Composite Fan Casing with Sandwich Abradable System
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Solution Overview
Problem
Current composite containment casings for gas turbine engines, such as fan casings, face issues with impact resistance due to radial weakness in honeycomb cores, leading to increased weight, cost, and labor-intensive fabrication, as well as independent functioning of abradable systems, which are not effectively designed to absorb energy during fan blade out events.
Innovation Solution
The integration of a sandwich structure with a strong radial and weak circumferential design, utilizing a core layer configuration such as cell, columnar, or truss configurations, and an abradable layer made of low-density syntactic film epoxy, applied directly to the fan casing, providing improved impact resistance and energy absorption while reducing weight and fabrication complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a thick, monolithic hardwall design is used to withstand impact and fragmentize ice or released fan blades, then impact resistance is improved, but the fan casing becomes heavier and more difficult to manufacture
Solution Approach 1:
The fan casing is divided into a hardwall body and a separate abradable system with sandwich structure. The sandwich structure itself is segmented into facesheets and core layers with specific configurations (cell, columnar, or truss). This segmentation allows each component to be optimized independently - the hardwall provides impact resistance while the sandwich structure provides controlled weakness for energy absorption, reducing the need for excessive thickness throughout the entire casing.
Solution Approach 2:
The invention uses composite materials throughout - the hardwall body uses composite construction, the sandwich structure uses composite facesheets with composite core materials, and the abradable layer uses syntactic foam epoxy. These composite materials provide high strength-to-weight ratios, allowing the casing to maintain impact resistance while reducing overall weight compared to monolithic metal designs.
2Weight of moving object
If a honeycomb core is used in the abradable system, then lightweight construction is achieved, but radial weakness occurs causing fan blades to cut through the core
Solution Approach 1:
The core structure is designed with local quality variations - using cell, columnar, or truss configurations that provide enhanced radial strength specifically where needed to stop fan blades, while maintaining lightweight properties in other areas. The core layers can have different densities and structures at different radial positions, optimizing both weight and localized strength requirements.
Solution Approach 2:
The sandwich structure uses composite construction with facesheets bonded to core layers. This composite approach allows the relatively weak honeycomb or cell core to be reinforced by the strong facesheets, creating a structure that is lightweight yet has sufficient radial strength to prevent fan blade penetration while maintaining the energy absorption characteristics.
3Reliability
If numerous layup, bonding, cure, and machining cycles are used to fabricate the abradable system, then structural integrity is improved, but fabrication becomes labor intensive and costly
Solution Approach 1:
The abradable system components - sandwich structure and abradable layer - are designed to be integrally joined as a single assembly. This merging reduces the number of separate fabrication operations needed compared to assembling multiple independent components. The integral joining maintains structural integrity while simplifying the manufacturing process by reducing the number of bonding and assembly cycles required.
4Adaptability or versatility
If the abradable system is fabricated separately and then attached to the fan casing, then manufacturing flexibility is improved, but the system functions independently rather than as a unitary system
Solution Approach 1:
The abradable system is designed to be integrally joined to the fan casing, merging the previously separate components into a unitary system. This integral joining ensures that the abradable system and hardwall body function together as a coordinated whole, improving energy absorption effectiveness while maintaining the manufacturing flexibility to fabricate them as separate components that are then permanently joined.
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 integrated abradable system effectively absorbs up to 25% of the impact energy generated by a released fan blade, reducing the load on the fan casing body and allowing for a thinner, lighter design, while also enabling easier repair by replacing only damaged portions, thus reducing time and expense.
Implementation Method 1
The integrated abradable system effectively absorbs up to 25% of the impact energy generated by a released fan blade, reducing the load on the fan casing body
Implementation Method 2
The abradable system integrally joined to the interior of the body of the fan casing wherein the abradable system comprises a sandwich structure including a first facesheet and a second facesheet position about at least one core layer, and at least one abradable layer applied to the sandwich structure wherein the sandwich structure is strong radially and weak circumferentially
Data Source
AI summary
Composite containment casing including a body having an interior, an abradable system integrally joined to the interior of the body of the containment casing wherein the abradable system comprises, a sandwich structure including a first facesheet and a second facesheet position about at least one core layer, and at least one abradable layer applied to the sandwich structure wherein the at least one core layer comprises any of a cell configuration, a columnar configuration, or a truss configuration and wherein the sandwich structure is strong radially and weak circumferentially.