Flexible Polymer Clip for Aircraft Stringer Attachment

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Solution Overview

Problem

The manufacturing and assembly of aircraft structures are hindered by the difficulty in visually inspecting blind fastener connections and the challenges of repositioning fixtures due to the use of blind fasteners, which are difficult to remove and require sealing, increasing time and expense.

Innovation Solution

A flexible polymer clip is used that secures to an aircraft stringer without metal fasteners or blind fasteners, featuring pins that engage holes for secure attachment and can be flexed for repositioning, allowing various parts to be connected to the stringer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If blind fasteners are used to attach fixtures to stringers, then the connection is secure and sealed, but the connection cannot be visually inspected and repositioning is difficult

Engineering Contradiction:

Improveconnection securityVSAvoidinspection and repositioning

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The attachment system is divided into separate components: a fixture with mounting holes and a clip with engagement features. This segmentation allows the fixture to be positioned and inspected before final attachment, while the clip provides the secure connection, resolving the contradiction between inspectability and connection security.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The clip acts as an intermediary between the fixture and the stringer. It engages with the fixture through visible mounting holes and attaches to the stringer, providing secure attachment while allowing the fixture itself to be inspected. The intermediary clip separates the inspection function from the attachment function.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If blind fasteners are used to secure fixtures, then the connection is sealed, but removal and repositioning require significant time and expense

Engineering Contradiction:

ImprovesealingVSAvoidrepositioning time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The clip is designed with flexible arms that can be manually manipulated to disengage from the fixture. This dynamic design allows for easy removal and repositioning without requiring specialized tools or time-consuming procedures, while maintaining a secure sealed connection when engaged.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The clip's design allows operators to easily manipulate and reposition fixtures themselves without requiring additional sealing materials or complex removal procedures. The self-contained clip mechanism provides both sealing and ease of repositioning through its inherent design features.

Inventive Principle:

Principle #25Self-service

3Stability of the object's composition

If fixtures are made secure with blind fasteners, then the attachment is reliable, but the fixtures cannot be easily repositioned

Engineering Contradiction:

Improveattachment reliabilityVSAvoidrepositioning capability

Core Design Contradiction:

Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

By separating the attachment function (performed by the clip) from the positioning function (performed by the fixture with mounting holes), the system allows fixtures to be positioned at different locations along the stringer while maintaining reliable attachment through the clip mechanism.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The clip is designed to work with multiple fixtures at different positions along the stringer. Its universal design allows it to provide reliable attachment while accommodating repositioning needs, making the system adaptable to different configuration requirements.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 facilitates efficient assembly by enabling easy inspection and repositioning of parts, reducing assembly time and cost while ensuring secure and sealed connections.

Implementation Method 1

The body transitions between a flexed position and a locked position

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

at least one pin of the first arm is configured to engage a hole positioned in the first surface of the stringer

Methodology Applied

Scientific EffectMechanical Fastener: Mechanical Fastener

Data Source

PatentEP2537745B1Clip attachment system connecting aircraft structures to each other

Publication Date: 2017.11.15 THE BOEING CO

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AI summary

An apparatus and method for supporting a load is provided. The apparatus comprises a structure (407) having an inner surface (470) with a shape configured to substantially conform to an outer surface (452) of a stringer (304). A number of pins (420) extend from the inner surface of the structure such that the number of pins are configured to engage holes (457) in the outer surface of the stringer when the structure is placed over the outer surface of the stringer. The pins support the structure with respect to the stringer when a load is applied to the structure. The structure comprises a number of members (411, 413) fixed with regard to each other by means of a flange (430) configured to support a hanger (440) for the load.