ROTATING CRACK MODEL WITH TRANSITION TO SCALAR DAMAGE

Traditional smeared-crack models for concrete fracture are known to su ffer by stress locking (meaning here spurious stress transfer across w idely opening cracks), mesh-induced directional bias, and possible ins tability at late stages of the loading process. The present paper sugg ests to overcome these deficiencies by combining the standard rotating crack model with the scalar damage concept. The combined model keeps the anisotropic character of the rotating crack but it does not transf er spurious stresses across widely open cracks. This is documented by examples including the three-point bending, wedge splitting, and four- point shear single-edge-notched specimens. The model is then extended to a nonlocal formulation, which not only acts as an efficient localiz ation limiter but also alleviates mesh-induced directional bias. Trans ition to damage can prevent a special type of material instability ari sing due to negative shear stiffness of the rotating crack model.