Composite Engine Case Axial Interface Design
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Solution Overview
Problem
Composite bypass ducts in gas turbine engines face challenges due to low circumferential stiffness at mid-span and difficulties with mitered turned-up axial and circumferential flanges, which complicates the interface arrangement and increases the likelihood of voids and labor-intensive lay-up processes.
Innovation Solution
The implementation of an axial interface configuration using an alternating mix of full-length and partial plies for strength, along with flyaway inserts co-cured into the lay-up, provides substantial circumferential stiffness and simplifies the lay-up process by eliminating 3D corner flanges, reducing voids, and optimizing ply orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If turned-up axial flanges are used on composite components, then the duct structure can be assembled, but the circumferential stiffness at mid-span is insufficient
Solution Approach 1:
The duct is divided into multiple sections with axial interfaces that include circumferential flanges. These flanges are segmented into different ply orientations (0-degree and 90-degree plies) to provide both assembly capability and circumferential stiffness. The segmentation allows each section to be manufactured separately and assembled while maintaining structural integrity.
Solution Approach 2:
The patent uses composite material construction with specific ply orientations (0-degree and 90-degree plies) at the axial interfaces to achieve both ease of assembly and sufficient circumferential stiffness. The composite structure allows for optimized material placement where 90-degree plies provide circumferential stiffness while 0-degree plies provide axial strength.
2Ease of manufacture
If mitered turned-up axial and circumferential flanges are used, then the interface arrangement can be achieved, but the lay-up process becomes labor-intensive and void formation increases
Solution Approach 1:
The patent extracts the complex 3D mitered corner flange geometry and replaces it with a simplified axial interface design. The interface uses flat axial flanges with standardized ply orientations instead of complex mitered turns, eliminating the labor-intensive aspects of creating tight corners while maintaining the necessary interface arrangement between duct sections.
Solution Approach 2:
Instead of turning up flanges in complex 3D mitered configurations, the patent inverts the approach by using flat axial flanges with plies oriented at 0 and 90 degrees. This inversion simplifies the lay-up process by avoiding tight corner bends while achieving the same interface arrangement function through a different geometric approach.
3Ease of manufacture
If 3D corner turned-up flanges are used, then the duct interface can be formed, but the likelihood of voids increases and the mold becomes more complex
Solution Approach 1:
The patent inverts the traditional approach of creating 3D corner turned-up flanges by using flat axial interfaces with plies oriented at 0 and 90 degrees. This eliminates the tight corner bends that create voids during manufacturing, as the plies lay flat without requiring complex 3D shaping. The interface formation is achieved through a simpler, more reliable method.
Solution Approach 2:
The patent uses thin composite plies (0-degree and 90-degree orientations) that can be easily laid up and cured without requiring complex 3D forming. These thin film structures are less prone to void formation compared to thick 3D turned-up flanges, as they can conform to the mold surface more easily and cure more uniformly.
Data Source
AI summary
A composite engine case with an axial interface. One configuration includes an alternating mix of full length and partial plies, in order to provide the total thickness needed for the axial overlap. Another configuration provides only full-length structural plies with a flyaway insert adjacent the axial interface.