Composite Fan Case Ballistic Liner for Lightweight Blade Containment
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Solution Overview
Problem
Gas turbine engines face challenges in balancing blade containment with low weight and high strength, particularly in large diameter engines where metallic cases are too heavy for effective penetration resistance.
Innovation Solution
A fan case design incorporating a hard ballistic liner made of composite materials like KEVLAR or ceramic, combined with an abradable layer and honeycomb structure, provides lightweight yet effective containment by resisting blade fragment penetration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick metallic case is used to resist blade fragment penetration, then blade containment capability is improved, but weight increases prohibitively for large diameter engines
Solution Approach 1:
The patent applies composite materials consisting of multiple layers including a metallic case, a ceramic matrix composite (CMC) liner, and a metallic backup structure. The CMC liner provides high-temperature oxidation resistance and mechanical strength to contain blade fragments, while the metallic case and backup structure provide structural support. This composite structure achieves adequate blade containment capability without requiring prohibitively thick metallic walls, thus reducing overall case weight for large diameter engines.
2Weight of stationary object
If a light weight ballistic fabric is used in softwall design, then case weight is reduced, but structural integrity and penetration resistance deteriorate
Solution Approach 1:
The patent replaces simple ballistic fabric with a sophisticated composite structure including a ceramic matrix composite (CMC) liner bonded to a metallic case with a backup structure. The CMC material provides both light weight and high strength/penetration resistance, overcoming the limitation of softwall designs where fabric alone cannot maintain structural integrity after penetration. The composite structure maintains case shape and supports blade containment while keeping weight low.
Solution Approach 2:
The patent applies different materials with specific properties to different regions of the case structure. The CMC liner is applied specifically where blade containment is most critical, providing localized high-temperature oxidation resistance and mechanical strength. The metallic case and backup structure provide structural support in regions requiring rigidity. This localized application of specialized materials optimizes both weight and penetration resistance.
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 design achieves robust blade containment while maintaining low weight, using a composite material that resists impact and maintains structural integrity.
Implementation Method 1
an abradable layer and honeycomb structure, provides lightweight yet effective containment by resisting blade fragment penetration
Implementation Method 2
a light weight, high strength ballistic fabric such as KEVLAR is wrapped in multiple layers around a relatively thin, penetration susceptible metallic case. In operation, a separated blade fragment penetrates the case and strikes the fabric.
Data Source
Figure 1
Figure 2~3
AI summary
A fan case for a gas turbine engine includes an outer case (68) defined about an engine axis (A) and a hard ballistic liner (66) defined about the engine axis, the hard ballistic liner being located within the outer case. The outer case can be manufactured of a composite material, and the hard ballistic liner can be manufactured of one of a resin impregnated KEVLAR, a ceramic material and a metallic material. The invention also extends to a gas turbine engine with such a case, and to a method of fan blade containment within a gas turbine engine comprising locating a hard ballistic liner within a composite outer case radially adjacent to an array of fan blades.