Fig. 1. Schematic diagram of the electromechanical transducer vibratory energy harvesters.

Fig. 2. Model of nonlinear capacitor.^[42]

Fig. 3. Frequency-resonance curves for different amplitudes of voltage source.

Fig. 4. Frequency-resonance curves for different cubic nonlinear coefficients.

Fig. 5. Frequency-resonance curves for different resistors R₁.

Fig. 6. Frequency-resonance curves for different damping coefficients.

Fig. 7. Frequency-resonance curves for different magnetic strengths B₁.

Fig. 8. Frequency-resonance curves for different magnetic strengths B₂.

Fig. 9. Comparison of the internal resonance and the linear results.

Fig. 10. Comparison of the analytical and the numerical results.