Fiber Structure for Composite Parts with Reduced Thickness
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Solution Overview
Problem
The production of fibrous reinforcing structures for composite materials faces challenges in achieving regular surface states and minimizing fiber variations, particularly at portions of decreasing thickness, which can lead to misalignments and microcracking due to thread removal during weaving.
Innovation Solution
A fibrous structure is woven in a single piece with surface continuity and discontinuity yarn removal portions, where underlying yarns replace extracted yarns, maintaining continuous surface yarns over the entire portion of decreasing thickness, and interlacing yarns before exit to reduce fiber content variations and weaving difficulties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If wires are removed during weaving to accommodate thickness reductions, then the part can achieve the desired shape and dimensions, but fiber misalignments and matrix-rich areas are created leading to micro-cracking
Solution Approach 1:
The patent applies preliminary action by performing wire withdrawal and replacement operations during the weaving process itself, rather than after. By withdrawing underlying wires and replacing them with surface wires at specific locations (such as the trailing edge), the structure achieves the desired shape reduction while maintaining fiber alignment and avoiding matrix-rich areas that would cause micro-cracking.
2Shape
If all floats are cut to remove surface wires, then the surface finish is improved, but significant variation in fiber content is created locally
Solution Approach 1:
The patent applies local quality by implementing wire withdrawal and replacement only at specific locations where thickness reduction is needed (such as the trailing edge), rather than uniformly across the entire structure. This localized approach maintains the desired surface finish in critical areas while preserving fiber content uniformity in regions where it is not required.
3Stability of the object's composition
If surface wires are kept continuous throughout the decreasing thickness portion, then fiber alignment is maintained, but weaving becomes difficult due to friction from crossing multiple weft layers
Solution Approach 1:
The patent applies segmentation by dividing the decreasing thickness portion into multiple sections with alternating wire withdrawal and replacement operations. This segmentation allows surface wires to maintain continuity and alignment in certain regions while being replaced in other regions to reduce friction during weaving, thus balancing fiber alignment with manufacturing ease.
Data Source
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AI summary
The invention relates to a fiber structure (200) for reinforcing a composite material part woven into a single part by means of multilayer weaving between a first plurality of thread layers (C1-C10) and a second plurality of thread layers (T1-T10). The fiber structure includes a portion (204) having a decreasing thickness and has a plurality of surface continuity thread setback portions (210, 211, 212) on said portion, wherein each portion has threads (Fc3; Fc8; Fc4), from a thread layer (C3; C8; C4) of the first thread layer plurality underlying the thread layer of the first thread layer plurality located on the surface of the structure, that are interrupted, and several surface discontinuity thread setback portions (220, 221), wherein each portion has threads (Fc1; Fc10), from the thread layer (C1; C10) of the first thread layer plurality located on the surface of the structure, that are interrupted. Each interrupted thread (Fc1; Fc10) is replaced, on the surface of the structure, by a thread (Fc2; Fc9) from a thread layer (C2; C9) underlying the first thread layer plurality. The threads from the layers from the second thread layer plurality (T1- T10), located on the surface of the fiber structure, are continuous over at least the entire portion (204) having a decreasing thickness.