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   On predictive modelling of yield stress increase in fresh cement pasteHuang, Haiqin  ; Zilian, Andreas in Proceedings in Applied Mathematics and Mechanics (2019), 19(1), Detailed reference viewed: 120 (4 UL) High-performance modeling of concrete ageingHabera, Michal ; Zilian, Andreas in Proceedings in Applied Mathematics and Mechanics (2019), 19(1), Long-term behaviour of concrete structural elements is very important for evaluation of its health and serviceability range. The phenomena that must be considered are complex and lead to coupled ... [more ▼] Long-term behaviour of concrete structural elements is very important for evaluation of its health and serviceability range. The phenomena that must be considered are complex and lead to coupled multiphysics formulations. Such formulations are difficult not only from physical perspective, but also from computational perspective. In this contribution attention to computational efficiency and effective implementation is payed. Presented model for concrete ageing is based on microprestress-solidification (MPS) theory of Bazant [1], Kunzel’s model for heat and moisture transport [2] and Mazars model for damage [3]. Ageing linear viscoelastic response, which is immanent to MPS theory and concrete creep, leads to ordinary differetial equation for internal variables solved for every quadrature/nodal point. Numerical structure of the finite element discretisation is examined. Few simplifications on physical model lead to a very efficient linear algebra problem for which standard preconditioned Krylov solvers are reviewed. In parallel, weak and strong scaling tests are performed. All results are produced within open-source finite element framework FEniCS [4]. These models are usually a basis for more involved thermo-hygro-chemo-mechanical (THCM) models with migrating chemical species. It is anticipated, that presented results will help practitioners or other structural engineerers with the choice of suitable and efficient methods for long-term concrete modeling. [less ▲] Detailed reference viewed: 299 (41 UL)Non-localized Contact Between Beams with Non-Circular Cross SectionsMagliulo, Marco ; Zilian, Andreas ; Beex, Lars in Proceedings in Applied Mathematics and Mechanics (2019) In this contribution, we introduce a contact formulation between beams finite elements with (hyper)elliptical cross sections. The contact scheme allows to model scenarios in which the contact area is ... [more ▼] In this contribution, we introduce a contact formulation between beams finite elements with (hyper)elliptical cross sections. The contact scheme allows to model scenarios in which the contact area is finite or the contact area occurs along a line. Although some contact schemes are yet able to do this, they require one of the beams to have a circular cross section. Here however, we focus on non-circular cross-sections. Consequently, new projections are required, in which the beam surfaces are used explicitly to formulate contact kinematics. [less ▲] Detailed reference viewed: 163 (14 UL)Model order reduction applied to ALE‐fluid dynamicsBaroli, Davide ; Zilian, Andreas in Proceedings in Applied Mathematics and Mechanics (2019) Detailed reference viewed: 99 (4 UL)Phase-field predictive model for setting of fresh self-compacting concreteHuang, Haiqin ; Zilian, Andreas in Proceedings in Applied Mathematics and Mechanics (2018), 18(1), The initial setting of fresh concrete is mainly caused by the dissolution of cement grains and the precipitation of calcium-silicate-hydrates during cement hydration. Progressing hydration drives the ... [more ▼] The initial setting of fresh concrete is mainly caused by the dissolution of cement grains and the precipitation of calcium-silicate-hydrates during cement hydration. Progressing hydration drives the transition from a dense suspension to a porous solid phase. Fresh mixture of self-compacting concrete (SCC) can be considered as a phase-changing multi-component material and can be described as a continuum at the macro scale, interacting with a set of transport-reaction-diffusion processes which in turn are driven by phenomena at the level of the microstructure. This contribution focuses on a predictive model for the setting of fresh SCC where the liquid-solid phase transition is captured by a phase-field variable using the Ginzburg-Landau type free energy function. Hydration-related chemical reactions together with heat and mass transfer are volume coupled with the mechanical behaviour and determined by the environmental conditions. The weak form of the predictive model is discretised using the finite element method and implemented with the FEniCS computational framework. [less ▲] Detailed reference viewed: 134 (9 UL) |
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