EMAT Checkerboard Magnet Array for Dual Lamb and Shear Horizontal Wave Generation
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Solution Overview
Problem
Existing EMATs are limited in their ability to simultaneously generate both Lamb waves and shear horizontal waves due to their distinct designs, which restricts their performance and applicability in non-destructive evaluation.
Innovation Solution
An EMAT design incorporating a magnet array with alternating polarizations arranged in a checkerboard pattern, featuring a multiplexing-coil arrangement or a moving magnet/moving coil configuration, allowing for the generation of both Lamb waves and shear horizontal waves using a single magnet array and printed circuit board, with coils positioned along boundaries and center lines of the magnet array to excite each wave type independently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If distinctive EMAT designs are used for Lamb wave and SH wave excitation, then each wave type can be excited effectively, but the device complexity and number of separate EMAT units increase
Solution Approach 1:
The patent combines two separate EMAT designs into a single unified EMAT structure. The magnet array uses a checkerboard pattern of alternating polarizations that can generate both Lamb waves and SH waves. Two coils are positioned at different locations relative to the magnet array: one coil for exciting Lamb waves and another coil for exciting SH waves. This merging eliminates the need for separate EMAT units while maintaining effective excitation of both wave types.
Solution Approach 2:
The unified EMAT design achieves multi-functionality by incorporating a magnet array with alternating polarizations that can serve dual purposes. The same magnet array structure supports both Lamb wave and SH wave generation through appropriately positioned coils. This universal design allows a single EMAT unit to perform multiple functions that previously required separate specialized devices.
2Reliability
If separate EMAT units are used for different wave types, then each wave type can be optimized independently, but the overall device volume, footprint, and weight increase
Solution Approach 1:
The patent merges multiple EMAT units into a single compact structure. The magnet array with alternating polarizations is shared between both wave excitation functions, and the coils are positioned at different locations within the same device footprint. This consolidation significantly reduces the overall volume, footprint, and weight compared to using separate EMAT units for each wave type.
3Adaptability or versatility
If a single magnet array with alternating polarizations is used, then both wave types can be generated from one device, but the coil positioning and design complexity increases
Solution Approach 1:
The patent applies local quality by positioning coils at specific locations relative to the magnet array. One coil is positioned to effectively excite Lamb waves, while another coil is positioned to effectively excite SH waves. Each coil location is optimized for its specific wave type, allowing the single magnet array to serve multiple functions through spatially differentiated coil placements.
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 the simultaneous excitation of Lamb waves and shear horizontal waves in a compact, single-EMAT setup, enhancing defect detection capabilities and reducing the device's volume, footprint, and weight compared to traditional dual-EMAT systems.
Implementation Method 1
An electro-magnetic acoustic transducer (EMAT) includes a magnet array, a first electrical conductor coil, and a second electrical conductor coil... A Lamb wave is generated when the first coil is excited with an electrical current and a shear horizontal wave (SH) is generated when the second coil is excited with an electrical current
Implementation Method 2
The magnet array has magnets with alternating polarizations. The magnets are arranged in columns and rows so that the alternating polarizations form a checkerboard pattern
Data Source
AI summary
An electro-magnetic acoustic transducer (EMAT) generates both Lamb waves and shear horizontal (SH) waves or Lamb waves only. In configurations, the EMAT includes first and second coils shifted in alignment relative to one another and a magnet array overlaid over the coils. The EMAT generates a Lamb wave when the first coil is excited with an electrical current and generates a SH wave when the second coil is excited with an electrical current. In other configurations, the EMAT includes a coil and a magnet array which are movable relative to one another between a first position and a second position shifted in alignment relative to one another. The EMAT generates a Lamb wave when the coil is excited with an electrical current while in the first position and generates a SH wave when the coil is excited with an electrical current while in the second position.