A physically based model for bcc materials including non-Schmid effects and its application to single crystals of alpha-iron at different model scales

A dislocation density based model is developed to govern physics of complex mechanical behavior of bcc materials. Non-Schmid effects are incorporated into a novel dislocation density based model by using three-term projection operators. The model is used to explain dependence of mechanical response to crystal orientation, temperature, strain-rate and as well as tension-compression asymmetry. Simulations at different scales that include; a material point, a single finite element and a finite element model of exact test geometry are performed. The proposed model successfully captures crystal orientation, temperature, and strain-rate dependence of the experimentally observed stress-strain curves and also well explain the tension-compression asymmetry of experimental flow stresses of alpha-iron. The forest projection scheme that uses the slip plane normal, hardening interactions between slip systems for bcc materials, non-Schmid projections, and Peierls energy barrier for thermal activation of slip are important features of the model to imitate experimental mechanical behavior of bcc materials successfully at all scales with a better agreement though a finite element model considering exact tensile speciment geometry.