Gas Turbine Fan Containment Case Using Composite Bands
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Solution Overview
Problem
Existing hardwall fan containment cases in gas turbine engines are heavy due to their metal construction, which increases weight without adequately addressing the structural strength needed to withstand a fan blade-off event, and there is a need for a lighter alternative that maintains structural integrity.
Innovation Solution
A hardwall fan containment case with a barrel comprising multiple bands of carbon composite and poly p-phenylene-2,6-benzobisoxazole (PBO) fiber composite, where the PBO fiber composite is fully encapsulated within carbon composite bands to enhance cutting resistance and reduce environmental degradation, while maintaining structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hardwall fan containment case is made of titanium or metal to withstand fan blade-off impact, then the structural strength is improved, but the weight of the gas turbine engine increases
Solution Approach 1:
The fan containment case uses a composite structure consisting of multiple bands of different materials (carbon composite, PBO fiber composite, aramid fiber composite) to achieve both high strength and reduced weight. This composite material approach allows the containment case to withstand fan blade-off impacts while being lighter than traditional solid metal constructions.
Solution Approach 2:
The barrel is divided into multiple discrete bands of different materials arranged in specific sequences. This segmentation allows each material to perform its optimal function (carbon for compression, PBO for cutting resistance, aramid for toughness) while collectively providing the required structural strength at reduced weight.
2Weight of moving object
If the hardwall fan case is made lighter using alternative materials, then the weight is reduced, but the ability to withstand fan blade-off impact may be compromised
Solution Approach 1:
The patent employs a multi-material composite construction where carbon composite provides compressive strength, PBO fiber composite provides exceptional cutting resistance, and aramid fiber composite provides toughness and energy absorption. This combination maintains structural strength while achieving weight reduction compared to solid metal cases.
Solution Approach 2:
Different material bands are strategically positioned at different locations within the containment case structure based on the specific stress and impact requirements of each region. This local optimization ensures that each area has the appropriate material properties to handle its specific loading conditions while minimizing overall weight.
3Strength
If PBO fiber composite is exposed on the surface to provide cutting resistance, then the impact resistance is improved, but the material is susceptible to environmental degradation
Solution Approach 1:
The PBO fiber composite bands are nested or enclosed within bands of other materials (carbon composite and/or aramid fiber composite). This nesting protects the PBO from direct environmental exposure while maintaining its cutting resistance properties, as the protective outer bands shield it from moisture and other degrading factors.
Solution Approach 2:
Carbon composite or aramid fiber composite bands serve as intermediary protective layers between the PBO fiber composite and the external environment. These intermediary layers prevent direct contact between the PBO and degrading environmental factors while allowing the PBO to maintain its exceptional cutting resistance against fan blade impacts.
Data Source
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AI summary
A fan containment case (60) for a gas turbine engine is provided which includes a barrel (68) having a first band (91) of material on an outside (86) of the barrel. The first band is made of carbon fiber composite (88). The barrel further includes a second band (92) of material inboard of the fan case and made of poly p-phenylene-2,6-benzobisoxazole (PBO) composite (90). The barrel also includes a third band (93) of material made of carbon fiber composite (88) inboard of the second band.