Exponentially Tapered Bimorph Piezoelectric Vibration Energy Harvester.
Abstract: This thesis
examines the effectiveness of an exponentially tapered piezoelectric plate for use as a
vibration energy harvester (VEH). Typically piezoelectric energy harvesters have been
designed as cantilever beams or "cymbal" type structures. For these devices there is a
known resonant frequency at which displacement is maximized to produce maximum power.
While this can produce good ... read moreresults for applications in which a device vibrates at a
specific frequency, many environmental vibration sources are wide-band and random. The
exponentially tapered plate investigated in this work was 55.88mm in length and tapered
exponentially from an initial width of 9.4mm to a final width of 71.12mm. The
effectiveness of this type of structure was investigated to determine how well this
system functioned as a broadband vibration energy harvester. Experimental and
computational analyses demonstrated the presence of an evanescent cut-off frequency of
approximately 3800 Hz below which very little energy is transferred from the input into
the plate. The result of this is very inefficient power conversion at or below this
cut-off frequency. Since this is a critical feature of this type of energy harvester
this structure will only be effective at higher frequencies above the cut-off. The
mounting assembly design itself was shown to accurately model an exponentially tapered
plate using a square PZT plate rather than having to have the PZT custom milled to the
desired shape. This greatly reduces the cost of the materials used and should be
considered for use in future research related to exponentially tapered plates. In
addition the experimental results showed that as the frequency of the input is
increased, the amount of energy transmitted around the mounting structure and therefore
into the plate from the sides increased. This makes the mounting structure more suitable
for low frequency experimentation, below
Thesis (M.S.)--Tufts University, 2012.
Submitted to the Dept. of Mechanical Engineering.
Advisor: Robert White.
Committee: Jason Rife, and Masoud Sanayei.
Keyword: Mechanical engineering.read less