Composite Fan Containment Case with Integral Stiffeners
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Solution Overview
Problem
As gas turbine engine fan containment cases are scaled up to larger fan diameters with slower fan blade speeds, the design challenge shifts from fan blade out events to droop and ovalization due to the case's own weight, affecting rubstrip clearances and fan efficiency, with thickening the case not being the most weight-efficient solution.
Innovation Solution
The integration of integral stiffeners with a rounded triangular cross-section and vent openings in the fan containment case, formed from braided composite materials, helps resist ovalization and maintain structural integrity without the need for additional stiffening components, thereby optimizing weight and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the fan containment case shell is thickened to address ovalization, then structural rigidity is improved, but weight increases
Solution Approach 1:
The fan containment case is segmented by incorporating discrete stiffeners (ribs and rings) at specific locations rather than uniformly thickening the entire shell. This segmentation allows rigidity to be enhanced only where structurally necessary, maintaining weight efficiency while addressing ovalization and droop concerns in the scaled-up larger fan diameter application.
Solution Approach 2:
The fan containment case utilizes composite material construction with braided carbon fiber and epoxy resin system. This composite material provides high strength-to-weight ratio, enabling the thin-walled design to achieve sufficient structural rigidity without requiring increased thickness, thus resolving the contradiction between rigidity and weight.
2Weight of moving object
If the fan containment case is made thin-walled for weight optimization, then weight is reduced, but structural rigidity deteriorates
Solution Approach 1:
The thin-walled fan containment case is reinforced with strategically placed stiffeners (axial ribs and circumferential rings) that segment the shell structure. This segmentation provides localized rigidity enhancement at critical areas without requiring overall shell thickening, maintaining the weight optimization benefits of a thin-walled design while preventing excessive droop and ovalization.
Solution Approach 2:
The stiffeners extend in the radial dimension outward from the thin-walled shell, creating a multi-dimensional structural system. This radial extension provides additional structural support and rigidity in the thin-walled construction without significantly increasing overall weight, effectively resolving the rigidity-deficiency issue of thin-walled design.
3Ease of manufacture
If traditional fabrics or unidirectional composites are used, then manufacturing simplicity is maintained, but structural capability decreases
Solution Approach 1:
The patent employs braided carbon fiber composite material with epoxy resin system, which provides superior structural capability compared to traditional fabrics or unidirectional composites at similar laminate thicknesses. The braided construction delivers enhanced strength and stiffness properties necessary for the scaled-up fan containment application while maintaining manufacturability through established composite fabrication processes.
Data Source
Figure 1
Figure 2
Figure 2A~2B
AI summary
A gas turbine engine component includes a tubular body section (66) including a plurality of fiber wraps encompassed within a matrix composition and one or more integrally-formed stiffeners (84) extending from an outer surface (86) of the body section and in a component circumferential direction around the body section. The stiffener includes one or more fiber wraps extending radially outwardly from the body section over a form and to the body section from the form.