Trends in acoustic properties of iron particle seeded auxetic polyurethane foam

The sound absorption characteristic of a clean, open-cell configuration, typical polyurethane flexible foam is shown against that of an auxetic foam made from it, and this same foam after it has been seeded with a magnetorheological fluid (then dried), having 2-5 mum carbonyl iron particles and subjected to zero, weak and concentrated magnetic fields in an acoustic impedance tube facility. The resultant foam indicates the capability of shifting the peak acoustic absorption coefficient within a given frequency bandwidth when constant intensity magnetic fields are applied.