12.80 Zhao (Journal of Pressure Vessel Technology, 2003) performed fatigue tests on a servohydraulic machine at a temperature of 240°C, under total strain control, using a symmetrical push–pull triangular wave mode. Six total strain amplitudes were used and seven randomly assigned specimens were tested at each total strain amplitude level. The resulting stress amplitude ( /MPa), Young’s modulus

(E/MPa), virtual stress amplitude (S/MPa), and fatigue life (N/cycles) were recorded, as shown in Table 12.25.

a Compare mean stress amplitude for the six strain ranges, using the 5% error rate.

b Compare mean Young’s modulus for the six strain ranges, using the 5% error rate.

c Compare mean virtual stress amplitude for the six strain ranges, using the 5% error rate.

d Compare mean fatigue life for the six strain ranges, using the 5% error rate.