Demagnetization Effect on the Magnetoelectric Response of Composite Multiferroic Cylinders

Strain-mediated multiferroic composite structures are gaining scientific and technological attractions because of the promise of low power consumption and greater flexibility in material and geometry choices. In here, the direct magnetoelectric coupling coefficient (DME) of composite multiferroic cylinders, consisted of two mechanically bonded concentric cylinders, was analytically modeled under the influence of a radially emanating magnetic field. The analysis framework emphasized the effects of shear lag and demagnetization on the overall performance. The shear lag effect was analytically proven to have no bearing on the DME since it has no effect on the induced radial displacement due to the conditions imposed on the composite cylinder. The demagnetization effect was also thoroughly considered as a function of the imposed mechanical boundary conditions, geometrical dimensions of the composite cylinder, and the introduction of a thin elastic layer at the interface between the inner piezomagnetic and outer piezoelectric cylinders. The results indicate that the demagnetization effect adversely impacted the DME coefficient between 70% and 86%. In a trial to compensate for the reduction in peak DME coefficient due to the presence of demagnetization, non-dimensional geometrical analysis was carried out to identify the geometrical attributes corresponding to the maximum DME. It was observed that the peak DME coefficient is nearly unaffected by varying the inner radius of the composite cylinder, while it approaches its maximum value when the thickness of the piezoelectric cylinder is almost 60% of the total thickness of the composite cylinder. The latter conclusion was true for all of the considered boundary conditions.