Damage accumulation in specimens with edge crack in the prefracture region under nonstationary few-cycle loading

We present the results of experimental studies of strain and fracture of the aluminum alloy D16-T and titanium alloy VT5-1 under nonstationary few-cycle loading by a symmetric three-point bending and consider several loading conditions under which the load is gradually increased or decreased. The parameter determining the damage accumulation process is found. Special attention is paid to the distinction between the damage accumulation mechanisms in titanium and aluminum alloys. It is shown that, as a rule, the damage accumulation is of nonlinear character and significantly depends on the type of the stepwise variation in the load (increase or decrease). In experiments, we also succeeded in relating the characteristic point on the “deflection-force” graph in the case of single loading to a similar point on the graph constructed for a few-cycle loading, which permits predicting the structure survivability in a few-cycle loading from a single loading.