Issue 35

T. Sadowski et alii, Frattura ed Integrità Strutturale, 35 (2016) 492-499; DOI: 10.3221/IGF-ESIS.35.55 498 The high temperature causes that material properties R m as well as R 0,2 significantly decrease (Fig. 8) and plastic deformations in the material are much higher. Together with the increase of cycle numbers the plastic deformations grow and lead to the damage increase due to material fatigue. 40 50 60 70 80 90 100 110 120 130 Figure 12: Crack path. C ONCLUSIONS he major conclusions resulting from the above investigation can be formulated as follows: 1. All investigations were conducted in conditions considerably exceeding the parameters of blade working conditions. There still exists large reserve of durability of the blade in case of unexpected resonance or higher temperatures. For example, with the increase of rotator speed by 19% it is also necessary to raise the temperature of combustion gases by about 25% in order to initiate damage resulting from fatigue. 2. Occurrence of pitting on the blade surface due to corrosion or erosion caused by solid particles impacts requires constant monitoring of service life of the engine. The use of protective layer TBC can therefore extend the working time of the blade. It will be the subject of next investigations. 3. The use of protective the TBC layer has significant influence on the level of temperature of thermal shocks which occur in the engine during starting of the airplane. Application of the TBC allows for decreasing of the working temperature about 15% in reference to the blade without covering, after the same time of heating. It leads to considerable increase of the turbine blade safety due to reduction or elimination of plastic deformations and excluding plastic damage initiation and further growth. 4. The limiting parameters for the blade without TBC layer causing damage initiation and further growth as a results of the thermo – mechanical fatigue were established. For the rotator speed equal to 35800 rot/min the fatigue of material damage can take place for the temperature higher than 1000 0 C. In the working temperature equal to 900 0 C the failure due to thermo-mechanical fatigue can appear for the rotator speed of about 42970 rot/min. A CKNOWLEDGEMENT 1) Financial support of Structural Funds in the Operational Programme - Innovative Economy (IE OP) financed from the European Regional Development Fund - Project "Modern material technologies in aerospace industry", No POIG.0101.02-00-015/08 is gratefully acknowledged (RT-10 : Modern barrier covers on critical engine parts). 2) This work was financially supported by Ministry of Science and Higher Education within the statutory research number S/20/2015. R EFERENCES [1] Weroński, A., Thermal fatigue of metals (in Polish), WNT, Warszawa, (1983). T