The paper focuses on thermal and mechanical analysis of Periodic Surface Structure (PSS). PSS is a continuous surface with a specific topology that is mathematically formulated by geometric factors. Cubic P-surface (“primitive”), D-surface (“diamond”), and G-surface (“gyroid”) structures were simulated under load and heat transport using a numerical approach. We conducted our study by solving the stress and heat equations using the Finite Element Method (FEM). We achieved results using our software module, which generates PSS and simulates stress and temperature distribution. The stress model defined by dependence between stress and strain, gained from an experiment, and correlation of strain and displacement, gained from geometric conditions, was used in numerical experiments. The influence of geometric factors on the thermal and mechanical behavior of PSS was qualitatively determined. We showed decreasing effective stress values with an increased number of cells in the cubic domain for concerned PSS. It is important, because the increase in the number of cells does not increase the structure’s volume.

The paper describes a three-dimensional temporary temperature field in the semi-infinite body caused by a moving laser heat source with any trajectory. In considerations the model of the surface heat source with the Gaussian distribution of power density was adopted. The trajectory of the source was approximated by straight sections. The calculation model of the temperature field takes into account changes in temperature caused by successive passes of the laser (temperature rise associated with the source action the source and cooling areas previously heated). Temperature field calculations in a rectangular steel member were carried out. The results of the calculations were illustrated by distributions of temporary and maximum temperature in a heated element.

The article presents the modeling of temporary temperature and phase share calculations during SAW (submerged arc welding) overlaying of steel elements. The input heat of a melted electrode and the heat of direct electric arc impact have been taken into consideration in the temperature field solution. The characteristic areas (fusion, full and incomplete transformation), have been determined by solidus, A₃ and A₁ temperatures, respectively. The limit temperatures of the phase trandformations during cooling, based on the cooling rate in the temperature range 800–500 °C according to S355 steel time-temperature-transformation welding diagram, have been determined. The JMAK (Johnson–Mehl–Avrami–Kolmogorov) law and KM (Koistinen–Marburger) formula were used in the phase change kinetic description. Theoretical considerations were illustrated with examples of temperature and phase share computations for welding overlaid S355 steel plate. The analysis of the history of changes in temperature and structural components (phases) was carried out based on the results of numerical simulations as well as metallographic examination after SAW overlaying. The dimensions of the HAZ (heat-affected zone), obtained experimentally, and the structure types confirmed the results of the computation.

In this paper we focus on the application of a mixed time partitioning methods to raise efficiency of the solidification kernel in the NuscaS system. We are proposing using a fixed time step in the casting and its integer multiple in other parts of mould because the time step size determines the accuracy of the simulation results. By means of numerical experiments we show that our approach allows for up to about three times performance improvement as compared to the standard approach without loosing precision of results. Moreover, this methods will be extended to 3D numerical simulation in a future work. We notice also that our method can be combined with parallel processing to further improve performance of solidification kernels.

We present a description of the effects of thermal interactions, which take into account formation of a shrinkage gap, that affect the level of stresses in a system casting – mold. Calculations were carried out in our own computer program which is an implementation of the finite element method used to solve the equations describing a thermo-elastic-plastic model of material and the heat conduction, including solidification. In the computing algorithm we use our own criteria for mechanical interaction between the casting and mold domains. Our model of mechanical interactions between the casting and the mold allows efficient modeling of stresses occurring in the casting and an impact of development of the shrinkage gap on cooling course.