In this paper, the mathematical model and numerical simulations of the molten steel flow by the submerged entry nozzle and the filling process of the continuous casting mould cavity are presented. In the mathematical model, the temperature fields were obtained by solving the energy equation, while the velocity fields were calculated by solving the momentum equations and the continuity equation. These equations contain the turbulent viscosity which is found by solving two additional transport equations for the turbulent kinetic energy and its rate of dissipation. In the numerical simulations, coupling of the thermal and fluid flow phenomena by changes in the thermophysical parameters of alloy depending on the temperature has been taken into consideration. This problem (2D) was solved by using the finite element method. Numerical simulations of filling the continuous casting mould cavity were performed for two variants of liquid metal pouring. The effect of the cases of pouring the continuous casting mould on the velocity fields and the solid phase growth kinetics in the process of filling the continuous casting mould was evaluated as these magnitudes have an influence on the high quality of the continuous cast steel slab.

The work concerns of modeling the process of manufacturing machine parts by casting method. Making a casting without internal defects is a difficult task and usually requires numerous computer simulations and their experimental verification at the prototyping stage. Numerical simulations are then of priority importance in determining the appropriate parameters of the casting process and in selecting the shape of the riser for the casting fed with it. These actions are aimed at leading shrinkage defects to the riser, so that the casting remains free from this type of defects. Since shrinkage defects usually disqualify the casting from its further use, this type of research is still valid and requires further work. The paper presents the mathematical model and the results of numerical simulations of the casting solidification process obtained by using the Finite Element Method (FEM). A partial differential equation describing the course of thermal phenomena in the process of 3D casting creating was applied. This equation was supplemented with appropriate boundary and initial conditions that define the physical problem under consideration. In numerical simulations, by selecting the appropriate shape riser, an attempt was made to obtain a casting without internal defects, using a simple method of identifying their location. This is the main aim of the research as such defects in the casting disqualify it from use.

The mathematical model and numerical simulations of the solidification of a cylindrical shaped casting, which take into account the process of filling the mould cavity by liquid metal and feeding the casting through the riser during its solidification, are presented in the paper. Mutual dependence of thermal and flow phenomena were taken into account because have an essential influence on solidification process. The effect of the riser shape on the effectiveness of feeding of the solidifying casting was determined. In order to obtain the casting without shrinkage defects, an appropriate selection of riser shape was made, which is important for foundry practice. Numerical calculations of the solidification process of system consisting of the casting and the conical or cylindrical riser were carried out. The velocity fields have been obtained from the solution of momentum equations and continuity equation, while temperature fields from solving the equation of heat conductivity containing the convection term. Changes in thermo-physical parameters as a function of temperature were considered. The finite element method (FEM) was used to solve the problem.

The mathematical model and numerical simulations of the solidification of a cylindrical casting, which take into account the process of the mould cavity filling by liquid metal and the feeding of the casting through the conical riser during its solidification, are proposed in the paper. The interdependence of thermal and flow phenomena were taken into account because they have an essential influence on solidification process. The effect of the pouring temperature and pouring velocity of the metal on the solidification kinetics of the casting was determined. In order to obtain the casting without shrinkage defects, an appropriate selection of these parameters was tried, which is important for foundry practice. The velocity fields have been obtained from the solution of Navier-Stokes equations and continuity equation, while temperature fields from solving the equation of heat conductivity containing the convection term. In the solidification modelling the changes in thermo-physical parameters as a function of temperature were considered. The finite element method (FEM) was used to solve the problem.

Knowledge about complex physical phenomena used in the casting process simulation requires continuous complementary research and improvement in mathematical modeling. The basic mathematical model taking into account only thermal phenomena often becomes insufficient to analyze the process of metal solidification, therefore more complex models are formulated, which include coupled heat-flow phenomena, mechanical or shrinkage phenomena. However, such models significantly complicate and lengthen numerical simulations; therefore the work is limited only to the analysis of coupled thermal and flow phenomena. The mathematical description consists then of a system of Navier-Stokes differential equations, flow continuity and energy. The finite element method was used to numerically modeling this problem. In computer simulations, the impact of liquid metal movements on the alloy solidification process in the casting-riser system was assessed, which was the purpose of this work, and the locations of possible shrinkage defects were pointed out, trying to ensure the right supply conditions for the casting to be free from these defects.

In the present study, the evolution of different failure mechanisms in carbon fiber reinforced polymer composites is being investigated using acoustic emission technique, unsupervised clustering technique and improved b-value analysis. The experimental part involved the realization of tensile tests of different materials, namely samples with [0/90]2S uniaxial layer configuration and [0/90]2S twill fabric samples. Both types of tests were monitored using one wideband acoustic emission sensor, while the tensile tests of twill fabric samples were additionally supplemented with resonant acoustic emission sensor to perform a comparative analysis between datasets from resonant/wideband acoustic emission sensor. The comparative study itself was preceded by the failure mechanisms characterization process, which has been performed on the tensile test dataset of [0/90]2S layer configuration with the contribution of clustering technique. The subsequent analysis of the twill fabric resonant/wideband acoustic emission sensor datasets included the improved b-value technique, which relates the magnitude of fracture with the slope of the amplitude distribution. The presented results, especially in terms of the improved b-value technique applied to individual clusters, show enhanced ability to assess in more detail the actual structural integrity depending on the applied load.

The work done in this study is a preliminary investigation into the possibility of modelling the filling and solidification process of castings in molds made with the additive method. The work originated from an experiment to produce a bronze casting with a high tin content in an additive mold. The mold filling and solidification simulation was carried out in the MAGMASO FT program, and the lambda thermal conductivity coefficient used in the program’s material database was corrected based on the actual temperature values of the printed form. The results were compared with the modeling results for the physical properties of furan molds based on the program database. The microstructure of the castings obtained in the compared forms was assessed.