Manufacturing method of composite material zero-expansion tapered truss rod

Abstract

This invention relates to the field of truss manufacturing technology, and more particularly to a method for manufacturing a composite material zero-expansion tapered truss, comprising the following steps: S1: preparing a carbon fiber / cyanate ester resin prepreg; preparing a tapered truss mold. S2: starting from the small end of the tapered truss mold, using the carbon fiber / cyanate ester resin prepreg, forming the tapered truss in the order of the layup structure to form an uncured tapered truss. S3: curing the uncured tapered truss. The advantages of this invention are that the high-cyanate ester resin used results in tapered trusses with higher performance. Secondly, through layup design and the use of a variable-angle winding method, with the winding angle gradually decreasing from the small end to the large end, the thermal expansion coefficient of any segment of the tapered truss is guaranteed to be within the required range, meeting product usage requirements.

Description

Technical Field

[0001] This invention relates to the field of truss manufacturing technology, and in particular to a method for manufacturing a composite material zero-expansion tapered truss. Background Technology

[0002] Carbon fiber possesses the advantages of being lightweight and high-strength. Furthermore, as an anisotropic material, it exhibits excellent designability. In the design of space optical cameras, carbon fiber is cleverly incorporated into truss structures. The zero-expansion characteristic of trusses ensures that the optical camera maintains excellent imaging quality even under significant temperature variations. Truss structures consist of multiple members, primarily columns. Research on zero-expansion carbon fiber columns has accumulated considerable experience both domestically and internationally, and related products are nearing maturity. Currently, leading domestic and international truss structures have achieved an advanced thermal expansion coefficient of ±0.2e-6 / ℃. However, compared to traditional columns, tapered rods are less commonly used in truss structures. Yet, with the same material and weight, truss structures using tapered rods exhibit higher fundamental frequencies and stability. However, the design and manufacturing process of zero-expansion tapered rod layups are more complex. Currently, research literature on zero-expansion tapered rods is relatively scarce, and this field requires further in-depth exploration. Summary of the Invention

[0003] In view of this, the present invention aims to provide a method for manufacturing a zero-expansion tapered truss rod of composite materials. By preparing a high-cyanate ester resin, the impact strength of the cyanate ester resin is improved, the water absorption of the resin is reduced, the coefficient of thermal expansion is decreased, the thermal conductivity is increased, and the curing temperature is lowered, thereby enabling the prepared tapered truss rod to possess higher performance. Furthermore, through a layup design and a variable-angle winding method, with the winding angle gradually decreasing from the small end to the large end, this method ensures both winding quality and that the coefficient of thermal expansion of any segment of the tapered truss rod remains within the required range, meeting the product's usage requirements.

[0004] To achieve the above objectives, the technical solution of this invention is implemented as follows: A method for manufacturing a composite material zero-expansion conical truss rod, comprising the following steps:

[0005] S1: Prepare carbon fiber / cyanate ester resin prepreg; prepare tapered truss rod molds.

[0006] S2: Starting from the small end of the tapered truss rod mold, the tapered truss rod is formed using carbon fiber / cyanate ester resin prepreg in the order of the layup structure to form an uncured tapered truss rod.

[0007] S3: Curing uncured tapered truss members.

[0008] Furthermore, in step S2, the design method for the layered structure includes the following steps:

[0009] S21: Confirm the longitudinal modulus, transverse modulus, longitudinal coefficient of thermal expansion, and wall thickness of the tapered truss member.

[0010] S22: Determine the winding angle range based on the winding angle range calculated from the longitudinal modulus, the winding angle range calculated from the transverse modulus, and the winding angle range required by the longitudinal thermal expansion coefficient index.

[0011] S23: Based on the classical laminated plate theory and combined with the range of the winding angle determined in step S22, determine the layup structure of the tapered truss rod.

[0012] Furthermore, the 0° layer of the ply structure is laid out using a lay-up process, while the angle layers of the ply structure are wound using a winding process.

[0013] Furthermore, in step S2, the angle layer of the layup structure begins to wind from the small end of the tapered truss rod mold, and as it moves towards the large end of the tapered truss rod mold, its winding angle gradually decreases.

[0014] Furthermore, in step S1, the method for preparing the cyanate resin in the carbon fiber / cyanate ester resin prepreg includes the following steps:

[0015] S11: A cyanate prepolymer was prepared by compounding and prepolymerizing bisphenol E-type cyanate monomer and bisphenol S-type cyanate monomer.

[0016] S12: Fluorine-containing epoxy resin is added as a modifier to the cyanate ester prepolymer to obtain a modified cyanate ester resin prepolymer.

[0017] S13: Hydroxyl multi-walled carbon nanotubes are uniformly dispersed into the modified cyanate ester resin prepolymer by grinding and ultrasonic dispersion to obtain a modified cyanate ester resin prepolymer containing hydroxyl multi-walled carbon nanotubes.

[0018] S14: An active hydrogen catalyst, a transition metal catalyst, and dibutyltin dilaurate are added to the modified cyanate ester resin prepolymer containing hydroxyl multi-walled carbon nanotubes obtained in step S3 to finally obtain the cyanate ester resin.

[0019] Furthermore, in step S11, the ratio of bisphenol E cyanate monomer to bisphenol S cyanate monomer is 3:1.

[0020] Furthermore, in step S12, the mass percentage of fluorinated epoxy resin relative to cyanate ester prepolymer is 8%.

[0021] Furthermore, in step S13, the mass percentage of hydroxyl multiwalled carbon nanotubes relative to the modified cyanate ester resin prepolymer is 0.5%.

[0022] Furthermore, in step S14, the mass percentage of dibutyltin dilaurate relative to the modified cyanate ester resin prepolymer containing hydroxyl multi-walled carbon nanotubes is 0.05%.

[0023] Compared with existing technologies, this invention achieves the following beneficial effects: First, this invention proposes a method for preparing a cyanate ester resin formulation for zero-expansion tapered truss rods. This method improves the impact strength of the cyanate ester resin, reduces its water absorption, lowers its coefficient of thermal expansion, increases its thermal conductivity, and lowers its curing temperature, resulting in tapered truss rods with higher performance. Second, this invention proposes a layup design method for zero-expansion tapered truss rods. This method designs the layup based on performance requirements and employs a variable-angle winding method, with the winding angle gradually decreasing from the small end to the large end. This ensures winding quality and guarantees that the coefficient of thermal expansion of any segment of the tapered truss rod remains within the required range, meeting product usage requirements. Attached Figure Description

[0024] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0025] Figure 1 This is a structural schematic diagram of a tapered truss rod provided according to an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram showing the unfolded shape of the winding line of the tapered truss rod according to an embodiment of the present invention;

[0027] Figure 3 This is an example of the unfolded diagram of the winding line of the tapered truss rod provided according to an embodiment of the present invention.

[0028] The attached reference numerals include: 1. tapered truss member Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0030] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0031] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0032] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0033] The invention will now be described in detail with reference to specific embodiments.

[0034] A method for manufacturing a composite material zero-expansion tapered truss rod includes the following steps:

[0035] S1: Fabricate M55 carbon fiber / cyanate ester resin prepreg; prepare tapered truss rod molds. In this embodiment, the thickness of the M55 carbon fiber / cyanate ester resin prepreg is 0.1 mm. Figure 1 , Figure 2 As shown, the side view of the tapered truss member 1 unfolds into a fan shape, which can be approximated as a trapezoid. In this embodiment, the unfolding angle α of the tapered truss member 1 is 1.12°. To achieve the winding of the angle layers in the ply structure, a CNC tape winding machine with at least four axes is used.

[0036] S2: Starting from the small end of the tapered truss rod mold, using M55 carbon fiber / cyanate ester resin prepreg, the tapered truss rod is formed according to the layup sequence of the ply structure to form an uncured tapered truss rod 1.

[0037] The ply structure design method includes the following steps:

[0038] S21: Confirm the longitudinal modulus, transverse modulus, longitudinal coefficient of thermal expansion, and wall thickness of tapered truss member 1.

[0039] In this embodiment, the tapered truss rod 1 should meet the following requirements: longitudinal modulus ≥ 180GPS, transverse modulus ≥ 50GPS, longitudinal thermal expansion coefficient ± 0.2e-6, and wall thickness 9mm.

[0040] S22: Determine the winding angle range of the tapered truss rod based on the winding angle range of the longitudinal modulus, the winding angle range of the transverse modulus, and the winding angle range required by the longitudinal thermal expansion coefficient index.

[0041] Based on classical laminate theory, composite material simulation software was used to calculate the longitudinal modulus, transverse modulus, and longitudinal coefficient of thermal expansion under different winding angles θ. The results showed that the longitudinal modulus increases with increasing winding angle θ, while the transverse modulus decreases. The longitudinal coefficient of thermal expansion initially increases and then decreases with increasing winding angle θ. According to the longitudinal modulus requirement (≥180 GPS), a winding angle θ within the range of 0° to 90° is sufficient. According to the transverse modulus requirement (≥50 GPS), the winding angle θ needs to be greater than or equal to 52.5°. According to the longitudinal coefficient of thermal expansion requirement (±0.2e-6), the winding angle θ needs to be set within the range of 43.6° to 73.6°. In conclusion, the winding angle θ needs to be set within the range of 52.5° to 73.6°.

[0042] S23: Based on the range of the winding angle determined in step S22, determine the ply structure of the tapered truss rod 1. The ply structure is [0 / θ / 0 / -θ / 0]9s. Where 0 represents that the fiber direction is parallel to the longitudinal direction of the rod, i.e., 0°. θ represents the winding angle, which is variable.

[0043] In this embodiment, the 0° layer of the ply structure is laid manually, and the angle layers (winding angle θ) of the ply structure are laid using a winding process. The specific winding process is as follows:

[0044] like Figure 2 , Figure 3 As shown, during the continuous winding process, the winding angle changes uniformly with each turn relative to the previous turn, and the angle of change is α (α is the unfolding angle of the conical truss member 1), that is... Because the winding process is continuous, therefore .

[0045] Using computer-aided design software (SutoCSD), the winding line pattern is drawn based on the geometry of the tapered truss mold and the allowable range of the winding angle θ. Winding begins at the small end of the tapered truss mold, with the initial winding angle set to the maximum value within the allowable range of winding angle θ. With each turn, the winding angle changes uniformly according to angle α to ensure no wrinkling of the prepreg. Using the computer-aided design software, the winding line is drawn from the smaller diameter end to the larger diameter end according to the set angle variation, and the value of the winding angle at the larger end is checked to ensure it is not lower than the minimum value within the allowable range of winding angle θ. If the winding angle at the larger end is less than the minimum allowable value, it indicates that the range of variation of the winding angle is too large, and the initial winding angle θ at the small end needs to be adjusted to keep the winding angle θ within the allowable range for better control of the thermal expansion coefficient of the tapered truss.

[0046] Based on the designed winding pattern, a winding program for the CNC tape winding machine is written. This program precisely controls the movement trajectory of the winding machine, ensuring that the prepreg does not wrinkle during the winding process. The program also includes axial distance measurement for each winding turn, with the axial distance in mm. Figure 3 As shown. To ensure the dimensional accuracy of the tapered rod, M55 carbon fiber / cyanate ester resin prepreg is placed at the small end of the tapered rod mold, and the winding process is started to form the uncured tapered truss rod 1.

[0047] S3: After the winding is completed, the uncured tapered truss rod 1 is cured.

[0048] In this embodiment, the curing temperature is 120℃~200℃ and the curing time is 2h~4h.

[0049] Furthermore, the method for preparing cyanate resin in M55 carbon fiber / cyanate ester resin prepreg includes the following steps:

[0050] S11: A cyanate prepolymer was prepared by compounding and prepolymerizing bisphenol E-type cyanate monomer and bisphenol S-type cyanate monomer.

[0051] A cyanate prepolymer with low water absorption and low viscosity was prepared by compounding and prepolymerizing bisphenol E-type cyanate monomers and bisphenol S-type cyanate monomers. The prepared cyanate prepolymer exhibited good prepreg processability. When the ratio of bisphenol E-type cyanate monomer to bisphenol S-type cyanate monomer was 3:1, the cyanate prepolymer showed good prepreg processability, with a water absorption rate of 0.59%, while the water absorption rate of conventional cyanate monomers was greater than 1%.

[0052] S12: Fluorine-containing epoxy resin is added as a modifier to the cyanate ester prepolymer to obtain a modified cyanate ester resin prepolymer.

[0053] Fluorinated epoxy resin was added as a modifier to a cyanate ester prepolymer to obtain a modified cyanate ester resin prepolymer. Preferably, the added fluorinated epoxy resin accounted for 8% of the mass percentage of the cyanate ester prepolymer. At this point, the properties of the modified cyanate ester resin prepolymer changed significantly. Its impact strength was 8.5 KJ / m² before modification. 2 Increased to 16.9 KJ / m 2 Meanwhile, the addition of fluorinated epoxy resin improves the hydrophobicity of the modified cyanate ester resin prepolymer, increasing the water contact angle on the surface of the modified cyanate ester resin prepolymer from 111° to 128°, and reducing its water absorption rate from 0.56% to 0.3%.

[0054] The water contact angle refers to the angle between a liquid droplet and a solid surface due to surface tension.

[0055] In theory, when the water contact angle is less than 90°, it means that the liquid can wet the solid surface well and exhibits hydrophilicity; when the water contact angle is greater than 90°, it means that the liquid has difficulty wetting the solid surface and exhibits hydrophobicity.

[0056] S13: Hydroxyl multi-walled carbon nanotubes are uniformly dispersed into the modified cyanate ester resin prepolymer by grinding and ultrasonic dispersion to obtain a modified cyanate ester resin prepolymer containing hydroxyl multi-walled carbon nanotubes.

[0057] Hydroxyl-containing multi-walled carbon nanotubes (HWHMs) were introduced into modified cyanate ester resin prepolymers as a functional filler via grinding and ultrasonic dispersion techniques. Preferably, the added HWHMs accounted for 0.5% of the mass percentage of the modified cyanate ester resin prepolymer. At this point, the HWHM-containing modified cyanate ester resin prepolymer exhibited significantly improved overall mechanical properties. Compared to the modified cyanate ester resin prepolymer without HWHMs, the HWHM-containing prepolymer showed increases in flexural strength and tensile strength of 25.8% and 21.8%, respectively, as well as significant increases in elongation at break and impact strength of 60.6% and 53.3%, respectively. Its coefficient of thermal expansion also decreased from 47.4 × 10⁻⁶. -6 / ℃ decreased to 38.8×10 -6 / ℃, while the thermal conductivity increased from 0.37W / m·K to 0.51W / m·K.

[0058] S14: An active hydrogen catalyst, a transition metal catalyst, and a highly efficient catalyst, dibutyltin dilaurate, are added to the modified cyanate resin prepolymer containing hydroxyl multi-walled carbon nanotubes obtained in step S13 to finally obtain the cyanate resin.

[0059] An active hydrogen catalyst, a transition metal catalyst, and a highly efficient catalyst, dibutyltin dilaurate, are added to a hydroxyl-containing multi-walled carbon nanotube-modified cyanate ester resin prepolymer. These three catalysts work synergistically to lower the curing temperature of the prepolymer. Specifically, the mass percentages of the added active hydrogen catalyst and transition metal catalyst relative to the mass of the prepolymer are both in the range of 0.01%-1%. Preferably, the added highly efficient catalyst, dibutyltin dilaurate, has the best catalytic effect. At this point, the maximum curing temperature of the final cyanate ester resin is reduced from 200℃ to 140℃, with a degree of cure of 94.8%, and it exhibits good thermal stability, with a glass transition temperature of 220℃ and a thermal decomposition temperature exceeding 380℃. At a temperature of 200℃, the mechanical properties of cyanate ester resin retain more than 50% of those at room temperature, meaning that its strength, stiffness, toughness, and other mechanical properties can still be maintained at more than half of those at room temperature even at high temperatures.

[0060] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for manufacturing a zero-expansion conical truss rod made of composite materials, characterized in that, Includes the following steps: S1: Fabricate carbon fiber / cyanate ester resin prepreg; prepare tapered truss rod molds; S2: Starting from the small end of the tapered truss rod mold, using carbon fiber / cyanate ester resin prepreg, the tapered truss rod is formed according to the layup sequence to create an uncured tapered truss rod; the design method of the layup structure includes the following steps: S21: Confirm the longitudinal modulus, transverse modulus, longitudinal coefficient of thermal expansion, and wall thickness of the tapered truss member; S22: Determine the winding angle range based on the winding angle range calculated from the longitudinal modulus, the winding angle range calculated from the transverse modulus, and the winding angle range required by the longitudinal thermal expansion coefficient index; S23: Based on the classical laminated plate theory and combined with the range of the winding angle determined in step S22, determine the ply structure of the tapered truss rod; S3: Curing uncured tapered truss members.

2. The method for manufacturing a composite material zero-expansion tapered truss rod according to claim 1, characterized in that, The 0° layer of the ply structure is laid out using a lay-up process, while the angle layers of the ply structure are wound using a winding process.

3. The method for manufacturing a composite material zero-expansion tapered truss rod according to claim 2, characterized in that, In step S2, the angle layer of the layup structure starts to wind from the small end of the tapered truss rod mold, and as it moves towards the large end of the tapered truss rod mold, its winding angle gradually decreases.

4. The method for manufacturing a composite material zero-expansion tapered truss rod according to claim 1, characterized in that, In step S1, the method for preparing cyanate resin in carbon fiber / cyanate ester resin prepreg includes the following steps: S11: A cyanate prepolymer was prepared by compounding and prepolymerizing bisphenol E-type cyanate monomer and bisphenol S-type cyanate monomer; S12: Fluorine-containing epoxy resin is added as a modifier to cyanate ester prepolymer to obtain modified cyanate ester resin prepolymer; S13: Hydroxyl multi-walled carbon nanotubes are uniformly dispersed into the modified cyanate ester resin prepolymer by grinding and ultrasonic dispersion to obtain a modified cyanate ester resin prepolymer containing hydroxyl multi-walled carbon nanotubes. S14: An active hydrogen catalyst, a transition metal catalyst, and dibutyltin dilaurate are added to the modified cyanate resin prepolymer containing hydroxyl multi-walled carbon nanotubes obtained in step S13 to finally obtain the cyanate resin.

5. The method for manufacturing a composite material zero-expansion tapered truss rod according to claim 4, characterized in that, In step S11, the ratio of the bisphenol E cyanate monomer to the bisphenol S cyanate monomer is 3:

1.

6. The method for manufacturing a composite material zero-expansion tapered truss rod according to claim 4, characterized in that, In step S12, the mass percentage of the fluorinated epoxy resin relative to the cyanate prepolymer is 8%.

7. The method for manufacturing a composite material zero-expansion tapered truss rod according to claim 4, characterized in that, In step S13, the mass percentage of the hydroxyl multiwalled carbon nanotubes relative to the modified cyanate ester resin prepolymer is 0.5%.

8. The method for manufacturing a composite material zero-expansion tapered truss rod according to claim 4, characterized in that, In step S14, the mass percentage of the dibutyltin dilaurate relative to the modified cyanate resin prepolymer containing hydroxyl multi-walled carbon nanotubes is 0.05%.

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