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Method for reducing yarn reduction gradient of variable-thickness three-dimensional woven preform and preform

A technology of variable thickness and prefabrication, applied in textiles, papermaking, fabrics, textiles, etc., can solve the problems of reducing the mechanical properties of composite materials, and achieve the effects of avoiding molding quality problems, reducing yarn reduction gradients, and small yarn reduction gradients

Active Publication Date: 2020-06-30
NANJING FIBERGLASS RES & DESIGN INST CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At the same time, the steps formed by yarn reduction will form resin-rich areas, which will bring local defects, thereby reducing the mechanical properties of composite materials

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
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  • Method for reducing yarn reduction gradient of variable-thickness three-dimensional woven preform and preform
  • Method for reducing yarn reduction gradient of variable-thickness three-dimensional woven preform and preform
  • Method for reducing yarn reduction gradient of variable-thickness three-dimensional woven preform and preform

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] This example is a method of reducing the yarn gradient of the variable thickness preform along the warp direction, such as figure 1 As shown, the main body of a variable thickness preform 1 in this example is composed of two system yarns, warp yarn and weft yarn, wherein a1-a4 are warp yarn systems, e11-e155 are weft yarn systems, and the direction from a1 to a4 is the thickness direction, and e11 The direction to e151 is the warp direction, and the direction perpendicular to the warp direction and the thickness direction is the weft direction. Along the warp direction, the first layer at the n1 variable thickness section begins to be drawn out, that is, e41 to e151 are drawn out and no longer participate in weaving. In the prior art, warp a1 is usually drawn out at the cross section n1, in order to reduce the thickness change gradient. , the present invention keeps a1 temporarily while keeping the same movement with the warp yarn a2 of the adjacent layer during continu...

Embodiment 2

[0032] This example is a method of reducing the yarn gradient of the preform with variable thickness along the weft direction, such as image 3 As shown, the main body of a variable thickness preform 3 in this example is composed of two system yarns, warp yarn and weft yarn, wherein a11-a155 are warp yarn systems, e1-e4 are weft yarn systems, and the direction from e1 to e4 is the thickness direction, and a11 The direction to a151 is the weft direction, and the direction perpendicular to the weft direction and the thickness direction is the warp direction. Along the weft direction, the first layer of warp yarns at the n5 variable thickness section begins to be drawn out, that is, a41 to a151 are drawn out and no longer participate in weaving. In the prior art, the weft yarn e1 is usually drawn out at the section n5, in order to reduce the thickness change gradient. , the present invention temporarily retains e1 while keeping the same movement with the adjacent layer of weft ya...

Embodiment 3

[0034] This example is a method of reducing the yarn gradient of the laminated variable thickness preform, such as Figure 5 As shown, the component 8 is a variable thickness preform, which is formed by superimposing three single-layer preforms 5 to 7. In the prior art, the three single-layer variable-thickness preforms usually have the same yarn reduction positions, that is, they are all at the cross-sections n9 and n12. and n15, in order to avoid the concentration of yarn reduction points and the large gradient of thickness change, the present invention redistributes the yarn reduction points of the 3-layer preform, and the yarn reduction points are dislocated along the direction of variable thickness, and the yarn reduction positions of the single-layer preform 5 are n9 respectively. , n12 and n15, the yarn reduction positions of the single-layer preform 6 are n10, n13 and n16 respectively, and the yarn-reduction positions of the single-layer preform 7 are respectively n11, ...

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
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Abstract

The invention discloses a method for reducing the yarn reduction gradient of a variable-thickness three-dimensional woven preform and the perform. The method comprises the steps: extracting at least one layer of weft yarns from the (2n-1)-th variable-thickness section from the maximum thickness part of the preform, and temporarily reserving the warp yarns of the layer corresponding to the at leastone layer of extracted weft yarn, wherein the motion path of the temporarily reserved warps is changed, the paths of the warps on the corresponding layer are kept consistent with those of the warps on the uppermost layer or the lowermost layer which are not drawn out before the warps are drawn out, the warps on the corresponding layer are drawn out at the 2n-th variable-thickness section, the warps or wefts drawn out at the variable-thickness section are interrupted from the variable-thickness section, and n is larger than or equal to 1. At least one layer of warp yarns or weft yarns is drawnout from each variable-thickness section in the direction that the thickness of the preform is gradually reduced compared with the previous variable-thickness section. According to the method, the yarn reduction gradient of the variable-thickness three-dimensional woven preform is reduced, a large gradient formed by simultaneously reducing warp yarns and weft yarns is avoided, and the problem offorming quality caused by influence on resin flow is avoided.

Description

technical field [0001] The invention belongs to the technical field of three-dimensional woven composite materials, and in particular relates to a method and a preform for reducing the yarn gradient of a three-dimensional woven preform with variable thickness. Background technique [0002] The three-dimensional woven structure preform has good structural integrity because the yarns are intertwined in the three-dimensional space. In practical engineering applications, some composite parts are shaped with variable thickness, for example, the thickness gradually decreases along the length or width. In order to realize the profiling design of the net size, the thickness change is often achieved by reducing the yarn. [0003] Before and after the yarn reduction of the preform will inevitably bring about a sudden change in the thickness of the preform, and steps will form on the surface of the preform. During the composite molding process of the preform, the flow speed of the resi...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): D03D25/00
CPCD03D25/005
Inventor 周海丽李超孙方方韩晨晨张立泉
Owner NANJING FIBERGLASS RES & DESIGN INST CO LTD
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