Thermoelastoplastic deformation of a thick-walled cylinder with a radial crack

The thermoelastoplastic fracture mechanics problem of a thick-walled cylinder subjected to internal pressure and a nonuniform temperature field is solved by the method of elastic solutions combined with the finite-element method. The correctness of the solution is provided by using the Barenblatt crack model, in which the stress and strain fields are regular. The elastoplastic problem of a cracked cylinder subjected to internal pressure and a nonuniform temperature field are solved. The calculation results are compared with available data. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 3, pp. 173–183, May–June, 2008.     

Axisymmetric frictionless contact of functionally graded materials

The main interest of this study is a new method to solve the axisymmetric frictionless contact problem of functionally graded materials (FGMs). Based on the fact that an arbitrary curve can be approached by a series of continuous but piecewise linear curves, the FGM is divided into a series of sub-layers with shear modulus varying linearly in each sub-layer and continuous at the sub-interfaces. With this model, the axisymmetric frictionless contact problem of a functionally graded coated half-space is investigated. By using the transfer matrix method and Hankel integral transform technique, the problem is reduced to a Cauchy singular integral equation. The contact pressure, contact region and indentation are calculated for various indenters by solving the equations numerically. An erratum to this article can be found at     

Water wave radiation by a sphere submerged in water with an ice-cover

Using the multipoles method, we formulate the problems of radiation (both heave and sway) of water waves by a submerged sphere in deep as well as in uniform finite depth water with an ice-cover, with the ice-cover being modelled as an elastic plate of very small thickness. In each case this leads to an infinite system of linear equations which are solved numerically by standard techniques. The added-mass and damping coefficients for a heaving and swaying sphere are obtained and depicted graphically against the wave number for various values of the radius of the submerged sphere and flexural rigidity of the ice-cover to show the effect of the presence of ice-cover on these quantities. When the flexural rigidity is taken to be zero, the numerical results for the added-mass and damping coefficient for water with a free surface are recovered.     

Numerical method and models for anti-plane strain of a system with a thin elastic wedge

The paper presents a general method to find asymptotics for a (multi-)wedge system containing a thin wedge. It employs separation of the symmetric and anti-symmetric parts of the boundary displacements and tractions of the wedge. The method is applicable when the angle of the thin wedge turns to zero. A physical interpretation of the derived equations is obtained by using power expansions of non-polynomial functions, which appear after the Mellin transform. We establish that the first term in the expansion of the symmetric part corresponds to shear, while the first term of the anti-symmetric part describes deflection of the wedge axis. Numerical experiments, performed by using a code developed on the basis of the theory, show that using only the first terms of the expansions insignificantly influence accuracy: the approximate results coincide with the exact values of roots to the third significant digit even for the wedge angle of 30°.     

Isoperthiocyanic acid (3-amino-5-thione-l, 2, 4-dithiazole) as a new reagent for the selective detection of nitrite ion

Summary A new, simple, and selective test is described for the detection of nitrite ion with isoperthiocyanic acid (I) as the reagent. The test is based on the reaction of a 5% solution ofI with the nitrite ion solution, a deep orange precipitate being formed. Conversely, the test can be used in the identification ofI itself. Presumably, the coloured product is 3-hydroxy-5-thione-1, 2, 4-dithiazole, formed by the action of nitrous acid (producedin situ by the action of sulphuric acid and nitrite) on the 3-amino group ofI. The limit of detection is 300g of NO₂ ^– in a drop (0.05 ml). Most anions (including IO₃ ^–) do not interfere. Only I^–, thiourea, and hydrogen peroxide interfere; S₂O₃ ^2– interferes only when present in large amounts.

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Zusammenfassung Ein neuer, einfacher und selektiver Nachweis von Nitrit mit Isoperthio cyansäure (I) wurde beschrieben. Er beruht auf der Umsetzung einer 5% igen Lösung von I mit Nitritlösung, wobei ein tief orange gefärbter Niederschlag entsteht. Umgekehrt kann die Reaktion auch zum Nachweis von I dienen. Vermutlich handelt es sich bei dem gefarbten Produkt um 3-Hydroxy-5-thion-1, 2, 4-dithiazol, das durch Einwirkung der salpetrigen Säure auf die 3-Aminogruppe von I entsteht. Die Erfassungsgrenze betragt 300g NO₂ ^–im Tropfen (0,05 ml). Die meisten Anionen (inklusive JO₃ ^–) stören nicht. Nur J^–, Thioharnstoff und H₂O₂ stören; Thiosulfat stört nur in großen Mengen.

     

Template synthesis in the nickel(II)–thiocarbohydrazide–propanone triple system

The complexing process proceeding in the Ni^II–thiocarbohydrazide (H₂N–H–NC(=S)–NH–NH₂)–propanone triple system in EtOH solution and nickel(II)hexacyanoferrate(II) gelatin-immobilized matrix has been studied. It has been found that in the first case, template synthesis leading, as a minimum, to formation of three coordination compounds of Ni^II with (N,N,S,S)-donor tetradentate ligands having NiL¹, NiL² and NiL³compositions where L¹ is 4,6,6-trimethyl-2,3,7,8-tetraazanonen-3-di(thiohydrazide)-1,9, L² is 4,6,6,12-tetrametyl-1,9-dithio-2,3,7,8,10,11-hexaazatridekadien-3,11-hydrazide-1 and L³ is 2,8,10,10,16-pentamethyl-5,13-dithio-3,4,6,7,11,12,14,15-octaazaheptadekatrien-2,7,15 is observed, whereas in the gelatin-immobilized matrix, a complexing process in the system considered does not occur.