Multi-Piece Mandrel Segmentation for CMC Airfoil Extraction
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Solution Overview
Problem
The removal of mandrels from ceramic matrix composite (CMC) airfoils presents challenges, particularly for certain airfoil designs, due to the complex shapes and materials involved.
Innovation Solution
A mandrel body composed of at least two interfitting parts is used, with specific profiles and features like grooves, twists, and chamfers, allowing for separate removal of these parts after the airfoil formation, facilitating the extraction process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single-piece mandrel is used to form complex airfoil shapes, then the mandrel can provide precise geometric definition, but the mandrel becomes difficult or impossible to remove after densification
Solution Approach 1:
The mandrel is divided into multiple separable parts (first mandrel part and second mandrel part) that can be detached from each other. The first mandrel part has a bowed profile while the second has a straighter outer shape, allowing them to be removed sequentially after densification without damaging the complex airfoil structure.
2Manufacturing precision
If the mandrel has a complex bowed profile to match the airfoil shape, then the airfoil geometry is accurately formed, but the mandrel cannot be easily extracted from the densified structure
Solution Approach 1:
The complex bowed mandrel profile is segmented into two parts: the first mandrel part retains the bowed profile for accurate airfoil formation, while the second mandrel part has a straighter outer shape that facilitates easy extraction. The parts are connected via interfitting features during formation but can be separated for removal.
Solution Approach 2:
The second mandrel part is designed to be extractable from the first mandrel part after densification. The interfitting features (tongue and groove, chamfers) allow the second part to be removed first, creating access to remove the first part with its complex bowed profile.
3Strength
If the mandrel parts are tightly interfitted to maintain structural integrity during airfoil formation, then the mandrel can support the densification process, but the parts become difficult to separate for removal
Solution Approach 1:
The interfitting features (tongue and groove connections, chamfers) are designed in advance to provide both strong connection during airfoil formation and controlled separation during removal. The features are engineered to maintain structural integrity during densification while allowing deliberate disassembly afterward.
4Stability of the object's composition
If the mandrel is designed as a single rigid piece, then it provides stable support during densification, but it cannot be removed after the airfoil is formed
Solution Approach 1:
The mandrel is segmented into multiple parts that work together as a stable structure during densification but can be separated for removal. The interfitting features ensure stability during the manufacturing process while enabling disassembly afterward to access the densified airfoil.
Data Source
Figure 1
Figure 2~3A
Figure 3B
AI summary
A mandrel (122) includes a mandrel body upon which to build ceramic matrix composite ("CMC") yarns to provide a shear tube (124) for building up an airfoil (110) from CMC fabric layers (118). The mandrel body formed of at least two mandrel parts (126, 128; 150, 152) interfitting to define a desired shape for the shear tube (124), and such that after formation of the airfoil (110) the at least two parts of the mandrel body (126, 128; 150, 152) can be separately removed from the shear tube (124) in order to facilitate removal. A method is also disclosed.