A dual-beam piezo-magneto-elastic wake-induced vibration energy harvesting system for high-performance wind energy harvesting

Wind-induced vibration energy harvesting has a great potential for utilizing wind energy to supply power for low-powered devices.To improve the working performance of energy harvesters effectively,a suitable structural design is crucial.This paper proposes a dual-beam piezo-magneto-elastic wake-induced vibration energy harvesting system to enhance the functional performance of aeroelastic energy harvesters in environments with variable wind speeds.The system contains two piezoelectric beams coupled by magnets(forming upstream and downstream energy harvesters),and each beam is attached with a foam cylinder.A corresponding dynamic model is provided,and output characteristics are obtained at different wind speeds.Results and experimental verification indicate that both upstream and downstream energy harvesters can realize efficient energy harvesting.When the wind speed exceeds a certain critical value,the amplitudes of the system’s displacement and voltage are high.The wind speed threshold value is approximately 1.25 m/s.When the wind speed and magnet spacing are 10.2 m/s and 20 mm,respectively,the output power of the system reaches 4.9×10^(−4)W.Moreover,the wind speed threshold value of the proposed system can be adjusted by an equivalent nonlinear restoring force.

On the stochastic response regimes of a tristable viscoelastic isolation system under delayed feedback control

In this paper,a tristable viscoelastic isolation system with stochastic excitation under both displacement and velocity delayed feedback control is considered.Firstly,the theoretical expressions of the mean first-passage time(MFPT)to measure the activated escape between different potential wells are derived.Induced nonlinear transition dynamics due to the noise and time delays are mainly discussed.It is found that the delay-induced behaviours affect the transitions between the equilibrium points of the system,the corresponding phenomenon of the delay-enhanced stability is observed.In this respect,the existence of the maxima of the MFPT1 and the MFPT2 is found in one period.Meanwhile,the MFPT1 and the MFPT2 show the monotonic behaviour with the increase of the noise intensity.Additionally,the stationary probability density of the amplitude and the stationary mean amplitude are derived.The influence regimes of the system parameters on both stationary probability density of the amplitude and the stationary mean amplitude are explored.This paper establishes the relationship between system parameters and dynamical properties of the tristable viscoelastic isolation system.This provides a fundamental guidance for the optimization of the viscoelastic isolation by utilizing the technique of delayed feedback control.