Elastic postbuckling response of bilaterally constrained non-prismatic columns

Axially loaded bilaterally constrained columns can attain multiple snap-through buckling events in their elastic postbuckling response for use as energy concentrators that transform external quasi-static displacement input to high-rate motions to excite vibration-based piezoelectric transducers. Regulation of the postbuckling behavior can lead to increased performance of the energy harvesting device. This paper presents how stiffness variations along the column element lead to enhanced control of the noted elastic postbuckling response. Results from experiments and numerical simulations show that non-uniform stiffness designs are able to tailor the location and sequence of buckling events by creating a concentrated buckling region on the column. Compared to a uniform design, non-prismatic columns can attain a higher number of mode transitions under the same global strain level and also create local stress waves that propagate along the element due to the stiffness variations, which leads an enhanced kinetic energy generation during the postbuckling response.