Energy harvesting technologies for structural health monitoring of airplane components - a review

With the aim of increasing the efficiency of maintenance and fuel usage in airplanes, structural health monitoring (SHM) of critical composite structures is increasingly expected and required. The optimized usage of this concept is subject of intensive work in the framework of the EU COST Action CA18203 "Optimising Design for Inspection" (ODIN). In this context, a thorough review of a broad range of energy harvesting (EH) technologies to be potentially used as power sources for the acoustic emission and guided wave propagation sensors of the considered SHM systems, as well as for the respective data elaboration and wireless communication modules, is provided in this work. EH devices based on the usage of kinetic energy, thermal gradients, solar radiation, airflow, and other viable energy sources, proposed so far in the literature, are thus described with a critical review of the respective specific power levels, of their potential placement on airplanes, as well as the consequently necessary power management architectures. The guidelines provided for the selection of the most appropriate EH and power management technologies create the preconditions to develop a new class of autonomous sensor nodes for the in-process, non-destructive SHM of airplane components.The work of S. Zelenika, P. Gljušcic, E. Kamenar and Ž. Vrcan is partly enabled by using the equipment funded via the EU European Regional Development Fund (ERDF) project no. RC.2.2.06-0001: “Research Infrastructure for Campus-based Laboratories at the University of Rijeka (RISK)” and partly supported by the University of Rijeka, Croatia, project uniri-tehnic-18-32 „Advanced mechatronics devices for smart technological solutions“. Z. Hadas, P. Tofel and O. Ševecek acknowledge the support provided via the Czech Science Foundation project GA19-17457S „Manufacturing and analysis of flexible piezoelectric layers for smart engineering”. J. Hlinka, F. Ksica and O. Rubes gratefully acknowledge the financial support provided by the ESIF, EU Operational Programme Research, Development and Education within the research project Center of Advanced Aerospace Technology (Reg. No.: CZ.02.1.01/0.0/0.0/16_019/0000826) at the Faculty of Mechanical Engineering, Brno University of Technology. V. Pakrashi would like to acknowledge UCD Energy Institute, Marine and Renewable Energy Ireland (MaREI) centre Ireland, Strengthening Infrastructure Risk Assessment in the Atlantic Area (SIRMA) Grant No. EAPA\826/2018, EU INTERREG Atlantic Area and Aquaculture Operations with Reliable Flexible Shielding Technologies for Prevention of Infestation in Offshore and Coastal Areas (FLEXAQUA), MarTera Era-Net cofund PBA/BIO/18/02 projects. The work of J.P.B. Silva is partially supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UIDB/FIS/04650/2020. M. Mrlik gratefully acknowledges the support of the Ministry of Education, Youth and Sports of the Czech Republic-DKRVO (RP/CPS/2020/003

Energy Harvesting & Wing Morphing Design Using Piezoelectric Macro Fiber Composites

Energy harvesting from vibration sources was a very promising field of research throughout the last few decades among the engineers and scientist as considering the necessity of renewable/green energy for the welfare of mankind. Unused vibration energy exists in the surrounding or machineries was always tried to be utilized. Since then, by using piezoelectric transduction, researchers started to harvest the vibration energy. However, after the invention of piezo ceramics Macro Fiber Composites (MFC) by NASA, the research in this field augmented a lot due to its high efficiency to convert mechanical strain or vibration to useful electrical power and vice versa. Apart from energy harvesting researcher concentrated to utilize this harvested energy for daily life and hence application of this harvested energy for structural health monitoring inaugurated. Recent study showed that, the vibration energy harvested from the vehicles or aerospace (UAV) structure is good enough to power its onboard structural health monitoring unit though for feeding this power to any other onboard electrical system is still challenging due to low power generation along with its random production. Moreover, Macro Fiber Composites (MFC) can be used as an actuator to change the shape of aircraft wing to enhance aerodynamic performance and hence, application of MFC for wing morphing design has become popular throughout these years. The purpose of this research work is to depict the recent progress & development that took place in the field of energy harvesting & wing morphing research using macro fiber composites and combining the existing knowledge continue the work further, the future of this harvested energy, new design concept & upcoming challenges along with its possible solution. This work investigates the different configuration of macro fiber composites (MFC) for piezoelectric energy harvesting and its contribution for wing morphing design with enhanced aerodynamics. For the first part of this work, uniform MFC configuration was modeled and built up based on the Euler-Bernoulli beam theory. When the governing differential equations of the systems were derived, by applying the harmonic base excitation, coupled vibration response and the voltage response were obtained. The prediction of the mathematical model was at first verified by unimorph MFC with a brass substrate obtained from the state of art and then validation was justified by MFC unimorph along with three different substrate materials (copper, zinc alloy & galvanized steel) and thickness for the first time in this type of research. Computational & analytical solution revealed that, among these three substrates and for same thickness, maximum peak power at resonance excitation was obtained for the copper substrate. For the second part of the study (i) computational analysis was performed and the output was compared with the real time data obtained from the wind tunnel experiment and the conclusion stood that, with the increment of the incoming flow velocity, the power output from the MFC increases with a thin aerofoil made of copper substrates and two MFC on its upper surface (ii) wing morphing design was performed for a NACA 0012 aerofoil for the first time where macro fiber composite actuators were used to change the top and bottom surfaces of the aerofoil with a view to recording the enhanced aerodynamics performance the designed morphing wing. CFD simulation results were compared with the wind tunnel testing data from the state of art for NACA 0014 for all identical parameters. The enhanced aerodynamics performance observed for designed wing morphing can be used for future concepts like maneuvering of the aircraft without the help of ailerons or for the purpose of active flow control over the aircraft wing

Vibration Energy Harvesting for Wireless Sensors

Kinetic energy harvesters are a viable means of supplying low-power autonomous electronic systems for the remote sensing of operations. In this Special Issue, through twelve diverse contributions, some of the contemporary challenges, solutions and insights around the outlined issues are captured describing a variety of energy harvesting sources, as well as the need to create numerical and experimental evidence based around them. The breadth and interdisciplinarity of the sector are clearly observed, providing the basis for the development of new sensors, methods of measurement, and importantly, for their potential applications in a wide range of technical sectors

Resonance frequency tuning in vibration-based energy harvesting systems

Energy harvesting technologies that rely on the conversion of ambient vibration into a usable form of energy have become the subject of significant research in recent years . The most common types of transduction methods are piezoelectric, electromagnetic and electrostatic. Among these three methods, piezoelectric convertors have been recognized to offer more benefits. They have presented a potential solution to the problem of power systems which have a short battery life and high maintenance costs. Battery replacement is more of a problem for Micro Electro Mechanical Systems (MEMS). For some applications, often it is not practical to replace the dead battery because they are not easily accessible. Therefore, the concept of low-power MEMS devices that are able to scavenge, or harvest energy from their operating environment have gained growing attention over recent years. In this thesis, an overview of energy harvesting technology based on different transduction methods is presented and discussed in detail. Most energy harvesters are designed to work at resonance frequency in order to obtain maximum output power, and they are usually manufactured to have resonance frequencies that match the frequencies of excitation. However, in some cases, there is a mismatch between the resonance and excitation frequencies due to manufacturing errors or changes in the working environment. Particularly, in MEMS devices due to the fabrication process such as mask alignment, deposition, photolithography, etching and drying, manufacturing tolerances are generally high and, in some cases, can be higher than ±10% of nominal values. Therefore, parameter uncertainty can significantly affect the performance of MEMS devices. To overcome this problem, a MEMS piezoelectric harvester with electrostatically adjustable resonance frequency is proposed. The main aim is to control the resonance frequency of the piezoelectric harvester with the application of a DC voltage to the electrostatic system in order to maximize the harvested power. Based on the voltage applied to the electrostatic system, the resonance frequency of the harvester can be adjusted through hardening and softening mechanisms. The problem addressed in this thesis is non-linear due to electrostatic forces. Moreover, by considering uncertainty in the model parameters; we are dealing with a dynamic problem with the effects of both nonlinearities and uncertainties which has not received significant attention in the literature. In this study, for the first time to our knowledge, the shooting method in conjunction with Monte Carlo Simulation has been used to solve a nonlinear uncertain problem. In addition, due to the similarity between electrostatic and electromagnetic forces, an experimental set-up based on the nonlinear electromagnetic forces has been designed to show the concept of the proposed model in macro scales. The experimental results have been verified numerically and it has been shown that the proposed model has great potential in practical applications

Development Of A Dynamic Force Sensor

Sensors are employed for various applications in different industries. Chief of these applications is in the process and equipment monitoring. Most sensors used in the equipment monitoring are mostly after-market devices. This research answered the question of how can we include the condition monitoring of equipment into the design phase of the equipment. This research developed a dynamic force sensor using a PolyVinyliDene Fluoride (PVDF) film. The piezoelectric film attached to a fixed-fixed substrate which serves to support film and the properties of which the sensor equations were based. The sensor was tested in the laboratory by subjecting it to harmonic and random excitations of different magnitude and frequencies.The measured force as obtained from the sensor is compared to the corresponding excitation force in plots. The results obtained show that the sensor is accurate with an error of about 7% for an excitation with a frequency lesser than the first natural frequency of the substrate of the sensor. This result shows that dynamic sensors using piezoelectric materials can be designed and adapted to any application with the selection of the right substrate and boundary conditions

The Effect of Noise on the Response of a Vertical Cantilever Beam Energy Harvester

An energy harvesting concept has been proposed comprising a piezoelectric patch on a vertical cantilever beam with a tip mass. The cantilever beam is excited in the transverse direction at its base. This device is highly nonlinear with two potential wells for large tip masses, when the beam is buckled. For the pre-buckled case considered here, the stiffness is low and hence the displacement response is large, leading to multiple solutions to harmonic excitation that are exploited in the harvesting device. To maximise the energy harvested in systems with multiple solutions the higher amplitude response should be preferred. This paper investigates the amplitude of random noise excitation where the harvester is unable to sustain the high amplitude solution, and at some point will jump to the low amplitude solution. The investigation is performed on a validated model of the harvester and the effect is demonstrated experimentally

Semi-Passive Control Strategy using Piezoceramic Patches in Non Linear Commutation Architecture for Structural-Acoustic Smart Systems

The demands for novel smart damping materials can be summarized in: external power source not required for operation; device not needing to be tuned to a specific frequency; device operation not affected by changes in modal frequency; device suppressing vibration over a number of modes, weight and size minimized; self-contained unit device. This thesis focuses on these points and it shows that the dilemma between active and passive vibration control may be solved with a new approach, implementing a semipassive technique without penalties in terms of robustness and performance. Connecting a shunt circuit to a piezoelectric transducer leads to a simple and low cost vibration controller that is able to efficiently suppress unwanted structural vibrations: this is a way to fulfil the abovementioned demands. The objective of this work is to develop and validate by an experimental campaign a computational tool integrated with finite element Nastran software. An original 4-channel switched shunt control system has been realized using a tachometer device. The control system has been tested first of all on a simple cantilevered beam attaining a max vibrations reduction of 16.2 dB for the first bending mode. Further reference test article consisted of a 10 ply fibreglass laminate plate. A multimodal control has applied within a band range of 700Hz including the first seven modes. A maximum reduction of 16 dB has been found. Further numerical and experimental tests have been planned to extend the ability of the SSC to produce structural-borne sound reduction in acoustic rigid cavities for fluid-structure interaction problems. Numerical sound power radiation of an aluminium plate, controlled by synchronized switch system, compared with the experimental acoustic energy detected in acoustic room, has been planned in the ongoing activities

Functional modelling and prototyping of electronic integrated kinetic energy harvesters

The aim of developing infinite-life autonomous wireless electronics, powered by the energy of the surrounding environment, drives the research efforts in the field of Energy Harvesting. Electromagnetic and piezoelectric techniques are deemed to be the most attractive technologies for vibrational devices. In the thesis, both these technologies are investigated taking into account the entire energy conversion chain. In the context of the collaboration with the STMicroelectronics, the project of a self-powered Bluetooth step counter embedded in a training shoe has been carried out. A cylindrical device 27 × 16mm including the transducer, the interface circuit, the step-counter electronics and the protective shell, has been developed. Environmental energy extraction occurs exploiting the vibration of a permanent magnet in response to the impact of the shoe on the ground. A self-powered electrical interface performs maximum power transfer through optimal resistive load emulation and load decoupling. The device provides 360 μJ to the load, the 90% of the maximum recoverable energy. The energy requirement is four time less than the provided and the effectiveness of the proposed device is demonstrated also considering the foot-steps variability and the performance spread due to prototypes manufacturing. In the context of the collaboration with the G2Elab of Grenoble and STMicroelectronics, the project of a piezoelectric energy arvester has been carried out. With the aim of exploiting environmental vibrations, an uni-morph piezoelectric cantilever beam 60×25×0.5mm with a proof mass at the free-end has been designed. Numerical results show that electrical interfaces based on SECE and sSSHI techniques allows increasing performance up to the 125% and the 115% of that in case of STD interface. Due to the better performance in terms of harvested power and in terms of electric load decoupling, a self-powered SECE interface has been prototyped. In response to 2 m/s2 56,2 Hz sinusoidal input, experimental power recovery of 0.56mW is achieved demonstrating that the device is compliant with standard low-power electronics requirements