[en] Shape Memory Alloys (SMA) are metallic alloys with different thermomechanical properties compared to more conventional ones such as iron or aluminum alloys. This kind of alloys have two types of behaviours depending on the temperature. In a high temperature state, they are able to achieve large deformations (until 10 %) and recover them elastically, dissipating a lot of energy due to hysteresis that takes part in this process. This behaviour is known as superelastic effect. On the other hand there is the behaviour at low temperatures, due to a load application, apparently it produces a plastic deformation. But when increasing material temperature, it is able to recover its initial shape, behaving like a mechanical actuator. This behaviour is known as shape memory effect. In recent years, this type of alloys have been investigated and used in applications of different industries such as medical, automotive and aeronautics. The components developed using this type of actuators are able to vary their shape and stiffness, allowing the adaptation of the parts to different boundary conditions. To design such components have been developed a lot of numerical models to simulate the SMAs. It has been observed that few models take into account the nonlinear behaviour of the inner loops of material. Moreover, it has been found that fractional models have great ability to represent nonlinear behaviour using few parameters. In this thesis a fractional model to represent the nonlinear behaviour of the inner loops of the SMA have been developed. It has been also studied new ways to enable quicker simulations containing fractional operators. To do this, we have developed a methodology, where using the Proper Orthogonal Decomposition (POD), it is possible to precalculate some representative results and through interpolation of these results having faster solutions during simulations Finally it has been manufactured a carbon fibre reinforced composite, which has one SMA adhered to it. Through this experiment has analysed the ability of SMAs to reshape rigid structures both unloaded and loaded cases.

[eu] Forma Memoria duten Aleazioak (SMA Shape Memory Alloy ingelesez), ohiko aleazioekin (burdinazko edo aluminiozko aleazioak) alderatuta propietate termomekaniko desberdinak dituzte. SMAk bi portaera mota desberdin ditu tenperaturaren arabera. Tenperatura altua denean, elastikoki deformazioa handiak jasateko ( %10 arte) eta berreskuratzeko gaitasuna du materialak, energia asko disipatuz jasaten duen histeresi prozesuaren bitartez. Efektu hau, efektu superelastikoa bezala ezagutzen da. Bestalde, tenperatura baxuetako portaera dago, non itxuraz deformazio plastikoa jasan arren, materiala bere hasierako forma berreskuratzeko gai da tenperatura handitzerakoan. Ezaugarri hauek kontutan edukita, eragingailu mekaniko bezala erabiltzeko gaitasuna du SMAk. Efektu honi, forma memoria efektua bezala ezagutzen da. Azken urteotan, aleazio mota hau ikertzeaz gain, besteak beste, medikuntzan, automobilgintzan eta aeronautikan bezalako hainbat industrietan erabili da. Eragingailu mota hauen bitartez, SMAk dituzten konponenteen forma eta zurruntasuna aldatzea ahalbidetzen da, eta baldintza ezberdinen aurrean portaera ezberdina izan, beharrezkoak diren baldintzen arabera. SMAzko eragingailuak dituzten konponenteak garatzeko, modelo matematikoak garatzea beharrezkoa izan da denboran zehar. Garatu diren modeloen artean, ikusi da gutxi batzuk saiatu direla SMAtan ikusten den barne portaera modelizatzen. Hori horrela izanda, lan honetan modelo frakzionario bat proposatu da, SMAk duen barne portaera modelizatzeko gai delarik. Bestalde, operadore frakzionarietan oinarritutako modeloen simulazio azkarragoak lortzeko teknika berri bat garatu da. Horretarako, Proper Orthogonal Decomposition teknikan (POD) oinarritu da. Estrategia horretan, lehenik emaitzak aurrekalkulatzen dira eta ondoren emaitza horien interpolazioa erabiliz, emaitza berriak azkarrago kalkulatzea lortuz. Azkenik, karbono zuntzez indartutako epoxi erretxina plaka bati, SMAzko eragingailu bat itsatsi zaio. Komponente honek duen portaera aztertzeko intentzioz. Esperimentu honen bidez, SMAk egitura zurrun bat deformatzeko duen gaitasuna aztertu da.