References of "Habera, Michal 50030244"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailHigh-performance modeling of concrete ageing
Habera, Michal UL; Zilian, Andreas UL

in Proceedings in Applied Mathematics and Mechanics (in press)

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: 209 (28 UL)
Full Text
See detaildolfiny: Convenience wrappers for DOLFINx
Zilian, Andreas UL; Habera, Michal UL

Scientific Conference (2021, March 23)

With the increased flexibility of DOLFINx and its reduction to core functionality, the responsibility for even some basic components of computational analysis is shifted to the user. This presentation ... [more ▼]

With the increased flexibility of DOLFINx and its reduction to core functionality, the responsibility for even some basic components of computational analysis is shifted to the user. This presentation provides an overview of the open-source package dolfiny, which provides end-user API interfaces to mesh/meshtags generation and processing, expression list handling, function interpolation and projection as well as the restriction of function spaces to parts of the computational domain. This functionality is consistently considered in interfaces to PETSc/SNES as nonlinear solver and SLEPc as eigensolver backend, both allowing the operation on block and nested operators. In addition, the package provides a convenient approach to incorporate time integration into the UFL formulation of the problem, which is exemplified for the generalised alpha method. The capability of dolfiny is demonstrated in a number of examples, ranging between finite strain structural analysis, plasticity and fluid-structure interaction. [less ▲]

Detailed reference viewed: 67 (3 UL)
See detailScalable computational modelling of concrete ageing and degradation
Habera, Michal UL

Doctoral thesis (2021)

The typical lifespan of concrete structures ranges from tens to hundreds of years. During such a long period of time many external factors including weather conditions, loading history or environmental ... [more ▼]

The typical lifespan of concrete structures ranges from tens to hundreds of years. During such a long period of time many external factors including weather conditions, loading history or environmental pollution. play a crucial role in concrete health and serviceability state. Prediction (via the means of computer simulation) of the long-term material properties of concrete can thus provide valuable insights and lead to better reusability of construction components. Several very complex multi-physics models were developed in the past decades for this purpose. While these models usually include a wide range of phenomena, the numerical problem which has to be solved poses major challenges and significantly increases required computational time. This makes a predictive simulation of any larger-scale structure non-feasible. On the other hand, commercial codes (ABAQUS, ANSYS, etc.) either lack the material models for a more accurate creep prediction or provide custom material routines which are not computationally optimised. In addition, a specific model and discretisation approach often requires a very specific choice of solvers and preconditioners in order to achieve good parallel scaling properties, so much required for execution on modern HPC infrastructures. In this thesis a 3-D material model for a reinforced concrete based on the micro-prestress solidification theory (MPS) of Bažant, continuum damage mechanics and the temperature and humidity model of Kunzel is efficiently implemented in the finite-element software FEniCS. A high-performance code for the assembly of residual and tangent operators is automatically derived using automatic differentiation capabilities (AD) of FEniCS. Seamless parallel integration with the linear algebra solvers suite PETSc then offers a wide range of solvers. The combination of AD, code generation techniques (e.g. FEniCS), and parallel performance of PETSc solvers for predictive modelling of concrete degradation is not present in the existing literature. It is believed that the results presented here allow the study of reusability and degradation of concrete components also for larger structures, where the conventional existing approaches cannot provide a reasonable computation time. [less ▲]

Detailed reference viewed: 55 (6 UL)
Full Text
See detailModelling of concrete and cementitious materials
Zilian, Andreas UL; Habera, Michal UL

Presentation (2021, January 26)

Detailed reference viewed: 28 (4 UL)
Full Text
See detailXDMF and ParaView: checkpointing format
Habera, Michal UL; Zilian, Andreas UL; Hale, Jack UL et al

Scientific Conference (2018, March 21)

Checkpointing, i.e. saving and reading results of finite element computation is crucial, especially for long-time running simulations where execution is interrupted and user would like to restart the ... [more ▼]

Checkpointing, i.e. saving and reading results of finite element computation is crucial, especially for long-time running simulations where execution is interrupted and user would like to restart the process from last saved time step. On the other hand, visualization of results in thid-party software such as ParaView is inevitable. In the previous DOLFIN versions (2017.1.0 and older) these two functionalities were strictly separated. Results could have been saved via HDF5File interface for later computations and/or stored in a format understood by ParaView - VTK’s .pvd (File interface) or XDMF (XDMFFile interface). This led to data redundancy and error-prone workflow. The problem essentially originated from incompatibilities between both libraries, DOLFIN and ParaView (VTK). DOLFIN’s internal representation of finite element function is based on vector of values of degrees of freedom (dofs) and their ordering within cells (dofmap). VTK’s representation of a function is given by it’s values at some points in cell, while ordering and geometric position of these points is fixed and standardised within VTK specification. For nodal (iso- and super-parametric) Lagrange finite elements (Pk , dPk ) both representations coincide up to an ordering. This allows to extend XDMF specification and introduce intermediate way of storing finite element function - intrinsic to both, ParaView and DOLFIN. The necessary work was done as a part of Google Summer of Code 2017 project Develop XDMF for- mat for visualisation and checkpointing, see https://github.com/michalhabera/gsoc-summary. New checkpointing functionality is exposed via write checkpoint() and read checkpoint() methods. [less ▲]

Detailed reference viewed: 295 (32 UL)