Keyed Brake Disk Wear Liner Shear Force Resistance
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Solution Overview
Problem
Aircraft brake systems face challenges with friction disks made of steel being destroyed by high heat during high-speed landings and rejected takeoffs, and while carbon composite materials are more suitable, they are expensive and prone to delamination due to shear forces during braking.
Innovation Solution
The use of a stator and rotor friction disk assembly with a core and replaceable wear liners featuring key notches and mating surfaces to prevent rotation and counteract shear forces, ensuring the wear liners remain securely attached and extend the lifespan of the core.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If carbon composite wear liners are bonded to a core, then manufacturing cost is reduced, but the wear liners delaminate from the core due to high shear force during braking
Solution Approach 1:
The wear liner is segmented into a friction portion and a bonding portion, with the bonding portion extending onto the friction surface. This segmentation allows the bonding portion to anchor into the core while the friction portion maintains contact with the opposing friction surface, distributing shear forces across multiple bonding interfaces and preventing delamination.
Solution Approach 2:
The bonding portion extends radially outward from the core onto the friction surface, adding a radial dimension to the bonding interface. This creates an L-shaped bonding structure that resists shear forces in multiple directions, transforming a simple axial bonding problem into a multi-dimensional attachment solution.
2Ease of manufacture
If steel friction disks are used, then manufacturing cost is low, but the disks are destroyed by high heat during high-speed landings and rejected takeoffs
Solution Approach 1:
The friction disk uses a composite structure with a metallic core providing structural strength and heat dissipation, while carbon composite wear liners provide high-temperature friction surfaces. This composite material approach combines the advantages of both materials: the metal core withstands thermal stress and the carbon liners resist wear at high temperatures.
Solution Approach 2:
The friction disk is divided into a structural core and replaceable wear liners. This segmentation allows the heat-generating friction function to be separated from the heat-resistant structural support function, with each component optimized for its specific role in withstanding thermal and mechanical loads.
3Strength
If the inner core thickness is increased to prevent delamination, then attachment strength is improved, but the overall device complexity increases
Solution Approach 1:
The core is segmented into a spine and an inner core with different thicknesses. The inner core has increased thickness specifically at the bonding interface to provide enhanced attachment strength, while the spine maintains its original dimensions for structural support. This localized segmentation adds strength only where needed without increasing overall device complexity.
Solution Approach 2:
The inner core thickness is increased locally at the bonding interface rather than uniformly throughout the entire core. This local quality change provides enhanced attachment strength precisely where the wear liner bonds to the core, while maintaining optimal structural properties in other regions of the core.
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 design effectively prevents delamination of wear liners and extends the lifespan of the stator core by counteracting shear forces during braking, reducing the risk of heat damage and maintaining the structural integrity of the brake system.
Implementation Method 1
The rotor key contacts the at least one lug to oppose a shear force applied to the wear liner
Implementation Method 2
The friction disks withstand and dissipate the heat generated from contact between one another during braking
Data Source
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AI summary
Friction disks, such as rotors (42) and stators (40), including keyed wear liners (50;60) are disclosed. The friction disks (40;42) may include a core (48;49) and a replaceable wear liner (50;60) coupled to each side of the core (48;49). The wear liners (50;60) may include a plurality of keys (254;440) which engage key notches (246;430) in the core (48;49). The key notches (246;430) may prevent the wear liners (50;60) from rotating with respect to the core (48;49) in response to a shear force, such as a force applied during braking.