Forming limit diagrams: A micromechanical approach

A method for obtaining the forming limit diagram (FLD) from a micromechanical approach is proposed. Periodic representative volume elements (RVEs) characteristics for the microstructure of a two-phase material containing particles are subjected to biaxial stretching with different strain paths. In the course of straining, a groove forms and grows, finally leading to a stress drop in the overall response. This deformation instability is obtained as a natural result of the strain field fluctuations caused by the inclusions in the two-phase material. For this approach, only the geometry of the microstructure and the material data of the constituents have to be known; no additional assumptions about the deformation process or about a macroscopic inhomogeneity are necessary. The influence of the RVE representation on the possible deformation patterns is investigated.