Composite Fan Casing with Integrated 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 in fabrication, as well as inefficiencies in energy absorption and repairability during events like fan blade outs and ice shedding.
Innovation Solution
The method involves creating a composite containment casing with an integrated abradable system using a sandwich structure with radial strength and circumferential weakness, infused with resin and featuring an abradable layer, which is applied directly to the casing, reducing the need for multiple layup and bonding cycles and allowing for easier repair.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a thick, monolithic hardwall design is used for fan casing, then impact resistance is improved, but weight and fabrication complexity increase
Solution Approach 1:
The fan casing is segmented into multiple functional layers: a hardwall containment structure for impact resistance, an abradable system with sandwich structure for energy absorption, and a composite face sheet for structural integrity. Each layer performs a specific function, allowing the overall structure to achieve high impact resistance without requiring excessive thickness throughout the entire casing.
Solution Approach 2:
The invention uses composite materials including glass/epoxy composite face sheets bonded to Nomex honeycomb core, and abradable layers with specific material properties. This composite construction provides superior strength-to-weight ratio compared to monolithic designs, achieving the required impact resistance with reduced weight.
2Weight of moving object
If a honeycomb core is used in the abradable system, then weight is reduced, but radial strength is insufficient causing fan blades to cut through upon impact
Solution Approach 1:
The abradable system uses a sandwich structure with facesheets and core that provides localized strength where needed. The honeycomb core is positioned and configured to provide adequate radial strength for energy absorption during impact, while maintaining the lightweight advantage. The structure is designed with appropriate thickness and material properties in the radial direction to prevent blade penetration.
3Ease of manufacture
If the abradable system is fabricated separately and then attached to the fan casing, then manufacturing flexibility is improved, but fabrication time and labor cost increase
Solution Approach 1:
The abradable system is integrated directly into the fan casing fabrication process rather than being manufactured separately and attached later. The sandwich structure and abradable layers are positioned within the casing mold and co-cured with the main casing structure, eliminating separate attachment operations and reducing overall fabrication time and labor costs.
Solution Approach 2:
The abradable system components are prepared and positioned in advance within the mold cavity before the final curing cycle. This preliminary positioning allows the abradable system to be integrated into the casing structure during the normal fabrication sequence, avoiding post-fabrication attachment operations.
4Strength
If multiple layers of construction are used in the abradable system, then impact energy absorption is improved, but the system becomes heavier and more costly
Solution Approach 1:
The abradable system uses a optimized number of layers in the sandwich structure that provides sufficient impact energy absorption capability. Rather than using excessive layers that would increase weight, the design employs the minimum necessary layers with appropriate material properties and thickness to achieve the required energy absorption, balancing performance with weight constraints.
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
This approach enhances impact resistance by absorbing up to 25% of the impact energy generated by a released fan blade, reduces the weight and thickness of the casing, and simplifies repair by allowing for localized replacement of damaged abradable layers, thereby reducing time and cost.
Implementation Method 1
infusing a resin into the containment casing preform
Implementation Method 2
infusing a resin into the containment casing preform
Implementation Method 3
curing the containment casing preform
Data Source
AI summary
Method for making a composite containment casing having an integrated abradable system involving providing a mandrel having a pocket, positioning a sandwich structure into the pocket, applying at least one ply of a material about the mandrel having the pocket containing the sandwich structure therein to produce a containment casing preform, infusing a resin into the containment casing preform, curing the containment casing preform to produce a containment casing, and applying at least one abradable layer to the sandwich structure of the containment casing to produce the containment casing having the integrated abradable system.