Impact of 3D-model thickness on FE-simulations of microstructure

To investigate the effect of model thickness on simulated strain and stress fields in two-phase materials three-dimensional and two-dimensional finite element simulations were performed.The microstructure of the models was generated both by a stochastic procedure and by transforming computer tomograms representing the microstructure into a FE mesh (artificial and realistic models, respectively). The simulated equivalent plastic strains at the surface of the realistic model were compared to equivalent strain maps obtained by digital image correlation of SEM images.The results of this study demonstrate that 2D FE simulations generally do not describe the mechanical behaviour of two-phase materials adequately. The calculated distribution of surface strain coincides with the measured one only if the thickness of 3D model exceeds a minimum value that corresponds to microstructural length scale of the material. Therefore, the thickness should be equal or larger than this minimum to get correct results at the surface.