A New Accelerating Creep Constitutive Model and its Parameters Sensitivity Analysis

Abstract

In this study, Perzyna visco-plasticity theory and Nishihara component model were combined to establish a universal creep constitutive model for describing the entire process of creep, including transient creep, steady-state creep and accelerating creep. Based on the internal energy theory, the constitutive model defined the critical internal energy density value of accelerating creep to describe the mutation characteristics of materials' creep behavior and predict the time of accelerating creep effectively. Overall, the numerical simulation results agreed with the experimental data. Furthermore, according to the sensitivity analysis of parameters, such as flow rule, cohesive force, internal friction angel and Poisson's ratio, and study the constitutive equation change rule with the change of major parameters to further verify the rationality of model. Research shows that, the flow rule and internal friction angle have influence on the time of accelerating creep, and the influence law is close to a parabola form. But the influence law shows a straight line form for the cohesive force and Poisson's ratio. The flow rule, cohesive force and internal friction angle affect steady-state creep strain rate, and the influence law is close to a straight line form. However, Poisson's ratio has no effect on it. The parameters sensitivity of steady-state creep strain rate from small to large in the order is Poisson's ratio, flow rule, cohesive force and internal friction angle. But the sequence turns into Poisson's ratio, cohesive force, flow rule and internal friction angle for the time of accelerating creep.