Interaction of ultrasound with macroscopic defects in solids

The interaction between ultrasound and macroscopic defects in solids is considered using the nonlinear theory of elasticity. It is shown that, due to the resonance nature of the vibrations of the defect, considerable anharmonism occurs even when the intensity of the ultrasonic wave is weak. Because of this, effective conversion of the ultrasonic wave into internal vibrational states of the macrodefect occurs.V. D. Kuznetsov Siberian Physico-Technical Institute, Tomsk State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 3–9, November, 1994.     

Track detectors in radiation monitoring of the sunken submarine “Komsomolets”

Track method (using the CN and CR-39 detectors, spark couner of tracks as well as selective sorbents for plutonium and uranium) is applied in 1994 and 1995 together with many other methods in radioecological monitoring of water in the region of the sunken nuclear submarine (NS) “Komsomolets”. The detection assembles were installed with the help of the submersibles MIR. The results obtained inside the NS and on its surface as well as near and on the remote buoy station do not contradict the data obtained by other methods confirming the absence of the plutonium leakage outside of the submarine.     

Generalizations in the problem of Lipschitz stability

The problem of Lipschitz stability of nonlinear systems of differential equations is considered. Theorems extending previous results are stated. Translated fromDinamicheskie Sistemy. Vol. 12, pp 101–105, 1993.     

Interaction of a turbulent wake with the outer flow

The integral methods of boundary-layer theory are used to examine the interaction of a turbulent wake with the outer flow for the example of planar flow.In contrast with the known Crocco-Lees theory [1], the turbulent layer in the gas is described with the aid of an appropriate family of velocity profiles rather than by means of a Dorodnitsyn-type transformation of the incompressible turbulent layer. The selection of the simplest among the possible systems of first order interaction equations is justified; this system reduces to a single differential equation and an estimate is given of the influence of the arbitrariness in the equation selection on the final results.The hydrodynamic meaning of the singular and nonsingular integral curves and the singular point of the interaction equation is clarified on the basis of an examination of the interaction of compression and rarefaction waves in the outer supersonic stream with the wake. The effect of blowing (suction) and the initial boundary layer on the base pressure and the supersonic interaction flow as a whole is examined on the basis of the integral conditions for the splicing of the interaction flow with the isobaric mixing flow behind the corner. It is shown that, with proper selection of the single constant in the turbulent viscosity formula, the computational results are in satisfactory agreement with experiment.In conclusion, the authors wish to thank G. G. Chernyi for helpful discussions of the study, and L. V. Kapranova and Z. A. Donskova for assistance in the calculations.     

Failure criterion of a solid with a hierarchy of defects of the same physical type

A multi-scale percolation model of solids failure under loading has been proposed. It is associated with an infinite cluster of microdefects of the same physical type and takes into account a random distribution and size of defects in a space volume. A percolation criterion is given in terms of defect size distribution and defect scale correlation. Analyzed is the validity of scaling defects in solids undergoing failure.