Ceramic Panel Fastener Assembly for Thermal Expansion Locking
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Solution Overview
Problem
The mounting of ceramic and ceramic matrix composite parts in the hot sections of gas turbine engines faces challenges due to differential thermal expansion of metallic and non-metallic components, leading to issues such as fastener loosening and potential damage to engine components.
Innovation Solution
A panel assembly is designed with a ceramic or ceramic matrix composite body, where fasteners with expandable heads are used. The fasteners are initially formed with non-protuberant heads, which are then expanded in situ by pressurized fluid to create a protuberance that backlocks the fastener, ensuring secure mounting despite thermal expansion differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metallic fasteners are used to mount ceramic matrix composite panels, then the fastening system provides initial secure attachment, but differential thermal expansion causes fastener loosening and potential damage to components
Solution Approach 1:
The fastener head is designed to transition from a non-protuberant state during assembly to a protuberant state after actuation, creating a dynamic locking mechanism that adapts to thermal expansion forces rather than resisting them statically
Solution Approach 2:
Pressurized fluid is used to actuate the fastener head expansion, providing controlled force to transform the fastener from a non-protuberant to protuberant state, enabling reliable locking without excessive mechanical assembly forces
2Reliability
If fasteners are designed with expandable heads that require pressurized fluid actuation, then secure locking is achieved against thermal expansion, but device complexity increases
Solution Approach 1:
The fastener head contains internal structural features that automatically transform from non-protuberant to protuberant state when subjected to pressurized fluid, eliminating the need for external complex actuation mechanisms
Solution Approach 2:
The fastener head geometry is designed to undergo a parameter change in its radial dimension when pressurized, transforming from a compact non-protuberant configuration to an expanded protuberant configuration that provides locking
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 effectively addresses the issue of differential thermal expansion by providing a secure fastening system that maintains the integrity of both ceramic and metallic components, reducing the likelihood of fastener loosening and potential damage to engine components.
Implementation Method 1
The fasteners are initially formed with non-protuberant heads, which are then expanded in situ by pressurized fluid to create a protuberance that backlocks the fastener
Data Source
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AI summary
Attaching a fastener (50) to a ceramic matrix composite or ceramic body by inserting a portion of the fastener (50) into a compartment of the body, the compartment having a first portion (82) and a second portion (84), the second portion (84) outboard of and narrower than the first portion (82); and delivering a fluid into the fastener (50) to expand a portion (70) of the fastener (50) within the compartment first portion (82).