Composite Fan Casing Fragment Catcher Design

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Solution Overview

Problem

Current composite containment technologies for gas turbine engine fan casings are inadequate in capturing released fan blade fragments, leading to potential damage to the aircraft due to radial weakness in honeycomb cores and labor-intensive, costly fabrication processes.

Innovation Solution

Integration of a fragment catcher within the composite containment casing, combined with a radially strong and circumferentially weak sandwich structure abradable system, which includes a first and second facesheet positioned around a core layer, and an abradable layer applied to the sandwich structure, positioned in a forward orientation to capture and deflect released fan blade fragments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a thick monolithic hardwall design is used to withstand impact, then the fan casing can absorb impact energy, but the fabrication process becomes labor intensive and costly with numerous layup, bonding, cure, and machining cycles

Engineering Contradiction:

Improveimpact resistanceVSAvoidfabrication complexity

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The fan casing is divided into functional segments: a hardwall containment structure and a separate abradable system with sandwich structure. This segmentation allows each part to be optimized independently - the hardwall provides impact resistance while the abradable system provides energy absorption, reducing overall fabrication complexity by allowing specialized manufacturing processes for each segment

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention uses composite materials throughout, including glass/epoxy composite face sheets bonded to Nomex honeycomb core in the abradable system, and carbon fiber reinforced polymer in the hardwall. These composite structures provide high strength-to-weight ratios and can be manufactured more efficiently than monolithic thick walls, reducing both weight and fabrication complexity while maintaining impact resistance

Inventive Principle:

Principle #40Composite materials

2Weight of moving object

If a honeycomb core is used to reduce weight, then the fan casing becomes lightweight, but the radial weakness causes released fan blades to cut through the core

Engineering Contradiction:

Improvefan casing weightVSAvoidradial strength

Core Design Contradiction:

Weight of moving objectVSStrength

Solution Approach 1:

The abradable system incorporates a sandwich structure with facesheets and honeycomb core specifically positioned in the radial path where fan blade impacts occur. This localized reinforcement provides radial strength exactly where needed without requiring the entire fan casing to be heavier. The sandwich structure's facesheets bear the radial impact loads while the honeycomb core provides lightweight spacing and energy absorption

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The abradable system with sandwich structure is positioned ahead of the hardwall containment in the radial direction, serving as a cushioning layer that absorbs and dissipates impact energy before it reaches the main structural walls. This preliminary energy absorption reduces the force transmitted to the honeycomb core, preventing blade fragments from cutting through while maintaining the core's lightweight properties

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Ease of operation

If the abradable system is fabricated separately and attached to the fan casing, then the system can be assembled in parts, but the two parts function independently rather than as a unitary system

Engineering Contradiction:

Improveassembly flexibilityVSAvoidsystem integration

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The invention merges the abradable system and hardwall containment into a unitary integrated structure where the sandwich structure facesheets are bonded to the hardwall inner surface, creating continuous load paths and ensuring the components function together as a single system. This integration maintains assembly flexibility while eliminating the independence problem, as the bonding creates structural continuity that ensures coordinated behavior during impact events

Inventive Principle:

Principle #5Merging (Combining)

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 fragment catcher and abradable system effectively absorb and deflect fan blade fragments, reducing the likelihood of severe aircraft damage and simplifying the fabrication process by reducing the number of layup, bonding, and machining cycles, resulting in a lighter and more efficient fan casing.

Implementation Method 1

The construction of the fan casing provides for the dissipation of impact energy using any of a number of mechanisms including fiber/matrix interference failure, matrix microcracking and ply delamination.

Methodology Applied

Scientific EffectFiber/matrix interference failure:

Implementation Method 2

Methodology Applied

Scientific EffectMatrix microcracking:

Implementation Method 3

Methodology Applied

Scientific EffectPly delamination:

Implementation Method 4

Current hardwall designs generally consist of an abradable system having an abradable layer attached to a substrate structure

Methodology Applied

Scientific EffectAbrasion: Abrasion

Data Source

PatentUS8403624B2Composite containment casings having an integral fragment catcher

Publication Date: 2013.03.26 GENERAL ELECTRIC CO

AI summary

Composite containment casings including a body having an interior and a fragment catcher integrally joined to the interior of the body of the containment casing.