Washer-Assisted Friction Disk Riveting for Wear Liner Protection
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Solution Overview
Problem
The existing riveting process for coupling carbon wear liners to ceramic matrix composite (CMC) cores in aircraft brake systems often causes damage to the wear liners and the reusable friction disk core during assembly and de-riveting.
Innovation Solution
The use of washers, specifically a first washer positioned between the upset head of the rivet and the wear liner, and a second washer positioned between the rivet head and the wear liner, to distribute the load of the rivet and prevent damage to the wear liners and the friction disk core.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the rivet upset head is formed directly against the wear liner, then the riveting process is simple, but the wear liner and friction disk core are damaged
Solution Approach 1:
A washer is introduced as an intermediary component between the rivet upset head and the wear liner. The washer distributes the concentrated load of the upset head over a larger area, preventing damage to the wear liner and friction disk core while maintaining the structural integrity of the assembly.
Solution Approach 2:
The washer is pre-installed in the counterbore before forming the upset head. This preliminary positioning ensures that the load distribution surface is already in place, allowing the upset head to be formed without direct contact with the wear liner, thus preventing damage from the outset.
2Ease of manufacture
If the rivet load is concentrated on a small area, then the riveting process is straightforward, but the wear liner and friction disk core are damaged
Solution Approach 1:
The washer serves as a load-distributing intermediary that spreads the concentrated rivet load over a larger area of the wear liner and friction disk core. This prevents stress concentration that would otherwise cause damage while maintaining the straightforward riveting process.
Solution Approach 2:
The washer performs multiple functions: it distributes the load of the upset head, prevents damage to the wear liner and friction disk core, and can be designed to conform to the counterbore geometry. This multi-functionality is achieved through a single component that addresses both structural and protective requirements.
3Duration of action of stationary object
If the wear liner becomes thin due to wear, then the friction disk can be reused, but the wear liner becomes susceptible to warpage
Solution Approach 1:
The washer modifies the stress distribution parameters on the wear liner by spreading the concentrated load over a larger area. This change in load distribution prevents the localized stress that would cause warpage in thin, worn wear liners, allowing the friction disk core to be reused safely.
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 solution effectively reduces the risk of damage to the wear liners and the friction disk core during the riveting and de-riveting processes, thereby extending the lifespan of these components and improving the efficiency of the aircraft braking system.
Implementation Method 1
the upset head pushes against the washer thereby spreading a load of the upset head to at least one of the first wear liner or the second wear liner
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A friction disk is provided. The friction disk includes a friction disk core (49), a first wear liner (156a) located over a first surface of the friction disk core, a second wear liner (156b) located over a second first surface of the friction disk core, a washer (174), and a rivet (170). The first wear liner and the second wear liner are coupled to the friction disk core via the rivet. The washer is configured to be positioned at a distal end of the rivet, such that, in response to the distal end of the rivet being upset forming an upset head (410), the upset head pushes against the washer thereby spreading a load of the upset head to at least one of the first wear liner or the second wear liner.