転位密度を考慮した構成モデルによる二軸ラチェット変形シミュレーション

抄録

This paper treated a series of experiments and simulations concerned with biaxial ratcheting behavior. The biaxial ratchetting tests were conducted using SUS304 stainless steel subjected to cyclic torsion with superposed axial tensile or compressive stresses. Experimental results showed that (1) the axial strain occurred due to even zero superposed axial stress, and (2) biaxial ratchetting strain due to the tensile superposed stress was larger than that due to the compressive superposed stress. The biaxial ratchetting behavior was simulated by a constitutive model based on a viscoplastic potential related to dislocation density. To explain the axial strain due to zero or nonzero superposed stresses, a constitutive model was proposed, where the effect of the latent hardening on the back stress was considered in the evolution equation of the back stress. The constitutive model successfully simulated the axial strain due to zero or nonzero superposed stresses. The difference of the biaxial ratchetting strain due to the tensile and compressive superposed stresses was also well explained by the constitutive model.