Influence of changes of the bending plane position on the fatigue life

The paper concerns influence of changes of the bending plane position on the fatigue life. The obtained results were analyzed and compared with the fatigue results for oscillatory bending. The applied specimens were smooth, they had round sections, and they were made of the leaded brass CuZn40Pb2 (MO58). The results obtained under cyclic bending with the plane position change were compared with the results obtained for the specimens with the same parameters under pure oscillatory bending. A change of the bending plane position occurred every 10% fatigue life determined under pure oscillatory bending at the given amplitude of the bending moment, according to the defined fatigue characteristics. Calculated values of nominal stress in a cross section were recalculated according with cyclic material properties and values of elasto‐plastic stress were obtained.     

Reputation as optimality measure in Wireless Sensor Network-based monitoring systems

In this paper we propose a new optimality measure for Wireless Sensor Network-based structural monitoring systems. First, we present the results of experiments showing the reasons for random effects in Wireless Sensor Network (WSN) functioning. Then, the formulas for calculating a network’s reputation measure are given. Finally, we conclude with arguments for the application of the reputation-based optimality measure in WSNs. We propose significantly new recommendations for the design and usage of WSNs.     

Infrared and raman investigations of the charge ordering phenomena in the monoclinic salts κ-(BEDT-TTF)4[M(CN)6][N(C2H5)4]·2H2O (M=CoIII, FeIII)

The monoclinic crystals of κ-phase charge-transfer salts formed by BEDT-TTF with Co(CN)₆ or Fe(CN)₆ anions undergo a phase transition at T=150 K. Temperature dependences of FT-NIR Raman spectra and IR reflectance spectra were studied. We show that the phase transition is related to a charge ordering and there exist charge fluctuations above 150 K.     

Evolution of the microstructure in the hot rolling process

A thermomechanical finite-element model of flat rolling is coupled with closed form equations describing the process of recrystallization and is applied to study hot rolling of low carbon steel strips. Formulae for the recrystallized grain diameters, developed by various authors, are considered. Calculated diameters of the grains are compared with the results of the measurements carried out after experimental hot rolling of the carbon steel samples. Evaluating the accuracy of the calculations, using each of the expressions for the diameter of the recrystallized austenite grains, indicates that the relation of Roberts is closest to the measurements.     

The microstructure of liquid immiscible Fe–Cu-based in situ formed amorphous/crystalline composite

In the microstructures of slowly and rapidly cooled liquid of the immiscible alloy Fe₃₀Cu₃₂Ni₁₀Si₁₃Sn₄B₉Y₂ two distinct regions were observed following arc melting and slow cooling, confirming that liquid/liquid phase separation had occurred. Rapid cooling from a temperature within the liquid immiscibility gap, melt spinning, resulted in an amorphous/crystalline composite, formed from the previously melted Fe- and Cu-rich regions, respectively. Transmission electron microscopic studies of this melt-spun ribbon revealed the glassy nature of the Fe-rich matrix, as well as of the Fe-rich spheres formed within the previously existing Cu-rich liquid.     

Electrodeposition of amorphous/nanocrystalline and polycrystalline Ni-Mo alloys from pyrophosphate baths

Pyrophosphate plating bath was found to be a good alternative to citrate bath for deposition of Ni-Mo amorphous alloys. The addition of wetting agents such as 2-butyne-1,4-diol and rokafenol N-10 to the pyrophosphate bath resulted in the removal of bumps, spheres and cracks from the Ni-Mo alloy surface. The plated alloy layers adhered well to Cu-Zn brass and steel, were of thickness from a fraction to tens of micrometers and the molybdenum content was independent of the distance from the support. An increase in the concentration of the molybdate ion in the bath leads to an increase in the amount of Mo in the alloys up to 33-35 at.% and to a decrease in the deposition rate. These changes and the influence of pH are discussed in the paper. The atom arrangement in the alloys changes from (2 2 0) preferred for pure-nickel deposition to (1 1 1) for content of Mo higher than 15 at.%. For 20 and more at.% of Mo the structure of the alloy is amorphous like. An analysis of SEM and STM micrographs obtained indicates that contrary to the Ni-W alloy the “amorphous” phase is made of circa 10-50 nm in diameter objects and not by long needles perpendicular to the substrate.     

Various Approaches in Kinetics Modeling of Real Feedstock Hydrodesulfurization

This brief review discusses various important approaches in kinetics modeling of real feedstock hydrodesulfurization. These include analytical aspects of dealing with complicated real feedstock, structural approaches, linear-free energy relationships, and the continuum theory in hydrodesulfurization modeling.     

Influence of local postbuckling behaviour on bending of thin-walled beams

The influence of the local postbuckling behaviour on the bending of thinwalled beams is studied. The analysis of the postbuckling behaviour of a prismatic column-beam subject to compression and bending is employed in order to determine the overall flexural stiffness of a beam after local buckling. The asymptotic Koiter method is used in the second order approximation. The determination of post-buckling coefficients enables one to find the beam's flexural stiffness without the necessity of using hypotheses on effective widths of eccentrically compressed plates. It is shown that the post-buckling equilibrium branch in a bending moment-global curvature coordinate system for a perfectly elastic thin-walled beam is rectilinear (in the second order approximation of' the asymptotic method). Simple analytical relations are presented between the slope of the post-buckling equilibrium branch of global bending and post-buckling coefficients for local buckling mode. The results obtained are compared with data reported by other authors.     

Bestimmung des Grenzumformgrades mit dem Torsionsversuch

Die Bestimmung des Grenzumformgrades eines Stahles, der während der plastischen Verformung nicht überschritten werden kann, ist von großer Bedeutung. Die vorliegende Arbeit berichtet über Ergebnisse von Warmtorsionsversuchen, aus denen der Grenzumformgrad als Funktion von Temperatur und Umformgeschwindigkeit ermittelt wurde. Die Versuche wurden an den Stählen X 10 CrNiTi 18 9, 10 CrMo 9 10, X 10 CrNiMoTi 18 12, X 20 CrMoV 12 1 und X 2 NiCrNb 25 18 durchgeführt.     

A study of the electrical conductivity processes in amorphous semiconductors using the computer simulation method I. One-dimensional case

In this paper we present a computational model of electrical conductivity processes via variable range hopping of electrons between localized states (‘sites’) in quasi one-dimensional disordered systems. For two, slightly different models, the temperature dependence of the conductivity of parallel connected systems of filaments and of quasi-infinite, single filaments are discussed and compared with theoretical and experimental results.