Attachment Boss for FRP Fan Case Using Embedded Metal Body
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Solution Overview
Problem
Fiber reinforced polymers (FRP) used in aircraft engine fan cases, such as carbon fiber reinforced resin (CFRP), lose strength when discontinuous fibers are used, making it difficult to securely attach auxiliary devices without compromising the structural integrity.
Innovation Solution
An attachment boss system comprising a pedestal made of layered reinforcement fibers and a metal or ceramic embedded body with anti-displacement and anti-rotation features, allowing secure fixation of auxiliary devices via bolts without damaging the fan case, using a combination of adhesive and bolt tightening for attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If fiber reinforced resin (FRP) is used for the fan case to reduce weight and increase strength, then weight is reduced and strength is improved, but the ability to securely attach auxiliary devices deteriorates due to loss of strength when discontinuous fibers are used
Solution Approach 1:
The attachment boss is divided into two distinct parts: a pedestal made of FRP that integrates with the fan case, and an embedded body made of metal or ceramic that provides the attachment interface. This segmentation allows each component to be optimized for its specific function while maintaining the overall benefits of FRP construction.
Solution Approach 2:
The invention uses composite construction by combining FRP (for the pedestal) with metal or ceramic materials (for the embedded body). This composite approach leverages the weight and strength advantages of FRP while incorporating the superior attachment properties of metal or ceramic materials, resolving the contradiction between weight reduction and attachment strength.
2Ease of operation
If auxiliary devices are attached to FRP fan case by conventional methods, then attachment is achieved, but structural integrity is compromised due to fiber discontinuity and strength loss
Solution Approach 1:
The embedded body with threading is pre-installed into the pedestal during manufacturing, creating a ready-made attachment interface before the fan case is put into service. This preliminary action ensures that when auxiliary devices need to be attached, a robust metal or ceramic threading structure is already in place, eliminating the need to compromise FRP structural integrity during field attachment operations.
3Strength
If continuous fibers are used in FRP to maintain high strength, then strength is maintained, but adaptability to attach auxiliary devices at arbitrary sites deteriorates
Solution Approach 1:
The invention applies local quality by concentrating the attachment functionality in a specific localized region (the embedded body) rather than requiring continuous fibers throughout the entire fan case. The pedestal can be manufactured with continuous fibers for strength, while the localized embedded body provides the adaptability for attachment at arbitrary sites, resolving the contradiction between maintaining overall strength and enabling localized attachment versatility.
Data Source
Figure 1A~1B
Figure 2A~2C
Figure 3
AI summary
A boss for attachment of an auxiliary device to a fan case of an engine is comprised of a pedestal including a plurality of accumulated layers of reinforcement fibers and a matrix combining the reinforcement fibers together, the pedestal comprising a bottom face in a shape capable of being in close contact with an outer periphery of the fan case; and an embedded body embedded in the pedestal and including a combining structure combinable with the auxiliary device.