Impact compressibility of a poly(ethylene glycol)-based nanocomposite fluid

The behavior of a poly(ethylene glycol)-based nanocomposite shear thickening fluid (STF) under impact loading conditions has been experimentally studied using the Kolsky method and related techniques. The dependence of the pressure in the STF on the volume strain magnitude has been determined. It is established that the radial and axial components of the stress tensor almost coincide, which shows that the material behaves like an incompressible liquid. The character of the stress-strain curves (hysteresis) indicates that the STF is characterized by some energy dissipation in the load-unload cycle.     

Potassium ion conducting K<Subscript>1 − 2<Emphasis Type="Italic">x</Emphasis></Subscript>Cd<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>FeO<Subscript>2</Subscript> solid electrolytes

New potassium ion conducting solid electrolytes based on potassium monoferrite have been prepared through partial substitution of the divalent cation Cd²⁺ on the potassium site, and their properties have been investigated. The introduction of cadmium cations sharply increases the electrical conductivity of KFeO₂ over the entire temperature range studied. In addition to the maximum in conductivity at the boundary of the K_{1 − 2x} Cd _x FeO₂ solid solution, there is a maximum at a higher cadmium content (x = 0.30–0.35). The possible origins of this maximum are discussed.     

Physical metallurgy conditions for retaining the load-carrying ability of the gas-main pipeline metal during long-term operation

The causes and mechanisms of the failures in the operation of a gas-main pipeline that has been operating successfully for several decades are analyzed. Fractography is used to detect the presence of regions in a fracture surface that undergo brittle fracture at the stage of crack propagation. The temperature dependence of the impact toughness demonstrates that the appearance of such brittle fracture regions in the fracture surfaces forming during the operation of a gas-main pipeline is caused by high cold-shortness susceptibility of the pipeline metal. The reliability criterion for the gas-main pipeline metal consists in avoiding brittle fracture even in local volumes. The conditions that ensure the reliability of the gas-main pipeline metal consist in its low upper cold-shortness threshold temperature and high brittle fracture energy.     

Effect of external force fields on the domain structure of equiatomic CuAu alloy

Peculiarities of the ordered-structure formation in the equiatomic CuAu alloy, which are caused by changes in the sample dimensions and by an applied external force field, have been studied. The rate of the microstructure transformation in the ordered alloy has been found to increase with increasing thickness of the sample. It has been shown that tensile stresses applied during heat treatment can affect the growth direction of c domains and, thus, makes it possible to avoid the low-temperature cracking of the material.     

Using brazing alloys in resistance spot welding of joints in aluminium–magnesium alloys

The results of mathematical modelling of the process of propagation of heat in the parent metal in submerged-arc surfacing with a composite strip electrode are presented. The mathematical model was constructed by solving the differential equation of heat conductivity by the finite element method. The calculations and plotting of the graphs were carried out using the MSC Patran software. The model was used to determine the main parameters of the composite strip electrode influencing the shape and dimensions of the pool and the non-uniformity of penetration. The comparison of the calculated and experimental data shows that they are in good agreement.     

Estimation of residual strength of components of composite constructions after low-speed impact

A methodology of computing the damageability of composite materials at low-speed impact is suggested. The methodology is based on applying a fracture criterion of the monolayer and following computation of material damageability taking the interaction of different damage evolution mechanisms into account. This approach allows us to obtain the distribution of damageability parameters in the surface of the monolayer and the width of material at an arbitrary moment of time until complete destruction of the construction component, computing the degradation of elastic properties, and the position and sizes of delamination regions after the impact. Applying this methodology for estimating residual strength permits the avoidance of excessive conservatism of the projected strength of construction components from composite materials which have incurred impact damage.     

Oxidation-abrasion of TiC-based cermets in SiC medium

The aim of the current study was to investigate the effect of oxidation on abrasive wear behaviour of TiC based cermets at temperatures ranging from 20 to 900 °C. Three types of material performance maps were constructed: oxidation rate maps, wear rate maps and maps showing the effect of oxidation on abrasion. Discussion on the performance of different cermet grades is supported by the SEM images combined with EDS and XRD analysis. The results should facilitate the selection of TiC-based cermets providing optimum composition of cermets for high temperature applications.     

Use of laser trimming for the development of a project for accuracy-normalization of the resistance of resistors in hybrid integrated circuits

The possibilities for laser trimming are studied, the disadvantages of this method are revealed, and the ways of developing this approach on the basis of computer-aided design and modeling are proposed. The hierarchy analysis method and the fuzzy-set theory are used to evaluate the normalization projects.     

Pseudomutagenesis. The persistent increase in the level of cellular variability induced by radiation and some other agents

Electron microscopic investigation of capillary endothelium cells in myocardium of irradiated rats revealed an unusual effect of persistent increase of probability of cell damage, similar in many relations to that described earlier for various unicellular species. New effect, unlike those traditionally studied, is characterised by non-stochastic nature, large number of the involved cells, reveals itself even after faint influences, and can be induced as well by agents other than radiation. The question is put on the probable commonness between these changes and the pseudomutagenesis which has the similar phenomenology.