“…The latter belonging to the wider class of piezoelectrics and being characterized by the capability of switching spontaneous polarization, still play a crucial role herein, combining large stiffness and actuation power with distinguished responsivity. The nonlinear constitutive behavior of ferroelectrics, often illustrated by so-called butterfly hysteresis loops or those of electric displacement versus electric field, has extensively been investigated in the past both theoretically (Chen and Lynch, 1998; Cocks and McMeeking, 1999; Huber and Fleck, 2001; Huber et al, 1999; Hwang and McMeeking, 1998; Hwang et al, 1995, 1998; Kessler and Balke, 2001) and experimentally (Förderreuther, 2003; Franzbach et al, 2014; Huan et al, 2014; Mauck and Lynch, 2003; Wang and Li, 2020) to name only a few of the outstanding works. To validate constitutive models or identify model parameters, the maximum of strain and polarization versus electric field and the respective remanent values are essentially taken as a basis.…”