FEA Dual Model and Experimental Characterization to Investigate the Effect of an FCC Microstructure on the Macroscale and Microscale Stresses of a PZT Actuated Vibrating Thin Plate ^†

A numerical finite element analysis (FEA) dual model which combines a macroscale (Ansys) and a microscale (Abaqus) model, was employed to investigate the effect of a face centre cubic (FCC) microstructure on the macroscale and microscale stresses of a piezoelectrically (PZT) actuated Pd/Ni alloy thin plate subjected to high frequency vibration. The method of Electron backscatter diffraction (EBSD) was used to characterise the alloy microstructure, identifying the crystal orientations. Ansys multiphysics harmonic analysis was conducted to evaluate the macroscale stresses and strains of the orthotropic Pd/Ni plate subjected to high frequency vibration. It was found that the global maximum stresses and strains occur at the centre of the vibrating plate. Ansys predicted displacement at the centre of the vibrating plate was successfully validated experimentally using a laser doppler vibrometer (LDV) instrument. The crystal orientations identified at the centre of the vibrating plate was incorporated into an Abaqus crystal plasticity analysis within a representative volume element. The biaxial strain obtained from the Macroscale Ansys model was applied to the Microscale representative volume element to reproduce the deformation at the centre of the Pd/Ni plate. Using this material microstructure, the Microscale model investigated the local failure mechanism within the linear elastic regime. It was found that the microscale simulation (Abaqus) predictions of the magnitude of the stresses are consistent with those at the macroscale level (Ansys). The dual FEA model simulation results revealed that high stress or strain occurs at some grain boundaries and within grains with a [101] orientation. These stresses could be sufficiently high to cause failure at the macroscale, in particular for the case of a duplex type of microstructure of the bulk of the material, situated perpendicular to the direction of vibration. The FEA dual model predictions were confirmed experimentally by a continuous seven days fatigue-cycling test conducted on the Pd/Ni vibrating plates.