Shape memory alloy (SMA) dampers have been used in several applications due to their high reliability without requiring a continual monitoring. Unfortunately, several aspects related to SMA dampers need to be further analyzed. In this paper, a cantilever beam with two SMA wires working in opposition is dynamically loaded by a harmonic displacement of the fixed end while the displacement of the free end is measured. The effect of prestraining the SMA wires and the thermal effect related to the phase transformation are the phenomena being studied for different loading frequencies. The harmonic displacement is generated by a conventional testing machine while the displacement is monitored by a laser measuring sensor.  Finite element simulations are also carried out and validated by the experiments. Prestrained SMA wires seem to provide better damping properties than unprestrained wires, but preliminary experiments point out a temporal evolution of the SMA properties that should be considered with cautiousness.