Liu Yujie1£¬Cai Lixun1£¬Qiu Shaoyu2£¬Yang Xianjie1
(1.Department of Applied Mechanics and Engineering, Southwest Jiaotong University, Chengdu 610031,China;2.National Key Laboratory for Nuclear Fuel and Material,Nuclear Power Institute of China, Chengdu 610041,China)
Abstract:The uniaxial ratcheting behavior of T225NG titanium alloy at 350¡æ was experimentally investigated. A new viscoª²plastic constitutive model with the memory surface was presented.A memory surface for maximum strain was introduced and different plastic flow rules were applied according to the memory surface.The monotonic tensile response and cyclic response were separated and the determination of constants in the model was simplified.The threshold of equivalent strain was introduced into the evolution equation for kinematic hardening back stress and the yield platform and hardening effect were described exactly.To describe the experimental phenomenon that ratcheting strain rate decreases quickly with the increasing of cyclic number, the modification of viscosity exponent was adopted. The model was applied to simulation for uniaxial ratcheting behavior of T225NG alloy at 350¡æ, and demonstrated a satisfied agreement of the simulated results with the experimental ones.
Keywords:ratcheting;constitutive model;elevated temperature;titanium alloy