Kinetics of Fatigue Cracks under Cyclic Thermomechanical Loading

We describe some results of investigations into processes accompanying the growth of fatigue cracks under cyclic thermal and thermomechanical loading of structural elements made of heat-resistant alloys. On the basis of experimental data on the kinetics of damage of materials and the results of numerical simulation of their thermostressed state under loads reproducing service conditions, we analyze the conditions of propagation of fatigue cracks by using methods of fracture mechanics. In addition, we present recommendations concerning the evaluation of the endurance of structural elements like blades of gas-turbine units.     

Threshold Fatigue and Fretting Fatigue of Metals

General regularities in the variation of threshold stress intensity factors of metals are considered taking into account the influence of various factors. Justification is offered of the possibility of predicting fatigue limits for smooth specimens and specimens under conditions of fretting from the known characteristics of threshold stress intensity factors.     

Investigation into threshold stress intensity factors of materials under cyclic loading. Report 2. Prediction of fatigue limits and fatigue crack growth

On the basis of the results described in Report 1 [Probl. Prochn., No. 4, 5–16 (1998)], the author considers the possibility of using threshold stress intensity factors for the prediction of fatigue limits for titanium alloys by the formulas of linear elastic fracture mechanics and presents a substantiation of the method for predicting fatigue crack growth in structural elements. Institute for Problems of Strength, National Academy of Sciences of Ukraine, Kiev, Ukraine. Translated from Problemy Prochnosti, No. 5, pp. 5–11, September–October, 1998.