Aircraft Brake Disc Stack Spacer Design for Temperature Distribution
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Aircraft brake disc stacks experience uneven temperature distribution due to differential cooling effects, leading to higher peak temperatures at the center, which can be exacerbated by the use of spacers in existing systems, resulting in reduced service life and increased weight.
Innovation Solution
The method involves forming brake elements in two separable parts with a spacer inserted between them to maintain even tribological engagement and temperature distribution, allowing for extended service life and reduced weight by using carbon-carbon or siliconised carbon composite materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If spacers are fitted to one or both ends of the stack to replace worn material thickness, then the service life of the brake disc stack is extended and the wear stroke of the actuating piston is minimized, but the peak temperature of the brake disc stack increases
Solution Approach 1:
A thermal barrier coating is applied to the outer surfaces of the brake disc stack, acting as an intermediary layer that reduces heat transfer from the braking surfaces to the surrounding environment. This allows the stack to maintain higher operating temperatures during braking while preventing excessive peak temperatures that would reduce service life, thereby resolving the contradiction between extending service life and controlling peak temperature.
2Weight of moving object
If the mass of the brake disc stack is reduced to minimize aircraft weight, then operating costs are reduced, but the stack temperatures increase to their highest levels
Solution Approach 1:
The brake disc stack utilizes composite material construction with varying density layers, where the outer regions have lower density to reduce overall mass and the inner regions maintain higher density to provide thermal mass for heat absorption. This composite structure allows weight reduction while maintaining adequate thermal management capabilities, resolving the contradiction between minimizing aircraft weight and controlling stack temperatures.
3Loss of energy
If the cooling effect is more effective for outermost portions than central brake discs, then heat dissipation from outer regions is improved, but the peak temperature remains at the centre of the stack
Solution Approach 1:
The brake disc stack is designed with spatially varying properties where the outer regions have enhanced cooling characteristics (higher porosity, different material composition) to maximize heat dissipation, while the central regions maintain higher thermal mass and different geometric features to control peak temperature development. This local differentiation resolves the contradiction between improving heat dissipation and controlling central peak temperature.
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 ensures a more even temperature distribution across the brake disc stack, reducing peak temperatures and extending the service life while minimizing weight, thus improving the efficiency and longevity of the braking system.
Implementation Method 1
operating an actuator to cause the wear portions of brake elements to tribologically engage and thereby wear
Implementation Method 2
Carbon-carbon composite (C-C) materials have become the established material of choice for brake discs used in the aforementioned aircraft braking systems. The high specific heat of carbon allows relatively large quantities of energy to be absorbed by a brake heat pack having a relatively low mass
Implementation Method 3
the cooling effect of the airflow around the brake disc stack in use is more effective for the outermost portions of brake disc stacks than it is for the central brake discs
Data Source
AI summary
A brake apparatus (1) and method of operating the apparatus are disclosed. The apparatus (1) has a plurality of brake elements (2, 3, 4, 5, 6) with a combined thickness of Y. At least one of the brake elements (2, 3, 4, 5, 6) has a wear portion (22a, 22b) for tribological interaction with a wear portion (52b, 62a) of an adjacent element (5, 6) and is formed in two separable parts (21a, 21b) having thicknesses A1 and A2. The method includes operating an actuator (8) at an actuation extension length less than a maximum actuation extension length to cause the wear portions (22a, 22b, 52b, 62a) of the brake elements (2, 5, 6) to tribologically engage and thereby wear. This tribological engagement is such that as the elements (2, 5, 6) wear to a combined thickness of less than Y the extension length of the actuator is increased. A spacer (23) is inserted between the two parts (21a, 21b) of the brake element (2) to cause the wear portions (22a, 22b, 52b, 62a) to be tribologically engagable at a actuation extension length less than the increased actuation extension length.