Fig. 1

(a) Three-dimensional view of the spatial ball-pendulum energy harvester; (b) schematic of the motion of a free-rolling magnetic ball in the inner cavity of the resonator (left: front view; right: top view) (color online)"

Table 1

Parameters of energy harvesting resonator"

Fig. 2

Amplitude-frequency response curve of energy harvesting system (color online)"

Fig. 3

Construction of viscoelastic metamaterials. (a) Viscoelastic phononic crystals with periodic arrays of spherical cavities; (b) periodic arrays of spatial spherical pendulum energy harvesters; (c) viscoelastic metamaterials for vibrational isolation and energy harvesting (color online)"

Fig. 4

Microelement analysis of a typical cell in a viscoelastic metamaterial equivalent to a Timoshenko beam (color online)"

Fig. 5

(a) Finite element model of cell and (b) finite element model of viscoelastic metamaterial (color online)"

Table 2

Physical parameters of viscoelastic metamaterial beam cell"

Fig. 6

Complex energy band structure and frequency response of viscoelastic metamaterials. (a) Real part; (b) imaginary part; (c) amplitude-frequency response curve (color online)"

Fig. 7

Output power curve of resonator around excitation point (color online)"

Fig. 8

The variation of band gap with different geometrical parameters (a) cell size; (b) magnetic ball mass; (c) spherical cavity size (color online)"

Table 3

Experimental parameters of viscoelastic metamaterial cell"

Fig. 9

(a) Experimental diagram of a metamaterial beam under transverse excitation; (b) schematic diagram of the experimental system (color online)"

Fig. 10

The amplitude-frequency response curve of viscoelastic metamaterials under transverse harmonic excitation (color online)"

Fig. 11

(a) Time domain response at 5.4 Hz and (b) time domain response at 38.5 Hz (color online)"

Table 4

Band gap vibration isolation efficiency"

Fig. 12

Output voltages of the space ball pendulum energy harvesting device at four positions at 3.3 Hz (before the local resonance band gap frequency) (color online)"

Fig. 13

Output voltages of the space ball pendulum energy harvesting device at four positions at 5.3 Hz (in the local resonance band gap frequency) (color online)"

Fig. 14

Output voltages of the space ball pendulum energy harvesting device at four positions at 7.3 Hz (after the local resonance band gap frequency) (color online)"