Vibration analysis and testing of a thin-walled gradient coil model

Ongoing development of magnetic resonance imaging (MRI) technology leads to high magnetic field strength (up to 7–9 T) and high-speed switching current in gradient coils for the purpose of improving MRI image quality. These two factors among others contribute largely to the high levels of structure-borne noise that surrounds current MRI scanners. In this paper, the forcing function and distribution acting on gradient coils are described (gradient coils x, y and z). Single point forces and vibration responses of harmonic, transient and impulsive excitations are investigated. Modal expansion method is used to predict the whole cylinder vibration of a thin-walled model under these excitations. Experimental testing of a thin-walled model and a single-layered gradient coil is done by using National Instruments PXI. The measured whole-body radial vibration modes show an agreement with the analytical results. This agreement indicates that modal expansion method could be used to predict the whole-body vibration modes of gradient coils in the low-frequency range.