Issue 35

T. Sadowski et alii, Frattura ed Integrità Strutturale, 35 (2016) 492-499; DOI: 10.3221/IGF-ESIS.35.55 496 400 500 600 700 800 900 1000 1100 0 200 400 600 800 1000 Temperature [C] Rm, R0,2 [MPa] Rm R0,2 Figure 8: Mechanical properties of the casting heat-resistant alloy with nickel matrix . The used numerical model of the turbine blades core material incorporates internal ductile damage, when a critical value of plastic deformations is reached. The fracture energy criterion was taken into account for description of cracks propagation. The TBC layer was made of zirconia partially stabilized by yttria (ZrO 2 /7%Y 2 O 3 ) with properties specified in [5,6]. N UMERICAL RESULTS ig. 9 presents the temperature distribution of the blades without and with the TBC after the same period of time starting from the beginning of the engine ignition. One can notice, that the thin TBC layer with thickness 0.3mm very effectively prevents the negative influence of highly active exhaust gas. The heat outflow from working piece of the blade proceeded to the rotor, which was cooled by the air from a compressor. The maximum temperature of combustion gases was equal to 1300 0 C and was about 160% higher than the real operation temperature in the air-engine. Blade without TBC Blade with TBC Figure 9: Distributions of the temperature in the turbine blade. Curves presented in Fig. 10 show dependence between quantity of damaged elements related to the number of the whole model and the quantity of the thermo – mechanical loading cycles. With steady rotator speed equal to 35800 rot/min and maximum amplitudes of temperature 1000 0 C as well as 1300 0 C the damage was initiated after 60 and 30 cycles. Below the value of 1000 0 C the blade could work infinitely long without any visible damage. The total separation of the blade into F