Dumbbell-Shaped Anchor Rod for Defined Shear and Yield Failure

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Solution Overview

Problem

Existing anchor systems lack optimal load characteristics while being difficult and costly to manufacture and handle.

Innovation Solution

An anchor system comprising a drop-in anchor with a dumbbell-shaped anchor rod, featuring distinct shear absorbance and yield regions, allowing for efficient load distribution and defined failure points, while using less material.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of substance

If the anchor rod has uniform cross section throughout, then manufacturing is simpler, but material usage is excessive and load characteristics are not optimized

Engineering Contradiction:
Improvematerial usageVSAvoidanchor rod geometry
Core Design Contradiction:
Loss of substanceVSDevice complexity

Solution Approach 1:

The anchor rod features a dumbbell-shaped cross-section with varying properties along its length: the first region has a larger cross-section for strength, the second region has a smaller cross-section for material savings and defined failure behavior. This local differentiation optimizes both material usage and structural performance.

Inventive Principle:
Principle #3Local quality

2Strength

If the anchor rod shear absorbance region is positioned optimally for load characteristics, then shear performance improves, but manufacturing precision requirements increase

Engineering Contradiction:
Improveshear characteristicsVSAvoidregion positioning
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The anchor rod is divided into distinct functional regions: a first region with larger cross-section for strength, a second region with smaller cross-section for material efficiency, and a third region for threading. This segmentation allows each region to be optimized for its specific function while maintaining manufacturability.

Inventive Principle:
Principle #1Segmentation

3Loss of substance

If the anchor rod yield region is made weaker to save material, then material usage decreases, but reliability might be compromised

Engineering Contradiction:
Improvematerial usageVSAvoidload characteristics
Core Design Contradiction:
Loss of substanceVSReliability

Solution Approach 1:

The weaker second region with smaller cross-section, which initially might seem to reduce reliability, actually provides a predetermined yield point and defined failure mode. This controlled weakness allows the structure to fail in a predictable manner, enhancing overall reliability while reducing material usage.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

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 system provides superior shear characteristics with well-defined load failure modes, reducing material usage and manufacturing complexity, and ensuring reliable performance.

Implementation Method 1

a plug that is able to be driven into an installed position within the anchor sleeve, in which the plug expands the expandable first end

Methodology Applied
Scientific EffectMechanical expansion: Mechanical Force

Implementation Method 2

the anchor sleeve further comprises an internal thread for threadedly engaging the first external thread of the anchor rod

Methodology Applied
Scientific EffectThreaded engagement: Screw

Data Source

PatentEP4575238A1Anchor system with dumbbell-shaped anchor rod
Publication Date: 2025.06.25 HILTI AG
  • EP4575238A1 patent drawingFigure 1
  • EP4575238A1 patent drawingFigure 2~5
  • EP4575238A1 patent drawing

AI summary

Anchor system comprising a drop-in anchor and an anchor rod, which comprises an anchor rod first end, and a first external thread provided at the anchor rod first end. The drop-in anchor comprises an anchor sleeve having an expandable first end and an anchor sleeve second end, a plug that is able to be driven into an installed position within the anchor sleeve, and an internal thread for threadedly engaging the first external thread. The anchor rod further comprises an anchor rod shear absorbance region and an anchor rod yield region, which is located between the anchor rod shear absorbance region and the anchor rod first end. The anchor rod is so dimensioned that the anchor rod shear absorbance region is located within the anchor sleeve second end when installed. The anchor rod has, within the anchor rod yield region, smaller cross section than it has in the anchor rod shear absorbance region.