Composite Shear Tie for Aircraft Wing Attachment

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Solution Overview

Problem

Aircraft wing designs face challenges in securely attaching composite ribs to skins due to loads experienced during flight and on the ground, which can cause ribs to be pushed or pulled away from the skin, and existing methods using fasteners are susceptible to electromagnetic interference and require additional components like shims and bolts.

Innovation Solution

The use of a composite shear tie assembly that includes a shear-tie web, flanges, and tabs stitched to a stringer and skin, allowing for co-curing during the manufacturing process, which eliminates the need for fasteners and enhances the structural integrity by distributing loads more efficiently.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If fasteners are used to attach composite ribs to skins, then the attachment can be secured, but electromagnetic interference occurs and additional components like shims and bolts are required

Engineering Contradiction:

Improveattachment securityVSAvoidelectromagnetic interference

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent removes fasteners (bolts, shims) from the attachment system entirely, extracting the harmful electromagnetic interference source while maintaining attachment functionality through a purely composite construction approach

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention uses composite materials (carbon fiber reinforced polymer) for the shear tie and rib assembly, allowing the structure to be attached to the skin through composite-to-composite bonding and mechanical interlocking rather than metal fasteners, thereby eliminating electromagnetic interference

Inventive Principle:

Principle #40Composite materials

2Reliability

If fasteners and additional components are used for attachment, then secure connection is achieved, but device complexity increases

Engineering Contradiction:

Improveattachment securityVSAvoidnumber of components

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the shear tie, rib, and attachment functionality into a single integrated composite assembly, eliminating the need for separate fasteners, shims, and bolts, thereby reducing component count while maintaining attachment security

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The composite shear tie assembly serves multiple functions simultaneously: it acts as a structural connector, provides electromagnetic interference protection, and enables secure attachment without requiring additional specialized components

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If traditional attachment methods are used, then ribs can be attached to skin, but manufacturing time and costs increase

Engineering Contradiction:

Improveattachment securityVSAvoidmanufacturing time

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The shear tie and rib are pre-assembled as an integrated composite structure before installation, allowing the entire assembly to be installed as one unit rather than requiring separate attachment operations, thereby reducing manufacturing time

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces mechanical fastening systems with a composite construction approach that uses material properties and geometric design to achieve attachment, eliminating the need for time-consuming fastener installation and removal operations

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 solution increases the force required to detach the shear tie, reduces electromagnetic interference risks, and integrates a weight-efficient rib web, while also reducing manufacturing time and costs by co-curing components, thus enhancing the structural stability and reducing the risk of crack propagation.

Implementation Method 1

The first stringer flange is stitched to and integrated with the stringer base charge and the skin

Methodology Applied

Scientific EffectAdhesive bonding: Adhesive

Implementation Method 2

The first shear-tie flange is stitched to and integrated with the first stringer flange

Methodology Applied

Scientific EffectMechanical fastening: Mechanical Fastener

Implementation Method 3

integrating a stringer base charge with a skin of the aircraft wing during a co-curing process

Methodology Applied

Scientific EffectResin curing: Chemical Bonding

Data Source

PatentUS11772775B2Shear ties for aircraft wing

Publication Date: 2023.10.03 THE BOEING CO

AI summary

An example aircraft wing includes a skin, a composite shear tie, a stringer base charge overlaying the skin, and a stringer overlaying the stringer base charge. The composite shear tie includes a shear-tie web, a first shear-tie flange extending from a first side of the shear-tie web, a second shear-tie flange extending from a second side of the shear-tie web, and a first shear-tie tab extending from an end of the first side of the shear-tie web. The stringer includes a stringer web, a first stringer flange extending from a first side of the stringer web, and a second stringer flange extending from a second side of the stringer web. The first stringer flange is stitched to and integrated with the stringer base charge and the skin. Further, the first shear-tie flange is stitched to and integrated with the first stringer flange.