Numerical analysis of temperature field during hardfacing process and comparison with experimental results

The three-dimensional transient nonlinear thermal analysis of the hard facing process is performed by using the finite element method. The simulations were executed on the open source Salome platform using the open source finite element solver Code_Aster. The Gaussian double ellipsoid was selected in order to enable greater possibilities for the calculation of the moving heat source. The numerical results were compared with available experimental results

Comparative thermal buckling analysis of functionally graded plate

A thermal buckling analysis of functionally graded thick rectangular plates according to von Karman non-linear theory is presented. The material properties of the functionally graded plate, except for the Poisson's ratio, were assumed to be graded in the thickness direction, according to a power-law distribution, in terms of the volume fractions of the metal and ceramic constituents. Formulations of equilibrium and stability equations are derived using the high order shear deformation theory based on different types of shape functions. Analytical method for determination of the critical buckling temperature for uniform increase of temperature, linear and non-linear change of temperature across thickness of a plate is developed. Numerical results were obtained in MATLAB software using combinations of symbolic and numeric values. The paper presents comparative results of critical buckling temperature for different types of shape functions. The accuracy of the formulation presented is verified by comparing to results available from the literature

Reaction of a 3-aryilidene-2-thiohydantoin derivative with polymeric trans-[CuCl2(DMSO)(2)](n) complex: unexpected isomerization to dinuclear cis-[{CuCl(DMSO)(2)}(mu-Cl)](2)

The 3-arylidene-2-thiohydantoin derivative, 3-[(2-hydroxybenzylidene)amino]-2-thioxoimidazolidin-4-one, was synthesized in a two-step condensation reaction of 2-hydroxybenzaldehyde, thiosemicarbazide and ethyl chloroacetate. The ligand was structurally characterized by NMR and IR spectroscopy, as well as by elemental analysis. In the reaction of the well-known polymeric trans-[CuCl2(DMSO)(2)](n) complex with the polydentate thiohydantoin type ligand, instead of the corresponding copper thiohydantoin complex, unexpectedly, the dinuclear cis-[{CuCl(DMSO)(2)}(mu-Cl)](2) complex (1) was formed predominantly as the final stable product. The structure of the complex 1 was confirmed by single crystal X-ray diffraction analysis. The cis-complex is obtained through assisted isomerization of the trans-form, in which the thiohydantoin derivative has a crucial role

Assessing speleoarcheological geoheritage: Linking new Paleolithic discoveries and potential cave tourism destinations in Serbia

The aim of this paper is to perform a tourist assessment of the representative speleoarchaeological geoheritage in Serbia for the purposes of establishing new cave tourism destinations in Serbia. Seven caves have been selected based on their speleoarcheological values. However, only two of them are currently available for visiting. The research results were obtained by using the M-GAM model and they indicate exceptional tourist potential which still remains mainly untapped. To maximize this potential and develop this type of tourism in the future, an initiative strategy for the inclusion of speleoarchaeological values into contemporary tourism flows was also proposed. The focus is set on the establishment of speleoarchaeological visitor centers and a unique tourist affirmation of the researched scientific and educational potential. The presented strategy must be set as a priority in the future in order to contribute to further sustainability of scientific and socio-economic progress through speleotourism development

Geomorphological and hydrological heritage of Mt. Stara Planina in SE Serbia: From river protection initiative to potential geotouristic destination

Mt. Stara Planina is located in the eastern part of the Republic of Serbia and represents the westernmost part of the large mountain massif of the Balkans. Both endogenous and exogenous forces created interesting geomorphological and hydrological features for geotourism development in this area. This article proposes a preliminary list of geomorphological and hydrological sites and analyses them to reveal which geosite possesses geotourism potential. This research was carried out by applying the modified geosite assessment model. In this article, ten geosites were singled out based on the degree of their attractiveness for geotourism development. The results reveal information about the key fields of improvement for each evaluated geosite, and identify which areas require more attention and better management in the upcoming period for Mt. Stara Planina to become a well-known geotourism destination that would attract a large number of tourists in the future

Dynamic fracture testing using Charpy instrumented pendulum

Charpy impact testing of a high strength low-alloyed (HSLA) steel has been performed by simultaneously recording two independent signals. The magnetic emission (ME) and potential drop (PD) techniques were used to determine critical crack initiation properties on standard V-notched and pre-cracked three-point bending specimens at room temperature. Both signals (ME and PD) were recorded and compared, with the purpose of more precise identification of critical fracture mechanics parameters determining the onset of ductile crack growth. Standard Charpy specimens made of HSLA steel, oriented perpendicular to rolling direction were tested by a modified instrumentation of the Charpy machine, which included the original magnetic emission, and the potential drop techniques. The strain gauges and emission probes, located on the hammer tup, measured the force, thus both the magnetic and electric potential drop signals were monitored and recorded as a function of time. The obtained results indicate good agreement between ME and PD techniques on evaluation of ductile crack growth initiation point

Dynamic fracture testing using Charpy instrumented pendulum

Charpy impact testing of a high strength low-alloyed (HSLA) steel has been performed by simultaneously recording two independent signals. The magnetic emission (ME) and potential drop (PD) techniques were used to determine critical crack initiation properties on standard V-notched and pre-cracked three-point bending specimens at room temperature. Both signals (ME and PD) were recorded and compared, with the purpose of more precise identification of critical fracture mechanics parameters determining the onset of ductile crack growth. Standard Charpy specimens made of HSLA steel, oriented perpendicular to rolling direction were tested by a modified instrumentation of the Charpy machine, which included the original magnetic emission, and the potential drop techniques. The strain gauges and emission probes, located on the hammer tup, measured the force, thus both the magnetic and electric potential drop signals were monitored and recorded as a function of time. The obtained results indicate good agreement between ME and PD techniques on evaluation of ductile crack growth initiation point

Dynamic fracture mechanics testing of the HSLA steel

The high strength low alloyed steel (HSLA) has been tested using instrumented Charpy pendulum in order to assess its impact fracture resistance. Testing was performed at different temperatures (-70°C; -30°C; +20°C), using different energy levels (300 J and 62.5 J) on standard three-point bending specimens with different crack lengths (a/W=0.35+0.65), having the parallel and perpendicular orientation to rolling. The applied magnetic emission (ME) technique was used to determine initiation of crack propagation. The ME signal was recorded by digital oscilloscope and used to determine initiation of brittle fracture, whereas for ductile fracture the signal was integrated (MF). The representative dynamic fracture property, Ji, is determined from data obtained from measurements that arc handled by a spreadsheet procedure.[https://www.gruppofrattura.it/ocs/index.php/esis/ecf12/paper/view/5905/3059

Dynamic fracture mechanics testing of the HSLA steel

The high strength low alloyed steel (HSLA) has been tested using instrumented Charpy pendulum in order to assess its impact fracture resistance. Testing was performed at different temperatures (-70°C; -30°C; +20°C), using different energy levels (300 J and 62.5 J) on standard three-point bending specimens with different crack lengths (a/W=0.35+0.65), having the parallel and perpendicular orientation to rolling. The applied magnetic emission (ME) technique was used to determine initiation of crack propagation. The ME signal was recorded by digital oscilloscope and used to determine initiation of brittle fracture, whereas for ductile fracture the signal was integrated (MF). The representative dynamic fracture property, Ji, is determined from data obtained from measurements that arc handled by a spreadsheet procedure.[https://www.gruppofrattura.it/ocs/index.php/esis/ecf12/paper/view/5905/3059

Application of two independent measurement techniques for determination of ductile crack growth initiation

Charpy impact testing of the high strength low-alloyed steel has been performed by simultaneously recording two independent signals. The magnetic emission (ME) and potential drop (PD) techniques were used to determine critical crack initiation properties on standard three-point pre-cracked bending specimens at room temperature. Both signals (ME and PD) were recorded by digital oscilloscope with a high sampling rate and compared, with the purpose of more precise identification of critical fracture mechanics parameters determining the onset of ductile crack growth