Composite Fan Case Attachment Tool Design

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Solution Overview

Problem

Attaching components to composite fan cases in gas turbine engines using threaded fasteners can degrade the structural integrity of the case, as these fasteners create openings that weaken the material.

Innovation Solution

An attachment tool made of molded thermoplastic material with a threaded insert that engages the composite fan case, eliminating the need for mechanical fasteners and enhancing structural integrity by using helical or key-locking inserts and ribs to create internal cavities for fluid connection and pressure equalization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If threaded fasteners are used to attach components to the composite fan case, then component attachment is achieved, but the structural integrity of the fan case is degraded

Engineering Contradiction:

Improvecomponent attachmentVSAvoidstructural integrity of fan case

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent replaces traditional mechanical threaded fasteners with a chemical bonding system using epoxy adhesive. The adhesive is applied through channels in the attachment tool to bond the bracket directly to the composite fan case surface, eliminating the need for threaded holes and mechanical fasteners that would compromise the composite structure's integrity

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an epoxy adhesive as an intermediary bonding agent between the bracket and the composite fan case. This adhesive layer provides strong chemical bonding without requiring penetration into the composite material, thus maintaining structural integrity while achieving secure component attachment

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If threaded fasteners are used to attach components to the composite fan case, then component attachment is achieved, but weight is increased

Engineering Contradiction:

Improvecomponent attachmentVSAvoidweight of fan case assembly

Core Design Contradiction:

Ease of manufactureVSWeight of moving object

Solution Approach 1:

The patent eliminates heavy metal threaded fasteners and replaces them with a lightweight epoxy adhesive bonding system. This substitution significantly reduces the overall weight of the fan case assembly while maintaining effective component attachment capability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If threaded fasteners are used to attach components to the composite fan case, then component attachment is achieved, but the number of openings in the case increases

Engineering Contradiction:

Improvecomponent attachmentVSAvoidsurface area of fan case

Core Design Contradiction:

Ease of manufactureVSArea of stationary object

Solution Approach 1:

The patent replaces mechanical fastening requiring physical holes with adhesive bonding that applies to the existing surface. This eliminates the need for additional openings in the fan case, preserving the complete surface area and maintaining the aerodynamic and structural continuity of the composite structure

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP2977589B1Bolt attachment to composite gas turbine engine fan case

Publication Date: 2020.05.06 RTX CORP

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AI summary

A fan case (60) includes a composite fan case (60) body including an outer surface and at least one attachment tool (62) attached to the outer surface of the fan case (60) body. The attachment tool (62) includes a boss (90) that has at least one fastener opening (72) with a threaded insert (74). A channel (84) extends from at least one interior cavity (85) of the attachment tool (62) through an outer wall (76) of the attachment tool (62).