The Assessment of Elastic Follow-Up Effects on Cyclic Accumulation of Inelastic Strain Under Displacement-Control Loading

Abstract

Assessment of strain accumulation due to nonlinear events like creep, plasticity or ratcheting phenomenon has gained importance, as it causes an increase in creep and fatigue damage in structures. Some factors such as the magnitude of loading, constitutive equations or the elastic regions around the nonlinear events have an effect on the rate of strain accumulation. The elastic follow-up can explain the mechanism of plastic strain accumulation. This phenomenon may occur when a mechanical structure with elastic manner is connected to nonlinear events. In cyclic loading with nonzero mean stress, the plastic strain may be accumulated. This behavior is known as ratcheting and usually takes place under cyclic load-control conditions. A new simplified method is proposed in this paper in order to assess the effects of elastic follow-up on the strain accumulation (ratcheting) behavior of two-plate model made up of AISI 1045 steel under displacement-control loading, and a set of experimental tests is conducted to verify this method. The tests were carried out by a servo-hydraulic Zwick–Roell machine. The test results confirm the accuracy of the proposed method and also reveal that in the presence of EFU in the system, the cyclic accumulation of plastic strain in addition to the load-control conditions may occur locally in the displacement-control conditions.