  Over the past few decades, the prospect of energy generation from an
oscillating piezoelectric patch has gained attention. A typical setup of this
kind would be a piezoelectric patch mounted on a flexible plate that is
exhibiting self-sustained flapping motion. Piezoelectric patches are generally
multilayered consisting of piezoelectric, substrate and electrode layers placed
on top of each other. In this paper, we first propose a quasi-monolithic
formulation with exact interface tracking to simulate the fluid-multilayered
structure interactions. We validate the proposed formulation, using an in-house
solver, by considering a simple two-layered plate-like structure with identical
material properties against a single-layered plate. We then use this
formulation to study a two-layered flexible plate, wherein each layer of the
plate has independent material properties. Systematic parametric simulations
are conducted to understand the effect of difference in material properties
between the two layers of a plate on the self-sustained flapping dynamics. The
parametric simulations are performed at a Reynolds number Re=1000 by selecting
different values of Young's modulus and density for each of the layers such
that the average structure to fluid mass ratio (m)avg=0.1 and average
non-dimensional bending stiffness (KB)avg=0.0005. Firstly, the effects of
difference in elasticity between the two layers on the flapping amplitude,
frequency, forces and vortex shedding patterns are investigated. Following
this, the effect of such difference in elastic properties on the onset of
flapping is investigated for a case with Re=1000, (m)avg=0.1 and (KB)avg=0.0008
and two distinct response regimes are observed: (a) fixed-point stable and (b)
periodic LCO. Finally, we look into the effects due to the difference in the
structural density between the two layers on the flapping dynamics of the
plate.
