Polyimide Composite Inner Shroud for Engine Wear and Weight Reduction
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Solution Overview
Problem
Airplane engine parts require materials that are wear-resistant, thermally stable, and lightweight, as metal components suffer from wear and thermal instability, particularly in the interaction between stator vanes and inner shrouds.
Innovation Solution
A composite ring or segment made from 40 to 90 weight percent of a polymer component, such as polyimide derived from biphenyltetracarboxylic acid, combined with at least 9 weight percent of a carbonaceous filler like graphite, offering thermal oxidative stability and low friction, suitable for replacing metal parts in engine shrouds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If metal components are used for inner shrouds and stator vanes, then strength and durability are sufficient, but wear occurs between vane spindle and shroud and weight is excessive
Solution Approach 1:
The patent applies composite materials by combining polymer matrices (such as polyimide, polyamide-imide, polyether imide, or polybenzimidazole) with carbonaceous fillers (such as graphite, carbon black, or carbon fibers) to create a composite inner shroud that is both lightweight and wear-resistant. The composite material provides reduced density compared to metal while maintaining durability through the wear-resistant properties of the polymer and filler combination.
2Reliability
If polymer bushings are used to reduce wear, then metal-to-metal wear is reduced, but thermal stability and structural integrity at high temperatures are compromised
Solution Approach 1:
The patent uses composite materials with high-temperature resistant polymer matrices (such as polyimide, polyamide-imide, polyether imide, or polybenzimidazole) combined with carbonaceous fillers to achieve both wear resistance and thermal stability. The polymer selection ensures stability at engine operating temperatures while the composite structure maintains structural integrity.
Solution Approach 2:
The patent changes the material parameters by selecting specific polymers with glass transition temperatures and decomposition temperatures suitable for high-temperature engine environments. The composite formulation adjusts the balance between polymer content and filler content to optimize both wear resistance and thermal stability for the specific application.
3Weight of moving object
If composite materials are used to reduce weight, then weight reduction is achieved, but manufacturing precision and material consistency become more difficult to control
Solution Approach 1:
The patent specifies precise compositional ranges for the composite material (40-90 weight percent polymer, 5-60 weight percent carbonaceous filler, and optional particulate up to 51 weight percent) to ensure material consistency. These controlled formulations, combined with standard manufacturing processes like compression molding or injection molding, enable reproducible manufacturing precision while maintaining the weight reduction benefits of composite materials.
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 composite parts provide significant weight reduction (40-75% lighter than metal), improved thermal stability, reduced wear, and lower friction, leading to longer component life and reduced air leakage, while eliminating the need for bushings and simplifying assembly.
Implementation Method 1
Polymer bushings of a high temperature resistant, wear resistant polymer such as Vespel® brand polyimide can be used to reduce metal-to-metal wear
Implementation Method 2
The composite has a thermal oxidative weight loss (TOWL) of less than 5% when determined after heating at 371°C (700°F) for 100 hours at 0.48 MPa (70 psi) in air
Data Source
Figure 1
AI summary
Disclosed herein is a composite part for an airplane engine comprising polymer selected from polyimide, polyamide-imide, polyether imides, polybenzimidazole, or blends thereof, and carbonaceous filler, which in combination provides thermal stability and wear resistance. Optionally, the composite may comprise particulate.