Ceramic Matrix Composite Preform Tensioning Device
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Solution Overview
Problem
Hollow parts made of ceramic matrix composite materials with intertwined fibers, particularly those braided, often exhibit shape defects due to preform relaxation during the densification process, leading to compromised mechanical characteristics and dimensional accuracy.
Innovation Solution
A stretching device with coaxial elements that apply tension to the preform in a longitudinal direction, maintaining it under tension during densification to prevent relaxation, comprising a main body, mounting members, and a control rod with helical connection, allowing gradual and smooth tensioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the preform is supported on a mandrel during densification, then the preform can be shaped and supported, but the preform relaxes before and/or during densification causing shape defects
Solution Approach 1:
The preform is stretched in the longitudinal direction before densification to pre-counteract the relaxation that will occur during the densification process. This preliminary anti-action ensures that when relaxation happens, the preform maintains its desired shape and dimensions without defects.
Solution Approach 2:
The preform is tensioned and stretched before the densification step to establish the correct geometry and fiber alignment in advance. This preliminary action ensures that the preform is ready to maintain its shape during subsequent densification, preventing shape defects.
2Manufacturing precision
If the preform is stretched to prevent relaxation, then shape accuracy improves, but the device complexity increases
Solution Approach 1:
The stretching device is divided into separate functional components: a stretching means for applying tension, a mandrel for support, and a control system. This segmentation allows each component to perform its specific function efficiently while maintaining overall system manageability and chemical compatibility.
Solution Approach 2:
A stretching device acts as an intermediary between the preform and the densification process. This intermediary applies controlled tension to the preform, preventing relaxation while maintaining chemical compatibility with the fibrous preform and densification products through proper material selection.
3Strength
If the preform is tensioned during densification, then mechanical properties improve, but the process complexity increases
Solution Approach 1:
The preform is maintained under continuous tension throughout the densification process, ensuring that the fibrous structure remains aligned and properly spaced. This continuous useful action prevents relaxation and ensures optimal mechanical properties are achieved in the final composite material.
Solution Approach 2:
The physical state and properties of the preform are changed through controlled tensioning before and during densification. By adjusting the tension parameter and maintaining it throughout the process, the fibrous structure is optimized for mechanical strength while the densification transforms the material properties.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach ensures optimal fiber volume fraction, improved mechanical properties, precise dimensional control, and enhanced resistance to internal and external pressures, maintaining the desired dimensions and tolerances of the final parts.
Implementation Method 1
a second preform mounting member, mounted by a helical connection on a control rod, itself mounted on the other end of the main body in a rotatable manner along its axis
Data Source
Figure 1~4
Figure 5a~7a
Figure 7b~7d
AI summary
The invention relates to a device for stretching a preform made of interwoven fibers and a method for manufacturing a part made of ceramic matrix composite material from this preform. During this method, the preform is tensioned before and during its densification using the stretching device (100), which comprises a main body (2), a first (3) and a second (4) mounting members, and a control rod. Rotating the control rod causes the second mounting member to translate, moving the first and second mounting members apart and tensioning the preform in a longitudinal direction.