Issue 47

S. Bressan et alii, Frattura ed Integrità Strutturale, 47 (2019) 126-140; DOI: 10.3221/IGF-ESIS.47.10 133 Bäumel-Seeger (B-S) for aluminum alloy   0.69 0.095 U f f σ  ε 1.67 (2 ) 0.35 2 2 N N E      (7) Bäumel-Seeger (B-S) for steel alloys:   0.58 0.087 U f f σ ε 1.50 (2 ) 0.59ψ 2 2 N N E      (8) where, ψ 1         U if E   (9) U U σ σ ψ 1.375 125   if     0.003 E E    (10) In order to evaluate the appropriate model to employ, fatigue data of smooth specimens under proportional and non- proportional loading have been synthesized with I-S parameter. The result of the correlation with USM, M-M and B-S for both 6061Al and 316LSS have been represented in Fig. 6 and Fig. 7. I-S parameter associated with B-S model describes accurately the behavior of aluminum. In case of steel, there is no consistent discrepancy between the proposed solutions. Therefore, B-S model has been selected for both materials. The Eq. (11) have been employed for 6061Al and Eq. (12) for 316LSS.   0.69 0.095 NP f f ε σ 1.67 (2 ) 0.35 2 2 E U N N      (11)   0.58 0.087 NP f f ε σ 1.50 (2 ) 0.59 2 2 E U N N      (12) Figure 6: Crack Correlation of fatigue life of 6061Al smooth specimens subjected to PP and CI loading paths by using I-S parameter associated with USM, M-M and B-S models.