Cyclic Behavior of Beams Based on the Chaboche Unified Viscoplastic Model

In this paper, ratcheting behavior of beams subjected to mechanical cyclic loads at elevated temperature, using the rate dependent Chaboche unified viscoplastic model with combined kinematic and isotropic hardening theory of plasticity, is investigated. A precise and general numerical scheme, using the incremental method of solution, is developed to obtain the cyclic inelastic creep and plastic strains. Applying the numerical method to the governing equations obtained based on the mentioned unified model, cyclic behavior of the beam due to the combined plastic and creep strains are obtained. Effect of loading rate, creep time, and mean load on ratcheting response and stress amplitude of the beam due to the combination of axial and bending moments at elevated temperatures are obtained. It is shown that increasing the loading rate, results into decrease in ratcheting rate and increase in stress amplitude. Also, the ratcheting strain increases with increasing the creep time while the stress amplitude decreases. The results obtained using the applied method in this paper is verified with the experimental data given in the literature search.