Fatigue life of 2017(A) aluminum alloy under proportional constant-amplitude bending with torsion in the energy approach

Fatigue life estimation for 2017A-T4 and 6082-T6 aluminium alloys subjected to bending-torsion with mean stress

“…During the experimental tests of the 2017(A)-T4 aluminium alloy [5,30,31], the effect of mean torsion stress on fatigue life was discovered. It must be noted that not all materials exhibit sensitivity to the mean torsion stress (e.g.…”

“…The new fatigue life estimation model is based on the criterion by Łagoda and Macha [4,7,[30][31][32]. The equivalent stress is a linear combination of normal and shear stresses and takes up the form: r a;eq ¼ Bðs gs;a þ s gs;m Þ þ Kðr g;a þ r g;m Þ; ð1Þ where r g,a -normal stress amplitude to the critical plane: r g;a ¼ r a cos a 2 þ s a sin 2a;…”

“…By analysing the stress condition for pure torsion and pure bending at constant-amplitude load conditions, a relationship is formulated which describes important factors for the combination of individual components. The coefficients can be presented as follows [30][31][32]:…”

“…The analysis involves the determination of the mean scatter E m described through the following relationship [30]: and the scatter coefficient is given by:…”

Analysis of the coefficient of normal stress effect in chosen multiaxial fatigue criteria

“…The present article is focused on the fatigue hypotheses that relate the reduction of multiaxial stress state with a plane in material with fixed orientation. This methodology has gather a lot of attention since its emerging in 1935 [13] due to its wide range of applicability and physical background [9,12,[14][15][16][17][18][19][20][21][22]. It is known as the critical plane approach.…”