Issue 33

A. Carpinteri et alii, Frattura ed Integrità Strutturale, 33 (2015) 376-381; DOI: 10.3221/IGF-ESIS.33.41 380 It can be observed that better results are derived by applying the new formulation, which has also the capability to be more computationally-efficient than that based on the time domain. T cal , [cycles] T exp , [cycles] 10 5 10 4 10 2 10 6 10 7 10 2 10 3 10 4 10 5 10 6  =   8 10 3 10 7 Time Frequency T cal , [cycles] T exp , [cycles] 10 5 10 4 10 2 10 6 10 7 10 2 10 3 10 4 10 5 10 6  =   4 10 3 10 7 Time Frequency Figure 4 : Comparison between experimental and theoretical fatigue lives ( / 8    ), the latter determined by employing: the frequency domain criterion here proposed (see solid symbols) and the time domain criterion reported in Ref. [4] (see hollow symbols). Figure 5 : Comparison between experimental and theoretical fatigue lives ( / 4    ), the latter determined by employing: the frequency domain criterion here proposed (see solid symbols) and the time domain criterion reported in Ref. [4] (see hollow symbols). C ONCLUSIONS frequency domain criterion is presented to evaluate the fatigue life of a smooth metallic structure subjected to multiaxial random loading. The critical plane orientation is determined through the PSD matrix of the stress tensor. Then, an equivalent PSD function is defined and processed through a damage model in order to determine the fatigue life of the structural component being examined. The comparison between theoretical and experimental results appears to be quite satisfactory for the cases analysed. R EFERENCES [1] Lagoda, T., Macha, E., Estimated and experimental fatigue lives of 30CrNiMo8 steel under in-phase and out-of-phase combined bending and torsion with variable amplitudes, Fatigue Fract. Engng Mater. Struct., 17 (1994) 1307-1318. [2] Wang, C.H., Brown, M.W., Life prediction techniques for variable amplitude multiaxial fatigue - Part 1: Theories, J. Eng. Mater. Technol., 118 (1996) 367-370. [3] Lagoda, T., Macha, E., Nieslony, A., Muller, A., Comparison of calculation and experimental fatigue lives of some chosen cast irons under combined tension and torsion, in: M. Fuentes et al. (Eds.), Proceedings of ECF13 - Application and Challenges, Elsevier, San Sebastian, Spain, (2000) 6 pages. [4] Carpinteri, A., Spagnoli, A., Vantadori, S., A multiaxial fatigue criterion for random loading, Fatigue Fract. Engng Mater. Struct., 26 (2003) 515-522. [5] Carpinteri, A., Spagnoli, A., Vantadori, S., Fatigue life estimation under multiaxial random loading using a critical plane-based criterion, in: Proceedings of the 2nd Int. Conference on Material and Component Performance under Variable Amplitude Loading, Darmstadt, Germany, (2009) 475-484. A