Characterisation of magnetostrictive or piezoelectric materials and transducers

There is an ever growing need to improve characterisation methods and techniques which can be applied to materials for transducers in order to improve their quality or reach higher specifications. Any characterisation process requires a suitable model to describe performance, a practical measurement of response followed by a comparison of the predicted and observed behaviours. Hitherto, descriptions have been based on hysteresis models or equivalent circuits but the present work or plane wave modelling (PWM) demonstrates clear advantages. It has been applied, for example, to the longitudinal resonance in a magnetostrictive rod, thereby gaining quantitative information not only on magnetomechanical coupling efficiency but also about frequency dependent loss mechanisms. PWM is adaptable to describe other resonant modes or complete device response for comparison with measured impedance, displacement velocity or acceleration data-and forms the basis of a versatile nondestructive evaluation method for either materials or transducers