Magnetostrictive Stress Sensor with Recessed Segmentation

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Solution Overview

Problem

Existing mechanical stress measurement technologies lack simplicity, cost-effectiveness, and robustness against environmental influences, and they often struggle to maintain stability and accuracy in measuring forces and torques on magnetostrictive bodies.

Innovation Solution

A device comprising a magnetostrictive body with remanent magnetization and strategically formed recesses on its end surfaces, which changes magnetization and magnetic susceptibility in response to mechanical stress, allowing for the detection and quantification of applied forces through a magnetic field sensor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a magnetostrictive body is used for measuring mechanical stress, then measurement capability is provided, but the device lacks robustness and rigidity against externally applied mechanical stress

Engineering Contradiction:
Improverobustness against mechanical stressVSAvoidrigidity against deformation
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The magnetostrictive body is segmented by forming first and second recesses that divide the body into distinct regions. These recesses create a segmented structure where the magnetostrictive material is divided into multiple zones with different functional characteristics, allowing the body to maintain rigidity in certain regions while enabling stress measurement in others.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The recesses create local variations in the magnetostrictive body's properties. The regions with recesses have different magnetic and mechanical characteristics compared to the solid portions, allowing localized stress detection while maintaining overall structural integrity. The local quality change enables the body to be sensitive to stress in specific zones while remaining rigid overall.

Inventive Principle:
Principle #3Local quality

2Measurement precision

If multiple coils are used to produce magnetic flux in the magnetostrictive body, then stress measurement capability is improved, but device complexity and manufacturing cost increase

Engineering Contradiction:
Improvestress measurement accuracyVSAvoidnumber of coils and magnetic components
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The invention extracts the magnetic flux generation function from separate external coils and integrates it into the magnetostrictive body itself through permanently magnetized regions. This eliminates the need for multiple external coils and their associated control systems, significantly reducing device complexity while maintaining measurement capability.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The magnetostrictive body merges multiple functions into a single component: it serves as both the measured object and the magnetic flux source through permanently magnetized regions. The body simultaneously experiences mechanical stress and generates magnetic fields, eliminating the need for separate coil assemblies and reducing overall system complexity.

Inventive Principle:
Principle #5Merging (Combining)

3Ease of manufacture

If the magnetostrictive body is made from a single sheet and welded to support, then manufacturing is simplified, but the device lacks robustness against environmental influences and disturbances

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidresistance to environmental influences
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The magnetostrictive body is formed as a composite structure with permanently magnetized regions integrated within the magnetostrictive material. This composite approach creates a multi-phase material system that combines the magnetostrictive properties with permanent magnetization, enhancing environmental stability while maintaining manufacturing feasibility through single-piece construction.

Inventive Principle:
Principle #40Composite materials

4Stability of the object's composition

If the magnetostrictive body is designed with high rigidity to maintain stability, then measurement stability is improved, but the body becomes more susceptible to deformation under mechanical stress

Engineering Contradiction:
Improvemechanical stabilityVSAvoiddimensional accuracy under stress
Core Design Contradiction:
Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The segmented structure created by the recesses allows the magnetostrictive body to maintain overall rigidity while creating localized regions that can deform elastically under stress. The solid portions provide structural stability, while the recessed regions enable controlled deformation for accurate stress measurement without compromising overall dimensional integrity.

Inventive Principle:
Principle #1Segmentation

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 device provides robust, cost-effective, and stable measurement of mechanical stress, maintaining rigidity and inelasticity against deformation, while being resistant to environmental disturbances like temperature and humidity.

Implementation Method 1

Some materials are capable of changing their shape and/or dimensions in response to being magnetized. This property is also referred to as the magnetostriction or the Joule effect. Similarly, these materials may also perform a change of the magnetic susceptibility when subjected to a mechanical stress. This may be referred to as the Villari effect.

Methodology Applied
Scientific EffectMagnetostriction: Magnetostriction

Implementation Method 2

Similarly, these materials may also perform a change of the magnetic susceptibility when subjected to a mechanical stress. This may be referred to as the Villari effect.

Methodology Applied
Scientific EffectVillari effect: Villari Effect

Data Source

PatentEP3745107B1Device and method for measuring mechanical stress based on magnetostriction
Publication Date: 2024.11.20 TECH HOCHSCHULE WUERZBURG-SCHWEINFURT
  • EP3745107B1 patent drawingFigure 1
  • EP3745107B1 patent drawingFigure 2
  • EP3745107B1 patent drawingFigure 3

AI summary

Disclosed herein is a device for measuring mechanical stress. The device comprises a magnetostrictive body enclosing a remanent magnetization. The magnetostrictive body comprises first and second end surfaces that are arranged opposite to each other. At least one of the first and second end surfaces is configured to receive a mechanical stress. The magnetostrictive body further comprises a first recess formed at the first end surface towards the second end surface and a second recess formed at the second end surface towards the first end surface. In a projection perpendicular to the first end surface, the first recess overlaps the second recess and extends beyond the second recess. Further disclosed are a method of manufacturing such a device and a method of measuring mechanical stress using such a device.