Convergence improvement in computation of strain-softening solids by the arc-length method

Abstract

© 2019 Elsevier B.V. This paper deals with problems emerging in a non-linear analysis of systems modelled by the strain softening material. Apart from sharp turns on the load-displacement diagram that characterize such numerical models, snap-back, artificial unloading and possibility of bifurcation occurrence are often encountered. These aspects challenge a non-linear system solver, in a sense of finding the appropriate equilibrium path. In this paper the CDPM2 concrete material model based on damage-plasticity is employed on notched geometry models in order to analyse convergence. A number of techniques for the solution of non-linear systems are tested and special emphasis is given to the snap-back occurrence and its influence on the convergence of the solution. A relatively simple new technique is developed for achieving better convergence throughout iterations to serve as an aid to conventional methods such as arc-length and line search.