Stress-strain relationship in Terfenol-D

The variability of Young's modulus (the AE effect) in giant magnetostrictive Terfenol-D has a significant impact on the performance and modeling of Terfenol-D transducers. While elastic modulus variability introduces nonlinearities in the transducer input/output relationship that are often deemed undesirable, it also affords opportunities for achieving novel device performance attributes. In this investigation, Terfenol-D's modulus of elasticity is characterized under controlled thermal, magnetic, and mechanical loading conditions. Quasi-static cyclic compressive Stress testing methods are used to quantify the variability in Young's modulus over a wide range of d.c. applied magnetic fields and stresses. Elastic modulus changes of four-fold or more are demonstrated through the variation of a d.c. applied magnetic field. The effect of decreasing cyclic stress amplitude giving rise to an increase in Terfenol-D's apparent elastic modulus is also examined. The thermally controlled transducer used throughout this investigation is described. This conference paper is a shortened version of the paper titled "Experimental Investigation of Terfenol-D's Elastic Modulus" that has been submitted for peer reviewed journal publication.