Mechanical Interlock Fastener for Brittle Material Assembly

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Brittle materials, such as ceramics, pose challenges in manufacturing and assembly due to structural issues and stress concentrations when traditional fastening methods are used, which can result in lower strength and design limitations.

Innovation Solution

A fastening system involving a ceramic article with an undercut region and a fastener having a protrusion and engagement feature, where the fastener is mechanically engaged with the ceramic article to provide compression and reduce stress concentrations, potentially eliminating the need for adhesives.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If traditional fastening methods are used with brittle materials, then assembly is simplified, but stress concentrations occur and strength is reduced

Engineering Contradiction:

Improveassembly simplicityVSAvoidfastening strength

Core Design Contradiction:

Ease of operationVSStrength

Solution Approach 1:

The fastening system is divided into separate functional components: a fastener with engagement features, a fixing member, and a mechanically engaged interface. This segmentation allows each component to be optimized for its specific function while distributing stress across multiple contact points rather than concentrating it at a single adhesive interface.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent replaces the chemical bonding mechanism of adhesives with a mechanical engagement system consisting of interlocking features such as protrusions, recesses, and threaded interfaces. This mechanical substitution eliminates the need for adhesive curing time and provides immediate structural strength while reducing sensitivity to environmental factors like humidity and temperature.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of manufacture

If adhesive-based fastening is used, then installation is simple, but variability and sensitivity to environmental factors increase

Engineering Contradiction:

Improveinstallation simplicityVSAvoidfastening consistency

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The mechanical engagement features are designed to self-align and self-engage during assembly. The protrusion automatically fits into the corresponding recess, and the threading mechanism guides the fixing member into proper engagement without requiring precise adhesive application or curing monitoring, thereby reducing variability and improving reliability.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent changes the bonding mechanism from chemical (adhesive) to mechanical (interlocking features), fundamentally altering the fastening parameters. This parameter change eliminates curing time requirements, reduces sensitivity to surface preparation quality, and provides consistent engagement forces that are not affected by environmental conditions.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If traditional fasteners are used with brittle materials, then design options are maintained, but stress concentrations and structural issues occur

Engineering Contradiction:

Improvedesign optionsVSAvoidstructural integrity

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The fastening system applies local quality by concentrating mechanical engagement features at specific locations on the brittle material where structural reinforcement is needed. The engagement features are strategically positioned to distribute loads away from critical stress zones while maintaining the overall structural integrity of the brittle component.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent transitions from two-dimensional surface bonding (adhesive application on surfaces) to three-dimensional mechanical interlocking (protrusions extending into recesses, threaded engagement through depths). This dimensional change creates volumetric engagement that distributes stresses throughout the fastener structure rather than concentrating them at surface interfaces.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 method enhances the pull-out strength and reduces variability compared to traditional adhesive-based fastening, relying on mechanical engagement for stability and minimizing sensitivity to environmental factors.

Implementation Method 1

a fastener having a body defining a securing cavity extending into the body, and a protrusion having an engagement surface extending from the body. The engagement surface can be engaged with the retaining surface.

Methodology Applied

Scientific EffectMechanical engagement: Mechanical Fastener

Data Source

PatentUS11268552B2Mechanical interlock connection of threaded fasteners to brittle materials

Publication Date: 2022.03.08 APPLE INC

AI summary

A fastener can include a body, an engagement feature, and a protrusion extending from the body. The engagement feature can receive and mechanically engage with a fixing member. The fastener can be positioned in a cavity of a brittle article, the cavity including an undercut region. A fixing member can pass through an aperture of a component positioned relative to the fastener such that the fixing member mechanically engages the fastener and a surface of the protrusion engages with an opposing surface of the undercut region.