Abstract
Development of new nanoscale devices has increased the demand for new types of small-scale energy resources such as ambient vibrations energy harvesters. Among the vibration energy harvesters, piezoelectric energy harvesters (PEHs) can be easily miniaturized and fabricated in micro and nano scales. This change in the dimensions of a PEH leads to a change in its governing equations of motion, and consequently, the predicted harvested energy comparing to a macroscale PEH. In this research, effects of small scale dimensions on the nonlinear vibration and harvested voltage of a nanoscale PEH is studied. The PEH is modeled as a cantilever piezoelectric bimorph nanobeam with a tip mass, using the Euler-Bernoulli beam theory in conjunction with Hamilton’s principle. A harmonic base excitation is applied as a model of the ambient vibrations. The nonlocal elasticity theory is used to consider the size effects in the developed model. The derived equations of motion are discretized using the assumed-modes method and solved using the method of multiple scales. Sensitivity analysis for the effect of different parameters of the system in addition to size effects is conducted. The results show the significance of nonlocal elasticity theory in the prediction of system dynamic nonlinear behavior. It is also observed that neglecting the size effects results in lower estimates of the PEH vibration amplitudes. The results pave the way for designing new nanoscale sensors in addition to PEHs.
Highlights
Several energy harvesters for powering nano-scale portable electronic systems have been developed as the demand for self-powered electronic devices grows rapidly.[1,2] One of the most common types of energy harvesters is piezoelectric harvesters
Tang et al.[17] used magnetic force to investigate influence of both monostable and bistable configurations in a piezoelectric energy harvesters (PEHs) under random excitations. They proved the superiority of these configurations over linear PEHs
The nonlinearity boosts the performance of a PEH and is desired in energy harvesting
Summary
Several energy harvesters for powering nano-scale portable electronic systems have been developed as the demand for self-powered electronic devices grows rapidly.[1,2] One of the most common types of energy harvesters is piezoelectric harvesters. Tang et al.[17] used magnetic force to investigate influence of both monostable and bistable configurations in a PEH under random excitations They proved the superiority of these configurations over linear PEHs. In summary, the nonlinearity boosts the performance of a PEH and is desired in energy harvesting. Ke and Wang[21] applied the nonlocal elasticity theory to study the linear vibrations of a piezoelectric nanobeam. Because piezoelectric beams in small scales are mostly fabricated in unimorph or bimorph forms, modeling bimorph and unimorph nanobeams in addition to applying appropriate continuum theory is necessary. The nanobeam is subjected to harmonic base excitation It is modeled using Euler-Bernoulli beam theory combined with nonlocal elasticity theory to address the size effects in nanoscale. The results show the behavior of the nanoscale PEH for different values of system parameters
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