International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

In this paper, in order to dimension the position and the number of vertical reinforcement, several numerical linear static simulations of bending circular manhole cover of ductile cast iron (grade EN-GJS-500-7) with 600 mm diameter are performed. The analysis of displacement and stress using the finite element method in the software package Autodesk Simulation Mechanical were conducted. Verification of numerical results for the solution of thin circular plate was performed with analytical bending solutions. After checking the numerical procedure on the thin circular plate, two circular vertical reinforcements were added on the underside: internal and external. Numerical simulations investigated the influence of the inner circular reinforcement position on the strength of the circular manhole cover, while equivalent stresses followed by energy theory of strength (von Mises) were monitored. Since maximal equivalent stresses remain on the plate by varying the position of the inner circular reinforcement, simulations with added radial reinforcements are performed. Finally, by optimizing the number of radial reinforcements, the optimum plate design is chosen.

This article presents the application of non-hazardous waste molding sand from gray cast iron foundry as an inexpensive adsorbent for removal of Zn(II) and Cu(II) ions from aqueous solutions. The experiments were performed at room temperature using a multi solution (Zn + Cu) with concentration was 100 mg/l. The process of removal of Zn(II) and Cu(II) ions was monitored at different contact times of waste molding sand and metal ions. The experimental data were processed by two different kinetic theories. The pseudo-first-order and pseudo- second-order models were used for modeling the kinetic rates.

Obtained results show that the waste molding sand has significant potential for the removal of Zn(II) and Cu(II) ions from aqueous solutions. Research shows that the removal of Cu(II) ions was better than removal of Zn (II) ions. It is possible to conclude that the mutual competition of Cu(II) and Zn(II) ions for adsorption sites affect the intensity of their removal.

For many years casting alloys are widely used in dental applications. Among them, titanium and its alloys reveal the best properties for this purpose. However, the casting is difficult but it may be improved by alloying. This research deals with titanium-based alloys with zirconium additions. Investigated alloys were prepared by melting and casting in an electro-arc furnace under argon atmosphere. In order to identify the phases present in alloys, structural analysis was performed by X-ray diffraction method. It was showed two-phases microstructure of alloys. Further, zirconium addition in higher percentage contributes to formation of the beta phase of titanium which possesses more adequate properties then alpha titanium. Microstructural observations by scanning electron microscopy and energy-dispersive spectrometry showed that phases have similar chemical composition. Measured Vickers hardness values were lower than for pure titanium and are acceptable for dental applications.