Bandwidth broadening through stiffness merging using the nonlinear cantilever generator

Abstract

Nonlinear systems are more attractive for the wide bandwidth in contrast to linear vibration energy harvesters. Most available generators belong to a certain type of nonlinear systems and the Duffing oscillator is a most popular kind. Once the system type is determined with a specific equation form, the performance optimization is limited in a certain range, generally related to the parameter study of the system within a given frame. In this paper, a novel generator is proposed by merging the stiffness curves of two different source generators through utilization of the nonlinear cantilever with a curve fixture. The special merged stiffness characteristics break the response limitation of the specific stiffness profile such as the Duffing equation and bring new benefits with the generator bandwidth further broadened by integrating the advantages of the source generator. In order to verify the stiffness-merging concept, two Duffing generators and a proposed generator with stiffness fitted from the former two are fabricated using the nonlinear cantilever with specially designed fixture curves. Experimental and numerical investigations reveal that the proposed generator with the merged stiffness has better performance than the generators with the typical stiffness characteristics of Duffing systems. The effectiveness of the stiffness-merging method is well demonstrated.