Recent advancements in technology have increased the demand for miniaturized energy harvesting, sensing and actuating devices. These applications are made feasible by multifunctional materials such as magnetostrictive and piezoelectric materials which possess a coupling behavior. Magnetoelectric (ME) composites comprising of magnetostrictive and piezoelectric materials show a larger coupling response as compared to naturally available single-phase ME materials. These composites are capable of generating voltage under the applied external magnetic field and vice versa, by means of a strain-mediated coupling.
Magnetostrictive materials show nonlinear coupling behavior at high magnetic fields which renders nonlinear ME characteristics. This gives rise to a need for developing a nonlinear constitutive relation for the magnetostrictive material. A brief review of literature reveals a variety of phenomenological and micro-scale models available for magnetostriction. Developing a model that can combine the merits of both the approaches by consideration of the magnetostrictive material at the meso-scale can prove insightful and computationally effective which is the objective of current work.
A nonlinear hybrid model is thus developed for the magnetostrictive material and is subsequently used to predict the nonlinear behavior of a special class of ME composites called pressfit composites. The pressfit method of fabrication offers improved strain transfer between the constituent phases and a better thermal stability as opposed to layered composites, due to the elimination of epoxy adhesives for bonding. Using the proposed constitutive model, a parametric study is adopted to determine the effect of the boundary conditions and aspect ratio of the piezoelectric phase. The results reveal that restriction of transverse displacements results in improved coupling due to the development of compressive stresses.