Abstract: Through assuming that the magnetostriction effect of bimorph giant magnetostrictive thin film(GMF) cantilever is equivalent to the effect of a uniformly distributed bending moment, a nonlinear deformation governing equation of GMF is proposed, based on the geometrical nonlinear deformation theory and the Hamilton principle. Moreover, a static geometrical nonlinear deformation model, a nonlinear primary resonance and superharmonic resonance model, are presented. Thereafter, experiments on TbDyFe-PI-SmFe cantilever show that the deformation of cantilever end reaches the 0.67 times size of cantilever thickness, and the GMF exhibits clear superharmonic resonance, where the efficiency of superharmonic resonance of order 2, 3 and 4 is comparable with that of the primary resonance. The comparison between the static deformation model and resonance model with the experimental data indicates that the proposed models can describe well the static and dynamic nonlinear deformation of bimorph GMF cantilever. Thus, the proposed model provides the necessary basis for developing and designing effective microactuators and microsensors with GMF.

Key words: Giant magnetostrictive thin film, Hamilton principle, Nonlinear vibration