In this paper, the algorithm for the discretization of 3D domains into tetrahedral boundary conforming meshes is presented. The algorithm is based on the Delaunay triangulation with special point ordering. The conformity of the resulting mesh with the initial triangulation of the domain boundary is ensured a priori thus the boundary recovery postprocessing step is eliminated. The constrained Delaunay triangulation of the boundary points is obtained using modified Watson's point insertion algorithm. The actual appearance of boundary faces in the final triangulation is achieved by the form of an oriented graph, of the violation of the empty-sphere property of all boundary faces. The cycle dependencies (closed loops in the graph) are eliminated by using the nodal perturbations, by classification of some of the violations as safe and (as the last resort) by forming a new tetrahedron using the advancing front technique. Once all the cyclic dependencies are eliminated, the point insertion process controlled by the dependency graph is started and the constrained Delaunay triangulation of the boundary points is built. In the next phase, additional points are inserted in the interior of the domain, while preserving the boundary constraints, to make the elements of appropriate size with aspect ratio close to one. The resulting mesh is then subjected to optimization in terms of the combination of Laplacian smoothing and topological transformations, in order to remove the potential slivers and to improve the overall mesh quality. and Obsahuje seznam literatury
Autogenous deformation is a phenomenon that origins in chemical shrinkage during the cement hydration. The physical mechanism is the consumption of capillary water during the hydration and the refinement of capillary porosity. The microscopic underpressure due to thermo-dynamical equilibrium in a pore exerts the negative pressure on the solid skeleton of the paste. This behavior is simulated by means of FEM, where the microstructure of cement paste is loaded directly by underpressure. Validation shows that creep of the cement paste must be also taken into account when good quantitative prediction is expected. and Obsahuje seznam literatury