Orthogonal Sensor Assembly for Ferromagnetic Surface Stress Measurement
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Solution Overview
Problem
Current sensor arrangements for detecting surface tension and structural state of ferromagnetic workpieces are complex and inadequate for determining two-dimensional stress distributions and shear stress, as they often require contact, complex setups, or limited directional sensitivity.
Innovation Solution
A sensor arrangement with multiple base coil systems, each with a ferrite core and aligned orthogonally to the workpiece surface, allowing for direction-sensitive magnetic flux measurements to determine mechanical surface stresses without contact, enabling the calculation of complete residual stress tensors and vector components of stresses in any orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a sensor arrangement with only two base coil systems is used, then the device complexity is reduced, but the measurement precision is insufficient because direction-dependent stress states cannot be determined
Solution Approach 1:
The patent transitions from a two-dimensional measurement system (two base coil systems) to a three-dimensional measurement system (three base coil systems arranged orthogonally). This dimensional expansion enables complete determination of the stress tensor by adding the third measurement direction, resolving the underdetermined system while maintaining manageable device complexity.
2Measurement precision
If the sensor head is made rotatable to obtain measurements from different orientations, then the measurement precision improves, but the productivity decreases because measurements can only be carried out in steps separated in time
Solution Approach 1:
Instead of using a single rotatable sensor head that measures sequentially, the patent segments the measurement function into three independent stationary base coil systems. Each system is fixed in a specific orientation (x, y, z directions), allowing simultaneous or rapid sequential measurements without mechanical movement, thus improving productivity while maintaining measurement precision.
Solution Approach 2:
The patent transforms the dynamic measurement approach (rotatable sensor head requiring movement) into a static configuration (three fixed orthogonal coil systems). This eliminates the need for mechanical rotation during measurement, enabling faster data acquisition and improving productivity while achieving complete stress tensor determination through the orthogonal arrangement.
3Measurement precision
If strain gauges are attached to the measuring point, then the measurement precision is high, but the ease of operation deteriorates due to complex attachment process and requirement for telemetry system
Solution Approach 1:
The patent replaces the mechanical contact method (strain gauges requiring physical attachment to the surface) with a non-contact electromagnetic induction method using base coil systems. This substitution eliminates the complex attachment process and telemetry requirements while maintaining measurement precision through inductive coupling with the workpiece.
Solution Approach 2:
The patent introduces magnetic flux as an intermediary between the measurement system and the workpiece surface. The base coil systems generate magnetic flux that penetrates the workpiece surface without physical contact, enabling stress measurement through magnetic permeability changes while avoiding the need for direct mechanical attachment of sensors.
4Ease of operation
If non-contact optical methods are used, then the ease of operation improves, but the device complexity increases and measurement precision is insufficient for complete stress tensor determination
Solution Approach 1:
The patent replaces complex optical measurement systems with a simpler electromagnetic induction system using base coil systems. The electromagnetic method achieves non-contact measurement with reduced device complexity by using magnetic flux generation and detection instead of sophisticated optical setups, while simultaneously enabling complete stress tensor determination through orthogonal coil arrangement.
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
Enables non-contact, application-free measurement of mechanical surface stresses on moving workpieces, allowing for rapid measurement of multiple points or surface mapping, and providing accurate determination of tensile, compressive, and shear stresses without direct contact or surface preparation.
Implementation Method 1
at least one first base coil system arranged in a first direction with a first direction sensitivity is provided, with the first base coil system comprising at least one excitation coil and one receiver coil on a common ferrite core for direction-sensitive magnetic flux through a surface of the workpiece
Implementation Method 2
direction-dependent determination of the permeability... from which the mechanical surface stresses of the workpiece can be determined at least partially
Data Source
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AI summary
The invention relates to a sensor assembly for detecting surfaces stresses and/or the microstructure state of a ferromagnetic workpiece, wherein at least one first base coil system having a first direction and a first directional sensitivity is provided, at least one second base coil system having a second direction and a second directional sensitivity is provided, and at least one third base coil system having a third direction and a third directional sensitivity is provided, and wherein at least the first base coil system and the second base coil system form a first differential angle and the second base coil system and the third base coil system form a second differential angle, and wherein the first base coil system is arranged outside of the second directional sensitivity and the third directional sensitivity, the second base coil system is arranged outside of the first directional sensitivity and the third directional sensitivity, and the third base coil system is arranged outside of the first directional sensitivity and the second directional sensitivity, such that the mechanical surface stresses of the workpiece can be at least partially determined. The invention further relates to a method for determining the mechanical surface stresses.