The experimental investigation of the mechanical properties of steel fibre-reinforced concrete according to different testing standards

Steel fibre-reinforced concrete (SFRC) is widely applied in the construction of civil infrastructure projects, including the following: industrial floors, slabs, walls, and foundations. The application of steel fibres in the reinforcement of concrete remarkably improves the postcracking behaviour of such concrete. In order to estimate this property, the energy involved in absorption is measured by using several valid testing standards: EVS-EN 14651:2005, EVS-EN 14488-5:2006, and ASTM C1550-12a. The objective of this study was to carry out a comparable analysis of the results that have been obtained using previously-mentioned standards and to be able to find a more reliable method for the determination of the fracture toughness of SFRC specimens. Experiments were carried out in accordance with the chosen standards. It was concluded that procedure involved in the ASTM standard provides a smaller variability of results with better levels of repeatability, therefore a smaller volume of specimens can be tested in one series in order to achieve reliable results

Comparison of Some Mechanical and Physical Methods for Measurement of Residual Stresses in Brush-Plated Nickel Hardened Gold and Silver Coatings

Hard gold and silver are applied in coating owing to their high hardness, good wear and corrosion resistance for engineering application (e.g. on generators slip rings, sliding contacts and small machine parts) and are typically plated on copper (mostly), brass and bronze. The studied nickel-hardened gold and silver coatings were brush plated on open thin-walled copper ring substrates. Residual stresses in the coatings were calculated from the curvature changes of the substrates. Biaxial intrinsic residual stresses were also determined by nanoindentation testing and by the X-ray technique. The values of the residual stresses represented tensile stresses and when determined by the techniques used they were comparable within a maximum limit of measurement uncertainty. These stresses relax; the dependence of relaxation time was approximated by a linear-fractional function.DOI: http://dx.doi.org/10.5755/j01.ms.22.1.7439</p

Interpretation of Experimental J^PC Exotic Signals

We investigate theoretical interpretations of the 1.4 GeV J^PC exotic resonance reported by the E852 collaboration. It is argued that interpretation in terms of a hybrid meson is untenable. A K-matrix analysis shows that the 1.4 GeV enhancement in the E852 eta pi data can be understood as an interference of a non-resonant Deck-type background and a resonance at 1.6 GeV. A final state rescattering calculation shows that the 1.6 GeV hybrid has a eta pi width which is bounded above by 57 \pm 14 MeV.Comment: 23 pages, LaTeX, 4 encapsulated postscript figures. Accepted for publication by Physical Review

Light Meson Spectroscopy

We survey the current status of light meson spectroscopy. We begin with a general introduction to meson spectroscopy and and its importance in understanding the physical states of Quantum Chromo Dynamics (QCD). Phemenological models of hadron spectroscopy are described with particular emphasis on the constituent quark model and the qualitative features it predicts for the meson spectrum. We next discuss expectations for hadrons lying outside the quark model, such as hadron states with excited gluonic degrees of freedom. These states include so-called hybrids glueballs}, as well as multiquark states. The established meson states are compared to the quark model predictions and we find that most meson states are well described by the quark model. However, a number of states in the light-quark sector do not fit in well, suggesting the existence of hadronic states with additional degrees of freedom. We end with a brief description of future directions in meson spectroscopy.Comment: 111 pages with 28 imbedded figures, in LaTeX2e with no special macros. Submitted to Reviews of Modern Physics, Nov.12, 199

Collins and Sivers asymmetries in muonproduction of pions and kaons off transversely polarised protons

Measurements of the Collins and Sivers asymmetries for charged pions and charged and neutral kaons produced in semi-inclusive deep-inelastic scattering of high energy muons off transversely polarised protons are presented. The results were obtained using all the available COMPASS proton data, which were taken in the years 2007 and 2010. The Collins asymmetries exhibit in the valence region a non-zero signal for pions and there are hints of non-zero signal also for kaons. The Sivers asymmetries are found to be positive for positive pions and kaons and compatible with zero otherwise. © 2015

IMPULSE-PERIODICAL MULTIFUNCTIONAL SOURCES OF IONS ON THE BASE OF A VACUUM ARC AND NON-TRADITIONAL METHODS OF THE IONIC-BEAM-IONIC-PLASMA PROCESSING OF MATERIALS

The law investigation of the formation of impulse one- and multicomponent beams of accelerated ions is the aim of the paper as well as the particular feature investigation of their interaction with the solid body surface. As a result the physical model for the control of parameters of impulse ionic beams and plasma flows in sources on the base of a vacuum arc has been created. Models for the obtaining of big concentrations of an alloying admixture at the impulse-periodical implantation have been developed as well as new ionic sources. The measuring-diagnostic complex with the sounding of a surface by a beam of ions of microne sizes has been created. New methods of the impulse-beam, ionic-plasma processing of materials have been represented. Methodologies and plants have been introduced into operation. The paper results may find their field of application in the ionic-beam processing of non-semiconducting materialsAvailable from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio

On the Determination of Residual Stress in Coatings from Measured Longitudinal Deformation of a Substrate

A method of measuring longitudinal deformation for determination of residual stresses in a long homogeneous cylinder by removal of thin cylindrical concentric layers was proposed by Heyn an Bauer [1]. In [2-6] it is shown that computation of residual stresses is possible from the longitudinal deformation of a cylindrical substrate, measured during coating deposition. The present paper presents a generalized theory of the method of measuring the longitudinal deformation of a long cylindrical substrate for determination of initial residual stresses in coatings. Unlike in [2-6], the possibility of prestressing the substrate by an elastic element (spring) is taken into account [7]. Special cases like (1) Poisson´s rations of the substrate and coating are equal, (2) Poisson´s ratios and the moduli of elasticity of the substrate and coating are equal, (3) a thin coating is applied on a rigid substrate, etc. are examined. A linear-fractional function is proposed for approximation of the dependence of initial stress on coating thickness

Consideration of Thermal Stresses in Experimental Residual Stress Analysis for Coatings

Usually, the coefficients of thermal expansion of the coating and substrate are different and the temperature of coating process differs from room temperature (20ºC). Therefore thermal stresses are generated in coated parts. In experimental analysis of residual stresses it may turn out that caoting temperature differs from the temperature at which the deformation parameters of the substrate are measured. In Susch cases the measurement results have to be corrected taking into account the thermal stresses. In this study, the equations for correction of the residual stresses in coatings, determined from the measured longitudinal deformations of the wire, and from the tubular and strip substrates [1-3], are presented. Three examples of application are given