Issue 33

M.Kurek et alii, Frattura ed Integrità Strutturale, 33 (2015) 302-308; DOI: 10.3221/IGF-ESIS.33.34 305 Figure 1 : Fatigue diagram for oscillatory bending and bilateral torsion for the 6082-T6 aluminum alloy (where  a ,  a are stress amplitudes generated by torsional moment and bending moment, respectively). Material Bending Torsion N fi σ a /τ a (N fi ) A  m  A  m  cycles PA6 (2017A) 21.87 -7.03 19.94 -6.87 2000000 1.696 GGG40 32.39 -10.95 35.48 -12.41 1000000 1.11 10HNAP 30.88* - 9.5* 25.28 - 8.2 2000000 1.874 PA4 (6082) 23.8 -8.0 21.4 - 7.7 2000000 1.68 30CrNiMo8 27.54 8.05 69.56 24.62 100000 1.5 CuZn40Pb2 19.99 5.86 45.3 17.17 1000000 0.92 Table 1 : Coefficients of regression equation for analysed materials. 0 ,45     . For each of the 46 angles calculated parameters B and K in accordance with the formulas (13) and (14). Fig. 2 presents B and K constants depending on the angle β for the PA4 aluminum alloy. , lg 10 eg a cal A m N    . 0 5 10 15 20 25 30 35 40 45 -40 -35 -30 -25 -20 -15 -10 -5 0 X: 13 Y: -2.935  , 0 B 0 5 10 15 20 25 30 35 40 45 0.35 0.4 0.45 0.5 0.55 X: 41 Y: 0.4393  , 0 K (a) (b) Figure 2 : The dependence of the parameter a) B, b) K from the angle β for aluminum alloy 6082 (PA4). 10 4 10 5 10 6 10 7 50 150 250 350 450 500 N f , cykle  a ,  a , MPa  a = 0  a = 0 log(N f )=23,8-8log(  a ) log(N f )=21,4-7,7log(  a )