Abstract: The assumption that the relation between magnetic field and
magnetization in a magnetostrictive material under constant stress can be
described by the Preisach hysteresis model, is justified in cases that the
relation exhibits the so-called return point memory. We show that
by virtue of energetic considerations, the constitutive equation
for the magnetostrictive butterfly hysteresis is then "almost uniquely"
determined by the Preisach distribution function.