Shear Tie Connector System for Composite Fuselage

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Solution Overview

Problem

The existing methods for securing interior structures of an aircraft to a composite fuselage skin require numerous holes to be drilled, which is time-consuming, adds weight, weakens the fuselage structure, and increases construction and operational costs.

Innovation Solution

A shear tie connector system that uses a fuselage mandrel with slots to position and secure shear tie connectors without drilling, employing an adhesive for co-bonding and inflatable bladders for retention, eliminating the need for fasteners and holes through the composite skin.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If straight shank fasteners are used to secure shear tie connectors to composite fuselage skin, then the frame components can be securely connected, but numerous holes must be drilled through the fuselage skin which weakens the structure and adds weight

Engineering Contradiction:

Improvestructural integrityVSAvoidfuselage weight

Core Design Contradiction:

StrengthVSWeight of stationary object

Solution Approach 1:

The patent replaces the mechanical fastening system (drilled holes with straight shank fasteners) with an adhesive bonding system. The adhesive is applied to the shear tie connector and bonds to the composite fuselage skin without requiring holes, thereby eliminating the structural weakening and weight penalty associated with numerous fastener holes while maintaining secure connection strength

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If numerous holes are drilled through the composite fuselage skin to install fasteners, then the shear tie connectors can be secured to the skin, but the construction time and cost increase significantly

Engineering Contradiction:

Improveconnection reliabilityVSAvoidconstruction time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The adhesive bonding process eliminates the time-consuming operations of drilling numerous holes through the composite fuselage skin and installing fasteners. The adhesive can be applied directly to the shear tie connector and bonded to the skin in a single operation, significantly reducing construction time while maintaining connection reliability through the adhesive bond

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If straight shank fasteners and sealant are used to secure shear tie connectors, then the connection is established, but the weight of the aircraft increases due to the fasteners and sealant

Engineering Contradiction:

Improveconnection reliabilityVSAvoidaircraft weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The patent extracts and eliminates the straight shank fasteners and sealant from the connection system, replacing them with an adhesive bonding system. This removal of unnecessary components (fasteners and sealant) directly reduces the overall aircraft weight while maintaining secure connection through the adhesive bond between the shear tie connector and composite fuselage skin

Inventive Principle:

Principle #2Taking out (Extraction)

4Ease of manufacture

If numerous holes are drilled through the composite fuselage skin, then the shear tie connectors can be installed, but the fuselage structure is weakened and air pressure containment is compromised

Engineering Contradiction:

Improveinstallation easeVSAvoidfuselage strength

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The adhesive bonding system replaces the hole-drilling mechanical installation method. The adhesive is applied to the shear tie connector and bonds to the composite fuselage skin surface without penetrating it, thereby maintaining the fuselage structure's integrity and air pressure containment while still enabling easy installation of the shear tie connectors

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach reduces construction time and costs, minimizes weight, enhances structural integrity, and improves passenger comfort by eliminating holes and fasteners, allowing for a thinner, lighter fuselage skin that maintains strength and better contains air pressure.

Implementation Method 1

employing an adhesive for co-bonding

Methodology Applied

Scientific EffectAdhesive bonding: Adhesive

Implementation Method 2

inflatable bladders for retention

Methodology Applied

Scientific EffectInflation:

Data Source

PatentUS11414172B2Fastener-less frame installation in a composite structure

Publication Date: 2022.08.16 THE BOEING CO

AI summary

A shear tie connector system for securing a frame component to a composite fuselage skin, which includes a shear tie connector and a fuselage mandrel, which defines a slot within which the shear tie connector is positioned.