Single-Layer Ceramic Knit Bulb Seals With Tailored Stiffness
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Solution Overview
Problem
Current thermal sealing members used in high-temperature applications, such as aircraft structures, face challenges with stiffness, deformation, and marginal thermal resistance, leading to performance degradation and burnout issues due to their multilayer construction and low stainless steel spring tube stiffness.
Innovation Solution
A single-layer ceramic-based knit fabric is developed by concurrently knitting continuous ceramic strands with metal alloy wires, including a load-relieving process aid strand and additional metal alloy wires for tailored stiffness, which are then formed into specific shapes like M-shaped or omega-shaped bulb seals, incorporating insulation for enhanced thermal protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If multilayer materials including stainless steel spring tube, multiple layers of woven ceramic fabric, and outer stainless steel mesh are integrated by hand, then thermal sealing members can be manufactured, but fabrication complexity increases and stiffness is insufficient leading to wrinkling and deformation
Solution Approach 1:
The patent combines multiple previously separate layers (ceramic fabric, metal mesh, insulation layers) into a single integrated knit fabric structure. The ceramic strands and metal wires are knitted together concurrently to form a unified single-layer fabric that eliminates the need for manual integration of multiple layers, reducing fabrication complexity while maintaining or improving structural stiffness.
Solution Approach 2:
The patent uses composite materials by integrating ceramic strands with metal alloy wires in a single knit fabric layer. This composite structure provides both the thermal resistance of ceramic and the stiffness and strength of metal, resolving the contradiction between ease of manufacture and structural strength.
2Reliability
If current thermal sealing members are repeatedly compressed in normal use, then sealing function is maintained, but they do not restore to proper shape and maintain the seal due to compression set
Solution Approach 1:
The patent changes the material parameters by using high-temperature alloy wires with enhanced elastic properties and optimizing the knit fabric structure to improve shape recovery. The modified material parameters allow the sealing member to withstand repeated compression and restore its original shape, maintaining seal reliability.
3Temperature
If current thermal sealing members are used at high temperatures, then sealing function is provided, but they burn out in excessively short time due to marginal thermal resistance
Solution Approach 1:
The patent uses composite materials combining ceramic strands with high-temperature resistant metal alloys in a single knit fabric. This composite structure provides superior thermal resistance compared to previous materials, enabling the sealing member to withstand high temperatures for extended periods without burning out, thus extending service life.
Solution Approach 2:
The patent moves away from disposable or short-lived thermal sealing members by creating a durable, long-lasting seal that can withstand repeated compression cycles and high-temperature exposure. The enhanced durability eliminates the need for frequent replacement.
4Weight of moving object
If single-layer ceramic-based knit fabric is used, then weight is reduced and manufacturing cost is lowered, but additional metal alloy wires are needed to provide sufficient stiffness
Solution Approach 1:
The patent creates a composite material system by integrating ceramic strands with metal alloy wires in a single knit fabric layer. This composite structure provides the necessary stiffness and strength while maintaining lightweight characteristics, as the ceramic provides thermal resistance and the metal provides structural support.
Solution Approach 2:
The single-layer knit fabric serves multiple functions simultaneously: the ceramic strands provide thermal resistance, the metal wires provide stiffness and strength, and the integrated structure provides both lightweight construction and durable sealing capability. This multi-functionality resolves the contradiction between weight reduction and strength maintenance.
Data Source
AI summary
Knit fabrics having ceramic strands, thermal protective members formed therefrom and to their methods of construction are disclosed. Methods for fabricating thermal protection using multiple materials which may be concurrently knit are also disclosed. This unique capability to knit high temperature ceramic fibers concurrently with a load-relieving process aid, such as an inorganic or organic material (e.g., metal alloy or polymer), both small diameter wires within the knit as well as large diameter wires which provide structural support and allow for the creation of near net-shape preforms at production level speed. Additionally, ceramic insulation can also be integrated concurrently to provide increased thermal protection.