Page 326 - Biaxial Multiaxial Fatigue and Fracture

3 10 EJ: LINO ET AL.

Fatigue tests were performed in a 250 kN Servo-Hydraulic MTS machine (see Fig. S), and
using the staircase method (DIN EN IS0 9964 [14]). The loading ratio CTM,~/CTM~ selected for
the tests was 0.1, and tests started with 50 YO of the aluminium alloy tensile strength. Figure 9
presents one pedal and some broken samples.

Fig. 8. Servo-hydraulic MTS machine for the fatigue tests.

Fig. 9. Brake pedal and broken fatigue aluminium samples.

To start the staircase fatigue test [ 16, 181, it was estimated that the fatigue limit was 50% of
the tensile strength. The number of levels used for each set of 20 samples was 7.
Tables 4 and 5 indicate the values employed in the test and the results obtained, respectively.
Surprisingly, the unacceptable samples only have a small decrease in the fatigue limit;