Shaikh Faruque Ali

The analysis of piezomagnetoelastic energy harvesters under broadband random excitations

This paper presents an analysis of piezomagnetoelastic energy harvesters under broadband random ambient excitations for the purpose of powering low-power electronic sensor systems. Their nonlinear behavior as a result of vibration in a magnetic field makes piezomagnetoelastic energy harvesters different from classical piezoelastic energy harvesters. An equivalent linearization-based analytical approach is developed for the analysis of harvested power. A closed-form approximate expression for the ensemble average of the harvested power is derived and validated against numerical Monte Carlo simulation results. Our results show that it is possible to optimally design the system such that the mean harvested power is maximized for a given strength of the input broadband random ambient excitation.

Analysis of energy harvesters for highway bridges

This article investigates the possibility of piezoelectric energy harvesters as energy scavenging devices in highway bridges. The structural vibration due to the motion of a load (vehicle) on the bridge is considered as the source of energy generation for the harvester. The energy generated in this way can be useful for wireless sensor networks for structural health monitoring of bridges by reducing or even eliminating the need for battery replacement/recharging. A highway bridge model with a moving point load is investigated and a linear single-degree-of-freedom model is used for the piezoelectric energy harvester. Two types of harvesters, namely, the harvesting circuit with and without an inductor, have been considered and the energy generated for a single vehicle has been estimated. These results may be used, together with traffic statistics, to obtain the variation of average power and thus, for a given application, help to design the energy management system.

Piezoelectric energy harvesting with parametric uncertainty

The design and analysis of energy harvesting devices is becoming increasing important in recent years. Most of the literature has focused on the deterministic analysis of these systems and the problem of uncertain parameters has received less attention. Energy harvesting devices exhibit parametric uncertainty due to errors in measurement, errors in modelling and variability in the parameters during manufacture. This paper investigates the effect of parametric uncertainty in the mechanical system on the harvested power, and derives approximate explicit formulae for the optimal electrical parameters that maximize the mean harvested power. The maximum of the mean harvested power decreases with increasing uncertainty, and the optimal frequency at which the maximum mean power occurs shifts. The effect of the parameter variance on the optimal electrical time constant and optimal coupling coefficient are reported. Monte Carlo based simulation results are used to further analyse the system under parametric uncertainty.

ENERGY HARVESTING IN PIEZOELASTIC SYSTEMS DRIVEN BY RANDOM EXCITATIONS

The inverted elastic beam is proposed as an energy harvester. The beam has a tip mass and piezoelectric layers which transduce the bending strains induced by the stochastic horizontal displacement into electrical charge. The efficiency of this nonlinear device is analyzed, focusing on the region of stochastic resonance where the beam motion has a large amplitude. Increasing the noise level allows the motion of the beam system to escape from single well oscillations and thus generate more power.

Dynamic response mitigation of floating wind turbine platforms using tuned liquid column dampers

In this paper, we experimentally study and compare the effects of three combinations of multiple tuned liquid column dampers (MTLCDs) on the dynamic performance of a model floating tension-leg platform (TLP) structure in a wave basin. The structural stability and safety of the floating structure during operation and maintenance is of concern for the performance of a renewable energy device that it might be supporting. The dynamic responses of the structure should thus be limited for these renewable energy devices to perform as intended. This issue is particularly important during the operation of a TLP in extreme weather conditions. Tuned liquid column dampers (TLCDs) can use the power of sloshing water to reduce surge motions of a floating TLP exposed to wind and waves. This paper demonstrates the potential of MTLCDs in reducing dynamic responses of a scaled TLP model through an experimental study. The potential of using output-only statistical markers for monitoring changes in structural conditions is also investigated through the application of a delay vector variance (DVV) marker for different conditions of control for the experiments.

Broadband Vibration Energy Harvesting from a Vertical Cantilever Piezocomposite Beam with Tip Mass

An inverted cantilevered beam vibration energy harvester with a tip mass is evaluated for its electromechanical efficiency and power output capacity in the presence of pure harmonic, pure random, and various combinations of harmonic and random base excitation cases. The energy harvester employs a composite piezoelectric material device that is bonded near the root of the beam. The tip mass is used to introduce nonlinearity to the system by inducing buckling in some configurations and avoiding it in others. The system dynamics include multiple solutions and jumps between the potential wells, and these are exploited in the harvesting device. This configuration exploits the nonlinear properties of the system using base excitation in conjunction with the tip mass at the end of the beam. Such a nonlinear device has the potential to work well when the input excitation does not have a dominant harmonic component at a fixed frequency. The paper presents an extensive experimental analysis, results and interesting conclusions derived directly from the experiments supported by numerical simulations.

Effect of Road Surface, Vehicle, and Device Characteristics on Energy Harvesting from Bridge-Vehicle Interactions

Energy harvesting to power sensors for structural health monitoring SHM has received huge attention worldwide. A number of practical aspects affecting energy harvesting and the possibility of health monitoring directly from energy harvesters is investigated here. The key idea is the amount of power received from a damaged and an undamaged structure varying and the signature of such variation can be used for SHM. For this study, a damaged bridge and an undamaged bridge are considered with harvesters located at different positions and the power harvested is accessed numerically to determine how energy harvesting can act as a damage detector and monitor. Bridge-vehicle interaction is exploited to harvest energy. For a damaged bridge, a bilinear breathing crack is considered. Variable surface roughness according to ISO 8606:1995E is considered such that the real values can be considered in the simulation. The possibility of a drive-by type health monitoring using energy harvesting is highlighted and the effects of road surface on such monitoring are identified. The sensitivity of the harvester health monitoring to locations and extents of crack damage are reported. This study investigates the effects of multiple harvesters and the effects of vehicular parameters on the harvested power. Continuous harvesting over a length of the bridge is considered semianalytically. A comparison among the numerical simulations, detailed finite element analysis, and experimental results emphasizes the feasibility of the proposed method.

Nonlinear oscillations of an elastic inverted pendulum

We examine the dynamics of the elastic inverted pendulum with a tip mass under horizontal harmonic excitation. In particular, we study the conditions when the potential barrier is overcome by the tip mass, and large amplitude oscillations occur, by means of the Melnikov criterion. The results have been confirmed by numerical simulations.

Magneto-mechanically coupled electromagnetic harvesters for broadband energy harvesting

A low frequency magneto-mechanically coupled energy harvesting system is proposed to increase the power magnitude and bandwidth simultaneously. The system consists of two pendulums that are magnetically and mechanically coupled. The analytical formulation for the coupled system is developed based on the extended Lagrangian formulation. The experimental and simulated results are reported. The results exhibiting the benefits of magneto-mechanical coupling are reported. The experiments show an increment of 30.69% in the power magnitude and 100% enhancement in the bandwidth when compared to independent harvesters even at a low amplitude of excitation. Moreover, Chaos is observed at low frequency and at a low amplitude, which tends to provide larger bandwidths with more power.

Energy Harvesting from Near Periodic Structures

In this research energy harvesting from near periodic structure is discussed. The near periodic system consists of two pendulums connected using a common linear spring. Mistuning in the simple coupled pendulum system is achieved by varying the length of one of the pendulums. Effect of this mistuning on amount of energy harvested is developed analytically and numerically. This will be discussed in this paper and at the same time effect of harvesting on mistuning will be presented. It is shown that with a proper electrical damping, optimal power can be obtained and effect of mistuning can be minimized. Same analysis is carried out with energy harvesting from both the pendulums. In case of harvesting from both the pendulums the harvesting bandwidth is increased and electrical damping required to minimize mistuning is more than that in case of harvesting with mistuned pendulum alone.