Modeling and Dynamic Design of a Piezoelectric Cantilever Energy Harvester with Surface Constraints

PurposeCantilever piezoelectric energy harvesters are suitable for low ambient excitation and have promising applications. However, the piezoelectric energy harvester with a simple cantilever is less efficient due to the beam only obtains large strain at the root. In order to improve the harvesting efficiency, this paper deals with the modeling and dynamic design of a cantilever-based energy harvester with surface constraints (EHSC). The design parameters for high efficiency in EHSC are obtained.MethodsBased on mechanics of materials and magnetizing current method, the expressions of nonlinear restoring force and magnetic force of EHSC are theoretically derived respectively. A more realistic lumped parameter model of EHSC is established from Newton's and Kirchhoff's laws. According to the static and dynamic analyses, the nonlinear behaviours of EHSC are studied. Then the parameter configuration with high harvesting performance can be obtained. At last, the experiment is carried out to verify the theoretical conclusions.ResultsBy comparing the dynamic performance of EHSC with the conventional bi-stable energy harvester without the constraints under same conditions, we find that EHSC can broaden the harvesting frequency band by about seven times and increases the output power by about 23%. So the proposed EHSC can generate more electric energy in a wider range at low frequency.ConclusionThe constraints enhance the nonlinear stiffness of the harvester system, which is beneficial to broaden the working frequency band. The constraints can also generate large strain even far away from the beam root, which is beneficial to improve the harvesting efficiency. Moreover, this work can provide some design and optimization guidance for such nonlinear piezoelectric energy harvesters.