MELO, O. B.; http://lattes.cnpq.br/8576191813872275; MELO, Oscar Borges.
Résumé:
NiTi alloys belong to a class of metal alloys that Has emphasis in the technological
and scientific field, the Leagues with Shape Memory Alloy (SMA), because they
have unique functional characteristics of Effect Memory of Form (EMF) and
superelasticity (SE), in addition to high mechanical resistance. These properties of
EMF and SE have led to the development of active composites that can be used
for shape and vibration control, as well as the controlled variation of damping and
stiffness. One way to achieve this goal is by combining SMA properties with
polymer properties. Given this, this work present a study of the thermomechanical
behavior of an active composite obtained by the introduction of NiTi SMA ribbons
into a flexible polymeric matrix (silicone). Accordingly, there were produced two
active composite with difference in number of embedded ribbons NiTi (4 and 6
ribbons). Initially, the ribbons were obtained from cold rolling of NiTi superelastic
wires, with subsequent heat treatment. The NiTi wires and ribbons, the silicone
polymer matrix and the compounds systems formed were characterized by
Dynamic Mechanical Analysis (DMA) and Differential Scanning Calorimetry (DSC),
checking behavior of elastic modulus, damping factor and phase transformation
temperatures. An analysis of the interface between the SMA NiTi/matrix was also
carried out through pullout tests and Scanning Electron Microscopy (SEM). From
the results, it was verified the activation capacity of the Silicone-NiTi active
systems, which had positive change of elastic modulus and damping factor when
heated above transformation temperatures of the NiTi ribbons. The composite
systems containing higher volume fraction of NiTi SMA ribbons showed the best
values of these properties. It was also verified that the NiTi ribbons generated a
better interface between matrix and SMA in relation to the wires, opening up more
possibilities of applications.
