关键词：本构方程弹塑性；切线模量；粘弹性
摘 要：Constitutive equations of irreversible deformation, e.g. elastoplastic, viscoelastic and viscoplastic deformations are described in rate forms in which the stress rate and the strain rate are related to each other through the tangent modulus. Therefore, numerical calculations are executed in their incremental forms by the input of load (stress) increment or displacement (deformation) increment, while the time increment is also input in rate-(or time-)dependent constitutive equations, e.g. viscoelastic and viscoplastic ones. The algorithm to pull-back the stress to the yield surface is required for the numerical calculation by the elastoplastic constitutive equations other than the subloading surface model possessing the automatic-controlling function to attract the stress to the yield surface. Numerical calculation by the explicit (or forward Euler) method results in the deviation from the exact solution or fails without convergence in the case that the tangent modulus is not constant, if an incremental step is taken large.