Fig. 13: Relation between the frequency of the 4.42 m.s-2 base excitation and and a) power from piezoelectric patched, b) power from electromagnetic coils, c) phase portrait. Conclusions A comprehensive experimental investigation was conducted on the vibrations characteristics and power generation of the novel hybrid nonlinear energy harvester. The harvester utilizes passive magnetic forces to both reduce the natural frequency and introduce useful nonlinearities to the harvesting system. The device has been modeled using energy methods. The first set of experiments is for the softly nonlinear system where only piezoelectric transduction is implemented. The second case study considers the softly nonlinear system where both piezoelectric and electromagnetic transductions harvest energy. The final set of tests is dedicated to bi-stable situation and the small amplitude oscillation, chaotic motion and limit cycle oscillations are all investigated. References [1] S. P. Beeby, M. J. Tudor, and N. M. White, "Energy harvesting vibration sources for microsystems applications," Measurement science and technology, vol. 17, p. 175, 2006. -0.04 -0.02 0 0.02 0.04 -1 0 1 5 6 7 8 9 base accel. (m.s -2 ) a b =4.4168 m.s -2 xt (m) vt (m.s -1 ) 476
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