Abstract
To solve large nonlinear finite element problems efficiently, the Newton-Krylov iterative methods may be employed in conjunction with robust preconditioners. In this study, the Neumann expansion preconditioners proposed recently are reexamined and compared with some popular preconditioners based on two slope examples and one footing example. It is found that among the Neumann expansion preconditioners, which are characterized with separated elastic stiffness and plastic stiffness, the zero-order Neumann expansion preconditioners (i.e. factorization based on the elastic stiffness) appear to be attractive, instead of only being attractive for those applications with non-associated plasticity and low percentage of yielding.