Carbon Fiber Preform Heating and Needling for Shear Strength
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for fabricating carbon/carbon brake disks with short carbon fibers face challenges in achieving sufficient fiber volume and compatible binding mechanisms for needle-punching processes, leading to poor inter-laminar shear strength and difficulties in manipulating pre-impregnated fibers during needle punching.
Innovation Solution
A method involving the formation of an intermediate web from short length carbon fibers and fusible thermoplastic fibers, followed by local heat application and pressure to create a self-standing preform with through thickness reinforcement, compatible with needle-punching processes, using air-laid or wet-laid technologies to achieve a net shape preform with enhanced shear strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If pre-impregnated fibers are used for carbon/carbon brake disk fabrication, then binding mechanism is provided, but needle-punching process compatibility deteriorates due to poor inter-laminar shear strength and manipulation difficulties
Solution Approach 1:
The invention divides the fiber reinforcement into two distinct components: short carbon fiber bundles (0.5-3 inches) providing structural strength and z-fibers (continuous or long-length fibers) providing through-thickness binding. This segmentation allows each component to fulfill its specific function optimally - the short bundles maintain good needle-punching compatibility while the z-fibers provide the needed inter-laminar shear strength.
Solution Approach 2:
The invention creates a composite fiber structure combining short carbon fiber bundles with z-fibers (continuous or long-length fibers) in a needled preform. This composite approach integrates the advantages of both fiber types: the short bundles offer good processability during needle-punching while the z-fibers provide the critical through-thickness reinforcement and inter-laminar shear strength that单一 short fiber systems cannot achieve.
2Ease of manufacture
If short carbon fiber bundles are used, then needle-punching process compatibility is improved, but fiber volume and through thickness reinforcement deteriorate
Solution Approach 1:
The invention segments the fiber system into short carbon fiber bundles (providing volume and processability) and separate z-fibers (providing through-thickness reinforcement). By using bundles of 0.5-3 inches rather than individual short fibers, the invention achieves both adequate fiber volume and maintained needle-punching compatibility, while the added z-fibers provide the missing through-thickness strength.
Solution Approach 2:
The invention adds a third dimension (through-thickness direction) to the fiber reinforcement by incorporating z-fibers that extend perpendicular to the preform planes. This dimensional addition addresses the fiber volume and through-thickness reinforcement deficiency of short carbon fiber bundles without compromising their in-plane needle-punching compatibility.
3Strength
If z-fibers are added to create through thickness reinforcement, then inter-laminar shear strength is improved, but preform manipulation and needle-punching compatibility worsen
Solution Approach 1:
The invention segments the reinforcement function between short carbon fiber bundles (for in-plane structure and ease of manipulation) and z-fibers (for through-thickness strength). The z-fibers are integrated in a way that provides inter-laminar shear strength while the dominant short bundles maintain the preform's manipulability during needle-punching operations.
Solution Approach 2:
The invention applies different fiber types in different orientations and locations: short carbon fiber bundles dominate the in-plane structure where flexibility and manipulability are needed, while z-fibers are strategically positioned in the through-thickness direction where inter-laminar shear strength is critical. This local differentiation optimizes both strength and ease of operation.
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 enables the creation of a preform with at least 21% fiber volume, improving shear strength and mechanical properties, while minimizing needling time and raw material costs, and allowing for effective densification using chemical vapor infiltration or resin infiltration.
Implementation Method 1
Heat may be locally applied to the blend of the plurality of short length carbon fiber bundles and the binder material to partially melt the binder material and form a preform section
Implementation Method 2
Pressure may be applied to the preform section to control preform section fiber volume
Implementation Method 3
The preform section and/or a portion of the preform section may be needled, such as on a circular needling loom to create a preform with z fibers
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A platen (300) comprising a shaped heat delivery assembly (310), wherein the shaped heat delivery assembly (310) is configured to deliver heat to a blend of a plurality of short length carbon fiber bundles and a binder material to form a partially melted net shape preform; and a pressure delivery surface (320) configured to apply pressure to the partially melted net shape preform, wherein the partially melted net shape preform is subsequently needled.