Triangular Coil Eddy Current Sensor for Directional CFRP Testing
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Solution Overview
Problem
Existing eddy current sensors require mechanical rotation to obtain directional information, which introduces inaccuracies and increased costs due to the need for automatic systems, making them inefficient for non-destructive testing of layered materials like carbon fiber reinforced polymers (CFRP).
Innovation Solution
The development of an eddy current sensor comprising a control unit and multiple eddy current sensor elements with triangular-shaped flat coils arranged in a quadrangular order, allowing for simultaneous signal application and shifting without mechanical rotation, utilizing antiparallel currents to create a resultant electromagnetic field that effectively probes the substrate without moving the sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mechanical rotation of the eddy current sensor is used to obtain directional information, then the orientation of carbon fibers can be detected, but the measurement precision deteriorates due to operator intervention and the device complexity increases due to the need for automatic rotation systems
Solution Approach 1:
The sensor is divided into multiple independent triangular coil elements (at least three elements) that can be individually controlled. Each element acts as an independent sensing unit, allowing the system to determine orientation by analyzing the response of individual segments rather than requiring rotation of a single large sensor.
Solution Approach 2:
The patent transitions from a single rotating sensor approach to a multi-element array approach where orientation information is obtained through the spatial arrangement and differential response of multiple triangular coils. This dimensional change from temporal rotation to spatial distribution eliminates the need for mechanical rotation while maintaining detection capability.
2Loss of information
If mechanical rotation of the eddy current sensor is used to probe different directions, then directional information can be acquired, but the execution time increases due to the time required for rotation operations
Solution Approach 1:
The triangular coil elements are pre-positioned in specific orientations relative to each other, with their axes arranged at known angles (e.g., 0°, 45°, 90°, 135°). This preliminary arrangement allows the sensor to simultaneously probe multiple directions without requiring rotation during measurement, as the directional information is encoded in the spatial configuration of the coils themselves.
Solution Approach 2:
The sensor can continuously acquire directional information by simultaneously exciting multiple triangular coil elements with different orientations. Instead of sequentially rotating the sensor to probe different directions, the system maintains continuous sensing capability by parallelizing the measurement process across multiple coils, thereby eliminating idle time associated with rotation operations.
3Area of stationary object
If a single large eddy current sensor is used to cover a larger surface area, then the inspection area is increased, but the device complexity increases due to the need for rotation to obtain directional information
Solution Approach 1:
The sensor is divided into multiple independent triangular coil elements (at least three elements) that can be individually controlled. Each element acts as an independent sensing unit, allowing the system to determine orientation by analyzing the response of individual segments rather than requiring rotation of a single large sensor.
Solution Approach 2:
Each triangular coil element serves multiple functions: it contributes to the overall surface coverage area while simultaneously providing directional sensitivity when combined with the other elements. The array of triangular coils creates a multi-functional sensor that can detect both the presence of defects and their orientation without requiring a single complex rotating sensor.
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 precise directional information acquisition without mechanical rotation, reducing execution time and costs, and improving the accuracy of non-destructive testing of layered materials by effectively using the collective outer edges of the coils for sensing.
Implementation Method 1
When a signal, e. g. an alternating voltage, is applied to the contacts at the end of the wire forming the coil, the sensor coil is excited and an alternating electromagnetic field is generated which penetrates into the material to be probed
Implementation Method 2
The alternating electromagnetic field induces in the material eddy currents which themselves are sensed by the coil as a change in the impedance
Data Source
Figure 1a~1b
Figure 2
Figure 3
AI summary
The invention relates to an eddy current sensor element (2) for non-destructive testing of a substrate, comprising an assembly (3) of at least a first and a second flat coil (4, 5, 6, 7), wherein the first flat coil (4) and the second flat coil (5) each have a triangular shape with a first to third coil edge, wherein one of the edges (4b) of the first flat coil (4) and one of the edges (5a) of the second flat coil (5) are arranged adjacent and parallel to each other, and wherein the assembly (3) has a quadrangular shape. The invention further relates to an eddy current sensor for the non-destructive testing of a substrate, comprising a plurality of the eddy current sensor elements (2).