one exemplary embodiment, such as Figure 8 As shown, the test method for R-angle deviation of prepreg components also includes: S700: Sample prepreg is prepared using sample resin and fiber.

[0045] S800. Lay the sample prepreg in a preset number of layers according to a preset rule, and heat-press to cure, to obtain the sample prepreg component.

[0046] In this embodiment, according to the preparation method of the prepreg component to be tested, each sample prepreg is prepared using sample resin and fiber (e.g., carbon fiber). Each sample prepreg is then laid in a preset number of layers (consistent with the laying rules in the preparation process of the prepreg component to be tested) according to a preset rule (consistent with the laying number in the preparation process of the prepreg component to be tested), and then hot-pressed and cured (under the same hot-pressing curing conditions as in the preparation process of the prepreg component to be tested) to obtain each sample prepreg component. For example, nine layers of sample prepreg can be sequentially laid on a hat-shaped stringer fixture according to the axial direction of the fiber (e.g., carbon fiber) in the sample prepreg, in a 45 / 0 / 0 / -45 / 90 / -45 / 0 / 0 / 45 direction, to obtain a hat-shaped stringer preform. A release film and a breathable felt are then sequentially covered on the surface of the preform, a vacuum curing bag is made, and a thermostatic precipitator is used to cure the preform into a sample prepreg component. The hot-pressing conditions were: a curing temperature of 180~186℃, a curing time of 120~180h, and a heating rate of 0.5~2℃ / min. The thickness of the radius (R-angle) of each prepreg sample was measured using a magnetic thickness gauge. The R-angle deviation value of each sample was obtained and used to establish a mapping relationship between viscosity correlation values ​​and R-angle deviation. This ensures the consistency between the preparation process of the prepreg sample and the sample prepreg used to establish the mapping relationship, eliminating the influence of different preparation processes on the R-angle deviation and ensuring the reliability of the established mapping relationship, thereby guaranteeing the accuracy of the R-angle deviation test results.

[0047] In an exemplary embodiment, the R-angle deviation includes positive R-angle deviation and negative R-angle deviation, and the mapping relationship between viscosity correlation value and R-angle deviation includes the mapping relationship between the first viscosity correlation value and the positive R-angle deviation and the correlation relationship between the second viscosity correlation value and the negative R-angle deviation.

[0048] During the molding process of prepreg components, the resin components undergo different rheological changes in different parts of the prepreg component. For example, at the convex (outer) corners of the prepreg component, the resin components tend to flow outwards under curing pressure, resulting in a thinning of the thickness at the convex corner. Conversely, at the concave (inner) corners, the resin components tend to accumulate, resulting in an increase in the thickness at the concave corner. Therefore, in this embodiment, when mapping the viscosity correlation value to the corner deviation, a first viscosity correlation value is established to map the convex corner deviation to the first corner, and a second viscosity correlation value is established to map the concave corner deviation to the second corner, thereby predicting the convex and concave corner deviation values ​​of the prepreg component.

[0049] In an exemplary embodiment, the mapping relationship between the first viscosity-related value and the deviation of the positive R-angle is expressed by the following equation (1): (1) in,x 1 represents the first viscosity-related value. y 1 indicates that the positive radius (R) is out of tolerance. <0, >0; like Figure 9 The figure shows the mapping relationship between the first viscosity correlation value and the excess of the positive R angle. The horizontal axis represents the first viscosity correlation value (e.g., the first viscosity integral value), and the vertical axis represents the excess of the positive R angle, with the unit being %. In this embodiment, the complex rheological characteristics in the prepreg preparation process are transformed into an intuitive linear relationship. Therefore, during the testing process, only the first viscosity correlation value of the resin used to prepare the prepreg component needs to be tested within a preset temperature range. This allows for the rapid prediction of the target excess of the positive R angle of the prepreg component, avoiding the inefficient operation of measuring the R angle point by point on the prepreg component with a complex shape. In addition, in equation (1) <0, The limitation of >0 also aligns with the characteristic that at the convex corner (outer radius) of prepreg components, the resin component is prone to flow outward under curing pressure, resulting in a reduction in thickness at the convex corner, and the deviation of the convex corner is generally negative.

[0050] In an exemplary embodiment, the mapping relationship between the second viscosity-related value and the deviation of the negative radius (R-angle) is expressed by the following equation (2): (2) in, x 2 represents the second viscosity-related value. y 2 indicates that the negative radius (R) is out of tolerance. >0, <0.

[0051] like Figure 10 The figure shows the mapping relationship between the second viscosity correlation value and the negative R-angle deviation, where the horizontal axis represents the second viscosity correlation value (e.g., the second viscosity integral value) and the vertical axis represents the negative R-angle deviation, in percentage. In this embodiment, the complex rheological characteristics in the prepreg preparation process are transformed into an intuitive linear relationship. Therefore, during the test, only the second viscosity correlation value of the resin used to prepare the prepreg component needs to be tested within a preset temperature range to quickly predict the target negative R-angle deviation of the prepreg component, avoiding the inefficient operation of measuring the R-angle point by point on the complex-shaped prepreg component. In addition, in equation (2) >0, The limitation of <0 also aligns with the characteristic that resin components tend to accumulate at the concave corners (recessed corners) of prepreg components, leading to increased thickness at the concave corners, and the deviation of the concave corners is generally positive.

[0052] In one exemplary embodiment, the radius of the positive R-angle is R5~R9, and the radius of the negative R-angle is R7~R11.

[0053] During the fabrication of prepreg components, the rheological properties at sharp and gentle radius (R-angle) angles generally differ significantly. In this embodiment, the radius of the positive radius (R-angle) is defined as R5~R9, and the radius of the negative radius (R-angle) is defined as R7~R11. Within this radius range, the radius of most prepreg components can be covered, and within this radius range, the prepreg component R-angle deviation testing method provided by the above exemplary embodiments of this disclosure has high accuracy.

[0054] To more clearly explain the technical solutions provided by the exemplary embodiments of this disclosure, a specific example of the R-angle deviation test method for prepreg components provided by the exemplary embodiments of this disclosure is given.

[0055] Nineteen different types of sample resins were selected, and the viscosity-temperature relationship curves of these 19 sample resins in the range of 100~180℃ were tested using a rotational rheometer in shear mode at a heating rate of 2℃ / min.

[0056] Based on the viscosity-temperature relationship curves of the above 19 samples, the viscosity integral values ​​of the 19 sample resins in the range of 100~180℃ were determined.

[0057] Using 19 different sample resins and carbon fibers, sample prepregs were prepared according to the preparation method of the prepreg components to be tested (34% resin content, 194 gsm carbon fiber basis weight). Then, based on the axial direction of the carbon fibers, nine layers of sample prepregs were sequentially laid on a cap-shaped stringer fixture in a 45 / 0 / 0 / -45 / 90 / -45 / 0 / 0 / 45 direction to obtain a cap-shaped stringer preform. A release film and a breathable felt were then sequentially covered on the surface of the preform, and finally, a vacuum curing bag was made. The positive radius (R5) of the cap-shaped stringer was used, and the negative radius (R7) was used. The preform was cured in an autoclave to form 19 cap-shaped stringer sample prepreg components. The curing conditions were: curing temperature of 180℃, curing time of 120 hours, and heating rate of 2℃ / min. Using a magnetic thickness gauge, the thickness of the inner and outer radius (R-angle) of 19 cured cap-shaped stringer sample prepreg components was measured and compared with the theoretical thickness to obtain the measured values ​​of the R-angle thickness exceeding the tolerance of the inner and outer radius of the 19 sets of cap-shaped stringer sample prepreg components.

[0058] The obtained viscosity integral values ​​of 19 samples and the R-angle thickness deviation values ​​of 19 sets of negative R-angle and positive R-angle were subjected to correlation analysis and curve fitting. The mapping relationship between the first viscosity correlation value and the deviation of positive R-angle was obtained as shown in Equation (3), and the mapping relationship between the second viscosity correlation value and the deviation of negative R-angle was obtained as shown in Equation (4).

[0059] (3) (4) Based on the prepreg component 1 (made of resin 1), prepreg component 2 (made of resin 2), and prepreg component 3 (made of resin 3), resin 1, resin 2, and resin 3 were tested using a rotational rheometer in shear mode at a heating rate of 2℃ / min. The viscosity-temperature relationship curves of resin 1, resin 2, and resin 3 in the range of 100~180℃ were obtained respectively.

[0060] Based on the viscosity-temperature relationship curves of resin 1, resin 2, and resin 3, the viscosity integral values ​​of resin 1, resin 2, and resin 3 in the range of 100~180℃ were determined.

[0061] Substituting the viscosity integral values ​​of resin 1, resin 2, and resin 3 in the range of 100~180℃ into equations (3) and (4) above, respectively, the model prediction values ​​of the target positive R-angle deviation and the target negative R-angle deviation of the prepreg component 1, prepreg component 2, and prepreg component 3 are obtained, as shown in Table 1: Table 1

[0062] As can be seen from the data in Table 1, the R-angle deviation test method for prepreg components provided in the exemplary embodiments of this disclosure can accurately predict the target R-angle deviation value of the prepreg component, which is close to the measured R-angle deviation value of the prepreg component. This can provide guidance and reminders to operators during the production process. For example, operators can adjust the production process of the prepreg component or the formulation of the resin components in a timely manner, without having to wait until the prepreg component is fully cured before measuring the R-angle deviation, greatly reducing costs and increasing the efficiency of resin component formulation development and iteration.

[0063] The above-described contents can be implemented individually or in various combinations, and all such variations are within the scope of this disclosure.

[0064] Finally, it should be noted that in this document, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0065] The above embodiments are only used to illustrate the technical solutions of this disclosure, and are not intended to limit it. Although this disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this disclosure.

Claims

1. A method for testing the R-angle deviation of prepreg components, characterized in that, The testing method includes: Determine the viscosity-related values ​​of the resin under test within the preset temperature range; Based on the mapping relationship between viscosity correlation value and R-angle deviation, and the viscosity correlation value, the target R-angle deviation of the prepreg component to be tested is determined; The prepreg component to be tested is made from the resin to be tested.

2. The R-angle out-of-tolerance test method for a prepreg member according to claim 1, characterized by, The determination of the viscosity-related values ​​of the resin under test within a preset temperature range includes: Obtain the viscosity-temperature relationship curve of the resin under test within a preset temperature range; Based on the viscosity-temperature relationship curve, the viscosity-related value is determined according to the viscosity value corresponding to each temperature point.

3. The R-angle out-of-tolerance test method for a prepreg member according to claim 2, characterized by, Based on the viscosity-temperature relationship curve, and the viscosity value corresponding to each temperature point, the viscosity-related values ​​are determined, including: Based on the viscosity-temperature relationship curve, the viscosity-related value is determined by integral method based on the viscosity value corresponding to each temperature point.

4. The R-angle out-of-tolerance test method for a prepreg member according to any one of claims 1 to 3, characterized in that, The testing method also includes: Provide a preset type of sample resin, and obtain the sample viscosity-temperature relationship curve of each sample resin within the preset temperature range; Based on the sample viscosity-temperature relationship curve, determine the sample viscosity correlation value of the sample resin within the preset temperature range.

5. The method of R-angle out-of-tolerance testing of a prepreg member of claim 4, wherein, The testing method also includes: The R-angle of each sample prepreg component was found to be out of tolerance; the sample prepreg components were prepared from the sample resins. Based on the viscosity correlation values ​​and R-angle deviations of each sample, a mapping relationship between the viscosity correlation values ​​and R-angle deviations is established.

6. The method for testing the R-angle deviation of prepreg components according to claim 5, characterized in that, The testing method also includes: Sample prepreg is prepared using the sample resin and fiber; The sample prepreg is laid in a preset number of layers according to a preset rule, and then hot-pressed and cured to obtain the sample prepreg component.

7. The method for testing the R-angle deviation of prepreg components according to claim 1, characterized in that, The preset temperature range is 100~180℃.

8. The method of R-angle out-of-tolerance testing of a prepreg member of claim 1, wherein, The R-angle deviation includes positive R-angle deviation and negative R-angle deviation; The mapping relationship between the viscosity correlation value and the R-angle deviation includes the mapping relationship between the first viscosity correlation value and the positive R-angle deviation, and the correlation relationship between the second viscosity correlation value and the negative R-angle deviation.

9. The R-angle out-of-tolerance test method for prepreg members according to claim 8, characterized by, The mapping relationship between the first viscosity-related value and the deviation of the positive radius (R-angle) is expressed by the following formula: wherein, x 1 represents the first viscosity related value, y 1 represents the positive R-angle excess, < 0, > 0; The mapping relationship between the second viscosity correlation value and the deviation of the negative radius (R-angle) is expressed by the following formula: wherein x 2 represents the second viscosity correlation value, y 2 represents the negative R-angle tolerance, > 0, < 0.

10. The method of R-angle out-of-tolerance testing of a prepreg member of claim 8, wherein, The radius of the positive R-angle is R5~R9, and the radius of the negative R-angle is R7~R11.

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