3D Woven Preforms for π-Shaped CMC Densification
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Solution Overview
Problem
Manufacturing π-shaped ceramic matrix composite (CMC) components, such as blade outer air seals (BOAS), is challenging due to voids or 'noodle regions' that are difficult to densify, leading to susceptibility to cracking and delamination, especially when using two-dimensional woven structures.
Innovation Solution
A three-dimensional woven fiber structure is developed with connecting weft tow sections that pass through the thickness of the base section, forming π-shaped structures with angled leg sections, which are then densified to enhance strength and thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If two-dimensional woven structures are folded to form π-shaped structures with angled leg sections, then the manufacturing complexity is reduced, but voids or 'noodle regions' are created at the base of leg/rib which are difficult to densify
Solution Approach 1:
The patent transitions from two-dimensional woven structures to three-dimensional woven structures. The 3D woven fabric inherently provides through-the-thickness connectivity with interlacing patterns that extend through the thickness of the preform, eliminating the need for folding operations and preventing the formation of void regions. This dimensional change allows the structure to be manufactured as a single integrated piece without creating difficult-to-densify noodle regions.
2Manufacturing precision
If noodle regions are filled with particulate material or filler fiber, then the voids are filled, but the region remains difficult to densify and lacks strength through the thickness
Solution Approach 1:
The patent eliminates the noodle region problem entirely by using 3D woven structures that prevent void formation in the first place. Instead of filling voids with particulate material or filler fibers and dealing with the resulting densification difficulties, the 3D woven architecture inherently provides continuous fiber pathways through the thickness, removing the need for filler materials and their associated processing challenges.
3Shape
If complex three-dimensional woven structures are formed from woven flat materials by folding, then the 3D structure is achieved, but the structure is difficult to form and creates manufacturing problems
Solution Approach 1:
The patent applies preliminary action by pre-organizing fibers into a three-dimensional woven structure before forming the final π-shaped component. The 3D weaving process establishes the through-the-thickness connectivity and interlacing patterns in advance, so that when the preform is formed into the π-shape, the structure maintains its integrity without requiring complex folding operations or creating void regions.
Data Source
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AI summary
Woven fiber preforms are disclosed which have a base section (210) and one or more leg sections (220a, 220b) positioned the base section (210), The base section (210) and the leg sections (220a, 220b) together are a made of a single three-dimensional woven fiber structure comprising warp and weft fiber tows. The woven structure includes connecting weft tow sections that connect the base section (210) to each of the leg sections (220a, 220b). The connecting weft tow sections include through-the-thickness tow regions that pass from a leg section (220a, 220b) through the thickness (height) of the base section (210).