High-performance fiber 2.5 D woven preform density design method

Abstract

The invention discloses a density design method for a high-performance fiber 2.5 D woven preform, the high-performance fiber 2.5 D woven preform is composed of warp yarns and weft yarns, the warp yarns and the weft yarns are connected layer by layer in the thickness direction, and an angle interlocking structure is a basic 2.5 D woven preform structure. The density of the designed angle interlocking structure woven prefabricated body is divided into warp density and weft density. Warp yarn density is determined by reeds, and weft yarn density is controlled by mechanical beating-up force. After the fiber bundle passes through the reed dent process, the cross section of the fiber bundle is influenced by extrusion deformation of the reed dent and is in a square shape, so that the diameter of the fiber bundle is theoretically calculated. The density of the woven preform is designed according to the diameter of the fiber bundle. According to the method, when the high-performance fiber 2.5 D prefabricated body is woven, fiber bundles cannot be extruded and deformed, the number of times of mutual entanglement and adhesion is small, fiber weaving abrasion is small, the weavability of the woven prefabricated body is improved, and the overall mechanical property of the woven prefabricated body is improved.

Description

Technical Field

[0001] The invention belongs to the field of preparation of high-performance woven preform textiles, and relates to a method for designing the density of a high-performance fiber 2.5D woven preform. Background Art

[0002] Advanced reinforced structural composite materials have excellent properties such as excellent specific strength, specific modulus, impact resistance, and high temperature resistance in extreme environments. They are widely used in engineering fields such as aerospace, transportation, and marine ships. Three-dimensional textile composite materials have diverse preform structures, a wide range of adjustable fiber orientation and fiber content, and the introduction of fibers in the thickness direction can improve the interlayer performance of the preform. They can be used as reinforced preforms for advanced composite materials. 2.5D braided preforms have the remarkable characteristics of simple process, fast molding, strong designability, and low cost. Their application in hot end components such as aerospace and aviation is gradually increasing. Therefore, it is particularly important to conduct in-depth research on the process design of 2.5D braided preform structures.

[0003] The 2.5D reinforced preform is composed of a basic warp yarn system and a weft yarn system, and is connected layer by layer through the warp yarn system. The traditional two-dimensional loom has the following problems when weaving high-thickness 2.5D woven preforms: few types of weaving, insufficient warp yarn, unclear opening, insufficient weft beating force, etc., which cannot meet the requirements of material technology for the mechanical and chemical properties of the preform. The new 2.5D multi-heald loom currently used uses a method of opening multiple openings and introducing multiple weft yarns at a time to replace the multiple openings and multiple weft introduction processes required when weaving 2.5D woven preforms on ordinary looms. At the same time, it greatly reduces the number of heald frames, which is of great breakthrough significance.

[0004] The new 2.5D multi-heddle loom can be used to weave high-performance fiber 2.5D preforms of various structures, which can improve the problems of insufficient warp yarn and unclear opening. However, the high-performance fiber monofilament has a relatively thick diameter, poor flexibility, and poor fiber bundling. During the molding process of the 2.5D woven preform, the fiber is easily subjected to the repeated stretching, friction, and bending of the steel reed and the weft beating force in the multi-heddle loom process. If the weaving density parameter design is not reasonably coordinated with the steel reed process, the fiber will be squeezed and deformed when passing through the steel reed, and the monofilaments in the fiber bundle will become loose and split, causing the fibers to entangle and adhere to each other, resulting in a higher frequency of "fibrillation" on the surface of the fiber bundle, making it more difficult to weave smoothly, and yarn breakage will occur in severe cases, thus affecting the quality of the preform. Summary of the invention

[0005] The purpose of the present invention is to provide a method for designing the density of a high-performance fiber 2.5D woven preform, which solves the problem that the density design parameters of the existing high-performance fiber 2.5D woven preform technology do not match the cross-sectional diameter of the fiber bundle, and the large number of woven fibers leads to fiber extrusion and deformation during the weaving process, resulting in problems such as broken warp and yarn wear, which affects the overall performance of the preform.

[0006] A method for designing the density of a high-performance fiber 2.5D braided preform is provided. The high-performance fiber 2.5D braided preform is composed of warp yarns and weft yarns. The warp yarns are connected layer by layer in the thickness direction. The corner interlocking structure is the basic 2.5D braided preform structure. The warp yarn density and weft yarn density of the braided preform with the corner interlocking structure are designed. The warp yarn density is determined by the steel reed, and the weft yarn density is controlled by the mechanical beating force. The weft yarn density is not greater than the warp yarn density.

[0007] The warp density is calculated by the following method: after the fiber bundle passes through the steel reed tooth process, the cross section of the fiber bundle is affected by the extrusion deformation of the steel reed teeth, and the cross section is square. The side length of the cross-sectional area of ​​the fiber bundle is obtained by theoretically calculating the ratio of the linear density to the volume density of the fiber bundle, and the side length is the diameter of the fiber bundle; the reed tooth spacing of the fiber passing through the steel reed is determined according to the diameter of the fiber bundle, and the number of reed teeth is obtained from the reed tooth spacing, and then the warp density of the woven preform is obtained.

[0008] The design method of warp yarn density is as follows:

[0009] Taking the cross section of the high-performance fiber bundle as the base point, during the weaving process of the 2.5D preform, the fiber bundle passes through the reed tooth spacing of the steel reed. When passing through the reed teeth, the diameter of the fiber bundle is the reed tooth spacing. First, the cross-sectional area of ​​the fiber bundle is calculated according to the ratio of the linear density to the volume density of the fiber bundle according to formula (1). The cross-sectional area of ​​the fiber bundle is a square. The side length of the fiber bundle, i.e., the diameter, is calculated according to formula (2). The diameter of the fiber bundle can be used to deduce the reed tooth gap, and the number of 10mm reed tooth and reed tooth gaps is calculated. Since there are reed blades between the reed tooth gaps, the width b of the reed blades must be introduced, as shown in formula (3). The calculation result is the density of the 2.5D woven preform. The formula is as follows:

[0010]

[0011]

[0012] S represents the cross-sectional area of ​​the fiber bundle, in mm 2 , T represents the linear density of the high-performance fiber bundle, in g / km, ρ represents the volume density of the fiber bundle, in g / cm 3 , a represents the diameter of the fiber bundle, in mm.

[0013]

[0014] n represents the warp density of the 2.5D woven preform, b is the reed width, the unit is the number of roots of 10 mm, that is, the density of the warp.

[0015] The high-performance fiber is one or more of carbon fiber, silicon carbide fiber, alumina fiber, and silicon nitride fiber.

[0016] In addition to the corner interlocking structure, the 2.5D woven preform can also be transformed into a variety of different structures by combining warp lining, weft lining and normal yarn.

[0017] High-performance fibers are fiber bundles composed of thousands or tens of thousands of fiber filaments. The cross-sectional area of ​​the fiber bundle is square, and the cross-sectional area of ​​the fiber bundle is the pure fiber area without any gaps.

[0018] The fiber bundle passes through the reed teeth of the steel reed. The gap between the reed teeth is rectangular. The width of the rectangle is the diameter of the fiber bundle. During the weaving process, the diameter of the fiber bundle is equal to or smaller than the gap between the reed teeth. The fibers are not squeezed by the gap between the reed teeth. The fibers pass through the gap between the reed teeth very easily, and the friction is reduced.

[0019] The density design of the 2.5D braided preform is not affected by single or multiple fiber bundles.

[0020] The beneficial effect of the present invention is that after the fiber bundle passes through the steel reed tooth process, the cross section of the fiber bundle is affected by the extrusion deformation of the steel reed tooth, and the cross section is square. Therefore, the side length of the cross-sectional area of ​​the fiber bundle is obtained by theoretically calculating the ratio of the linear density to the volume density of the fiber bundle. The high-performance fiber 2.5D braided preform density design method calculates the cross-sectional diameter of the fiber bundle and matches the gap between the steel reed teeth, and then introduces the design density of the 2.5D braided preform. This design method solves the problem that the fiber bundle will not be squeezed and deformed when weaving the high-performance fiber 2.5D preform, the number of entanglements and adhesions is small, and the fiber weaving wear is small, thereby improving the weavability performance of the braided preform and improving the overall mechanical properties of the braided preform. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the fiber bundle of the high-performance fiber 2.5D woven preform of the present invention passing through a reed. DETAILED DESCRIPTION

[0022] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0023] Example 1

[0024] A high-performance fiber 2.5D braided preform density design method, Figure 1The schematic diagram of the process of passing through the steel reed when weaving a 2.5D preform, ① is the reed teeth of the steel reed, ② is the spacing between the reed teeth, ③ is the harness, and ④ is the diameter of the fiber bundle. Taking the cross-section of the high-performance fiber bundle as the base point, in the process of weaving a 2.5D preform, the fiber bundle ④ passes through the reed tooth spacing ② of the steel reed. When passing through the reed teeth, the diameter of the fiber bundle is the reed tooth spacing. First, according to the ratio of the linear density to the volume density of the fiber bundle, as shown in formula (1), the cross-sectional area of ​​the fiber bundle is calculated. The cross-sectional area of ​​the fiber bundle is a square. According to formula (2), the side length of the fiber bundle, that is, the diameter, is calculated. The diameter of the fiber bundle can be used to deduce the reed tooth gap, and the gap between the 10mm reed teeth and the reed teeth is calculated. Since there is a reed blade between the reed tooth gaps, the width b of the reed blade should be introduced, as shown in formula (3), which is the density of the 2.5D woven preform. The formula is as follows:

[0025]

[0026] S represents the cross-sectional area of ​​the fiber bundle, in mm 2 , T represents the linear density of the high-performance fiber bundle, in g / km, ρ represents the volume density of the fiber bundle, in g / cm 3 , a represents the diameter of the fiber bundle, in mm.

[0027] The required reed tooth spacing can be derived from the fiber bundle diameter, and the density of the woven 2.5D preform can be obtained based on the reed tooth spacing, as shown in the following formula:

[0028]

[0029] n represents the density of the 2.5D braided preform, and b represents the width of the reed blade, which is expressed in the number of roots of 10 mm.

[0030] Example 2

[0031] The present invention is a high-performance fiber 2.5D braided preform density design method, which is described by taking the silicon carbide fiber 2.5D braided preform density design as an example. The third-generation silicon carbide fiber is selected as the raw material, with a linear density of T = 181tex and a bulk density of ρ = 3.01g / cm 3 , b = 1 mm. According to formulas (1), (2) and (3), we can get:

[0032]

[0033] According to the above formula, the design density of the silicon carbide fiber 2.5D braided preform is 8 fibers / 10 mm.

[0034] The principles, steps, etc. not explicitly described in the present invention are all obtainable by those skilled in the art through conventional technical means, and therefore are not described in detail. Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for designing the density of a high-performance fiber 2.5D braided preform, characterized in that: The high-performance fiber 2.5D woven preform is composed of warp yarn and weft yarn, which are connected layer by layer in the thickness direction by warp yarn. The corner interlocking structure is the basic 2.5D woven preform structure. The warp yarn density and weft yarn density of the woven preform with the corner interlocking structure are designed; the warp yarn density is determined by the steel reed, and the weft yarn density is controlled by the mechanical beating force. The weft yarn density is not greater than the warp yarn density; The warp density is calculated by the following method: after the fiber bundle passes through the steel reed tooth process, the cross section of the fiber bundle is affected by the extrusion deformation of the steel reed teeth, and the cross section is square. The side length of the cross-sectional area of ​​the fiber bundle is obtained by theoretically calculating the ratio of the linear density to the volume density of the fiber bundle, and the side length is the diameter of the fiber bundle; the reed tooth spacing of the fiber passing through the steel reed is determined according to the diameter of the fiber bundle, and the number of reed teeth is obtained from the reed tooth spacing, and then the warp density of the woven preform is obtained.

2. The method for designing the density of a high-performance fiber 2.5D braided preform according to claim 1, characterized in that: The design method of warp yarn density is as follows: Taking the cross section of the high-performance fiber bundle as the starting point, during the weaving process of the 2.5D preform, the fiber bundle passes through the reed tooth spacing of the steel reed. When passing through the reed teeth, the diameter of the fiber bundle is the reed tooth spacing. First, the cross-sectional area of ​​the fiber bundle is calculated according to the ratio of the linear density to the volume density of the fiber bundle according to formula (1). The cross-sectional area of ​​the fiber bundle is a square; the side length of the fiber bundle, i.e., the diameter, is calculated according to formula (2). The diameter of the fiber bundle is used to deduce the reed tooth gap, and the number of gaps between 10 mm reed teeth and reed teeth is calculated. Since there are reed blades between the reed tooth gaps, the width b of the reed blades must be introduced, as shown in formula (3). The calculation result is the warp density of the 2.5D woven preform, as shown below: S represents the cross-sectional area of ​​the fiber bundle, in mm 2 , T represents the linear density of the high-performance fiber bundle, in g / km, ρ represents the volume density of the fiber bundle, in g / cm 3 , a represents the diameter of the fiber bundle, in mm; n represents the warp density of the 2.5D woven preform, b is the reed width, the unit is the number of roots of 10 mm, that is, the density of the warp.

3. A method for designing the density of a high-performance fiber 2.5D braided preform according to claim 1 or 2, characterized in that: The high-performance fiber is one or more of carbon fiber, silicon carbide fiber, alumina fiber, and silicon nitride fiber.

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