CMC Preform Tooling for Z-Channel Needle Penetration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In the fabrication of ceramic matrix composites (CMCs), large voids between adjacent tows of a woven preform create defects, and the tortuous pore network hinders uniform infiltration, while existing z-channel formation techniques are obstructed by internal tooling, preventing full penetration of needles.
Innovation Solution
A tooling assembly with a mandrel and outer fixture featuring aligned holes and channels is used to facilitate the formation of z-channels, allowing needles to penetrate through the preform without interference, and includes through-holes and blind pockets to support reactant gas flow during densification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a needle is used to pierce the fibrous preform to form z-channels, then direct pathways for reactant gases are created, but the internal tooling obstructs the needle pathway, preventing full penetration
Solution Approach 1:
The tooling assembly is divided into two separate components: an outer fixture and an inner mandrel. The outer fixture contains the needle insertion holes, while the inner mandrel contains the internal tooling features. This segmentation allows the needle to pass through the outer fixture without being obstructed by the internal tooling, enabling full penetration of the preform to create z-channels.
Solution Approach 2:
The outer fixture acts as an intermediary component that facilitates needle insertion. It provides a clean pathway for the needle through its through-holes, allowing the needle to penetrate the preform fully without interference from the internal mandrel tooling. The intermediary outer fixture mediates between the needle insertion requirement and the internal tooling constraints.
2Manufacturing precision
If the pore network is highly tortuous in a woven system, then infiltration of reactant gases becomes uneven, but creating z-channels requires piercing through the preform which is obstructed by internal tooling
Solution Approach 1:
By segmenting the tooling into outer fixture and inner mandrel components, the system enables successful z-channel formation without obstruction. This allows creation of direct pathways that improve infiltration uniformity while maintaining ease of operation through the separated component design.
Solution Approach 2:
The solution moves the obstruction problem to a different dimensional arrangement by separating the outer fixture (with insertion holes) from the inner mandrel (with internal tooling). This dimensional separation in the tooling structure allows needles to pass through completely, creating the desired z-channels for improved gas flow and infiltration uniformity.
3Reliability
If large voids exist between adjacent tows in a woven preform, then infiltration is hindered, but modifying the preform structure requires complex tooling that obstructs needle pathways
Solution Approach 1:
The tooling is segmented into outer fixture and inner mandrel, simplifying the overall design while enabling effective modification of the preform. This segmentation allows creation of z-channels that address the void issues between tows without requiring overly complex integrated tooling, thereby improving composite properties while maintaining reasonable device complexity.
Data Source
AI summary
A tooling assembly for use in forming z-channels in a fibrous ceramic preform includes a mandrel having a first plurality of holes extending into a mandrel body, a first subset of the plurality of holes being through-holes extending completely through the mandrel, and a second subset of the holes comprising blind pockets, and a plurality of channels extending longitudinally along the mandrel in a direction orthogonal to the first plurality of holes. The tooling assembly further includes an outer fixture at least partially enclosing the mandrel, the outer fixture including at least one piece comprising a second plurality of holes extending completely through the at least one piece, the second plurality of holes being aligned with respective corresponding ones of the first plurality of holes such that a needle can be inserted through each of the second plurality of holes in the at least one piece and into the respective ones of the first plurality of holes in the mandrel.