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Mechanical properties of welded pipes produced by high frequency welding of the steel API J55
Get PDFSelection of steel, dimensions and methods of production of welded pipes is
a segment of the design process, because it is closely related to the function of a piping
as a structural whole under predetermined conditions and for a precisely anticipated
service life. The quality of welded pipes during the production process is defined by
characteristics that they must possess in order to meet certain requirements, which is
being achieved by choosing appropriate procedures and welding parameters, execution
of control process for all technological operations during the production, as well as by
carrying out mechanical and technological tests regarding the strength and straining of
base material and welded joints. This paper presents the results of tests carried out in
order to determine mechanical properties of longitudinally welded pipes made by highfrequency
contact welding of steel API J55
Standardizacija, ispitivanje i analiza nosivosti šipova
Get PDFU radu su prikazani aspekti standardizacije i karakteristični primeri ispitivanja nosivosti šipova sa određenom analizom rezultata, pri čemu se metodologija ispitivanja oslanja na postojeće ASTM i sopstvene standarde, sopstvena znanja i iskustva, ali i na metodologiju ispitivanja prikazanu u naučnom radu Pile Integrity and Load Testing: Methodology and Classification. Ispitivanja šipova su sprovedena primenom sopstvene opreme sa licenciranim hardverima i softverima za test statičkog opterećenja šipa (SLT - Static Load Test) i test dinamičkog opterećenja šipa (DLT - Dynamic Load Test). Ukazano je na aspekte primene različitih oprema i metodologija ispitivanja u različitim situacijama. Takođe, ukazano je na potrebu izrade plana ispitivanja nosivosti šipova kada su u pitanju veliki i značajniji objekti
The new tool insert design for prevention the rotation of horizontal wire during shear testing of welded fabric
Get PDFMany new requirements in the field of experimental mechanics, like testing of metallic materials, emphasize traceability and accuracy of test results as the end goal. These requirements have energy efficiency context too, due to the increase of mass productions of many finished and semi-finished products based on steel metallurgy. Combined, both of the above-noted perspectives impose the need for improvements of some of the existing test methods. This paper describes one such improvement, the developing of the new insert tool for testing of shear strength of the welded fabric, for civil engineering. The developed tool allows repeated testing of welded joints sampled from the welded fabric of different dimensions without tool changes and is generally related with the procedure for the determination of shear strength properties of different sizes of wires used for welded fabric. The construction of the tool insert allows aiming high operation safety and higher accuracy of results, which is described in detail. The paper also presents experimental results and the Finite Element Analysis performed in order to verify the impact of insert tool application on the testing results. The obtained results and conclusion about the possible contributions of the developed insert tool for extensively testing of welded fabric for civil engineering are discussed
Assessment of the effectiveness of producing mineral fillers via pulverization for ceramic coating materials
No full textThe effectiveness of employment of mechano-chemical activation in the production of high temperature ceramic coating materials was assessed. The properties of mineral fillers are directly dependant on the choice of activation variables. Mathematical modeling was employed for optimization of ultra-centrifugal pulverization and determination of optimal characteristics of investigated materials. The properties of treated resources were mathematically correlated to the variations in their granulometry. The dependencies between the set of the activation parameters and characteristics of a material were mathematically modeled and estimated. Chemometric methods were employed in the calculations. The samples are classified by Principal Component Analysis, while comprehensive comparison between analyzed samples was achieved by Response Surface Method and Standard Score. Mathematical models predict the quality parameters of activated powders with high accuracy in a broad range of processing parameters. The r2 values were in the range from 0.71 to 0.98 for established models for processing of talc, mica, fly ash and alumina powders. The set of processing parameters related to the 120 Μm sieve mesh size was selected as optimal procedure with acquired standard score values 0.7 for mica, 1.0 for talc, 0.9 for fly ash and alumina. Optimal processing parameters can diminish the negative effect of raw materials inherent properties on the target score, which in return enhances energetic and economic sustainability of the mechano-chemical activation of resource materials utilized in the production of ceramic coating materials
Analiza postupka ocenjivanja životnog ciklusa opekarskih proizvoda
Get PDFPoznato je da se u proizvodnji opekarskih proizvoda koriste velike količine sirovina koje takođe uključuju visoku potrošnju energije što se negativno odražava na kvalitet životne sredine. Ocenjivanje životnog ciklusa (eng. Life Cycle Assesment-LCA) je metod za analizu i kvantifikaciju mogućih uticaja proizvoda na životnu sredinu tokom celokupnog životnog veka proizvoda, od ekstrakcije sirovina, preko proizvodnje, upotrebe, postupanja na kraju životnog veka proizvoda, recikliranja i konačnog odlaganja. Shodno tome, u radu je predstavljena analiza postupka ocenjivanja životnog ciklusa opekarskih proizvoda u cilju proizvodnje održivih građevinskih proizvoda
Numerički proračun karakteristika betona za atenuaciju jonizujućeg zračenja
No full textU ovom radu se prikazuje metod numeričkog proračuna totalnog masenog atenuacionog koeficijenta kao jednog od osnovnih radijacionih karakteristika materijala od kojih se proizvode betoni za specijalnu namenu. Primenom softvera XCOM urađeni su numerički proračuni, a potom su upoređeni rezultati između vrednosti masenog atenuacionog koeficijenta za izabrani tip betona sa baritom, za betone koji su kombinacija čelika sa magnetitom i čelika sa limonitom, kao i za UHPC beton sa baritom i nanosilikom
The effect of aftershock on 2D RC frame founded on piles with P-Y curves
Get PDFThis paper presents the manner of modeling the aftershock (in an earthquake), the phenomenon whose significance has been noted in the second half of the 20th century. Itlists the constructional systems in which the consideration of the aftershock is important. It shows in more detail the model of the skeletal RC construction, i.e. the 2D RC facade frame constructed on the 60cm-diameter drilled RC piles. The dynamic interaction soil-pile, i.e. the non-linear behaviour of the soil is modelled with the horizontal p-y curves for sand, applying multiplastic link elements. For the accelerogram El Centro during time history (TH) the global and (local) drift, the condition of plastic hinges were considered
Effect of LCF on behavior and microstructure of microalloyed HSLA steel and its simulated CGHAZ
No full textNumerous structural components made of high strength low-alloyed steels are often exposed to low-cycle fatigue loading during their exploitation life. In order to study the fatigue behavior of one grade of structural steels produced in Yugoslavia during the eighties of the last century, a push-pull constant amplitude strain-controlled fatigue tests were conducted at room temperatures. This paper analyses behavior of two different materials, parent steel (PM) and its coarse-grained (CG) simulated heat-affected zone (SHAZ) exposed to the action of low-cycle fatigue (LCF) loading performed in the range from 1 to 10(4) cycles. LCF tests were conducted at strain ratio R = -1 at strain amplitude range from 0.3% to 0.8%. The materials' Coffin-Manson parameters appearing in the strain-life and cyclic stress-strain curves were calculated. Fracture surface analysis of both materials was done. The results showed that plasticity under dynamic load conditions is satisfactory for both materials which give them good resistance to crack initiation and propagation
Validation of energy-dispersive X-ray fluorescence procedure for determination of major and trace elements present in the cement based composites
No full textAdjustment and subsequent validation of energy-dispersive X-ray fluorescence (ED-XRF) method for cement based binders with addition of mineral raw materials (fly ash, zeolite and bentonite) was conducted. Eighteen chemical elements present in the material composition were analyzed: ten major elements (Si, Al, Fe, Ca, Mg, S, Na, K, Ti, P) and eight trace elements (Cr, Zn, Cu, As, Ni, Pb, Sr, Mn). Thirty-five samples of either certified reference materials or reference materials of cement, fly ash and clay were utilized during adjustment and optimization of the investigated ED-XRF procedure. The method was consecutively validated in terms of selectivity, precision, working range, linearity, accuracy, robustness, limits of detection and quantification. Thirty-two samples in total, i.e. three certified reference materials and twenty-nine reference materials, were simultaneously analyzed by ED-XRF and inductively coupled plasma optical emission spectrometry (ICP-OES). Comparison of the outputs of monitored methods showed infinitesimally small differences, as correlation coefficients were extremely good (approximate to 1), which highlighted ED-XRF as highly satiable alternative for ICP-OES for the chemical analysis of cement binders