Fibrous Preform Thickness Control via Sacrificial Expansion
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Solution Overview
Problem
Existing methods for producing composite material parts with varying thicknesses face challenges in achieving optimal fiber content and mechanical properties, as high fiber content can hinder matrix precursor access and densification, leading to suboptimal mechanical characteristics.
Innovation Solution
A process involving three-dimensional or multilayer weaving with a sacrificial part and an adjacent useful part, where expansion elements are inserted in the sacrificial part to achieve significant swelling and expansion, allowing for controlled fiber content and thickness in the useful part, thereby enabling optimal densification and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high count yarns are used locally in parts of extra thickness, then the capacity for reduction of thickness during shaping is reduced, but the fiber content becomes too high which hinders matrix precursor access and densification
Solution Approach 1:
The fibrous texture is divided into two distinct parts: a sacrificial part containing expansion elements (high count yarns) and a useful part with standard fiber content. This segmentation allows the expansion elements to provide necessary thickness control in the final part while being isolated from the useful part, preventing excessive fiber content from hindering matrix precursor access and densification in the functional region.
Solution Approach 2:
The expansion elements (high count yarns) are extracted and confined to the sacrificial part, separate from the useful part. This extraction allows the beneficial thickness-control function of high count yarns to be preserved while removing the harmful effect of excessive fiber content from the useful part, enabling proper matrix infiltration and densification.
2Volume of moving object
If expansion elements with greater section are inserted into the sacrificial part, then significant swelling and expansion is achieved in both sacrificial and useful parts, but the fiber content in the useful part must be controlled to allow optimal densification
Solution Approach 1:
The preform is segmented into sacrificial and useful parts with different fiber content requirements. Expansion elements are placed only in the sacrificial part, allowing volume expansion to achieve desired thickness while the useful part maintains controlled fiber content for optimal densification and matrix precursor access.
Solution Approach 2:
The sacrificial part acts as an intermediary that absorbs the expansion elements, mediating between the need for thickness (volume) and the need for controlled fiber content. The sacrificial part swells to provide thickness while protecting the useful part from excessive fiber content, enabling both objectives to be achieved.
Data Source
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AI summary
Disclosed is a process for manufacturing a fibrous preform for a part made of composite material, comprising creating a fibrous texture (200) by three-dimensional or multilayer weaving between a plurality of weft layers (202) and of warp layers (201), with an extra-thick portion (203) comprising a sacrificial portion (210) and useful portion (211) that are adjacent in the warp direction; placing the fibrous texture (200) in a forming toolset; shaping the fibrous texture; and removing the sacrificial portion. During the weaving, one or more expansion elements are inserted into the weft layers situated at the core of the sacrificial portion (210). Each expansion element has a cross section greater than the cross section or titer of the weft threads or strands present in the useful portion (211).