A Semi-incremental Scheme for Cyclic Damage Computations

Abstract

High fidelity structural problems that involve nonlinear material behaviour, when subjected to cyclic loading, usually demand infeasible computational resources; this demonstrates the need for efficient model order reduction (MOR) techniques in order to shrink these demands to fit into the available means. The solution of cyclic damage problems in a model order reduction framework is investigated in this chapter. A semi-incremental framework based on a large time increment (LATIN) approach is proposed to tackle cyclic damage computations under variable amplitude and frequency loadings. The involved MOR approach provides a low-rank approximation in terms of proper generalised decomposition (PGD) of the solution. The generated PGD basis can be interpreted as a set of linear subspaces altered on the fly to the current problem settings. The adaptation of PGD to new settings is based on a greedy algorithm that may lead to a large-sized reduced order basis (ROB). Thus, different orthonormalisation and compression techniques were evaluated to ensure the optimality of the generated ROB in [1] and will be overviewed here. The proposed implementation and a displacement formulated finite element (FE) incremental framework are compared to illustrate their differences in terms of memory footprint and computational time. Numerical examples with variable loadings are discussed, and a typical implementation is provided as open-source code, available at https://gitlab.com/shadialameddin/romfem.