Fatigue pulsating stress

The specimen (R = 0, R = -1) demonstrate clear effects of corrosion fatigue (Fig. 6 and 7). There evidently is a good correlation of the fatigue strength reduction between the pulsating stress (R = 0, uniaxial) and the pulsating pressure loaded pipe specimen (Fig. 8). The reversed bending probes (R = -1, uniaxial) exhibit some deviations. 

The corrosion fatigue data from uniaxial tests can be transmitted to the notched pulsating pressure loaded components quantitatively or with additional safety. The uniaxial pulsating stress yields to be the stricter criterion. 

It should be remembered [39], that when evaluating data about fatigue limits in the pulsating or alternating mode which have been determined with inert fluid environments, that the corrosion fatigue may not only effect remarkably the reduction of the admissible stresses but also depends on the number of cycles (a continuous small slope of the Wohler-curve). 

Fig. 7.16 Fatigue of Ce-TZP ceramics in static and cyclic (pulsating and reversed bending) tests a Ce-TZP-11, b Ce-TZP-IV, and c Ce-TZP-V. The applied stress values are given as statie stress Ss and maximum stress Smax for R = 0.2 and stress amplitude Sa for R = —1 Cf and

Servohydraulic, electrohydraulic, or pulsator fatigue-testing machines do not use an eccentric wheel to apply cychc stress and strain. These machines use a computer-controlled hydraulic drive or... 

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