Torsional fatigue test
For the torsional tests, a specific machine (AnalĂ³gica, Belo Horizonte,
Brazil) was used that measured the torque and controlled the rotation
angle through the connection to a computer, collecting all the data. The
tests performed was based on the ISO 3630-1 (1992)
Torque was measured through the force exerted on a small load cell
attached to a lever arm on the long axis of torsion. Ten instruments
from each system were used for this step. Before testing, the
instrument’s handles were removed at the point where they were attached
to the torsion shaft. The 3 mm ends of the instruments were attached to
a chuck connected to an electric motor. The electric motor was operated
clockwise at a speed of 2 rpm.