On the Effect of the Loading Cycle Shape on the Development of Brittle Fracture Process

The durability for a trapezoidal axial loading cycle can be estimated using a model of scale-structural fatigue for a sinusoidal shape. For materials with frequency-dependent fatigue properties, the evaluation of the rectangular cycle (except for the instantaneous impulses) by the sinusoidal cycle goes into a safety margin. At the zero load, the absence of a rectangular cycle, the maximum stress, on average, is 5\(\%\) lower (the durability is 2.5 times less) at the same number of cycles than that for a sinusoidal cycle and the loading period. The results are confirmed by experimental data on high- and very high fatigue of metals and alloys.