An effective inverse procedure for identifying viscoplastic material properties of polymer Nafion

An effective inverse procedure is suggested to identify the viscoplastic material properties of polymer Nafion, by minimizing differences in the force–displacement responses of uniaxial tension test between experimental and simulation results. In this procedure, a two-layer viscoplastic constitutive model is adopted to describe the viscoplastic behavior of Nafion. A response surface method is used as a forward solver to calculate the force–displacement response for given material property varying continuously in a certain range. An intergeneration projection genetic algorithm (IP-GA) is then employed as the inverse operator on the response surface to determine the unknown key constants. The selected viscoplastic constants, A, n and f, are varied iteratively using the proposed inverse procedure until the stopping criterion is satisfied. The identification results for two cases demonstrate the effectiveness of the present inverse procedure, as well as its robustness to the noises effects. It is found that this procedure is a potentially useful tool to effectively help determine the viscoplastic material properties of polymer Nafion.