Three-dimensional braided prefab with pre-set thread and manufacturing method thereof

Abstract

The invention discloses a three-dimensional braided prefab with a pre-set thread and a manufacturing method thereof. The three-dimensional braided prefab is characterized in that the prefab is of a skin-core structure; a core layer is formed by core yarns and a round three-dimensional braided structure which is braided through a four-step method and is provided with shaft yarns; a skin layer is ofa diagonal three-directional structure formed by arraying braiding yarns at the same side of the shaft yarns. The braiding yarns, which are located on the outermost layer of the core layer, are usedas diagonal three-directional shaft yarns, so that whole braiding of the skin-core structure is realized. The prefab is subjected to four-step cycle to obtain a prefab pitch length and the prefab witha target length is braided according to requirements. According to the manufacturing method of the prefab, the direction of the braiding yarns, the thickness of a skin-core layer and a diagonal three-directional pitch length can be flexibly designed and the difficulty that fibers are damaged when the three-dimensional braided prefab with the pre-set thread is used for wholly braiding and processing the thread is overcome; the whole mechanical properties of the prefab are easy to improve; meanwhile, the method has the advantages of simplicity in operation, stability in manufacturing and the like; the manufacturing requirements of high-performance and low-cost composite materials can be met.

Description

technical field [0001] The invention relates to the preparation technology of composite material fasteners, in particular to a method for manufacturing a three-dimensional braided prefabricated body with preset threads. The prefabricated body is used to prepare composite material fasteners, which can make the fibers of the threaded part continuous and improve the connection strength of the composite material fasteners. Background technique [0002] At present, a large number of fasteners are used in various types of aircraft at home and abroad. These fasteners include rivets and bolts, etc., and their weight accounts for 5% to 6% of the total weight of the aircraft. About 20% of the quantity, the cost of aircraft fasteners accounts for 3% to 5% of the aircraft cost. When selecting fastener materials, in addition to meeting the mechanical requirements, many factors need to be considered, such as maximum and minimum operating temperatures, corrosiveness of the environment, ga...

AI Technical Summary

Problems solved by technology

Composite fasteners reinforced with short fibers and continuous fibers are not suitable for occasions with large load-bearing forces, because there is no effective entanglement between fibers, fiber orientation is uncertain, and the structural integrity of fiber preforms can only be determined by The friction between fibers is determined; although the two-dimensional laminated structure solves the problem of intra-layer fracture, due to the lack of effective fiber reinforcement between layers, the strength between layers is restricted by the strength of the matrix, and it is easy to delaminate and produce cracks , the shear resistance is poor, and the isotropy is also poor; the needle punching technology relies on the inverted hooks on the needles to grab some fibers in the fiber web layer and bring them to the Z direction, so that the fibers between the layers Intertwined and constrained to form a quasi-three-dimensional network structure reinforcement with a certain strength between the plane and the layer, which overcomes the shortcomings of the lack of connection between the layers of the two-dimensional laminated material, and has uniform pore distribution, easy dense molding, and high In-plane and interlayer strength and other characteristics, but the bonding force between the fibers of this reinforcement is small, the fiber volume content is not high, and it is difficult to accurately control the orientation of the fibers, and the composite material fastener using the needle-punched structure as the reinforcement phase , the fiber volume content of the thread part is low, it is difficult to control the fiber orientation, after machining, most of them are discontinuous fibers, so the connection strength is not high

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