Small and micro-scale energy harvesting is an essential and viable option for the powering of
portable and maintenance free electronic devices, wireless sensor nodes, and similar applications. In
this regard, piezoelectric energy harvesters (PEH) have presented promising outcomes in last two
decades. The advancements in PEHs span right from early linear models to the recent nonlinear multistable asymmetric potential well harvesters. Dynamical behaviour of these harvester models, showing
interwell, multi-periodic and chaotic oscillations with improved broadband frequency response, is
simulated and discussed using a non-dimensional generalized model. Using the generalized model, a
sequential and comprehensive review of symmetric and asymmetric potential well based piezoelectric
harvester models and studies is carried out, which has proved beneficial in proposing the roadmap of
research and future works to be carried out for the thesis.
While exploring the benefits of the nonlinearity in the field of piezoelectric energy harvesting,
a crucial but often overlooked aspect is the life expectancy of the piezoelectric element used. It is
identified that the discussion is absent in literature regarding the assessment of the strain levels
induced and corresponding fatigue life of the piezoelectric element. With this as the motivation, an
analytical model is derived to obtain strain distributions under the applied moment in unimorph and
bimorph piezoelectric cantilever sections. Two normalization schemes are also proposed and will be
presented which exhibit interesting insights about the influence of geometric and material property
variations on the composite sections. The proposed model also helps in the selection of unimorph and
bimorph composite sections that are optimized for maximizing harvesting effect while limiting the
strain levels under the linear elastic limit of the piezoelectric element. Further, a study on relative
comparison between unimorph and bimorph composite section presents design guidelines. Results of
quasi-static experimental strain measurement tests are in agreement with the proposed model.