Carbon Brake Disk Preforms With Higher Fiber Volume Uniformity
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Solution Overview
Problem
Aircraft brake systems using carbon/carbon composites exhibit varying wear characteristics and friction coefficients due to the materials and heat treatments employed, leading to inconsistent performance.
Innovation Solution
A method involving the stacking of thinner and more uniform textile fabric layers made of oxidized polyacrylonitrile (PAN) fibers, needling to form a non-woven textile board, cutting fibrous preforms, and carbonizing them without compression weights, followed by densification with a carbon matrix using chemical vapor infiltration (CVI), results in carbonized preforms with improved uniformity and fiber volume ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional cross-lapping method is used to form non-woven fabric layers, then the fabric layers can be formed, but the uniformity and thickness consistency of the fabric layers deteriorate
Solution Approach 1:
The patent segments the continuous non-woven fabric formation process into discrete textile fabric layers that are stacked and needled together. Each layer can be manufactured separately with controlled thickness and uniformity, then assembled into the final preform structure, improving overall consistency while maintaining manufacturing feasibility
Solution Approach 2:
The patent changes the physical parameters of the fabric layers by using thinner individual layers with controlled thickness specifications. This parameter change allows better uniformity control during stacking and carbonization, addressing the consistency issues inherent in traditional thicker cross-lapped fabrics
2Volume of stationary object
If compression weights are applied during carbonization, then the preform density increases, but the manufacturing complexity and equipment requirements increase
Solution Approach 1:
The patent performs preliminary densification during the needling process before carbonization. The mechanical interlocking of fibers through needling creates a pre-compressed structure that maintains density during subsequent carbonization without requiring external compression weights or complex equipment
Solution Approach 2:
The needling process itself provides the compression and densification function that would otherwise require separate compression equipment during carbonization. The needles mechanically interlock the fabric layers, creating self-supporting density without external forces
3Productivity
If thicker fabric layers are used, then the manufacturing speed increases, but the uniformity and fiber volume ratio consistency deteriorate
Solution Approach 1:
Instead of using fewer thick layers, the patent segments the structure into multiple thinner fabric layers. This allows faster manufacturing of each individual layer while maintaining consistent fiber volume ratios, as thinner layers are easier to control and manufacture with precision
Solution Approach 2:
The patent uses a higher number of thinner layers than traditionally required, where the cumulative thickness achieves the desired preform thickness. This excessive number of layers compensates for the reduced thickness of individual layers, maintaining both manufacturing speed and fiber volume consistency
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 enhances the uniformity and mechanical properties of carbon/carbon composite brake disks, achieving a higher fiber volume ratio and reduced wear rate while maintaining or exceeding the performance of traditional cross-lapping methods without the need for external compression during carbonization.
Implementation Method 1
carbonizing the fibrous preform
Implementation Method 2
densification with a carbon matrix using chemical vapor infiltration (CVI)
Data Source
AI summary
A method of making a carbonized preform for a carbon-carbon composite brake disk may comprise: stacking a plurality of textile fabric layers, each textile fabric layer in the plurality of textile fabric layers including oxidized polyacrylonitrile (PAN) fibers, each textile fabric layer in the plurality of textile fabric layers being more uniform than a typical fabric layer formed from cross-lapping; each fabric layer being thinner than a typical fabric layer from cross-lapping, needling the plurality of textile fabric layers to form a needled non-woven board; cutting a fibrous preform from the needled non-woven board; and carbonizing the fibrous preform. The resultant non-woven carbonized preform maintains a higher fiber volume and more consistent properties throughout than what would otherwise be achieved using a typical fabric layer from cross-lapping.