Robust design of piezoelectric energy harvesters using polynomial chaos expansions and multi-objective optimization

Resumo

The generation of electrical energy from mechanical vibrations and using piezoelectric materials is an
attractive alternative due to the high density of electrical charge present in these materials. Although energy can be

harvested, the design of devices for this purpose must satisfy specific criteria, because the energy available for con-
version into electricity is low. This work suggests the robust design of beam type piezoelectric energy harvesters,

considering the presence of uncertainties in certain parameters. Thus, the study presents a finite element can-
tilever beam model and, through multiobjective optimization, designs the energy harvesting devices to maximize

the mean power and minimize the relative dispersion simultaneously. The mean and variance for the frequency

response function of the power output are estimated using polynomial chaos expansion. Results show that harvest-
ing devices with smaller length and larger masses generally lead to best nominal performance but also to higher

dispersions. Also, the dispersions can be reduced by using effective circuit resistances smaller than the nominal
values. With the increase of uncertainties in the parameters of the devices, better performances and decrease in the
response variability are achieved by using other design variables in the optimization.