Browsing by Subject "plasticity"

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Access status: Open Access ,
Plastic deformation mechanisms in BCC single crystals and equiatomic alloys: Insights from nanoindentation
(Wydawnictwa AGH, 2024) Dominguez-Gutierrez, Francisco Javier; Papanikolaou, Stefanos; Bonfanti, Silvia; Alava, Mikko
Deformation plasticity mechanisms in alloys and compounds may reveal the material’s capacity towards optimal mechanical properties. We conducted a series of molecular dynamics (MD) simulations to investigate plasticity mechanisms due to nanoindentation in pure tungsten, molybdenum, and vanadium body-centered cubic single crystals, as well as the body-centered cubic, equiatomic, random solid solutions (RSS) of tungsten–molybdenum and tungsten–vanadium alloys. Our analysis focuses on a thorough, side-by-side comparison of dynamic deformation processes, defect nucleation, and evolution, along with corresponding stress–strain curves. We also checked the surface morphology of indented samples through atomic shear strain mapping. As expected, the presence of Mo and V atoms in W matrices introduces lattice strain and distortion, increasing material resistance to deformation and slowing down dislocation mobility of dislocation loops with a Burgers vector of 1/2 ?111?. Our side-by-side comparison displays a remarkable suppression of the plastic zone size in equiatomic W–V RSS, but not in equiatomic W–Mo RSS alloys, displaying a clear prediction for optimal hardening response of equiatomic W–V RSS alloys. If the small-depth nanoindentation plastic response is indicative of overall mechanical performance, it is possible to conceive a novel MD-based pathway towards material design for mechanical applications in complex, multi-component alloys.
Access status: Restricted ,
Podstawy teorii sprężystości i plastyczności : z przykładami
(Wydawnictwo Politechniki Krakowskiej, 2006) Paluch, Marian; Politechnika Krakowska im. Tadeusza Kościuszki
Access status: Open Access ,
Simulations of fracture in concrete elements using continuous and discontinuous models
(2011) Bobiński, Jerzy Robert; Tejchman, Jacek
The paper presents results of numerical simulations of fracture in concrete using two different approaches. First, fracture was modelled in a smeared way by an elasto-plastic and a damage continuum model. In elasto-plasticity, a Rankine criterion was used. The degradation of the stiffness in the damage model was described as a scalar variable of an equivalent strain measure. To ensure mesh-independent results, a non-local theory was used. Second, fracture was simulated as discontinuities with the aid of cohesive elements and Extended Finite Element Method (XFEM). The experimental benchmark test for concrete by Nooru-Mohamed under mixed mode conditions was modelled. The obtained numerical results were compared with the corresponding experimental ones.