Abstract: The characteristics of optimization models for the united creep damage constitutive equations is discussed. The reason of fail of using the traditional gradient-based methods to optimize the problem is analysed, and the characteristics for the optimization methods which are adaptive to solve the kinds of problems are given. The evolutionary algorithm is used to optimize this problem and the better result is achieved. The conclusions may be helpful during optimizing the similar problems to this.

Key words: Constitutive equations, Creep damage, Optimization