Finite element characterisation of multilayer d31d31 piezoelectric macro-fibre composites

This work presents a methodology for the numerical characterisation of the effective properties of a d31d31 macro-fibre composite (MFC) transducer and their electric field dependence. This is done first by using a finite element homogenisation methodology proposed previously for shear d15d15 MFC to evaluate the effective properties of a d31d31 MFC based on known geometrical and material properties of its constituents, accounting in particular for the effect of electrode and protective layers on the effective elastic, piezoelectric and dielectric coefficients. Obtained results for the active layer agree very well with previously published ones obtained using mixing rules techniques, while obtained results for the full 5-layered MFC agree very well with properties provided by the manufacturer. Then, an analysis of the effect of the fibre volume fraction and electric boundary conditions on the main effective properties is presented. Next, experimental data describing the electric field dependence of soft piezoceramic fibres dielectric and piezoelectric properties are used to develop electric-field dependent material models. Finally, the homogenisation technique is performed for various electric field values to evaluate the electric field dependence of the effective d31d31 MFC properties. It is shown that effective piezoelectric and dielectric coefficients may vary substantially with electric field.