The Influence of TBC Aging on Crack Propagation Due to Foreign Object Impact

While a plane is maneuvering before take-off and landing, some solid particles (e.g. sand, dust, soil) may get into the engine with air. A vast majority of them are stopped by the compressor blades, but the smaller ones can get into a hot part of the engine and cause erosion. A pneumatic laboratory work station was built in order to investigate the impact of foreign object damage (FOD) particles with a diameter of 4 mm. Cylindrical samples with a diameter of 30 mm were used, each having a thermal barrier coating (TBC) deposited by the air plasma spray (APS) method with the application of yttria-stabilized zirconia (YSZ). Sample aging was performed for four ranges: 48, 89, 185, and 353 h at the temperature of 1000 °C. After aging, samples were subjected to impacts made with different energies. Various damage images were captured depending on the aging time and impact velocity. Numerical studies led to the determination of how the incidence angle of a foreign object and the blade temperature affected the number of elements that became damaged during impact. It was found that impacts perpendicular to the surface were the most dangerous, while heating the blade to the operating temperature resulted in a 27% decrease in the number of elements damaged during impact when compared to the cold blade.