Applied Engineering Letters

98-104

Authors: S.Miladinović, S.Veličković, M.Novaković

An experimental research is performed in this study in order to optimize the parameters of planetary driving gear. An orthogonal array and analysis of variance (ANOVA) are employed to investigate the factors: material, module and gear width on the safety coefficient for surface durability. Statistical methods of signal to noise ratio and ANOVA with 95% confidence were applied to quantify the effects of considered factors as well as to obtain the minimum value of the safety coefficient for surface durability. The results of this analysis have shown that the gear module with 80.953% has the greatest influence on the safety coefficient for surface durability of the gear. The second influential factor is a gear width with 18.392%. And the material with 0.615% has the least influence on the safety coefficient for surface durability of the gear. The regression analysis is also shown in the study.

111-114

Authors: L.Trško, O.Bokůvka, M.Jambor, F.Nový, A.Bača, Z.Florková

Article provides experimental results in the field of ultra-high cycle fatigue behaviour of C55 high grade carbon steel obtained at high-frequency loading (f ≈ 20 kHz, T = 20 ± 10 °C, R = -1). The results confirm a continuous decrease of fatigue lifetime beyond the conventional fatigue limit. Fatigue fracture surfaces were characterized by surface fatigue crack initiation in both high and ultra-high cycle region, what means that that influence of microstructure defects was not significant enough to cause the sub-surface crack initiation.