Flexible Eddy Current Probe for Weld Inspection
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Solution Overview
Problem
Eddy current probes face challenges in inspecting complex-shaped metal objects, particularly the joint between a weld and the base material, as traditional probes with a planar nature struggle to maintain close proximity to the surface, leading to suboptimal flaw detection and signal quality.
Innovation Solution
A flexible eddy current probe design featuring a pivoting sensor head and encoder wheel assembly, combined with a flexible wear surface and foam coil support, allows the probe to conform to curved surfaces, ensuring close contact and improved signal quality by using a flex circuit with independently suspended sensor coils and a multiplexer for signal management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a traditional planar array assembly is used, then the structure is simple and rigid, but the probe cannot conform to curved surfaces and maintain close proximity in complex-shaped areas
Solution Approach 1:
The probe array assembly is divided into multiple independently suspended sensor coils that can move relative to each other, allowing the assembly to conform to curved surfaces while maintaining structural organization
Solution Approach 2:
A flexible wear surface is introduced as the contact interface between the probe and the object, enabling the rigid sensor coils to maintain close proximity to curved surfaces without direct mechanical constraint
2Measurement precision
If the excitation coils are positioned close to the material surface, then the flaw detection and signal quality improve, but the probe cannot reach difficult geometries like the weld toe area
Solution Approach 1:
The sensor coils are independently suspended rather than rigidly fixed, allowing them to dynamically adjust their positions to maintain close proximity to the material surface even in complex geometries like weld toes
Solution Approach 2:
The flexible wear surface acts as a compliant interface that allows the sensor array to access difficult-to-reach areas while keeping the excitation coils close to the material for optimal signal quality
3Adaptability or versatility
If a flexible wear surface is used, then the probe can conform to curved surfaces, but the sensor coils may lose stable positioning
Solution Approach 1:
Each sensor coil is independently suspended within the flexible wear surface, allowing individual coils to maintain stable positioning while the overall array conforms to the surface geometry
Solution Approach 2:
The flexible wear surface provides local compliance at the contact interface while the sensor coil suspensions provide local stability, combining flexibility and positioning accuracy in different parts of the probe structure
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 flexible design enables effective flaw detection in complex geometries like welds by maintaining close proximity to the surface, enhancing signal quality and reliability, and simplifying the inspection process with reduced spurious signals and easier alignment.
Implementation Method 1
An alternating current is applied to an excitation coil placed in close proximity to the metal object under test. The alternating current induces an alternating current in the object
Implementation Method 2
Eddy current sensors are one device that may be used in non-destructive testing of metal objects. The alternating current induces an alternating current in the object, which can be sensed either by a separate sensor or by the effect on the impedance of the excitation coil
Data Source
AI summary
A flexible eddy current probe for non-destructive testing of a metallic object, the probe having a flexible printed circuit containing eddy current drive and sense coils and a rotary encoder configured to measure liner distance as the eddy current probe is scanned over the object. The probe features an encoder arm that adjustably connects a flexible eddy current sensor array to the rotary encoder.