Carbon Fiber Preform Web Formation for Through-Thickness Needling
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Solution Overview
Problem
Existing methods for fabricating carbon fiber preforms with through thickness reinforcement for brake applications face challenges such as poor inter-laminar shear strength and incompatibility with needle-punching processes due to resin prepreg steps, which harden fibers and hinder manipulation during the needling process.
Innovation Solution
A method involving the formation of an intermediate web or matt layer using a mixture of short length carbon fibers and fusible thermoplastic binding fibers, which are air-laid or wet-laid, and then heat-set to create a preform with sufficient fiber volume and mechanical strength, allowing for needle-punching without resin encapsulation, thereby enhancing shear strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If resin prepreg steps are used to bind carbon fibers, then fiber bundling and manipulation during needle-punching is hindered, but fiber placement precision is improved
Solution Approach 1:
The patent applies preliminary action by pre-forming the carbon fibers into a web structure with controlled randomness and orientation before the needle-punching process. This preliminary web formation allows fibers to be positioned in a statistically controlled manner while remaining loose and manipulable during subsequent needling, resolving the contradiction between placement precision and manipulation ease.
2Ease of manufacture
If traditional needling processes are used without through thickness reinforcement, then processing simplicity is maintained, but inter-laminar shear strength is poor
Solution Approach 1:
The patent employs composite materials by combining short carbon fibers with a minimal amount of binder material to create a web structure. This composite approach provides through-thickness reinforcement and improves inter-laminar shear strength while maintaining processing simplicity, as the binder content is kept low enough not to interfere with the needle-punching process.
3Strength
If fiber volume in preform is increased to improve mechanical strength, then shear strength is enhanced, but needling time increases
Solution Approach 1:
The patent applies parameter changes by optimizing the fiber volume fraction to a specific range (at least 21%) and controlling the statistical distribution of fiber orientations. This parameter optimization achieves sufficient mechanical strength and shear strength while minimizing needling time, as the controlled randomness reduces fiber entanglement and facilitates faster needling processing.
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
The method achieves a preform with at least 21% fiber volume, enabling effective through thickness reinforcement and minimizing needling time, while maintaining mechanical strength and reducing raw material costs, thus improving the internal inertia properties of the composite.
Implementation Method 1
heat-set to create a preform with sufficient fiber volume and mechanical strength
Implementation Method 2
fusible thermoplastic binding fibers
Implementation Method 3
air-laid or wet-laid
Implementation Method 4
air-laid or wet-laid
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A method and apparatus for fabricating a short length carbon fiber preform with a through thickness reinforcement is disclosed herein. The starting media for fabricating a net shape (e.g., annular disc) may meet specific requirements including a sufficient fiber volume and a binding mechanism compatible with the needle-punching process.