Layered CMC Fastener Structure for High-Temperature Reliability
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Solution Overview
Problem
Traditional metallic fasteners used for securing ceramic matrix composite (CMC) components in high-speed aviation equipment fail at high operating temperatures, necessitating improved fastening solutions that can withstand extreme conditions.
Innovation Solution
The development of ceramic matrix composite (CMC) fasteners with a body comprising an inner and outer portion, where the outer portion is constructed using CMC tape extending circumferentially around the inner portion, providing enhanced strength and resistance to delamination, formed through a method involving shaping a preform, applying layers, and finishing to create a layered structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If metallic hardware is used to secure CMC components, then fastening function is achieved, but the fasteners fail at high operating temperatures above safe operating conditions
Solution Approach 1:
The patent changes the material parameter of the fastener from metallic to ceramic matrix composite, enabling operation at temperatures exceeding 1700°F where metallic fasteners would fail. This material parameter change allows the fastener to maintain structural integrity and reliability in high-temperature hypersonic applications
Solution Approach 2:
The patent employs ceramic matrix composite materials with specific fiber reinforcement architectures (unidirectional, woven, or hybrid) to create a fastener that combines high-temperature resistance with mechanical strength. The composite structure enables the fastener to withstand extreme temperatures while maintaining fastening reliability
2Strength
If CMC tape is applied in multiple layers circumferentially around the inner portion, then interlaminar strength and resistance to delamination is improved, but manufacturing complexity increases
Solution Approach 1:
The patent segments the fastener construction into distinct functional portions: an inner portion providing core structural support and an outer portion formed by circumferentially applied CMC tape layers providing enhanced interlaminar strength. This segmentation allows each portion to be optimized independently while simplifying the overall manufacturing process through sequential assembly
Solution Approach 2:
The patent implements a nested structure where the outer CMC tape layers are applied circumferentially around the inner portion, creating a concentric layered architecture. This nesting approach simplifies manufacturing by allowing layers to be applied sequentially in a straightforward manner while maximizing interlaminar bonding and resistance to delamination forces
Data Source
AI summary
A method of forming a ceramic matrix composite (CMC) fastener, the method comprising: shaping a preform to form a green fastener; applying one or more layers to an outer surface of the green fastener to form a layered green fastener; and finishing the layered green fastener to form the CMC fastener.