LIMA, W. M.; http://lattes.cnpq.br/6476755567572293; LIMA, Walber Medeiros.
Resumo:
In this dissertation, the development of an experimental platform, containing a simply
supported flexible aluminum beam, strain-gauges and SMA wires as force actuators, to
analyze the behavior of the SMA wires of NiTi (Nickel-Titanium) and of NiTiCu (Nickel-
Titanium-Copper) and, in addition, to accomplish the deformation control in the beam.
In the platform for analysis of the behavior of wires are used strain-gauges, a LVDT
(Lineal Variable Differential Transducer) and a micro-thermocouple to measure respectively
the deformation and the deflexion in the beam , as well as the temperature in the SMA wires.
For the data acquisition, it developed a code in Visual Basic a spreadsheet to accomplish the
communication with the measurement instruments with interface GPIB (General Purpose
Interface Bus).
In the control platform the deformation control in the beam, the data acquisition and
control are implemented with an ADuC microcontroller based card. The system answer in
open-loop was used to identify the mathematical model of the system, using the technique of
direct tunning to find the appropriate controller. The PI controller have been used to control
the deformation in the beam for different types of reference signals, varying the frequencies
to be able to observe the bandwidth that the system answers. The microcontroller card is
connected to the PC running LabVIEW software to visualize the measurements in a graphic
user interface.
The analysis platform allowed to determine a no-lineal and lineal relationship, as well as
the appearance of a hysteresis in the behavior of the SMA wires. With the control platform,
it observed that the deformation in the beam can be controlled by a PI controller, obtaining
a deformation value through an electric voltage source that it makes to pass an electric
current in the SMA thread, accomplishing its heating for effect Joule.