Geometrical nonlinearities and shape effects in electromechanical models of piezoelectric bridge structures
Artikel i vetenskaplig tidskrift, 2021

We consider nonlinear shape effects appearing in the lumped electromechanical model of a bimorph piezoelectric bridge structure due to the interaction between the electromechanical constitutive model and the geometry of the structure. At finite proof-mass displacement and electrode voltage, the shape of the beams is no longer given by Euler-Bernoulli theory which implies that shape effects enter in both the electrical and mechanical domains and in the coupling between them. Accounting for such effects is important for the accurate modelling of, e.g., piezoelectrical energy harvesters and actuators in the regime of large deflections and voltages. We present a general method, based on a variational approach minimizing the Gibbs enthalpy of the system, for computing corrections to the nominal shape function and the associated corrections to the lumped model. The lowest order correction is derived explicitly and is shown to produce significant improvements in model accuracy, both in terms of the Gibbs enthalpy and the shape function itself, over a large range of displacements and voltages. Furthermore, we validate the theoretical model using large deflection finite element simulations of the bridge structure and conclude that the lowest order correction substantially improve the model, obtaining a level of accuracy expected to be sufficient for most applications. Finally, we derive the equations of motion for the lowest order corrected model and show how the coupling between the electromechanical properties and the geometry of the bridge structure introduces nonlinear interaction terms.


Fredrik Ohlsson

RISE Research Institutes of Sweden

Göteborgs universitet

Chalmers, Matematiska vetenskaper, Tillämpad matematik och statistik

Umeå universitet

Pontus Johannisson

RISE Research Institutes of Sweden

Cristina Rusu

RISE Research Institutes of Sweden

International Journal of Energy and Environmental Engineering

2008-9163 (ISSN) 2251-6832 (eISSN)

Vol. In Press

Smart MEMs Piezo based energy Harvesting with Integrated Supercapacitor and packaging (Smart-MEMPHIS)

Europeiska kommissionen (EU) (644378), 2014-12-15 -- 2018-06-14.


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