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Blocked polyisocyanate crosslinkers for powder coatings were synthesized using alicyclic diisocyanates (TMDI and IPDI), formic acid, (methylaminopropyl) hepta(isobutyl)Si 8O 12 (POSS), ε-caprolactam, dibutyltin dilaurate as well as triethylamine as catalysts. The chemical structures of these compounds were characterized by means of IR, 1H NMR and 13C NMR spectroscopy. The three-dimensional surface topography and surface chemical structure of the resulting powder coatings were investigated by using confocal microscope and ATR FT-IR. The values of surface roughness parameters were calculated. The surface topography was correlated with the chemical structure of the coatings and macroscopic surface behaviour: surface free energy, abrasion resistance, hardness, adhesion to the steel surface and impact resistance. Thermogravimetric analysis was employed to assess the hardening property of powder coatings and the thermal decomposition processes. © 2012 Elsevier B.V. Source

This paper presents results of the complex stress and crack initiation analysis of the PZL-10. W turbo-engine compressor blade subjected to high cycle fatigue (HCF). A nonlinear finite element method was utilized to determine the stress state of the blade during the first mode of transverse vibration. In this analysis, the numerical models without defects and also with V-notches were defined. The quality of the numerical solution was checked by the convergence analysis. Obtained results were next used as an input data into crack initiation (ε-. N) analyzes performed for the load time history equivalent to one cycle of the transverse vibration. In the fatigue analysis the different methods such as: Neuber elastic-plastic strain correction, linear damage summation and Palmgreen-Miner rule were utilized. As a result of ε-. N analysis, the number of load cycles to the first fatigue crack appearing in the compressor blades was obtained. Moreover, the influence of the blade vibration amplitude on the number of cycles to the crack initiation was analyzed. Values of the fatigue properties of the blade material according to Baumel-Seeger and Muralidharan methods were calculated. The influence of both the notch radius and values of the UTS of the blade material on the fatigue behavior of the structure was also considered. In the last part of work, the finite element results were compared with the results of an experimental vibration HCF tests performed for the compressor blades. © 2011 Elsevier Ltd. Source

Hanus R.,Rzeszow University of Technology
International Journal of Multiphase Flow

Measuring parameters of two-phase flows usually requires contactless measuring techniques to be used together alongside advanced methods of signal processing. One of these techniques, which has been employed for many years in measurements of liquid-gas, liquid-solids and gas-solid flows is a method of gamma-ray densitometry. Frequently in such measurements mutually delayed stochastic signals are received from the scintillation detectors. For the analysis of such signals a well-known cross-correlation function (CCF) is used due to the random nature of the signals and the presence of disturbances.This paper applies the Hilbert Transform to the time delay estimation in measurements of two-phase flow performed by using gamma-ray absorption. It presents the selected results of study of the modified CCFHT cross-correlation method, in which a Hilbert Transform of one measured signal is used. The experiments have been carried out for two-phase water-air flow through a horizontal pipeline of 30mm inner diameter. A sealed 241Am gamma ray source of 59.5keV energy has been used in the experiments mentioned above, together with scintillation detectors based on NaI(Tl) crystals. Based on obtained values of time delay the mean velocity of gaseous phase transported by liquid was calculated. It is stated, that the CCFHT method provides better metrological properties than the classical CCF. In the presented experiments combined uncertainties of the gas phase average velocity did not exceed 3.1% for CCF and 0.05% for CCFHT. © 2015 Elsevier Ltd. Source

This paper analyzes the shearing strength analysis of single-lap joints made by self-pierce riveting with a solid rivet for various joining parameters.The sheet metal joining with various pressure force while joining with the universal rivet. The shearing tests were performed for such prepared overlap joint specimens.The capabilities of joining various material with the solid rivet with conventional tool movement solutions were presented. The strength tests were based on the uniaxial shearing test of folded joints and single-side tearing test of L-specimens. The shearing test specimens were made of various thickness arrangements from 1.0. mm to 2.5. mm and materials as steel DC01, H320LA, H400LA, aluminum alloys 5754, 5556, and stainless steel X2CrNi12, X5CrNi18-10, too.The experiments were complemented with the FEM simulation in order to track the effect of rivet type on residual stress level. The FEM simulation was also performed for different pressure edge width values in order to observe the lower sheet material plastifying. © 2013 Elsevier Ltd. Source

Kaczmarski K.,Rzeszow University of Technology
Journal of Chromatography A

Packed chromatographic columns with the superficially porous particles (porous shell particles) guarantee higher efficiency. The theoretical equation of the Height Equivalent to a Theoretical Plate (HETP), for columns packed with spherical superficially porous particles, was used for the analysis of the column efficiency for finite rate of adsorption-desorption process. The HETP equation was calculated by the application of the moment analysis to elution peaks evaluated with the General Rate (GR) model. The optimal solid core radius for maximum column efficiency was estimated for a wide spectrum of internal and external mass transfer resistances, adsorption kinetic rate and axial dispersion. The separation power of the shell adsorbent for two component mixture, in analytical and preparative chromatography, was discussed. The conditions of the equivalence between the solutions of the General Rate model with slow adsorption kinetic and the Lumped Kinetic Model (LKM) or the Equilibrium Dispersive (ED) model were formulated. © 2010 Elsevier B.V. Source

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