Rotating crack model with transition to scalar damage

Traditional smeared-crack models for concrete fracture are known to suffer by stress locking (meaning here spurious stress transfer across widely opening cracks), mesh-induced directional bias, and possible instability at late stages of the loading process. The present paper suggests 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 transfer 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 localization limiter but also alleviates mesh-induced directional bias. Transition to damage can prevent a special type of material instability arising due to negative shear stiffness of the rotating crack model.