The purpose of this paper is to investigate the effect of stress classification on cyclic viscoplastic response of a structure (here, a thick spherical vessel which has an application in pressure vessel technology). The response is either reverse plasticity and shakedown or ratcheting behavior of a structure. The viscoplastic behavior of thick spherical vessels subjected to thermo-mechanical loads, using the rate-dependent Chaboche unified viscoplastic model with combined kinematic and isotropic hardening theory of plasticity, is evaluated. The material properties of the structure is assumed to be temperature dependent. A combination of generalized differential quadrature method (GDQ) and a precise numerical scheme, using the successive approximation iterative method, is employed to solve the resulting nonlinear differential equations. It is concluded that the Chaboche viscoplastic hardening model, as well as the plastic hardening model, predicts reverse plasticity under thermal cyclic loading with and without the creep consideration (a strain controlled cyclic loading). It is also shown that the rates of loading and unloading do not have significant influence on the cyclic viscoplastic behavior of the vessel, although they have influence on the strain and stress distributions.

本文的目的是研究应力分类对结构（此处为在压力容器技术中得到应用的厚球形容器）的循环粘塑性响应的影响。响应是结构的可逆塑性和摇晃或棘轮行为。使用速率依赖的Chaboche统一粘塑性模型，结合运动学和各向同性的可塑性硬化理论，评估了厚球形容器在热机械载荷下的粘塑性行为。假定结构的材料特性与温度有关。广义微分求积法（GDQ）和精确数值方案的组合，使用逐次逼近迭代法，用于求解所得的非线性微分方程。结论是，Chaboche粘塑性硬化模型以及塑性硬化模型都可以在考虑和不考虑蠕变（应变控制的循环载荷）的情况下，预测热循环载荷下的可逆塑性。还表明，装卸速率对容器的循环粘塑性行为没有显着影响，尽管它们对应变和应力分布有影响。