On the accurate analysis of vibroacoustics in head insert gradient coils

Purpose To accurately analyze vibroacoustics in MR head gradient coils. Theory and Methods A detailed theoretical model for gradient coil vibroacoustics, including the first description and modeling of Lorentz damping, is introduced and implemented in a multiphysics software package. Numerical finit...

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Bibliographic Details
Published in:Magnetic resonance in medicine 2017-10, Vol.78 (4), p.1635-1645
Main Authors: Winkler, Simone A., Alejski, Andrew, Wade, Trevor, McKenzie, Charles A., Rutt, Brian K.
Format: Article
Language:English
Subjects:
acoustics
Acoustics - instrumentation
Coiling
Computer Simulation
Coupling
Damping
Equipment Design
Finite Element Analysis
Finite element method
gradient coil
Head - diagnostic imaging
Humans
insertable head gradient
Lorentz damping
Magnetic resonance
Magnetic Resonance Imaging - instrumentation
Mathematical models
Models, Theoretical
Resonance
Simulation
Sound pressure
sound pressure level
Vibration
Vibroacoustics
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Summary:Purpose To accurately analyze vibroacoustics in MR head gradient coils. Theory and Methods A detailed theoretical model for gradient coil vibroacoustics, including the first description and modeling of Lorentz damping, is introduced and implemented in a multiphysics software package. Numerical finite‐element method simulations were used to establish a highly accurate vibroacoustic model in head gradient coils in detail, including the newly introduced Lorentz damping effect. Vibroacoustic coupling was examined through an additional modal analysis. Thorough experimental studies were used to validate simulations. Results Average experimental sound pressure levels (SPLs) and accelerations over the 0‐3000 Hz frequency range were 97.6 dB, 98.7 dB, and 95.4 dB, as well as 20.6 g, 8.7 g, and 15.6 g for the X‐, Y‐, and Z‐gradients, respectively. A reasonable agreement between simulations and measurements was achieved. Vibroacoustic coupling showed a coupled resonance at 2300 Hz for the Z‐gradient that is responsible for a sharp peak and the highest SPL value in the acoustic spectrum. Conclusion We have developed and used more realistic multiphysics simulation methods to gain novel insights into the underlying concepts for vibroacoustics in head gradient coils, which will permit improved analyses of existing gradient coils and novel SPL reduction strategies for future gradient coil designs. Magn Reson Med 78:1635–1645, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
ISSN:0740-3194
1522-2594
DOI:10.1002/mrm.26543