Self-securing Mounting Clip for Aircraft Stiffeners

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Solution Overview

Problem

Conventional methods for attaching components to stiffener structures, such as drilling and using fasteners or adhesives, are cumbersome and inefficient, especially for carbon composite structures like aircraft fuselages, where drilling is difficult and adhesives may not be preferred for permanent use.

Innovation Solution

A self-securing mounting clip with a U-shaped frame and deformable flexures that clamps onto stiffeners without drilling or adhesives, providing a compressive clamping force to secure components like wiring and fluid systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If drilling and fasteners are used to attach clips to stiffeners, then secure attachment is achieved, but installation becomes cumbersome and time-consuming

Engineering Contradiction:

Improveattachment securityVSAvoidinstallation speed

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The clip is designed with self-securing features including deformable flexures that automatically engage with the stiffener upon insertion, eliminating the need for separate fastening operations. The compliance members deform to accommodate the stiffener and then lock into place through geometric interlocking, allowing rapid installation without drilling or additional fasteners

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The clip incorporates deformable flexures and compliance members that dynamically adjust during installation. These elastic elements deform to accommodate the stiffener geometry and then lock into a secure locked position, providing both rapid installation and reliable attachment through mechanical deformation and geometric locking

Inventive Principle:

Principle #15Dynamics

2Reliability

If drilling through carbon composite structures is performed, then clip attachment is achieved, but difficulty and cost increase

Engineering Contradiction:

Improveclip attachmentVSAvoiddrilling difficulty

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The invention replaces the drilling and fastening mechanical system with a clamp-on mechanism. The clip attaches to the stiffener through external clamping action using deformable flexures and engagement members, eliminating the need to penetrate or drill through the carbon composite structure entirely

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The clip acts as an intermediary device that attaches to the stiffener without requiring modification of the stiffener itself. By using external clamping engagement members that wrap around the stiffener, the system avoids direct mechanical interaction that would require drilling through the composite material

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of manufacture

If adhesively-installed standoffs and clips are used, then attachment without drilling is achieved, but permanence and durability are reduced

Engineering Contradiction:

Improveinstallation simplicityVSAvoidpermanent attachment

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The engagement members are designed with curved surfaces that conform to the cylindrical geometry of the stiffener. This geometric curvature creates mechanical interlocking through rounded engagement surfaces that resist pull-off forces, providing permanent attachment without adhesives

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The deformable flexures are pre-loaded during installation to create immediate clamping force on the stiffener. This preliminary mechanical engagement establishes a secure locked position that resists removal forces, eliminating the need for adhesive curing time while ensuring permanent attachment

Inventive Principle:

Principle #10Preliminary action

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

Enables rapid and secure attachment of components to stiffeners without damaging the structure, offering a durable and efficient installation method that resists removal forces due to its compressive clamping mechanism.

Implementation Method 1

The flexures may deform in response to an insertion of the stiffener into the channel to translate the pad from a rest position to a clamped position

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 2

The outward translation of the pads results in a compressive clamping stress applied by the pads against the stiffener

Methodology Applied

Scientific EffectCompressive stress: Compression

Data Source

PatentUS10273991B2Mounting clip and related methods

Publication Date: 2019.04.30 THE BOEING CO

AI summary

A mounting clip may be provided that is configured to be secured to a stiffener and provide attachment of external components to the stiffener. In one example, the mounting clip includes a frame with a base and legs. Opposing engagement members extend from the legs. The opposing engagement members each include a pair of deformable flexures and a pad, which engages a surface of the stiffener. The stiffener may be inserted into a channel defined by engagement members and translated upwards, thus, translating the pads upward and inward. Subsequently, the pads and deformable flexures provide a compressive clamping stress on the stiffener and therefore permanently secure the mounting clip to the stiffener.