Cyclic viscosity reacts more sharply to the properties of the material than the limit of fatigue, and does not stand in a direct connection with the limit of fatigue; For example, usually with increased limits of fatigue (in alloy steels), cyclic viscosity is reduced.
The increased value of cyclic viscosity is advisable in the presence of voltage concentration in the element, since it helps to cut the stress peak. Therefore, alloy steels, having a smaller cyclic viscosity, react more strongly during vibration work to form defects than ordinary steel.
In the process of vibration work, the width of the loop remains almost constant, and the loop of the foci of fatigue and the elaboration of the fatigue crack closed throughout the appearance; Before destruction, the loop opens. The decrees of attenuation and the temperature of the sample are completely altogether. In the voltage of the cycle voltage, the width of the loop has a sharp overlap at the limit of fatigue, fully corresponding to temperature changes, so that the limit of fatigue can be likened to the limitarity of cyclic viscosity. The loop opening and increasing temperature in the last period of destruction of the core of the element, not damaged by a fatigue crack in the last period. The same law is very clearly manifested in the diagram of changes in the deflection of console samples (on the installation of a heeller) subject to testing for fatigue. This diagram has three areas – a certain increase in deflections, the constancy of deflection, depending on the size of the cargo attached to the model, and occupying the main fraction of the cycles, and the area of a significant increase in the deflections before destruction (fatigue current). The higher the limit of fatigue (with various types of cycles) and lower cyclic viscosity, the loop is installed after a larger number of cycles, during which (with open loops), deformations increase. According to some reports, a closed loop is installed on a curve, which is a continuation of the casing curve in the so -called natural Baushinger diagram.
