Simulation of Ratcheting Responses of Elbow Piping Components

Ratcheting damage accumulation in piping components may occur under repeated reversals of loading induced by earthquakes, mechanical and thermal operating conditions, and other extreme loading conditions. Ratcheting damage accumulation can cause failure of structures through fatigue cracks or plastic collapse. A major challenge in structural mechanics is the prediction of ratcheting responses of structures under various cyclic loading conditions. Accurate prediction of ratcheting-fatigue and ratcheting-collapse of elbow components is imperative in order to incorporate the ratcheting related failures into the ASME design Code in a rational manner. This would require predictions of both local (stress-strain) and global (load-deflection) responses simultaneously. Towards achieving this goal, a set of experimental responses of elbow piping components is developed. Advanced cyclic plasticity models, such as, modified Chaboche, Ohno-Wang, modified Ohno-Wang and Abdel Karim-Ohno, are implemented into ANSYS for simulating the experimental responses. Results from the experimental and simulation studies are presented in order to demonstrate the state of structural ratcheting response simulation by these models.