Finite element study of tunable cantilever plate structure using position change

Abstract

In this paper, a tunable cantilever plate structure is presented, in which a box is attached to each corner of its free sides and a ball is placed in each box. Change of the balls position makes natural frequency of the structure variable, which expands working bandwidth of the structure to accommodate the complex ambient vibration. The modal analysis of the tunable cantilever plate is carried out by the finite element software-ABAQUS. Changing the balls position, it is found that there are maximum and minimum values in the natural frequency of the self-tuning structure, which forms a resonance bandwidth. Moreover, there are multiple position combinations of two balls at the same natural frequency in the range of resonance band. The paper studies the influence of mass and geometrical dimensions of boxes and balls on the natural frequency and bandwidth. While ensuring strength and stiffness of the structure, optimal material and size parameters are selected to improve the resonant bandwidth. This provides a theoretical basis for applying the tunable structure to piezoelectric energy harvester.

Experimental study of auto-tuning piezoelectric energy harvester attaching balls in boxes

“…Reference [33] designed an auto-tuning instrument by attaching a box with two cylinders based on a cantilever beam structure, and did not further study the relationship between position and frequency/bandwidth. In 2019, Chen et al [34,35] proposed a tunable cantilever plate attaching a box at each corner of the free end and placing a ball in each box. It is found that the natural frequency of the structure changes between the maximum (f max ) and the minimum natural frequency (f min ) when the ball position changes in the box.…”

“…Therefore, the position of two balls is easier to be adjusted without colliding and squeezing each other, which is conducive to realize the auto-tuning function in a broad-frequency vibration environment. In this paper, hammering experiments are performed to verify the effect of the balls position on the natural frequency and the theoretical bandwidth, and to compare with the theoretical [35] and finite element results [34]. The stronger Hammer experiment.…”

“…A rectangular box is attached to each corner of the free end of the cantilever plate by AB epoxy resin, and a ball is placed in each box. The effect of size parameters and mass of boxes and balls on the natural frequency has been studied in [34,35]. In order to broaden the TFB, the mass ratio of balls to boxes should be increased.…”

“…The experimental, simulation [34] and theoretical results [35] of three cases are compared in figs. 3(a)-(c), represented by red, black, and blue lines, respectively.…”

“…Auto-tuning experiment. -Applying the finite element method [34], it is found that variations of the whole centroid position of the two balls lead to the changing of the PEH natural frequency. Unlike other structures [23][24][25][26][27][28][29][30][31][32][33] in which only one position corresponds to one centroid, one centroid in this structure corresponds to the multiple balls positions, which form an X-shaped region.…”