20.500.12556/RUL-180870 A unified elasto-viscoplastic model for rate-dependent materials This paper presents a generalized elasto-viscoplasticity framework for modelling material behaviour under static, impact, and potentially cyclic loading. A theoretical equivalence between the classical Cowper–Symonds formulation and Chaboche’s viscoplasticity law is established, demonstrating that both can be expressed within a unified constitutive structure. Based on this equivalence, a new procedure is proposed for identifying elastoplastic and viscoplastic parameters directly from tensile, compressive, or strain-controlled tests performed at different strain rates. The method eliminates the need for additional creep or relaxation experiments and enables decomposition of the stress–strain response into elastoplastic and viscoplastic contributions. Several variants of the viscoplasticity law are introduced, each satisfying relevant physical constraints, and a regression-based strategy is employed for robust parameter identification. The framework is validated using four materially diverse datasets: X2CrNi18-9 stainless steel, Ti6Al4V titanium alloy, short glass fibre-reinforced polybutylene terephthalate (PBT), and hydroxyl-terminated polybutadiene (HTPB) propellant. In all cases, excellent agreement with experimental data is obtained. The proposed formulation further enables prediction of stress–strain behaviour at the limiting cases of zero and infinitely high strain rates, which cannot be accessed experimentally. The results demonstrate that a single constitutive law can capture rate-dependent responses across metals, polymers, and elastomers, making it suitable for structural analyses under monotonic loading, with potential extension to cyclic, multiaxial, and thermo-mechanical conditions. viscoplasticity strain rate effects constitutive modelling elasto-viscoplasticity modelling finite element analysis cowper–symonds and chaboche models viskoplastičnost hitrost deformacij konstitutivno modeliranje analiza končnih elementov model cowper–symonds model chaboche true false true Angleški jezik Slovenski jezik Članek v reviji 2026-03-18 13:19:07 2026-03-18 13:19:15 2026-03-21 04:00:59 0000-00-00 00:00:00 2026 0 0 15 str. Vol. 314, art. 111410 2026 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 544.236.4:519.6 0020-7403 10.1016/j.ijmecsci.2026.111410 272121603 Nagode...A_unified....pdf Nagode...A_unified....pdf 1 1E288D82A8CCD4F1976BD1D3FD92ED8B be9e5f0b7cb34c91997bd78932f3b6864c5ba33138f7d6c9fbe6e6ca405745cf bcf31cb1-22c4-11f1-b0ab-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=230804 https://www.sciencedirect.com/science/article/pii/S0020740326002663 1 9bce3962-22c4-11f1-b0ab-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=230803 Fakulteta za strojništvo 0 0 0