Giant dynamic magnetostrain in rare earth-iron magnetostrictive materials

A dynamic peak-to-peak strain of 2440 p.p.m. has been measured at resonance in a Terfenol-D transducer which exceeds the 1600 p.p.m. static magnetostrain by 50%. This experimental result is in good agreement with theoretical calculation. It shows that static magnetostrain is not a real limit for dynamic strains at resonance. Dynamic limits are constrained only by the field limit and the stress limit. The main consequence for transducers is that, using high pre-stress and high bias, a Terfenol-D transducer is much more powerful than a PZT transducer of the same size, regardless of the mechanical quality factor. Most electrotechnic devices based on Terfenol-D should benefit from these giant dynamic strains