Barbed and Barbless Needles for Fibrous Preform Consolidation
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Solution Overview
Problem
The needling process for carbon/carbon parts, which involves creating z-fibers using barbed needles, can negatively impact the friction and mechanical strength of C/C parts by breaking and disrupting fibers, leading to reduced performance in applications like aircraft brake disks.
Innovation Solution
A method using a combination of barbed and barbless needles, where approximately 50% of the needles are barbed with varying barb densities and angles, and 50% are barbless with a tamp surface, to minimize z-needling and maintain compression, thereby improving fiber volume and reducing z-fiber formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If barbed needles are used to create z-fibers during needling, then fiber interlayer bonding is improved, but fiber disruption and z-fiber formation increase leading to reduced friction and mechanical strength
Solution Approach 1:
The needling process is segmented into two distinct phases using two different needle types: barbed needles for initial fiber interlacing and bonding, followed by barbless needles for compression without additional fiber disruption. This segmentation allows each needle type to perform its specific function optimally without the negative effects of the other.
Solution Approach 2:
The invention changes the physical parameters of the needles by varying barb density and angle. High barb density/angle needles are used for aggressive fiber interlacing where bonding is prioritized, while low barb density/angle needles are used in regions where fiber preservation is more important, thereby optimizing the balance between bonding and fiber disruption.
2Strength
If high barb density and high angle barbs are used, then fiber interlacing and bonding are enhanced, but fiber disruption increases leading to reduced friction performance
Solution Approach 1:
Different regions of the preform are needled with different needle configurations tailored to local requirements. High barb density/angle needles are applied in regions requiring strong bonding, while low barb density/angle needles are used in regions where friction performance is critical, creating local optimization of properties.
Solution Approach 2:
The invention applies barbed needles with high barb density/angle only partially - specifically in the first needling pass or in specific regions where bonding is most needed - rather than uniformly across the entire preform. This partial application reduces overall fiber disruption while maintaining necessary bonding in critical areas.
3Stability of the object's composition
If continuous needling is performed across the entire preform surface, then fiber mat consolidation is improved, but fiber disruption and processing time increase
Solution Approach 1:
The needling process is divided into periodic stages: a first needling pass using barbed needles for bonding, followed by a second pass using barbless needles for compression. This periodic alternation between different needle types allows consolidation to be achieved in discrete steps rather than continuous aggressive needling, reducing total processing time.
Solution Approach 2:
The barbed needles perform preliminary fiber interlacing and bonding actions in the first pass, preparing the fiber mat for subsequent compression. This preliminary action reduces the amount of work needed in the second compression pass, thereby reducing total processing time while maintaining consolidation quality.
Data Source
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Figure 3A~3B
AI summary
Systems and methods for forming a fibrous preform are disclosed. The method may comprise providing a plurality of needles (14) comprising a barbed needle (300, 350) and a barbless needle (400, 450) and penetrating the fibrous preform (10) with the plurality of needles.