A New Isotropic Hardening Law for the Barcelona Plastic-Damage Model

X. MARTINEZ; S. OLLER

Kos Island

Conferencia; 4th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COMPDYN 2013).; 2013

The plastic damage constitutive law developed by Lubliner et. al [1], also known as the Barcelona model, has proved to be an excellent formulation for the simulation of steel, capable of taking into account the initial hardening and posterior softening of the material. The model uses a yield surface, i.e. Von-Mises, to predict the plastic threshold and uses a hardening law, dependent on the fracture energy of the material, to define the initial hardening and posterior softening. The hardening law originally proposed by Lubliner et al. was an exponential curve with a maximum. Later on other types of hardening curves have been defined, but all of them where developed for the analysis of geomaterials [2]. Hence, the Barcelona model allows a correct qualitative simulation of steel, but itfails to obtain the exact behavior shown by experimental tests.Current work presents a new hardening law, developed for the Barcelona plastic-damage model, capable of adjusting with great accuracy a given experimental response of steel. The law developed is divided in three regions: The first region is defined with a straight line; the following region is a sixth degree polynomial defined with the least squares method to fit the given experimental data; and the last region is defined with an exponential function to simulate softening. This last region depends on the fracture energy of the material. These three regions, as well as the comparison between the experimental and numerical response, are shown in the following figure. The vertical green lines mark the limit of the different regions. The graph corresponds to an X52 steel.