Composite Fan Case Mounting Attachment
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Solution Overview
Problem
Attaching components to composite fan cases in gas turbine engines using traditional threaded fasteners is impractical and compromises structural integrity and maintainability.
Innovation Solution
A composite fan case assembly with a base component, spool component, and helical insert, featuring a non-cylindrical boss and threaded surfaces to securely attach external components without compromising the structural integrity of the composite material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional threaded fasteners are used to attach components to composite fan cases, then attachment functionality is achieved, but structural integrity is compromised and maintainability deteriorates
Solution Approach 1:
The patent introduces a mounting attachment as an intermediary component between the composite fan case and external components. This attachment includes a base component with a non-cylindrical boss that fits into a recess in the composite case, and a cylindrical portion with internal threads that receive external fasteners. The intermediary mounting attachment transfers loads from external components through the mounting attachment structure rather than directly through the composite material, preserving structural integrity while achieving attachment functionality.
Solution Approach 2:
The mounting attachment is segmented into multiple functional portions: a base component with a non-cylindrical boss for engagement with the composite case, a cylindrical portion with internal threading for receiving external fasteners, and a flange for external component mounting. This segmentation allows each portion to perform its specific function optimally - the boss provides secure engagement with the composite case without requiring threaded holes through it, while the cylindrical portion provides the threading functionality needed for external component attachment.
2Ease of operation
If traditional threaded fasteners are used to attach components to composite fan cases, then attachment functionality is achieved, but maintainability deteriorates
Solution Approach 1:
The mounting attachment is segmented into removable portions - the cylindrical portion with internal threads can be independently removed from the base component. This segmentation enables maintainability because if the internal threads become damaged or worn, only the cylindrical portion needs to be replaced, not the entire mounting attachment or the composite fan case. The base component with the non-cylindrical boss remains intact and can be reused.
3Adaptability or versatility
If threaded holes are created in composite fan cases for fastener installation, then component attachment is enabled, but damage to honeycomb or liners occurs
Solution Approach 1:
The mounting attachment serves as an intermediary that eliminates the need to create threaded holes in the composite fan case. The base component with the non-cylindrical boss engages with a pre-formed recess in the composite case, and the cylindrical portion with internal threads is attached to this base component. This intermediary structure provides the necessary threading functionality for component attachment without requiring any threaded holes to be drilled or tapped into the composite material itself, thereby preventing damage to the honeycomb or liners.
Solution Approach 2:
The recess with the non-cylindrical profile is pre-formed in the composite fan case during manufacturing, before any external components need to be attached. This preliminary action creates a ready-made engagement feature that accepts the non-cylindrical boss of the mounting attachment, eliminating the need for subsequent drilling or threading operations that would damage the composite structure.
Data Source
Figure 1~2
Figure 3A~3C
Figure 4
AI summary
An example composite fan case assembly (26) includes a composite fan case body (30) disposed on an axis. The fan case body has a radially inner surface (34) and a radially outer surface (36). There is at least one mounting attachment (32) to receive a threaded member. The at least one mounting attachment includes a base component (60) and a spool component (80). The base component extends through an opening in the fan case body from the radially outer surface and toward the radially inner surface of the fan case body. The base component including a base portion (62), a boss (64) having a non-cylindrical profile, and a cylindrical portion (66) The mounting attachment also includes a spool component disposed on the radially outer surface and attached to the base component. The spool component receives at least a portion of the base component. An outer surface of the cylindrical portion and an inner surface of the spool component are threaded and correspondingly mate to lock the spool component relative to the base component.