Piezo-electromechanical smart materials with distributed arrays of piezoelectric transducers: Current and upcoming applications

This review paper intends to gather and organize a series of works which discuss the possibility of exploiting the mechanical properties of distributed arrays of piezoelectric transducers. The concept can be described as follows: on every structural member one can uniformly distribute an array of piezoelectric transducers whose electric terminals are to be connected to a suitably optimized electric waveguide. If the aim of such a modification is identified to be the suppression of mechanical vibrations then the optimal electric waveguide is identified to be the 'electric analog' of the considered structural member. The obtained electromechanical systems were called PEM (PiezoElectroMechanical) structures. The authors especially focus on the role played by Lagrange methods in the design of these analog circuits and in the study of PEM structures and we suggest some possible research developments in the conception of new devices, in their study and in their technological application. Other potential uses of PEMs, such as Structural Health Monitoring and Energy Harvesting, are described as well. PEM structures can be regarded as a particular kind of smart materials, i.e. materials especially designed and engineered to show a specific andwell-defined response to external excitations: for this reason, the authors try to find connection between PEM beams and plates and some micromorphic materials whose properties as carriers of waves have been studied recently. Finally, this paper aims to establish some links among some concepts which are used in different cultural groups, as smart structure, metamaterial and functional structural modifications, showing how appropriate would be to avoid the use of different names for similar concepts. © 2015 - IOS Press and the authors

Optimization for finite element modeling of electronic components under dynamic loaDing

Usage of electronic components in the U.S. ARMY applications is becoming more challenging due to their usage in harsh environments. Experimental verification of these components is expensive and it can yield information about specific locations only. This research outlines the finite element modeling methodology for these electronic components that are subjected to high acceleration loads that occur over extremely short time such as impact, gun firing and blast events. Due to their miniature size these finite element models are computationally expensive. An optimization engine was presented to have an efficient analysis procedure that provides a combination of accuracy, computational speed and modeling simplicity. This research also involves experimental testing of the electronic components mounted on the circuit boards. Testing was conducted at different strain levels in order to study the behavior of boards. Finite element models were developed for these tests and compared with experimental results

Photonic simulation of entanglement growth and engineering after a spin chain quench

The time evolution of quantum many-body systems is one of the most important processes for benchmarking quantum simulators. The most curious feature of such dynamics is the growth of quantum entanglement to an amount proportional to the system size (volume law) even when interactions are local. This phenomenon has great ramifications for fundamental aspects, while its optimisation clearly has an impact on technology (e.g., for on-chip quantum networking). Here we use an integrated photonic chip with a circuit-based approach to simulate the dynamics of a spin chain and maximise the entanglement generation. The resulting entanglement is certified by constructing a second chip, which measures the entanglement between multiple distant pairs of simulated spins, as well as the block entanglement entropy. This is the first photonic simulation and optimisation of the extensive growth of entanglement in a spin chain, and opens up the use of photonic circuits for optimising quantum devices

Proceedings of the YIC 2021 - VI ECCOMAS Young Investigators Conference

The 6th ECCOMAS Young Investigators Conference YIC2021 will take place from July 7th through 9th, 2021 at Universitat Politècnica de València, Spain. The main objective is to bring together in a relaxed environment young students, researchers and professors from all areas related with computational science and engineering, as in the previous YIC conferences series organized under the auspices of the European Community on Computational Methods in Applied Sciences (ECCOMAS). Participation of senior scientists sharing their knowledge and experience is thus critical for this event.YIC 2021 is organized at Universitat Politécnica de València by the Sociedad Española de Métodos Numéricos en Ingeniería (SEMNI) and the Sociedad Española de Matemática Aplicada (SEMA). It is promoted by the ECCOMAS.The main goal of the YIC 2021 conference is to provide a forum for presenting and discussing the current state-of-the-art achievements on Computational Methods and Applied Sciences,including theoretical models, numerical methods, algorithmic strategies and challenging engineering applications.Nadal Soriano, E.; Rodrigo Cardiel, C.; Martínez Casas, J. (2022). Proceedings of the YIC 2021 - VI ECCOMAS Young Investigators Conference. Editorial Universitat Politècnica de València. https://doi.org/10.4995/YIC2021.2021.15320EDITORIA

Experimental investigations of the Mach-effect for breakthrough space propulsion

This research was conducted within the framework of the SpaceDrive project funded by the German Aerospace Center to develop propellantless propulsion for interstellar travel. The experiments attempted to measure mass fluctuations predicted by the Mach-effect theory derived from General Relativity and observed through torsion balance measurements by Woodward (2012). The combination of such mass fluctuations with synchronized actuation promises propellantless thrust with a significantly better thrust-to-power ratio than photon sails. Thus, experiments using different electromechanical devices including the piezoelectric Mach-effect thruster as tested by Woodward et al. (2012) were pursued on sensitive thrust balances. The tests were automated, performed in vacuum and included proper electromagnetic shielding, calibrations, and different dummy tests. To obtain appropriate driving conditions for maximum thrust, characterization of the experimental devices involved spectrometry, vibrometry, finite element analysis, and circuit modeling. Driving modes consisted of sweeps, resonance tracking, fixed frequency, and mixed signals. The driving voltage, frequency, stack pre-tension, mounting, and thruster orientation were also varied. Lastly, different amplifier electronics were tested as well, including Woodward’s original equipment. Experiments on the double-pendulum and torsion balances with a resolution of under 10 nN and an accuracy of 88.1 % revealed the presence of force peaks with a maximum amplitude of 100 nN and a drift of up to 500 nN. The forces mainly consisted of switching transients whose signs depended on the device’s orientation. These force transients were also observed in the zero-thrust configurations. No additional thrust was observed above the balance drift, regardless of the driving conditions or devices tested. In addition, finite element and vibrometry analysis revealed that the vibration from the actuator was transmitted to the balance beam. Moreover, simulations using a simple spring-mass model showed that the slower transient effects observed can be reproduced using small amplitude, high-frequency vibrations. Hence, the forces observed can be explained by vibrational artifacts rather than the predicted Mach-effect thrust. Then, centrifugal balance experiments measured the mass of a device subjected to rotation and energy fluctuations, with a precision of up to 10 µg and a high time resolution. The measurements relied on piezoelectric- and strain gauges. Their calibration methods presented limitations in the frequency range of interest, resulting in discrepancies of up to 500 %. However, the tests conducted with capacitive and inductive test devices yielded experimental artifacts about three orders of magnitude below the mass fluctuations of several milligrams predicted by the Mach-effect theory. Although the piezoelectric devices presented more artifacts due to nonlinearity and electromagnetic interaction, all rotation experiments did not show the expected dependence on the rotation frequency. In summary, the search for low thrust and small mass fluctuations consisted of challenging experiments that led to the development of innovative and sensitive instruments, while requiring a careful consideration of experimental artifacts. The results analysis led to the rejection of mass fluctuations and thrusts claimed by Woodward’s Mach-effect theory and experiments. The quest for breakthrough space propulsion must thus continue a different theoretical or experimental path.:List of Figures List of Tables List of Abbreviations List of Variables and Symbols 1. Introduction 1.1 Research Motivation 1.2 Objectives 1.3 Content Overview 1.4 Team Work 2. Literature Review 2.1 Fundamentals of Space Propulsion 2.2 Mach’s Principle 2.3 Woodward’s Mach-effect Theory 2.3.1 Derivation of the Mass Fluctuation Equation 2.3.2 Design of a Mass Fluctuation Thruster 2.4 Woodward-type Experiments 2.5 Force and Transient Mass Measurements 3. Electromechanical Characterization 3.1 Piezoelectric Actuators 3.1.1 Basic Properties 3.1.2 Actuator Design 3.1.3 Mach-effect Thruster Devices 3.1.4 Magnetostrictive Actuator 3.1.5 Numerical Analysis of MET Behavior 3.1.6 Vibrometry Analysis 3.1.7 Impedance Spectroscopy 3.1.8 Circuit Modeling 3.1.9 Predictions 3.2 Electronics 3.2.1 Description 3.2.2 Characterization 3.3 Torsion Balances 3.3.1 Description 3.3.2 Characterization 3.3.3 Simulation 3.4 Double-pendulum Balance 3.4.1 Description 3.4.2 Characterization 3.5 Laboratory Setup 3.5.1 Vacuum Chambers 3.5.2 Software and Test Setup 4. Thrust Balance Experiments 4.1 Torsion Balance I Test Results 4.1.1 Dummy Tests 4.1.2 CU18A 4.1.3 MET03 4.1.4 MET04 4.1.5 Discussion 4.2 Torsion Balance II Test Results 4.2.1 Dummy Tests 4.2.2 MET05 4.2.3 Beam Vibration 4.2.4 Discussion 4.3 Double-pendulum Balance Test Results 4.3.1 Dummy Tests 4.3.2 MET03 4.3.3 Discussion 5. Centrifugal Balance Experiments 5.1 Centrifugal Balance 5.1.1 Description 5.1.2 Centrifugal Devices 5.1.3 Predictions 5.2 Transducer Calibration 5.2.1 Quasi-Static Calibration I 5.2.2 Quasi-Static Calibration II 5.2.3 Dynamic Calibration 5.3 Centrifugal Balance Test Results 5.3.1 Characterization 5.3.2 CD01 5.3.3 CD02 5.3.4 CD03 5.3.5 CD04 5.3.6 CD05 5.4 Discussion & Error Analysis 6 Conclusions 6.1 Research Summary 6.2 Further Research Appendix A Appendix B Bibliograph

Parallel computations and control of adaptive structures

The equations of motion for structures with adaptive elements for vibration control are presented for parallel computations to be used as a software package for real-time control of flexible space structures. A brief introduction of the state-of-the-art parallel computational capability is also presented. Time marching strategies are developed for an effective use of massive parallel mapping, partitioning, and the necessary arithmetic operations. An example is offered for the simulation of control-structure interaction on a parallel computer and the impact of the approach presented for applications in other disciplines than aerospace industry is assessed

A local field emission study of partially aligned carbon-nanotubes by AFM probe

We report on the application of Atomic Force Microscopy (AFM) for studying the Field Emission (FE) properties of a dense array of long and vertically quasi-aligned multi-walled carbon nanotubes grown by catalytic Chemical Vapor Deposition on a silicon substrate. The use of nanometric probes enables local field emission measurements allowing investigation of effects non detectable with a conventional parallel plate setup, where the emission current is averaged on a large sample area. The micrometric inter-electrode distance let achieve high electric fields with a modest voltage source. Those features allowed us to characterize field emission for macroscopic electric fields up to 250 V/$\mu$m and attain current densities larger than 10$^5$ A/cm$^2$. FE behaviour is analyzed in the framework of the Fowler-Nordheim theory. A field enhancement factor $\gamma \approx$ 40-50 and a turn-on field $E_{turn-on} \sim$15 V/$\mu$m at an inter-electrode distance of 1 $\mu$m are estimated. Current saturation observed at high voltages in the I-V characteristics is explained in terms of a series resistance of the order of M$\Omega$. Additional effects as electrical conditioning, CNT degradation, response to laser irradiation and time stability are investigated and discussed

Experimental and Numerical Analysis of PZT Bonded Laminated Composite Plate

In this work, the bending and vibration behaviour of the PZT bonded laminated composite plate is investigated. The structural responses computed using a simulation model with the help of ANSYS and compared with experimental results. In this analysis, the maximum central deflections and the natural frequencies of PZT bonded laminated composite plate for close and open circuit conditions have been computed numerically with the help of present simulation model and compared with the result of the published literature. Further, the efficacy of the simulation model has been checked for different geometrical parameters (thickness ratio and support conditions) and discussed in detail