Publications

2024

1. 

   Complex nonlinear dynamics of a multidirectional energy harvester with hybrid transduction

   Luã G. Costa, and Marcelo A. Savi

   Smart Materials and Structures, Oct 2024

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   Mechanical energy harvesting has increasing scientific and technological interests due to novel energetic challenges. A critical issue in classical cantilever-based mechanical energy harvesting systems is the lack of multidirectional energy conversion capabilities and, due to that, deviations from the excitation source can drastically reduce their performance. This limitation has led to the development of energy harvesters with attached pendula, serving as a direction coupling mechanism. Nevertheless, the pendulum structure itself can act as an energy absorber, drastically reducing the harvester performance in certain scenarios. In order to overcome this issue, a hybrid multidirectional pendulum-based energy harvester has been introduced by the authors. The hybrid transduction integrates a piezoelectric element to capture energy from the principal direction and an electromagnetic transducer to harness rotational energy from the pendulum. This paper presents an in-depth analysis of the hybrid multidirectional pendulum-based energy harvester using a nonlinear dynamics perspective to evaluate the energy harvesting performance. A reduced-order model is proposed to represent the essential characteristics of such systems. A parametric analysis using a nonlinear dynamics perspective is carried out to map the system dynamics and performance. The emergence of complex and rich dynamics is observed, including chaos and hyperchaos. Results reveal the most and least effective combinations of structural parameters in terms of energy conversion. Additionally, the dynamical responses and patterns associated with high performance are identified. These responses are often characterized by a blend of irregular complex behaviors, coupled with a mix of oscillatory and rotational patterns of motion, resulting in wider bandwidth systems.

   @article{Costa_multidirectional_EH_2,
     doi = {10.1088/1361-665X/ad7ca7},
     url = {https://dx.doi.org/10.1088/1361-665X/ad7ca7},
     year = {2024},
     month = oct,
     publisher = {IOP Publishing},
     volume = {33},
     number = {11},
     pages = {115007},
     author = {Costa, Luã G. and Savi, Marcelo A.},
     title = {Complex nonlinear dynamics of a multidirectional energy harvester with hybrid transduction},
     journal = {Smart Materials and Structures},
     dimensions = {true},
   }

2. 

   Pendulum-based hybrid system for multidirectional energy harvesting

   Luã G. Costa, and Marcelo A. Savi

   Nonlinear Dynamics, Jul 2024

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   This work presents a hybrid multidirectional mechanical energy harvester to enhance the performance of a cantilever-based harvester when subjected to multidirectional excitations. The multidirectional capabilities are achieved by employing a pendulum structure. Hybrid transduction is provided by combining a piezoelectric element and an electromagnetic transducer. A reduced-order model is presented based on the electromechanical Lagrangian formulation, and numerical analyses are performed to characterize the system behavior. A comparison based on energy harvesting performance is established among the novel multidirectional hybrid energy harvester (MHEH), the classical piezoelectric harvester (CPEH), and a multidirectional piezoelectric harvester (MPEH). Results show that the addition of the pendulum alone indeed provides multidirectional capabilities, but the overall performance can be reduced in some scenarios since it works as an energy absorber. This limitation is overcome by the hybridization strategy of the MHEH, by incorporating an electromagnetic transducer into the pendulum support. Overall, a significant improvement is achieved in all scenarios by utilizing the hybrid system.

   @article{Costa_multidirectional_EH_1,
     author = {Costa, Luã G. and Savi, Marcelo A.},
     title = {Pendulum-based hybrid system for multidirectional energy harvesting},
     journal = {Nonlinear Dynamics},
     year = {2024},
     month = jul,
     day = {27},
     issn = {1573-269X},
     doi = {10.1007/s11071-024-10040-z},
     url = {https://doi.org/10.1007/s11071-024-10040-z},
     dimensions = {true},
   }

3. 

   Multistability investigation for improved performance in a compact nonlinear energy harvester

   Luã G. Costa, Luciana L. S. Monteiro, and Marcelo A. Savi

   Journal of the Brazilian Society of Mechanical Sciences and Engineering, Mar 2024

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   Nature provides abundant ambient mechanical energy in the form of vibration, sound, wave, wind, and biomechanical energy, which can be harvested to power electronic systems. Smart materials-based mechanical energy harvesting systems have attracted increasing attention over the past two decades due to their advantageous characteristics such as high power density, simple design, and scalability. Nevertheless, the design of compact and high-performing systems remains a challenge. This work deals with the analysis of a compact multistable dual-beam nonlinear energy harvester that can be configured for different stability layouts. By using a nonlinear dynamics analysis framework and suitable tools, a qualitative performance characterization of the harvester for each stability configuration is conducted. Results show that multistable characteristics associated with a softer inner beam characteristic and higher excitation levels are related to complex phenomena and can greatly enhance performance.

   @article{Costa_compact_EH_2,
     author = {Costa, Luã G. and Monteiro, Luciana L. S. and Savi, Marcelo A.},
     title = {Multistability investigation for improved performance in a compact nonlinear energy harvester},
     journal = {Journal of the Brazilian Society of Mechanical Sciences and Engineering},
     year = {2024},
     month = mar,
     day = {14},
     volume = {46},
     number = {4},
     pages = {212},
     issn = {1806-3691},
     doi = {10.1007/s40430-024-04766-5},
     url = {https://doi.org/10.1007/s40430-024-04766-5},
     dimensions = {true},
   }

4. 

   Nonlinear dynamics of a compact and multistable mechanical energy harvester

   Luã G. Costa, and Marcelo A. Savi

   International Journal of Mechanical Sciences, Mar 2024

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   The use of smart materials as transducers in mechanical energy harvesting systems has gained significant attention in recent years. Despite the numerous proposed solutions in the literature, challenges still exist in terms of their implementation within limited spaces while maintaining optimal performance. This paper addresses these challenges through the concepts of compactness and space-efficient design, as well as the incorporation of nonlinear characteristics and additional degrees-of-freedom. A multistable dual beam nonlinear structure featuring two magnetic interactions and two piezoelectric transducers is presented. A reduced order model with 2-degrees-of-freedom is established based on the harvester structure in order to capture the essential qualitative characteristics of the system. Stability analysis demonstrates that the combination of two nonlinear magnetic interactions furnish unprecedented multistable characteristics to this type of harvester. A framework using a nonlinear dynamics perspective is established to analyze multistable systems based on energy harvesting purposes. Different dynamical and stability characteristics are determined by the differences in the system stiffness ratio. Parametric analyses are carried out classifying regions of high performance in the external excitation parameter space. These regions are associated with rich and complex dynamics. Finally, a comprehensive comparison is conducted between the proposed harvester and the classical bistable harvester, revealing improvements in performance across nearly all relevant conditions. These findings highlight the enhanced capabilities of the proposed harvester design, solidifying its potential of application in diverse energy harvesting scenarios.

   @article{Costa_compact_EH_1,
     title = {Nonlinear dynamics of a compact and multistable mechanical energy harvester},
     journal = {International Journal of Mechanical Sciences},
     volume = {262},
     pages = {108731},
     year = {2024},
     issn = {0020-7403},
     doi = {10.1016/j.ijmecsci.2023.108731},
     url = {https://www.sciencedirect.com/science/article/pii/S0020740323006331},
     author = {Costa, Luã G. and Savi, Marcelo A.},
     keywords = {Energy harvesting, Smart materials, Nonlinear dynamics, Chaos, Lyapunov exponents, Compact structures, Multistability, Multiple DoF structures},
     dimensions = {true},
   }

2021

1. 

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

   Luã G. Costa, Luciana L. S. Monteiro, Pedro M. C. L. Pacheco, and 1 more author

   Journal of Intelligent Material Systems and Structures, Mar 2021

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   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.

   @article{Costa_bistable_duffing,
     author = {Costa, Luã G. and Monteiro, Luciana L. S. and Pacheco, Pedro M. C. L. and Savi, Marcelo A.},
     title = {A parametric analysis of the nonlinear dynamics of bistable vibration-based piezoelectric energy harvesters},
     journal = {Journal of Intelligent Material Systems and Structures},
     volume = {32},
     number = {7},
     pages = {699-723},
     year = {2021},
     doi = {10.1177/1045389X20963188},
     url = {https://doi.org/10.1177/1045389X20963188},
     eprint = {https://doi.org/10.1177/1045389X20963188},
     dimensions = {true},
   }