Abstract:The tensile plastic strain of material sampled from profiled areas under roller bending and pre-strained material was analyzed. The experimental data of high-cycle fatigue were approximated by a probabilistic Weibull cumulative distribution (P-S-N curve). The fatigue life prediction model was implemented for numerical simulations of roller bending in the LS-Dyna solver and experimental data. The cyclic behaviour of the material shows a decrease in the fatigue life distribution with increasing static failure levels. The fractographic analysis of the fracture surface shows an increased level of intergranular cracking for the tensile pre-strain as a result of the dislocation accumulation in the neighbourhood of grain boundaries. The estimation results of the proposed model show good correlation of probabilistic scatter bands (error below 10%).

Key words: 6063 aluminium alloy; pre-strain; high-cycle fatigue; P-S-N curve; Weibull distribution