Volume 3 Issue 3
Computational Modeling of Failure Patterns of Glass Panels with Imperfections Subjected to Air Blast
Authors: Hossein Ataei; James C. Anderson
Abstract: Glass fragments are a prime source of injury to occupants of buildings subjected to explosive events during which window glass breaks into either flying shards (annealed glass windows) or fragments (fully tempered glass). These account for injuries ranging from minor cuts to severe wounds. A successful blast-resistant glazing design requires balancing of the safety and security of the window panels with physical appearance and cost-effectiveness. Moreover, it should consider the principles of a reasonable degree of protection against explosive threats based on the proposed level of security and previous lessons learned. In this paper, explicit finite element method (FEM) with is used for modeling the window failure and investigate the failure patterns of annealed and fully tempered glass windows panels with embedded imperfections across the panel. For this purpose, the element-removal technique is utilized in accordance with the fracture micromechanics' principles and the brittle failure criteria of displacements; strains and stresses. The results of the analysis demonstrate that the response of the conventionally-framed window panels to blast loading cases depends upon the glazing technologies; blast load intensities; the glass types; and the location of imperfections. Through the application of element removal technique and stress redistributions at each infinitesimal time increment, the results of this paper further demonstrates that the existence of glass imperfections in the window panels will make them more vulnerable against the air blast overpressures for both annealed and fully-tempered glass panel cases: For fully tempered glass panels, the vulnerability arises from greater stress concentrations at the location of glass defects as well as higher brittleness of the panel itself when compared to the annealed glass panels. The results of this study show that the existence of defects along the edges will help in redistribution of the stresses in a way that the yield lines will pass through these imperfection locations. The general failure pattern for defective annealed glass panels subjected to small intensity air blast will be very similar to the failure pattern of homogeneous window panels yet with a faster pace. However, when subjected to a higher intensity air blast, the severity of the load will cause excessive rotation angles in the panel and subsequent computational divergence and instability. The panel failure will occur much faster and with different patterns compared to the case of annealed glass panels subjected to smaller intensity air blasts.
Keywords: Glass; Air Blast; Safety; Window Panels; Fracture Mechanics; Crack Propagation
Authors: Tsukuru Kodera; Shuuichi Shutou; Takashi Nakae; Takahiro Ryu; Hajime Ono; Hironori Matsuoka
Abstract: The present paper describes the influence of the viscosity of cutting oil on tool wear and the roughness of the finished surface when using a cemented carbide tool in dry and minimal quantity lubrication (MQL) systems for turning. The following results were obtained. (1) At a feed rate of 0.2 mm/rev, the side flank boundary wear reduction effect was obtained with cutting oil having a low viscosity of 4.9 mm2/s in the MQL system, irrespective of cutting speed. The front flank boundary wear increased in MQL compared to dry cutting, and double boundary wear was observed. (2) At a feed rate of 0.4 mm/rev, cutting oil having a moderate viscosity of 9.3 mm2/s provided suitable side flank boundary wear, irrespective of cutting speed. (3) The front flank boundary wear obtained using the MQL system was greater than that for dry cutting. The transcription of the groove of this front flank boundary wear formed the finished surface roughness.
Keywords: Cutting; Turning; Dry; MQL; Viscosity Grade; Tool Wear; Finished Surface Roughness
Authors: E. K. Kostikova; Yu. V. Zaika
Abstract: In the context of problems of hydrogen and thermonuclear power engineering intensive research is being conducted into ways to protect construction materials against hydrogen corrosion, chemical reactor design, materials suitable for hydrogen storage and transporting. Mathematical models help to specify physical-chemical ideas about the interaction of hydrogen and its isotopes with solids, to discover the limiting factors and to significantly reduce the expenses of experimental research by means of numerical simulation for different parameters and experimental conditions (including extreme ones). Classical diffusion models are often insufficient. The paper is devoted to the model and numerical solution of the boundary-value problems of hydrogen thermo desorption taking into account nonlinear sorption-desorption dynamics on the surface and its reversible capture in the bulk. Computational algorithms based on difference approximations and the results of computer simulation of the hydrogen thermo desorption flux from a structural material sample are presented.
Keywords: Hydrogen Interaction with Solids; Surface Processes; Thermo Desorption Method; Nonlinear Dynamical Boundary-value Problems; Finite-difference Schemes; Computer Simulation
Authors: Atul Chaskar; Sunil Virkar
Abstract: Anionic layered Mg-Al Layered Double Hydroxides (LDHs) have the potential to develop a broad range of new polymer nanocomposites with improved properties viz flame-retardancy (FR), retention or stabilization of dyes, additives, etc. New Low density polyethylene (LLDPE) based nonocomposite materials containing Mg-Al LDH and biocides (BIT) have been designed, synthesized and characterized. MAH-g-PE is used as a compatibilizer. Modification of LDH changes interlayer spacings (distance). Thermogravimetry analysis (TGA) depicted that the loss of biocides due to diffusion/ evaporation is clearly reduced by LDH. Scanning transmission electron microscopy (STEM) images of diluted samples show that most LDH still consist of several layers indicating incomplete or little e xfoliation.
Keywords: Low Density Polyethylene; Nanocomposite; Biocides; Compatibilizer; Scanning Transmission Electron Microscopy
Authors: M. Indira Devi; N. Bendangsenla; T. Moaienla
Abstract: The absorption spectra in transition metal ions involving d-d transitions have been used for following the kinetics of the chemical reaction leading to the development of the mechanism of chemical and biochemical reactions. The 4f-4f transition spectral intensity changes have very rarely been used for mechanistic and kinetic investigations. Thus, it has been considered quite interesting to explore the interaction of Pr3+with biomolecules in presence of Ca2+ by employing absorption spectral research owing to the ease of Ln3+ ions to act as surrogates for Ca2+ ions. The kinetics for the complexation of Pr(III): Amino acid with Ca(II) have been investigated in DMF medium at different temperatures viz., 298K, 303K, 308K, 313K and 318K. Three amino acids viz., Glycine, L-Alanine and L-Phenylalanine were selected for the kinetic study of the complexation reactions of Ln(III) ion and amino acid ligands in the presence of Ca(II) ion. From the values of the rate of reaction at different temperatures, the activation energy (Ea) of the various complexes are determined and from the calculated data of activation energies, thermodynamic parameters like ∆H0, ∆S0 and ∆G0 of the formation of complexes are evaluated. The determined activation energy parameters corresponding to the rate constants and thermodynamic parameters corresponding to the formation of the complexes of Pr(III): Amino acid: Ca(II) were found to be highly favourable.
Keywords: 4f-4f Transition; Absorption Spectral Studies; Kinetics; Activation Energy; Thermodynamic Parameters
Authors: V. Ganesan; Prasanta Jana
Abstract: Carbon foam is employed for trapping fission products (137Cs, 134Cs) and nickel foam is employed for trapping activated corrosion products (54Mn, 60Co) from primary sodium system of fast reactor. However, deployment of individual radionuclide traps with associated shielding for each trap in the active building of a reactor demands larger floor space which has substantial financial implication. Hence, it is desirable to reduce the floor space requirement by incorporating multi radionuclide traps in single location. Therefore, it is necessary to search for materials (termed as multi-trap material) capable of trapping fission and activated corrosion product radionuclides of interest simultaneously from primary sodium circuit. In line with this, the present work describes the development of composite foam materials containing carbon and nickel for multi-trap application. This paper describes three different types of carbon composites namely nickel dispersed carbon foam (density 0.09 g. cm-3 and porosity 96%), nickel dispersed carbon coated alumina foam (density 0.03 g. cm-3 and porosity 99%) and carbon coated nickel foam (density 0.28 g. cm-3 and porosity 97%). The synthesis route of these carbon composite foams follow solution combustion route. By varying the reagents and quantities, the foam materials of interest were obtained. Such carbon composite foam materials are suitable for multi-trap applications.
Keywords: Carbon Composite Foam; Multi Radionuclide Trap; Fission Products; Activated Corrosion Product; Activity Transport; Electron Microscopy
Authors: D.Y. Yakovlev; D.Y. Lipatov; I.A. Ivanov; M.A. Matusko; E.K. Malkin; V.K. Vasilyev; A.V. Golovin; V.V. Belyakov; V.S. Pershenkov; Y.R. Shaltaeva; E. A. Gromov
Abstract: The sampling unit of the device, based on ion mobility spectroscopy technique, for detection of ultra-small concentration of substances on human fingers and documents, is described. The vapor pressure of some substances is subtle; so the heating of an examined surface is a must for efficient detection of these substances. In the present work it was shown (by the thermal transfer investigation) that more efficient method of surface heating consists of the using of the impulse gas-discharge lamp in comparison with the use of a heated air flow or heat transfer from the warm body by thermal conductivity. However the heating of the human fingers by the irradiation of the gas-discharge lamp is not effective because of a small concentration of the melamine (pigment of the black or brown color) in the skin of the human palm. Therefore in this work the combination of the two methods is used: irradiation of the gas-discharge lamp heats grid and a grid heat the surface of the finger that is pressed to a grid. The system will be effective for the control of admission to public events and providing anti-terrorist measures [1-3].
Keywords: Ion Mobility Spectrometry; Explosives; Human Fingers; Documents; Personnel Portal Sampling