Abstract: The paper studies the behaviour of creep-damage of GH36 alloy at 650℃ . Based on Kachanov-Rabotnov theory, the constitutive equations of creep-damage are normalized to obtain a group of linear control equations, and then the modern variational principle developed from optimal control theory is applied to numerically solving and analysing the problem under the constrained conditions (i.e. linear control equations). The solved curves of creep and damage compared with the results of experiments are presented to show an application. The proposed method is easily put into practice. and may indicated a way for numerical analysis of creep-damage problems.

Key words: creep, damage, variational principle