Linear and Non-Linear Analysis of SMA Based Duffing Oscillators

Recently, there have been many applications involving shape memory alloy (SMA) to actuate or control small to large vibration in the field of aerospace, automobile, building structures, bioengineering devices, etc. The application of SMA over a wide field is due to its ability to apply large force and displacement with low power. It is also found that SMA can regain its original state after going through the cycle of heating and cooling processes. During the process of loading, the internal temperature change due to phase transformation which causes energy dissipation. Due to its effective energy dissipation capabilities, it can respond to slow loading, fast loading, sudden loading, and time varying loading, respectively. However, to understand the effective control of vibration of a structure, it is important to investigate its linear and nonlinear behavior under the different loadings conditions. In this thesis, we plan to investigate the linear and nonlinear response of SMA controlled cantiliver beam (spring) under different loading conditions. To do the study, we first present the thermomechanical constitutive model of SMA with a single degree of freedom system. Subsequently, we solve the equation to obtain linear frequency and nonlinear frequency response using the method of harmonic balance. To analyze the in uence of cubic and quadratic nonlinearity, we modify the governing equation and discuss the results based on the method of harmonic balance. Additionally, we also describe the method of averaging to obtain the nonlinear frequency response of SMA based oscillators. The analysis of results lead to various ways of controlling the nature and extent of nonlinear response of SMA based oscillators. Such findings can be effectively used to control the external vibration of different systems

Theoretical Approaches in Non-Linear Dynamical Systems

From Preface: The 15th International Conference „Dynamical Systems - Theory and Applications” (DSTA 2019, 2-5 December, 2019, Lodz, Poland) gathered a numerous group of outstanding scientists and engineers who deal with widely understood problems of theoretical and applied dynamics. Organization of the conference would not have been possible without great effort of the staff of the Department of Automation, Biomechanics and Mechatronics of the Lodz University of Technology. The patronage over the conference has been taken by the Committee of Mechanics of the Polish Academy of Sciences and Ministry of Science and Higher Education of Poland. It is a great pleasure that our event was attended by over 180 researchers from 35 countries all over the world, who decided to share the results of their research and experience in different fields related to dynamical systems. This year, the DSTA Conference Proceedings were split into two volumes entitled „Theoretical Approaches in Non-Linear Dynamical Systems” and „Applicable Solutions in Non-Linear Dynamical Systems”. In addition, DSTA 2019 resulted in three volumes of Springer Proceedings in Mathematics and Statistics entitled „Control and Stability of Dynamical Systems”, „Mathematical and Numerical Approaches in Dynamical Systems” and „Dynamical Systems in Mechatronics and Life Sciences”. Also, many outstanding papers will be recommended to special issues of renowned scientific journals.Cover design: Kaźmierczak, MarekTechnical editor: Kaźmierczak, Mare

Étude numérique et analyse physique du morphing électroactif pour des ailes et des profils hydrodynamiques à des écoulements turbulents à nombre de Reynolds élevé

La présente thèse étudie par simulation numérique et analyse physique les effets du morphing électroactif pour le design des ailes du futur permettant de réduire l’impact environnemental et d’accroître l’efficacité du transport aérien. La thèse examine les effets du morphing électroactif hybride. Ce concept consiste en une association de diverses classes d’actionneurs électroactifs opérant à des échelles de temps et de longueur multiples, en accord avec la dynamique du spectre turbulent et dans un contexte de bio-inspiration concernant l’actionnement des ailes, ailerons et plumes de grands oiseaux prédateurs. Le morphing électroactif hybride crée des modifications de la turbulence à de multiples échelles dans les zones cisaillées et le sillage proche et crée l’augmentation des performances aérodynamiques par l’action de mécanismes de rétroaction. La thèse effectue des simulations numériques à nombre de Reynolds élevé autour de configurations de profils d’aile et d’ailes d’avion supercritiques dans les régimes du bas subsonique correspondant aux phases du décollage et atterrissage, et transsonique correspondant au vol de croisière. Toutes les simulations sont effectuées par le code NSMB (Navier Stokes MultiBlock), en utilisant des approches de modélisation de la turbulence efficaces, permettant de prédire en accord avec les expériences physiques, le développement d’instabilités et de structures cohérentes gouvernant la dynamique des écoulements. Dans ce contexte, l’approche « Organized Eddy Simulation » (OES) a été employée et améliorée par des concepts de cascade inverse utilisant de la réinjection de la turbulence dans les zones fortement cisaillées. Cette méthode, basée sur un forçage stochastique des équations de transport turbulent a été étendue dans la présente thèse aux trois dimensions et ses bénéfices ont été quantifiés concernant l’évaluation des efforts aérodynamiques et le développement d’instabilités fluide. Les avantages de cette approche, qui a été introduite par ailleurs au sein de la « Detached Eddy Simulation », ont été étudiés concernant la prédiction du tremblement en régime transsonique et de l’interaction choc-couche limite. Les régimes du bas subsonique concernent les écoulements autour de profils et d’ailes de type A320 en configurations statiques et en morphing et sont étudiés en utilisant l’approche de modélisation OES également. Le morphing de la région proche du bord de fuite à l’aide de faibles déformations et de vibrations de fréquences dans le rang de 100-400 Hz a été étudié en synergie avec des résultats expérimentaux du projet Européen H2020 N° 723402 SMS : « Smart Moprhing and Sensing for Aeronautical configurations ». A l’aide d’une étude paramétrique détaillée, il a été mis en évidence que des combinaisons optimales de fréquence-amplitude de ces actionnements fournissent une augmentation drastique de la finesse aérodynamique. Ces effets ont été obtenus à l’aide de manipulation de la dynamique des interfaces « Turbulent - Non Turbulent » (TNT) et des interactions avec les interfaces « Turbulent- Turbulent » (TT). De plus, cette thèse a développé un modèle structural efficace permettant le contrôle de forme par des Alliages à Mémoire de Forme (AMF). Ces actionneurs permettent d’obtenir de grandes déformations à de basses fréquences en appliquant une grande cambrure de l’aile pour augmenter la portance et pour adapter la forme de l’aile aux différentes sollicitations aérodynamiques. La présente thèse propose un modèle efficace pour obtenir des formes-ciblées de configurations aérodynamiques utilisant des AMF embarqués. Un nouvel algorithme robuste a été développé et validé pour prédire la réponse non-linéaire de l’interaction AMF-structure. Cet algorithme a été couplé avec une méthode de prédiction de la structure et des paramètres opérationnels optimaux pour le design, fournissant ainsi des architectures de morphing plus performantes et réduisant l’impact environnementa

Electrostatic Micro-Tweezers

This dissertation presents a novel electrostatic micro-tweezers designed to manipulate particles with diameters in the range of 5-14 μm. The tweezers consist of two grip-arms mounted to an electrostatically actuated initially curved micro-beam. The tweezers offer further control, via electrostatic actuation, to increase the pressure on larger objects and to grasp smaller objects. It can be operated in two modes. The first is a traditional quasi-static mode where DC voltage commands the tweezers along a trajectory to approach, hold and release micro-objects. It exploits nonlinear phenomena in electrostatic curved beams, namely snap-through, snap-back and static pull-in and the bifurcations underlying them. The second mode uses a harmonic voltage signal to release, probe and/or interact with the objects held by the tweezers in order to perform function such as cells lysis and characterization. It exploits additional electrostatic MEMS phenomena including dynamic pull-in as well as the orbits and attractors realized under harmonic excitation. Euler-Bernoulli beam theory is utilized to derive the tweezers governing equation of motion taking into account the arm rotary inertia, the electrostatic fringing field and the nonlinear squeeze-film damping. A reduced-order model (ROM) is developed utilizing two, three and five straight beam mode shapes in a Galerkin expansion. The adequacy of the ROM in representing the tweezers response was investigated by comparing its static and modal response to that of a 2D finite element model (FEM). Simulation results show small differences between the ROM and the FEM static models in the vicinity of snap-through and negligible differences elsewhere. The results also show the ability of the tweezers to manipulate micro-particles and to smoothly compress and hold objects over a voltage range extending from the snap-back voltage (89.01 V) to the pull-in voltage (136.44 V). Characterization of the curved micro-beam show the feasibility of using it as a platform for the tweezers. Evidence of the static snap-through, primary resonance and the superharmonic resonances of orders two and three are observed. The results also show the co-existence of three stable orbits around one stable equilibrium under excitation waveforms with a voltage less than the snap-back voltage. Three branches of orbits are identified as a one branch of small orbits within a narrow potential well and two branches of medium-sized and large orbits within a wider potential well. The transition between those branches results in a characteristic of double-peak frequency-response curve. We also report evidence of a bubble structure along the medium sized branch consisting of a cascade of period-doubling bifurcations and a cascade of reverse period-doubling bifurcations. Experimental evidence of a chaotic attractor developing within this structure is reported. Odd-periodic windows also appear within the attractor including period-three (P-3), period- five (P-5) and period-six (P-6) windows. The chaotic attractor terminates in a cascade of reverse period-doubling bifurcations as it approaches a P-1 orbit

SOLID-SHELL FINITE ELEMENT MODELS FOR EXPLICIT SIMULATIONS OF CRACK PROPAGATION IN THIN STRUCTURES

Crack propagation in thin shell structures due to cutting is conveniently simulated using explicit finite element approaches, in view of the high nonlinearity of the problem. Solidshell elements are usually preferred for the discretization in the presence of complex material behavior and degradation phenomena such as delamination, since they allow for a correct representation of the thickness geometry. However, in solid-shell elements the small thickness leads to a very high maximum eigenfrequency, which imply very small stable time-steps. A new selective mass scaling technique is proposed to increase the time-step size without affecting accuracy. New ”directional” cohesive interface elements are used in conjunction with selective mass scaling to account for the interaction with a sharp blade in cutting processes of thin ductile shells

Magnetic Hybrid-Materials

Externally tunable properties allow for new applications of suspensions of micro- and nanoparticles in sensors and actuators in technical and medical applications. By means of easy to generate and control magnetic fields, fluids inside of matrices are studied. This monnograph delivers the latest insigths into multi-scale modelling, manufacturing and application of those magnetic hybrid materials

Proceedings of the ECCOMAS Thematic Conference on Multibody Dynamics 2015

This volume contains the full papers accepted for presentation at the ECCOMAS Thematic Conference on Multibody Dynamics 2015 held in the Barcelona School of Industrial Engineering, Universitat Politècnica de Catalunya, on June 29 - July 2, 2015. The ECCOMAS Thematic Conference on Multibody Dynamics is an international meeting held once every two years in a European country. Continuing the very successful series of past conferences that have been organized in Lisbon (2003), Madrid (2005), Milan (2007), Warsaw (2009), Brussels (2011) and Zagreb (2013); this edition will once again serve as a meeting point for the international researchers, scientists and experts from academia, research laboratories and industry working in the area of multibody dynamics. Applications are related to many fields of contemporary engineering, such as vehicle and railway systems, aeronautical and space vehicles, robotic manipulators, mechatronic and autonomous systems, smart structures, biomechanical systems and nanotechnologies. The topics of the conference include, but are not restricted to: ● Formulations and Numerical Methods ● Efficient Methods and Real-Time Applications ● Flexible Multibody Dynamics ● Contact Dynamics and Constraints ● Multiphysics and Coupled Problems ● Control and Optimization ● Software Development and Computer Technology ● Aerospace and Maritime Applications ● Biomechanics ● Railroad Vehicle Dynamics ● Road Vehicle Dynamics ● Robotics ● Benchmark ProblemsPostprint (published version

Magnetic Hybrid-Materials

Externally tunable properties allow for new applications of suspensions of micro- and nanoparticles in sensors and actuators in technical and medical applications. By means of easy to generate and control magnetic fields, fluids inside of matrices are studied. This monnograph delivers the latest insigths into multi-scale modelling, manufacturing and application of those magnetic hybrid materials

Proceedings of the 2018 Canadian Society for Mechanical Engineering (CSME) International Congress

Published proceedings of the 2018 Canadian Society for Mechanical Engineering (CSME) International Congress, hosted by York University, 27-30 May 2018