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Hyper-reduction of nonlinear hardening plasticity models using Petrov–Galerkin projection and gappy POD
Journal article   Open access   Peer reviewed

Hyper-reduction of nonlinear hardening plasticity models using Petrov–Galerkin projection and gappy POD

Alireza Ashkpour and Ahmad Raeisi Najafi
Computer methods in applied mechanics and engineering, v 461(Part A), 119155
01 Nov 2026
Featured in Collection :   Drexel's Newest Publications
url
https://doi.org/10.1016/j.cma.2026.119155View
Published, Version of Record (VoR) Open Access via Drexel Libraries Read and Publish Program 2026 Open CC BY-NC V4.0

Abstract

Reduced Order Model Nonlinear hardening plasticity Petrov–Galerkin projection
We present a projection-based reduced-order modeling (ROM) framework for nonlinear plasticity that combines a Least-Squares Petrov–Galerkin (LSPG) formulation with hyper-reduction via the Gauss–Newton with Approximated Tensors (GNAT) method. The framework addresses both associative von Mises and non-associative Drucker–Prager formulations with nonlinear isotropic hardening. At each integration point, a local Newton–Raphson method updates the stress state and plastic multiplier using history-dependent internal variables. Dimensional reduction is achieved with Proper Orthogonal Decomposition (POD), while gappy POD, combined with a greedy sampling strategy enables reconstruction of nonlinear residuals and Jacobian actions from a subset of sampled nodes, significantly reducing online evaluations. The ROM is trained over a parameter space encompassing variations in load magnitude and six elasto-plastic material parameters. We evaluated the method on two- and three-dimensional benchmark problems, demonstrating computational speedups of up to relative to full-order models, despite the limitations imposed by the Kolmogorov barrier. Finally, we assess the robustness of the LSPG formulation in the presence of non-symmetric, non-positive definite Jacobians arising from non-associative plasticity, showing that the proposed ROM maintains convergence under these challenging conditions.

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