Shape memory alloys (SMAs) are widely used in technological applications due to their unique properties. Many investigations have been done to improve the behavior of the hybrid structures by employing SMAs both in passive and active manner. Also SMA based actuators have gained lots of attention due to their high mechanical properties along with high compactness. This work begins with a discussion about unique features of the shape memory alloys (Shape memory effect, pseudoelasticity), presents their principle of operation and the applications. Also addresses the limitations and design challenges faced by the SMA developers. In the second part, functional characterization of Cu-Zn-Al thin sheets to be embedded in a hybrid structure, suitable for passive suppression of flexural vibration of beams and shells, is studied. Analytical method for evaluating the energy dissipation of the thin sheets with different shapes and patterns is developed and is followed by a shape optimization based on genetic algorithm. Eventually different configurations of the hybrid beam structure are proposed and compared in the term of damping capacity.
Leghe a memoria di forma (SMA) sono ampiamente utilizzati in applicazioni tecnologiche a causa delle loro proprietà uniche. Molti studi sono stati fatti per migliorare il comportamento delle strutture ibride impiegando SMA sia in modo passivo e attivo. Attuatori anche sulla SMA hanno guadagnato un sacco di attenzione per le loro elevate proprietà meccaniche con elevata compattezza. Questo lavoro inizia con una discussione su caratteristiche uniche delle leghe a memoria di forma (effetto memoria di forma, Effetto pseudoelastico), presenta il loro principio di funzionamento e le applicazioni. Affronta anche i limiti e le sfide progettuali affrontate dagli sviluppatori SMA Nella seconda parte, caratterizzazione funzionale di fogli sottili Cu-Zn-Al per essere incorporato in una struttura ibrida, adatto per la soppressione della vibrazione flessionale passiva di travi e gusci, studiata. Metodo analitico per valutare la dissipazione di energia dei fogli sottili con differenti forme e modelli è sviluppato ed è seguito da ottimizzazione forma del foglio sottile basata su un algoritmo genetico. Alla fine diverse configurazioni della struttura ibrida sono proposti e confrontati in termini di capacità di smorzamento.
Applied aspects of the shape memory alloys : passive damping of hybrid structures
HAGHDOUST, POUYA
2014/2015
Abstract
Shape memory alloys (SMAs) are widely used in technological applications due to their unique properties. Many investigations have been done to improve the behavior of the hybrid structures by employing SMAs both in passive and active manner. Also SMA based actuators have gained lots of attention due to their high mechanical properties along with high compactness. This work begins with a discussion about unique features of the shape memory alloys (Shape memory effect, pseudoelasticity), presents their principle of operation and the applications. Also addresses the limitations and design challenges faced by the SMA developers. In the second part, functional characterization of Cu-Zn-Al thin sheets to be embedded in a hybrid structure, suitable for passive suppression of flexural vibration of beams and shells, is studied. Analytical method for evaluating the energy dissipation of the thin sheets with different shapes and patterns is developed and is followed by a shape optimization based on genetic algorithm. Eventually different configurations of the hybrid beam structure are proposed and compared in the term of damping capacity.File | Dimensione | Formato | |
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https://hdl.handle.net/10589/104762