K. Lenik

METHODS OF DISCRETIZATION OBJECTS CONTINUUM IMPLEMENTED IN FEM PREPROCESSORS

Finite Element Method (FEM) called Finite Element Analysis is a tool for computeraided engineering and analysis. It is used to solve problems related to changes in the geometry of the structure as a result of external factors. FEM is used to model engineering processes where real objects are converted to discrete models. Finite Element Method uses a method of obtaining approximate solutions by approximation of partial differential equations. The process of testing and mathematical computation model is described by the equations function of the position and time for the nodes. The development of individual models and their groups and definitions of boundary conditions are carried out using computer programs for FEM.

NEW POSSIBILITY FOR THE USE OF PLASMA DISCHARGES TO IDENTIFY AMBER AND CHANGES IN AMBER STRUCTURE

Pulsed power discharge applied in air to the amber surface was found to cause improvement in its appearance and color changes such as to red, a color not natural to amber but attractive for jewelry. Needle and plate electrodes were used during experiments. Pulsed power discharges in air particularly turned amber red at the edges and around the needle electrode. Discharges in water did not change amber structure because discharge occurring on the surface does not cross the amber structure. Discharges in silicone oil had a different effect, with most discharge passing through the amber structure, causing fine cracks. Unfortunately, the absence of a consistent am ber structure causes difficulty in selecting the correct discharge (shock wave) power. Using new technology, we have changed the appearance a very old material-amber (about 40 – 60 million years old) – to make it more attractive for customers; this technology is also useful for detecting artificial amber (costume jewellery) without causing damage to the product.

Investigation of Changing of Chemical and Phase Composition of the Friction Surface Fe-Mn-C-B-Si-Ni-Cr

The paper presents the results of a SEM/EDS and XPS study of changing of chemical and phase composition of the friction surfaces Fe-Mn-C-B-Si-Ni-Cr hardfacing coatings depend on depth. The tribological examination was conducted in a pin-on disc system with unitary pressure of 10 MPa under dry friction conditions. A scanning electron microscope SEM/EDS as well as X-Ray photoelectron spectroscopy (XPS) were used to examine the structures on the friction surface and depend on depth 5, 10, 15, 20, 50, 100, 200, 6000 nm. The presence of compounds such as oxides (B2O3, SiO2, Cr2O3), carbides (Fe3C, Cr7C3), borides (FeB, Fe2B).

INNOVATIVE SYSTEM OF SIMULTANEOUS TRANSPORTATION AND TREATMENT OF SANITARY WASTEWATER IN SCATTERED DWELLING AREAS

The work presented the possibility of implementing an innovative system of simultaneous transportation and treatment of sanitary wastewater in scattered dwelling areas. Small-bore sewerage with a balanced flow enables simple and inexpensive simultaneous disposal and pre-treatment of fluid with from vast, undeveloped areas.

Analysis of cracking of low-alloy copper stretched at elevated temperature

This paper presents both mechanical and structural aspects of micro-cracking of CuNi2Si copper alloy in CNCS grade revealed during the static tensile test in the temperature range between 20oC and 800oC. The purpose of this paper is to determine the impact of plastic deformation temperature and structural condition of the tested alloy on the type and mechanism of its cracking under specified deformation conditions. Therefore, the subject of the detailed metallographic analysis in a microscopic scale is the location of initiation and propagation of cracking, morphology of precipitations and their impact on the cracking process, nature and type of the fractures formed during material decohesion as well as microstructural analysis of the alloy by electron diffraction method. The obtained results allow the determination of the impact of analysed factors on cracking mechanism in the tested alloy as well as the specification of effective methods for limitation of the effects of cracking and thus the improvement in plasticity of alloy and workability of its products