Rotatable-Head Fastener Structure to Protect Sealant Layers

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

In aeronautics, there is a challenge in maintaining a strong connection between fasteners and adjacent sealants or cover layers, as vibrations can cause relative movement, potentially damaging the sealants or cover layers.

Innovation Solution

A fastener design featuring a rotatable member supported by a stationary member, which prevents torque transmission to the cover layer, ensuring the fastener head does not rotate relative to the shank, and includes an adhesive surface for bonding with sealants or coatings, and a configuration that prevents axial removal, thereby maintaining the integrity of the sealant or cover layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the fastener head is directly connected to the fastener shank, then the structure is simple, but torque is transmitted to the cover layer during rotation causing damage

Engineering Contradiction:

Improvefastener structureVSAvoiddamage to cover layer

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The fastener head is segmented into a stationary member (integrally formed with the shank) and a rotatable member (separately positioned). This segmentation allows the rotatable member to rotate independently without transmitting torque to the stationary member and cover layer, thereby preventing damage while maintaining structural simplicity.

Inventive Principle:

Principle #1Segmentation

2Ease of operation

If the fastener head rotates during tightening, then the fastening function is achieved, but the rotating fastener head damages the sealant or cover layer

Engineering Contradiction:

Improvefastening functionVSAvoiddamage to sealant or cover layer

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The rotatable member acts as an intermediary between the driving tool and the stationary member. It rotates during tightening to enable fastening function, while the stationary member remains fixed relative to the cover layer, preventing damage. The rotatable member absorbs the rotational motion without transmitting it to the cover layer.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If a rotatable member is added to prevent torque transmission, then damage to the cover layer is prevented, but the device complexity increases

Engineering Contradiction:

Improvedamage to cover layerVSAvoidfastener structure

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

4Object-affected harmful factors

If the rotatable member is freely rotatable, then torque transmission is prevented, but axial movement of the rotatable member may occur

Engineering Contradiction:

Improvetorque transmissionVSAvoidaxial position stability

Core Design Contradiction:

Object-affected harmful factorsVSStability of the object's composition

Solution Approach 1:

The rotatable member has different local properties: it is freely rotatable in the rotational direction to prevent torque transmission, but it is constrained in the axial direction through engagement features (such as a recess in the stationary member receiving a protrusion on the rotatable member, or frictional engagement). This local differentiation allows independent control of rotational and axial movements.

Inventive Principle:

Principle #3Local quality

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 design effectively reduces the risk of damage to adjacent surfaces by preventing torque transfer during fastener rotation, ensuring a secure and adhesive bond between the fastener and the sealant or coating, even under mechanical stress like vibrations.

Implementation Method 1

the rotatable member includes an adhesive surface that is arranged on a side facing away from the fastener shank portion... the adhesive surface includes a surface structure or surface modification that is configured to provide or increase an adhesive bond with a sealant, coating, adhesive film or adhesive foil

Methodology Applied

Scientific EffectAdhesive bonding: Adhesive

Data Source

PatentEP4177484A1Fastener for joining parts and joint formed therewith

Publication Date: 2023.05.10 AIRBUS (SAS)

Figure 1
Figure 2
Figure 3

AI summary

In order to provide an improved fastener (10) that reduces the risk of damage to an adjacent surface, like a sealant or cover layer, the invention proposes a fastener (10) preventing the transmission of torque from the fastener shank portion (14) through the fastener head portion (12) to the cover layer (52). The fastener head portion (12) comprises a rotatable member (22) that is supported, so as to be rotatable relative to the fastener shank portion (14), and a stationary member (16) that is configured to be immovable relative to the fastener shank portion (14) about its longitudinal axis, and the rotatable member (22) is attached to the stationary member (16).