Interwell Motion Research Articles

Asymmetric tristable energy harvester with a compressible and rotatable magnet-spring oscillating system for energy harvesting enhancement

This paper proposes an asymmetric tristable energy harvester with a compressible and rotatable magnet-spring oscillating system to enhance the energy harvesting performance. The linear compressible and rotatable magnet-spring oscillating system is composed of two external magnets, a metal block and two parallel springs. The two external magnets are symmetrically located on the metal block and fixed to the base through the two parallel springs. Due to different compression of the two springs under variable magnetic force, the two external magnets can move along the spring's compression direction and rotate around the center of the metal block, thus to generate tunable and asymmetric potential function. The general governing equations and asymmetric potential function of the proposed harvester are established with Hamilton principle and point dipole method, respectively. The effects of system parameters on the nonlinear dynamic performances of the proposed harvester are numerically investigated. Experiments are carried out to validate the simulations. The results demonstrate that moderate spring stiffness can not only reduce the potential energy barrier and the threshold of snap-through, but also broaden the bandwidth of interwell motion, as well as enhance the energy harvesting efficiency. When the spring stiffness k = 900 N/m, the threshold value of snap-through of the TEH-A is 8 m/s2, the bandwidth of inter-well motion is 2.0∼4.5 Hz, and the maximum harvesting voltage and power reach 6.8 V and 4.6 × 10−5 W, respectively. These values are far better than the tristable energy harvester with symmetric potential wells, whose corresponding values are 3.8∼4.2 Hz, 9.8 m/s2, 0.81 V and 6.6 × 10−7 W, respectively.

Simple analytical models and analysis of bistable vibration energy harvesters

In order to scavenge the energy of ambient vibrations, bistable vibration energy harvesters constitute a promising solution due to their large frequency bandwidth. Because of their complex dynamics, simple models that easily explain and predict the behavior of such harvesters are missing from the literature. To tackle this issue, this paper derives simple analytical closed-form models of the characteristics of bistable energy harvesters (e.g. power-frequency response, displacement response, cut-off frequency of the interwell motion) by mean of truncated harmonic balance methods. Measurements on a bistable piezoelectric energy harvester illustrate that the proposed analytical models allow the prediction of the mechanical displacement and harvested power, with a relative error below 10%. From these models, the influences of various parameters such as the inertial mass, the acceleration amplitude, the electromechanical coupling, and the resistive load, are derived, analyzed and discussed. The proposed models and analysis give an intuitive understanding of the dynamics of bistable vibration energy harvesters, and can be exploited for their design and optimization.

Bistable programmable origami based soft electricity generator with inter-well modulation

Kresling origami features an axial compression and torsion coupled motion mechanism. The nonlinear stiffness is generated by this unique deformation mode, allowing Kresling origami to be employed in wave propagation control, mechanical storage devices, digital computing, and soft robotics. In this paper, a soft bistable electricity generator is developed based on Kresling origami. This soft electricity generator is capable of initiating inter-well motion for broadband energy harvesting at low frequency and low amplitude excitation based on delicately designed structural parameters, programmable bistable energy landscape and soft origami structure fabrication. Two asymmetric potential energy wells are obtained through combining the elastic potential energy of the origami structure with the gravitational potential energy of top mass. The prototype of the bistable Kresling origami structure is fabricated by a two-step mold procedure and the theoretical model is verified through quasi-static and dynamic experiments. The number of the stable states is tunable and the energy curve is programmable by varying the top mass, initial height hs and initial torsional angle. The nonlinear bistable origami has complex dynamic phenomena such as intra-well motion, inter-well motion and chaotic motion. Compared with intra-well motion, the harvested power of inter-well motion is increased by 18.5 times. The origami structure can be excited to the inter-well orbit under low intensity excitation of 0.19 m/s2 and low frequency of 2.5 Hz. An origami-based shoe pad is fabricated by integrating the origami generator into the shoe pad to not only harvest the energy but also measure the gait and motion information from the human motions. The proposed soft electricity generator of bistable programmable origami provides a competitive solution for broadband energy harvesting under low excitation acceleration and low frequency environment, i.e., human motion and bridge vibration, showing the great potential as power supply for wearable devices and bridge monitoring devices.

Coupling nonlinearities and dynamics between the hybrid tri-stable piezoelectric energy harvester and nonlinear interfaced circuit

Tri-stable piezoelectric vibration energy harvester (T-PVEH) recently has been widely investigated due to its good electro-mechanical performance. However, most studies emphasizing the mechanical configuration usually only regard the interfaced circuit as equivalent to a linear resistance load. The coupling nonlinearities and dynamics between the T-PVEH and the nonlinear interfaced circuit are yet to be well understood. Considering a hybrid T-PVEH interfacing with a nonlinear AC-DC rectifying circuit, this paper aims to derive its electro-mechanical equations to characterize the mechanical and energetic dynamics, as well as the coupling nonlinearities between the mechanical terminal and electrical terminal, which can be helpful to optimize the T-PVEH configuration and the circuit topology, so as to enhance the energy harvesting efficiency and effective broadband. The general harmonic balance solutions and the Jacobian matrix used to estimate the solution stability are presented based on the derived electro-mechanical equations. The influences of the magnetic distance, coupling constant and load resistance on the mechanical and energetic dynamics are simulated. The contradiction between the bandwidth and efficiency caused by the coupling nonlinearities is also analyzed. The results show that proper selection of the magnetic distance, load resistance and coupling constant in their suitable range is beneficial to enhance the effective bandwidth and harvested power of the global inter-well motions. It also shows that strong coupling constant with large load resistance will introduce additional mechanical damping and stiffness, attenuating the response amplitude and effective bandwidth of the system. Experimental results show reasonable agreement with the simulations. The rectified voltage obtained by experiment is 2.6 V, which meets the power supplying demand of the low-powered electronic devices.

A numerical-experimental dynamic analysis of high-efficiency and broadband bistable energy harvester with self-decreasing potential barrier effect

It is difficult for a conventional bistable energy harvester (CBEH) to form inter-well motion under a weak excitation, resulting in a narrow output bandwidth. In this paper, a bistable energy harvester with a self-decreasing potential barrier effect (BEH-DB) is proposed. It adopts a spring-magnetic oscillator to rectify the cantilever beam bi-directionally causing the potential barrier to be dynamically lowered when returning to the trivial position; while the potential energy is enhanced when moving away from the trivial position. The theoretical model is established by using Euler-Bernoulli's stepped beam and magnetic dipole theories. The influence of system parameters on the performance of the self-decreasing potential barrier is studied by tracking the trajectories on the potential energy surface. The frequency and amplitude sweeps, phase portraits, Poincare maps, and bifurcation analysis are used numerically to investigate the dynamics of the system. The simulation results present a series of complex dynamic behaviors such as intra-well, inter-well harmonic and sub-harmonic orbits, and chaotic motion. The BEH-DB is more easily to be excited to the inter-well orbit to form a large oscillation in an ultra-wide bandwidth, even at the low frequency. Its effective bandwidth and maximum average power are approximately 16.17 Hz and 9.02mW, respectively. Finally, the experiment was carried out, which illustrates that the power generation capacity and bandwidth of the BEH-DB are improved several times that of the CBEH. The experimental results are agreed qualitatively with the numerical simulation. The proposed BEH-DB can be used to harvest energy efficiently and broadly from a low or ultra-low frequency ambient vibration.

Hybridizing piezoelectric and electromagnetic mechanisms with dynamic bistability for enhancing low-frequency rotational energy harvesting

This Letter proposes a rotational energy harvester with hybrid piezoelectric and electromagnetic mechanisms and dynamic bistability. It consists of a piezoelectric stack with a force magnification frame and two connected springs, and two electromagnetic coils with inner impact stoppers. On the one hand, the hybrid energy transduction is applied in the gravity-based rotational energy harvester to enhance the energy output. On the other hand, the dynamic bistability by utilizing the centrifugal force is proposed to improve low-frequency performances. Simulation and experiments demonstrate that the proposed harvester starts to exhibit the bistability as the rotational frequency is increased from zero with subsequent interwell, chaotic, and intrawell motions, among which the interwell motions can increase the peak power from piezoelectric and electromagnetic parts by 24.99% and 57.41%, respectively. Specifically, the maximum total output power in experiments is measured to be 2.98 mW at 7.5 Hz and the spring stiffness of 4200 N/m. Moreover, the total power and frequency bandwidth are both higher but broader/narrower with a higher spring stiffness or impact distance, respectively.

Large stroke tri-stable vibration energy harvester: Modelling and experimental validation

An important issue in vibration energy harvesting is to increase the effective operation bandwidth. One solution is to develop multi-stable energy harvesters which can execute inter-well motion under certain conditions. However, almost all the n-stable harvesters are based on the cantilever-beam-magnets configuration if n > 2, namely, to arrange several fixed magnets near the free end of a piezoelectric cantilever beam with tip magnet, which usually has relatively small stroke due to the deformation limitation of the beam. In this paper, we propose a new tri-stable mechanism using four mechanical springs with well-designed configuration, which has large stroke due to the structural property. Thereafter a tri-stable electromagnetic energy harvester is constructed based on the proposed tri-stable mechanism. The dynamic response and electrical output characteristics are theoretically analyzed by numerical simulations using the dimensionless electromechanical coupled equations. It is shown that the inter-well oscillation can be activated in broadband low-frequency range, which generates considerable induced current. Experiments are also conducted to validate the theoretical model and to demonstrate the low-frequency broadband energy harvesting capability. The output power reaches the level of several hundred milliwatts, which is much larger than that of the previous tri-stable harvesters at milliwatt level.

Characterizing nonlinear characteristics of asymmetric tristable energy harvesters

Ambient vibration conditions greatly influence the response of nonlinear energy harvesters. Recently, simulations and experiments have verified that tristable energy harvesters have excellent energy harvesting performance and complex nonlinear characteristics, which are important in broadening their effective operating frequency range. The response mechanism of the asymmetric tristable energy harvester is more complex than its symmetric counterpart. Owing to the complexities of the former, streamlined design methodologies and methods remain scarce. To facilitate future innovation and research on asymmetric tristable energy harvesters, this paper examines their nonlinear characteristics and energy harvesting performance. The Melnikov method is employed to predict the occurrence of chaotic motion, which is verified by numerical simulations. The chaotic dynamical system theory provides a simplified analytical framework that provides deeper insights into the performance of the asymmetric tristable energy harvester. Compared with its symmetric counterpart, the asymmetric tristable energy harvester can more easily jump into the interwell motion and output the higher voltage under low-level excitations.

Theoretical Study on Widening Bandwidth of Piezoelectric Vibration Energy Harvester with Nonlinear Characteristics.

In order to make a piezoelectric vibration energy harvester collect more energy on a broader frequency range, nonlinearity is introduced into the system, allowing the harvester to produce multiple steady states and deflecting the frequency response curve. However, the harvester can easily maintain intra-well motion rather than inter-well motion, which seriously affects its efficiency. The aim of this paper is to analyze how to take full advantage of the nonlinear characteristics to widen the bandwidth of the piezoelectric vibration energy harvester and obtain more energy. The influence of the inter-permanent magnet torque on the bending of the piezoelectric cantilever beam is considered in the theoretical modeling. The approximate analytical solutions of the primary and 1/3 subharmonic resonance of the harvester are obtained by using the complex dynamic frequency (CDF) method so as to compare the energy acquisition effect of the primary resonance and subharmonic resonance, determine the generation conditions of subharmonic resonance, and analyze the effect of primary resonance and subharmonic resonance on broadening the bandwidth of the harvester under different external excitations. The results show that the torque significantly affects the equilibrium point and piezoelectric output of the harvester. The effective frequency band of the bistable nonlinear energy harvester is 270% wider than that of the linear harvester, and the 1/3 subharmonic resonance broadens the band another 92% so that the energy harvester can obtain more than 0.1 mW in the frequency range of 18 Hz. Therefore, it is necessary to consider the influence of torque when modeling. The introduction of nonlinearity can broaden the frequency band of the harvester when it is in primary resonance, and the subharmonic resonance can make the harvester obtain more energy in the global frequency range.

Analysis of Dynamic Characteristics of Tristable Piezoelectric Energy Harvester Based on the Modified Model

Taking into account the gravitational potential energy of the piezoelectric energy harvester, the size effect, and the rotary inertia of tip magnet, a more accurate distributed parametric electromechanical coupling equation of tristable cantilever piezoelectric energy harvester is established by using the generalized Hamilton variational principle. The effects of magnet spacing, the mass of tip magnet, the thickness ratio of piezoelectric layer and substrate, and the load resistance and piezoelectric material on the performance of piezoelectric energy capture system are studied by using multiscale method. The results show that the potential well depth can be changed by reasonably adjusting the magnet spacing, so as to improve the energy capture efficiency of the system. Increasing the mass of tip magnet can enhance the output power and frequency bandwidth of the interwell motion. When the thickness of the piezoelectric beam remains unchanged, the optimal load impedance of the system increases along with the increase of thickness ratio of piezoelectric layer and substrate. Compared with the traditional model, which neglects the system gravitational potential energy, the eccentricity, and the rotary inertia of the tip magnet, the calculation results of the frequency bandwidth and the peak power of the modified model have significantly increased.

Nonlinear broadband piezoelectric vibration energy harvesting enhanced by inter-well modulation

Broadening the working bandwidth of piezoelectric energy harvesting devices is of great importance owing to the wide frequency spectrum of environmental vibrations. Efforts, including stiffness nonlinearity and multimodal optimization, have been proposed to improve harvesters’ responses towards the broadband frequency region. This paper designs a spring-based bistable energy harvester (SBEH) and proposes its two configurations (SBEH-sup and SBEHsub) to achieve high working efficiency under different excitation levels through inter-well modulation. The nonlinear force produced by the compressed springs generates nonlinear dynamical responses, and thus broadens the effective bandwidth of the SBEH. Compared to the SBEH-sup configuration, the SBEH-sub configuration further utilizes magnetic force to dynamically alter the potential energy threshold in the nonlinear system, which contributes to the SBEH maintaining inter-well motion and enhancing the working performance under lower intensity excitation. The working mechanisms of the SBEH-sup configuration and the SBEH-sub configuration are revealed by derived mathematical models. The feasibility of the SBEH with two proposed configurations is verified by experimental tests. Compared with its linear counterpart, the significant advantages in the SBEH-sup configuration show 673% increment in effective bandwidth and 179% increment in working efficiency under suprathreshold-level excitation. Compared with the SBEH-sup configuration, the SBEH-sub configuration further broadens the operating bandwidth by 838% and enhances the working efficiency by 269% under subthreshold-level excitation. This spring-based bistable energy harvester provides a new design philosophy for nonlinear energy harvesters, its two configurations with inter-well modulation achieve satisfactory performance for scavenging energy from different-level vibrations.

A broadband magnetically coupled bistable energy harvester via parametric excitation

Owing to the excitation level of ambient vibrations, the wideband performance of multi-stable energy harvesters and parametrically excited energy harvesters is restricted. The bistable periodic interwell motion and parametric resonance initial threshold amplitude primarily depend on the base excitation level. In this paper, a wideband two-element piezoelectric energy harvester with both bistability and parametric resonance characteristics is presented (i.e. designed, theoretically tested, fabricated and experimentally tested) to tackle the issue of reducing the potential barrier and triggering the parametric threshold amplitude. This device is the first to utilise a directly excited element as an external oscillation source to trigger the large amplitude oscillation of a parametrically excited element through magnetic coupling effects; the periodic interwell motion revealed in the parametrically excited device infers its bistability feature; and a continuously effective operational bandwidth (10–17.3 Hz) is achieved for both elements, which infers the high-energy orbit motions. Theoretical modelling of the proposed device and the expression of the magnetic coupling effects are presented to predict the dynamics of the system, as well as verifying the experimental results. The effects of the base excitation level and the gap distance between magnets are also analysed to shed light on the flexibilities and limitations of the device.

A combined nonlinearity mechanism for potential well shaping of MEMS bi-stable energy harvester

This paper presents a combined nonlinearity mechanism for the enhanced capability in shaping double well potential energy of MEMS bi-stable energy harvester, which is critical for both wideband inter-well oscillation and high power output. In comparison with conventional magnetic-induced bi-stable energy harvester adopting linear mechanical support, mechanical nonlinearity is incorporated and cooperates with magnetic nonlinearity for effective potential well tuning. With specific control of this mechanical nonlinearity, system linear and nonlinear stiffness could be proportionally adjusted for the independent control of well-gap separating adjacent potential well. Moreover, higher restoring force governed by mechanical nonlinearity could be achieved for the counteraction of magnetic force within smaller deformation, bringing the effective narrowing of well-gap. Therefore, with the incorporation of mechanical nonlinearity, the well-gap could be independently adjusted within much wider range, while maintaining the corresponding barrier depth constant, which could contribute to the significant bandwidth extension of inter-well oscillation. The analysis result shows that at frequency-sweep excitation with acceleration of 1 g, the prototype with well-gap of 1.4 mm and barrier depth of 6 μJ achieves normalized power density of 36 mW cm−3 g−2 and wideband inter-well oscillation of 77 Hz, covering 85.6% of frequency range from 10 to 100 Hz. The test under random excitation confirms the role of the proposed mechanism in inducing effective potential well shaping for comprehensive performance enhancement of bi-stable energy harvester, and could be further applied to the recently proposed high-energy orbit sustaining strategy to achieve ultra-wide unique inter-well motion.

Nonlinear dynamics and parametric study of snap through electromagnetic vibration energy harvester using multi-term harmonic balance method

Abstract Vibration energy harvester (VEH) has proven to be a favorable potential technique to supply continuous energy from ambient vibrations and its performance is greatly influenced by the design of potential structures. A snap-through mechanism is used in an electromagnetic energy harvester to improve its effectiveness. It mainly comprises of three springs that are configured so that the potential energy of the system has two stable equilibrium points. In this work, a harmonically base excited snap-through electromagnetic vibration energy harvester is investigated by analytical and semi-analytical method. The approximate analytical outcomes are qualitatively and quantitatively supported by semi-analytical method using multi-term harmonic balance method (MHBM).The bifurcation diagram of response current shows that snap-through electromagnetic vibration energy harvesters exhibits periodic intrawell, interwell and chaotic motion when the system parameters are varied. The influence of system parameters on the response of snap-through electromagnetic vibration energy harvester are examined. Nonlinearity produced by the snap-through oscillator improves energy harvesting so that the snap-through electromagnetic energy harvester can outperform the linear energy harvester in the similar size under harmonic excitation. A fitness function was formulated and optimization of the selected parameters was done using genetic algorithm. The parametric optimization leads to a considerable improvement in the harvested current from the system.

Load Resistance Optimization of a Magnetically Coupled Two-Degree-of-Freedom Bistable Energy Harvester Considering Third-Harmonic Distortion in Forced Oscillation.

In this study, the external load resistance of a magnetically coupled two-degree-of-freedom bistable energy harvester (2-DOF MCBEH) was optimized to maximize the harvested power output, considering the third-harmonic distortion in forced response. First, the nonlinear dynamic analysis was performed to investigate the characteristics of the large-amplitude interwell motions of the 2-DOF MCBEH. From the analysis results, it was found that the third-harmonic distortion occurs in the interwell motion of the 2-DOF MCBEH system due to the nonlinear magnetic coupling between the beams. Thus, in this study, the third-harmonic distortion was considered in the optimization process of the external load resistance of the 2-DOF MCBEH, which is different from the process of conventional impedance matching techniques suitable for linear systems. The optimal load resistances were estimated for harmonic and swept-sine excitations by using the proposed method, and all the results of the power outputs were in excellent agreements with the numerically optimized results. Furthermore, the associated power outputs were compared with the power outputs obtained by using the conventional impedance matching technique. The results of the power outputs are discussed in terms of the improvement in energy harvesting performance.

Transition mechanism and dynamic behaviors of a multi-stable piezoelectric energy harvester with magnetic interaction

Multi-stable piezoelectric energy harvesters (MPEH) with magnetic interaction are more prone to oscillate into an inter-well motion at a lower excitation level to achieve high power generation than the bi-stable ones. However, the geometric nonlinearity induced by the large deformation of inter-well motion is ignored by most of the derived mathematic models, resulting in the transition mechanism and complicated dynamics of the MPEH are not well illustrated. This paper focuses on a MPEH configuration that is composed of a piezoelectric cantilever beam with a tip magnet and three external magnets. The magnetic interaction between the tip and external magnets is modeled as point dipole with the path integral approach, and the mathematic model of the MPEH is derived by taking into account the geometric nonlinearity of the beam. The transition mechanism from mono-stability to multi-stability is deeply investigated by means of equilibrium bifurcation, potential well diagrams and dynamic bifurcation, respectively. The complicated dynamic responses of the MPEH are then simulated by means of frequency sweeping method. A prototype is subsequently developed and the theoretical results are validated by experiments. The results show that experiments and simulations are in qualitative agreement. The MPEH has five transition modes from the mono-stability to the quad-stability and has three different potential-well shapes in quad-stable period state. The geometric nonlinearity of the cantilever beam introduces additional third-order and fifth-order nonlinear stiffness, which is conducive to generate inter-well motions and to broad frequency bandwidth of the MPEH, as well as to low the requirement of the excitation intensity that jumping from intra-well motion to inter-well motion.

Load Resistance Optimization of a Broadband Bistable Piezoelectric Energy Harvester for Primary Harmonic and Subharmonic Behaviors

In this study, optimization of the external load resistance of a piezoelectric bistable energy harvester was performed for primary harmonic (period-1T) and subharmonic (period-3T) interwell motions. The analytical expression of the optimal load resistance was derived, based on the spectral analyses of the interwell motions, and evaluated. The analytical results are in excellent agreement with the numerical ones. A parametric study shows that the optimal load resistance depended on the forcing frequency, but not the intensity of the ambient vibration. Additionally, it was found that the optimal resistance for the period-3T interwell motion tended to be approximately three times larger than that for the period-1T interwell motion, which means that the optimal resistance was directly affected by the oscillation frequency (or oscillation period) of the motion rather than the forcing frequency. For broadband energy harvesting applications, the subharmonic interwell motion is also useful, in addition to the primary harmonic interwell motion. In designing such piezoelectric bistable energy harvesters, the frequency dependency of the optimal load resistance should be considered properly depending on ambient vibrations.

Load Resistance Optimization of Bi-Stable Electromagnetic Energy Harvester Based on Harmonic Balance.

In this study, a semi-analytic approach to optimizing the external load resistance of a bi-stable electromagnetic energy harvester is presented based on the harmonic balance method. The harmonic balance analyses for the primary harmonic (period-1T) and two subharmonic (period-3T and 5T) interwell motions of the energy harvester are performed with the Fourier series solutions of the individual motions determined by spectral analyses. For each motion, an optimization problem for maximizing the output power of the energy harvester is formulated based on the harmonic balance solutions and then solved to estimate the optimal external load resistance. The results of a parametric study show that the optimal load resistance significantly depends on the inductive reactance and internal resistance of a solenoid coil––the higher the oscillation frequency of an interwell motion (or the larger the inductance of the coil) is, the larger the optimal load resistance. In particular, when the frequency of the ambient vibration source is relatively high, the non-linear dynamic characteristics of an interwell motion should be considered in the optimization process of the electromagnetic energy harvester. Compared with conventional resistance-matching techniques, the proposed semi-analytic approach could provide a more accurate estimation of the external load resistance.

Enhanced modeling of nonlinear restoring force in multi-stable energy harvesters

It is acknowledged that traditional linear piezoelectric cantilever energy harvesters are not effective to extract ambient energy due to the narrow resonant bandwidth and low efficiency. A popular strategy to overcome these disadvantages is applying external magnets to realize multi-stable energy harvesters. Under the external excitation, the inter-well motion occurs between different potential wells in multi-stable energy harvesters, so as to bring out larger displacement and higher voltage output than intra-well motion. The performance of multi-stable energy harvesters has a strong relationship with the nonlinear restoring force, but there is lack of models for accurately describing nonlinear restoring force. This paper proposes a new enhanced model of the nonlinear restoring force to improve the calculating accuracy by taking the influence of rotational angle and axial displacement into consideration. The rotational magnetic charge is presented to calculate the magnetic force exerted by the external magnets. Then, the trajectory method of cantilever beams is employed to reduce the calculation error caused by axial displacement during oscillation. The accuracy of the proposed model for magnetic force calculation along horizontal and vertical directions is verified by the results of numerical simulation. Additionally, experimental results of the nonlinear restoring force for multi-stable energy harvesters show a good agreement with theoretical results. The influence of system parameters on equilibrium points, nonlinear restoring force and dynamic responses of multi-stable energy harvesters has been investigated based on the proposed model.

A parametric analysis of the nonlinear dynamics of bistable vibration-based piezoelectric energy harvesters

Piezoelectric materials exhibit electromechanical coupling properties and have been gained importance over the last few decades due to their broad range of applications. Vibration-based energy harvesting systems have been proposed using the direct piezoelectric effect by converting mechanical into electrical energy. Although the great relevance of these systems, performance enhancement strategies are essential to improve the applicability of these system and have been studied substantially. This work addresses a numerical investigation of the influence of cubic polynomial nonlinearities in energy harvesting systems considering a bistable structure subjected to harmonic excitation. A deep parametric analysis is carried out employing nonlinear dynamics tools. Results show complex dynamical behaviors associated with the trigger of inter-well motion. Electrical power output and efficiency are monitored in order to evaluate the configurations associated with best system performances.