Coastal regions, particularly in the southeastern United States, are consistently confronted with the ongoing threat of hurricane-induced damage to their buildings and civil infrastructure. Consequently, there is a pressing need to concentrate efforts on the evaluation and prediction of structural integrity and reliability in such environments. This is paramount for minimizing losses and enhancing public safety in the face of these challenging climatic conditions. Current structural health monitoring systems are typically customized for specific buildings, rendering them excessively expensive and impractical for residential structures. This research presents a comprehensive feasibility study for an economical yet efficient system designed to anticipate potential failures and assess the safety and reliability of residential buildings. The proposed system employs integrated piezoelectric sensors to monitor alterations in the structural and material characteristics of building components. The collected sensor data may be transmitted to a mobile application using a WiFi or Bluetooth system. To validate the functionality of this innovative system, a proof-of-concept prototype building was constructed utilizing additive manufacturing, featuring integrated piezoelectric sensors. The system underwent experimental testing under base excitation at various frequencies, revealing distinct output variations at different locations. This substantiates the feasibility of employing integrated piezoelectric sensors within structural buildings for effective structural health monitoring. The collected data will serve as a foundational resource for accurately estimating the building’s reliability in anticipation of future hurricane events.
Increasing the bandwidth of the vibration energy harvesters is one of the research emphases to maximize the energy harvested from the ambient. Here we design a Two-Degree of Freedom Vibro-impact Triboelectric energy harvester with a double-impact configuration, which combines multi-modality and piecewise linearity to improve the harvesting bandwidth of triboelectric energy harvesters. The harvester structure consists of primary and secondary cantilever beams with two integrated energy harvesters. The two beams are designed to operate at close natural frequencies, and under the effect of the impact, triboelectricity is generated, and the bandwidths of the resonators are combined to create a wide bandwidth. The double impact system is investigated numerically to examine the structure’s dynamic behavior at different excitation levels, separation distance, and surface charge density to extract an optimal parameter for achieving a wide combined bandwidth. The system demonstrates the capability of connecting multi-modality and piecewise linearity to significantly broaden the triboelectric energy harvester’s bandwidth.
The efficiency of the energy harvesters can be improved by increasing the harvester bandwidth. Towards this, we presented a Two-Degree of Freedom (2-DOF) Vibro-impact Triboelectric Energy Harvester by combining multi-modality and piecewise linearity of two close resonant frequencies. The harvester structure consists of a primary cantilever beam attached to a secondary cantilever beam through a tip mass. The secondary beam is attached in the opposite direction to the primary beam. The bottom surface of the secondary beam acts as an upper electrode of a triboelectric generator. A lower electrode with bonded Polydimethylsiloxane (PDMS) insulator is attached at some gap separation distance underneath the upper electrode to create an impact structure. When the system vibrates, an impact between the triboelectric layers generates an alternating electrical signal. A 2-DOF system with lumped parameter theoretical model was developed to extract the governing equations. The structure’s dynamic behavior at different excitation levels, separation distance, and surface charge density were investigated theoretically. As a result, we achieved a wider bandwidth for the designed energy harvester. The proposed harvester demonstrated an increase in the maximum output voltage by more than 300 percent, and 250 percent increase in the bandwidth, by changing the excitation level from 0.1g to 0.7g. The result of this study can pave the way for an efficient energy harvester that can scavenge ambient vibrations over a wide range of excitation frequencies.
Recently, vibrational energy harvesting has been considered a promising alternative to batteries for powering microsystems for large wireless sensor network applications. However, ambient vibrations are below 100 Hz, while most machines and equipment operate relatively at high frequencies (more than 70 Hz). Herein, we propose a theoretical study to harvest energy from high frequencies using a frequency-down bistable piezoelectric energy harvester mechanism. We investigate the energy harvesting benefit in the down-conversion of a high-frequency signal to a low-frequency signal utilizing magnetic coupling. A high-frequency driving beam triggers a low-frequency generating beam. We use a spring-mass-damper equivalent model to understand the operation mechanism of the proposed piezoelectric vibration energy harvester. Based on the theoretical model, the static and dynamic effect of magnetic nonlinearity on the performance of the proposed piezoelectric vibration energy harvester is numerically analyzed. The targeted applications are the down-conversion and the filtering of high frequencies and mass sensing, particularly the harvester’s behavior for mass sensing applications.
Energy from mechanical vibrations is prevalent in the ambient, which can be effectively harvested using triboelectric generators. However, the efficiency of the harvesters is limited by the narrow bandwidth. Herein, we propose combining Vibro-impact and magnetic nonlinearity for Polydimethylsiloxane-based triboelectric energy harvesters to extend the operation bandwidth and enhance the efficiency of the traditional triboelectric harvesters. Our harvester design consists of a cantilever beam with a tip magnet facing another fixed magnet at the same polarity, inducing a nonlinear magnetic repulsive force. The lower surface of the tip magnet acts as an upper electrode of a triboelectric harvester, while the lower electrode with attached Polydimethylsiloxane (PDMS) insulator. Under the effect of base excitation, the system can vibrate in monostable or bistable oscillations by varying the distance between the two magnets, causing an impact on the triboelectric electrodes, and an alternative electrical signal is generated at a wide range of frequencies. The harvester’s static and dynamic behaviors are investigated theoretically and experimentally validated at different separation distances between the two magnets. We achieved higher bandwidth by combining Vibro-impact with magnetic nonlinearity, and triboelectric energy harvesters show promising applications for future wireless sensor networks at wider operation frequency bandwidth.
Total Hip Replacement (THR) involves a conventional medical implant where many interacting factors could cause patient dissatisfaction, sometimes leading to lengthy and risky procedures based on guesses. Energy harvesting from natural human motion is being investigated to create a reliable source that will power smart implants and monitor performance simultaneously without any replacement or exchanges. A novel design of Triboelectric Energy Harvester (TEH) is proposed to retrofit a TEH to the THR implant, making it a smart implant. A custom femoral head was designed to incorporate grooves onto the THR femoral head, maximizing energy production without increasing the overall size. The TEH consists of two Titanium layers separated by a PDMS insulator. The Finite Element Analysis shows that the mechanical spring maintains the contact separation motion of the TEH. A theoretical model of a single-degree-of-freedom system with piecewise functions is proposed based on the FEA results to model the contact and release modes and voltage estimations. This study can open the door and lead to new research in load monitoring for total hip replacement.
Triboelectric energy harvesters continue to show promising and efficient performance in transferring mechanical energy into electrical energy, making them a prime candidate for biomedical implants. Total Knee Replacement (TKR) is a widely used surgery worldwide and, more so, in the United States. In this paper, triboelectric performance in biomedical applications is evaluated, especially in TKR. Performance of two new configurations of triboelectric energy harvester in TKR is compared as self-powered implanted sensors for loads measurements. The first configuration is a full knee harvester, covering the whole area of the tibial tray. The second configuration consists of two harvesters at the lateral and medial locations. Both configurations to be fit in the knee implant. The two designs’ performance was experimentally evaluated when subjected to an axial cyclic load applied by a dynamic tester at different frequencies. Also, the lateral and medial generators were tested for load imbalance detection producing promising results. Moreover, this study’s findings would contribute to the improvement of TKR by transforming them from passive to smart TKR using these implants, which will lead to better health monitoring.
One major challenge to the usability of implants in total knee replacement (TKR) surgery is the limited of the postoperative knee joint loading data; therefore, the ability to continuously monitor these loads is an attractive concept. Integrating an energy harvester to scavenge the energy from human motion enables this monitoring. Recently, Triboelectric Generators have gained attention for energy harvesting because of their flexibility and easy fabrication processes. We investigate a triboelectric energy harvester for load sensing of TKR under simulated gait loading. The performance of triboelectric harvester prototypes was measured under simulated gait loading using a VIVO joint motion simulator. During cyclical loading, triboelectric harvesters undergo a contact and separation mechanism, which led to a voltage potential being generated. The power output is related to the amount of compressive load and the frequency. Therefore, the output power can be used to estimate joint loading and can act as a load-sensing implant component. Aiming to include biocompatible materials, we evaluated the performance of titanium as the triboelectric layer and showed the output is higher compared to Aluminum.
KEYWORDS: Magnetism, Beam shaping, 3D modeling, Energy harvesting, Finite element methods, Energy conversion efficiency, Amplifiers, Transducers, Electromagnetism, Resonators
This paper describes the finite element modeling and experimental testing of a magnetic T-shaped piezoelectric energy harvester that activates the internal resonance phenomena to increase voltage output and frequency bandwidth. The harvester consists of two magnets and two coupled beams, a cantilever piezoelectric beam attached to a clamped-clamped beam. A finite-element model is used to obtain the global mode shapes and natural frequencies of the system. We controlled the distance between the two magnets to achieve a nonlinear phenomenon of internal resonance of the structure, where the 2:1 ratio is satisfied between the modal natural frequencies. The T-shaped structure is combined with the magnetic nonlinearity such that a large, distinct internal resonance can occur at much lower excitation levels compared to a T-shaped structure without magnetic nonlinearity. Presented experimental results validate the benefits of the T-shaped structure nonlinearity when combined with a magnetic nonlinearity to achieve higher bandwidth and large responses, which can improve the energy conversion efficiency of the vibration energy harvester.
KEYWORDS: Energy harvesting, Magnetism, Polymers, Resonators, Composites, Smart materials, Bistability, Magnetic sensors, Wind energy, Solar energy, Transducers, Complex systems
Ambient energy in the form of mechanical kinetic energy is mostly considered waste energy. The process of scavenging and storing such energy is known as energy harvesting. Energy harvesting from mechanical vibration is performed using resonant energy harvesters (EH) with two major goals: enhancing the power scavenged at low frequency sources of vibrations, and increasing the efficiency of scavenging energy by increasing the bandwidth near the resonant frequency. Toward such goals, we propose a piezoelectric EH of a composite cantilever beam with a tip magnet facing another magnet at a distance. The composite cantilever consists of a piezoelectric bimorph with an extended polymer material. With the effect of the nonlinearity of the magnetic force, higher amplitude can be achieved because of the generated bi-stability oscillations of the cantilever beam under harmonic excitation. The contribution of the this paper is to demonstrate lowering the achieved resonant frequency down to 17 Hz compared to 100 Hz for the piezoelectric bimorph beam without the extended polymer. Depending on the magnetic distance, the beam responses are divided to mono and bi-stable regions, for which we investigate static and dynamic behaviors. The dynamics of the system and the frequency and voltage responses of the beam are obtained using the shooting method.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.