Variable-Thickness Brake Disk Reuse for Aircraft Overhaul
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Solution Overview
Problem
Aircraft brake systems face inefficiency in reusing friction disks, as C/C composite disks account for most wear while CMC disks are underutilized, leading to unnecessary discarding and increased overhaul costs.
Innovation Solution
A brake assembly design with stators and rotors of varying thickness, using CMC and C/C composite materials, where stators are reused by machining and repositioning to maintain optimal wear rates, reducing material waste and overhaul costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If hybrid brake stacks use CMC friction disks alternating with C/C composite friction disks, then the brake assembly achieves optimal wear distribution and extended service life, but the CMC disks are underutilized and both disk types are discarded when the C/C disks reach wear limit
Solution Approach 1:
The patent applies the discarding and recovering principle by removing worn C/C composite disks from the brake stack while retaining and repositioning the less-worn CMC disks for continued use in subsequent brake assemblies, thereby recovering valuable material and reducing waste
Solution Approach 2:
The brake stack is segmented into alternating layers of CMC and C/C composite disks, allowing differential wear management where each material type can be independently evaluated and handled based on its wear characteristics and remaining service life
2Reliability
If C/C composite disks account for 90-95% of total wear while CMC disks account for only 5-10% of total wear, then the brake assembly achieves balanced wear distribution, but both disks must be discarded when C/C disks reach wear limit
Solution Approach 1:
The patent recovers minimally worn CMC disks by removing them from exhausted brake stacks and repositioning them into new or refurbished brake assemblies, converting what would be waste into reusable components
Solution Approach 2:
CMC disks serve multiple functions across multiple brake assembly cycles - first in their original position, then repositioned to new assemblies where they continue to provide friction and wear protection, maximizing their utility
3Reliability
If both CMC and C/C composite disks are discarded when the brake stack reaches wear limit, then the brake assembly maintains safety standards, but overhaul costs increase due to unnecessary material replacement
Solution Approach 1:
The patent reduces overhaul costs by recovering and reusing CMC disks that have not reached their wear limit, replacing only the worn C/C composite disks rather than the entire brake stack
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 solution allows for the effective reuse of CMC stators across multiple wear cycles, reducing material waste and lowering overhaul costs by maintaining the mass and performance of the brake assembly through strategic repositioning and machining of worn components.
Implementation Method 1
Aircraft brake systems typically employ a brake stack comprised of a series of friction disks, which may be forced into contact with one another to stop the aircraft
Data Source
AI summary
A method of making a brake assembly using recycled friction disks may comprise removing a first friction disk from a worn brake assembly, removing a portion of the first friction disk to reduce a thickness of the first friction disk, and incorporating a previously unused friction disk and the first friction disk into a brake assembly comprising unworn rotor disks made of a first material. The previously unused friction disk and the first friction disk may comprise a second material different from the first material. The thickness of the first friction disk may be different from a thickness of the previously unused friction disk.