Monolithic Plastic Fastener Retention Design

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Solution Overview

Problem

Existing fasteners for securing insulating layers on aircraft stringers lack a secure and flexible solution that balances weight, cost, and ease of installation, often relying on metal skeletons or complex configurations.

Innovation Solution

A monolithic, 100% plastic fastener with a body having retention surfaces and resiliently flexible tongues, designed to be lightweight, easy to manufacture, and adaptable for various panel thicknesses, providing secure retention and flexibility through its conical and cylindrical geometries.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If traditional metal skeleton fasteners are used, then structural strength is improved, but weight increases and cost increases

Engineering Contradiction:
Improvestructural strengthVSAvoidfastener weight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The patent changes the material parameter from metal to plastic (polymer), transforming the fastener into a lightweight alternative while maintaining functional performance through optimized geometric parameters such as conical engagement surfaces and resilient tongue design

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention uses plastic as a composite or alternative material to replace traditional metal skeletons, achieving a balance between strength requirements and weight reduction goals through material science advancements in polymer engineering

Inventive Principle:
Principle #40Composite materials

2Reliability

If complex fastener configurations are used, then retention security is improved, but device complexity increases and ease of manufacture deteriorates

Engineering Contradiction:
Improveretention securityVSAvoidfastener configuration complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges multiple functions (retention, flexibility, positioning) into a single monolithic plastic structure, eliminating the need for separate metal skeleton components and reducing overall device complexity while maintaining retention security

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The fastener design incorporates multiple functional elements (conical retention surfaces, resilient tongues, positioning features) within a single universal plastic component that can adapt to various panel thicknesses and installation scenarios

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Weight of moving object

If monolithic plastic fasteners are used, then weight is reduced and ease of manufacture is improved, but retention security may deteriorate

Engineering Contradiction:
Improvefastener weightVSAvoidretention security
Core Design Contradiction:
Weight of moving objectVSReliability

Solution Approach 1:

The patent optimizes geometric parameters of the plastic fastener including conical surface angles, tongue dimensions, and material density to achieve retention performance comparable to metal fasteners while maintaining weight advantages

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention utilizes advanced plastic materials with enhanced mechanical properties to compensate for the inherent strength differences between plastic and metal, achieving reliable retention security through material selection and processing

Inventive Principle:
Principle #40Composite materials

4Adaptability or versatility

If resilient tongues are added to provide flexibility, then adaptability to panel thickness is improved, but device complexity increases

Engineering Contradiction:
Improveadaptability to panel thicknessVSAvoidfastener structure complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent incorporates resilient tongues that can dynamically flex and adapt to different panel thicknesses, allowing the fastener to transition from a rigid to a flexible state during installation and operation to maintain secure retention

Inventive Principle:
Principle #15Dynamics

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

The solution offers a more secure, flexible, and cost-effective fastening system that is lightweight and adaptable to different panel thicknesses, enhancing the installation process while maintaining structural integrity.

Implementation Method 1

The second portion includes resiliently flexible tongues spaced apart from each other

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

The first portion includes a plurality of retention surfaces, and in one example they are compressible conical geometries positioned longitudinally of a body of the fastener

Methodology Applied
Scientific EffectCompression: Compression

Data Source

PatentEP3104026B1Plastic lining fasteners
Publication Date: 2018.08.15 LISI AEROSPACE
  • EP3104026B1 patent drawingFigure 1~3
  • EP3104026B1 patent drawingFigure 4
  • EP3104026B1 patent drawingFigure 5~6

AI summary

A fastener is formed monolithically, or as a one-piece structure, for example 100% plastic. The fastener includes a body (22) having first and second portions (28, 30) on respective sides of a positioning wall or stop means. A first portion includes a plurality of compressible retention surfaces (42) separated from adjacent retention surfaces by a corresponding conical structure and a cylindrical surface on the body. A second portion includes a plurality of resiliently flexible tongues (46, 48) spaced apart from each other. The tongues may be positioned on opposite sides of the body from each other, and/or at different axial positions along the body.