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VOLUME 42, № 1, 2006 (January – February )


Pokhodnia I. K. V. V. Panasyuk – an outstanding scientist, organizer of science, public figure
Ostash O. P. New approaches in fatigue fracture mechanics

SUMMARY. It is shown that the process zone size, d*, is basic parameter of material depending on its microstructure, mechanical behaviour and test conditions, and determines various stages of the fatigue fracture of materials and structural elements. The proposed unified model of fatigue fracture based on d*-parameter makes it possible to assess the life time of cyclically loaded notched structural elements using the fatigue macrocrack growth curve only. The process zone size, d*, stipulates some peculiarities of fatigue fracture, in particular the typical points on the Kitagava–Takahashi and Smith–Miller diagrams.

Troshchenko V. T. Unlocalized fatigue damage of metals and alloys

SUMMARY. Analysis of regularities of cyclic inelastic deformation of metals and alloys shows that inelastic strain and inelastic strain energy per cycle can be used as a characteristic of nonlocalized fatigue damage. The interrelation between the general regularities of fatigue fracture of metals and alloys and the regularities of inelastic deformation is analyzed. Strain and energy criteria of fatigue fracture based on the regularities of nonlocalized fatigue damage are considered.

Burak Ya. Yo. and Chaplia Ye.Ya. On thermodynamic aspects of near surface phenomena in thermoelastic systems

SUMMARY. An energy approach and is proposed as well as a methodology for model description of kinetics of subsurface phenomenon formation in thermoelastic bodies in transition from the homogeneous (natural) state to a local gradient stationary one is proposed. The constitutive equations of a local thermodynamical state and dissipative processes are formulated. The obtained relationships are basic ones for both statement of corresponding initial-boundary value problems and quantitative analysis of subsurface phenomena depending on boundary conditions on the surface of the contact between the thermoelastic body and external medium.

Akid R., Dmytrakh I. M., and Gonzalez-Sanchez J. Fatigue damage accumulation: aspects of environmental interaction
Lobanov L. M., Kyrian V. I., and Knysh V. V. Improvement of welded metal structures life by high-frequency mechanical forging

SUMMARY. Results of investigations of high-frequency mechanical peening (HFMP) of welded joints of structural steels of different strength grades and aluminium alloys were generalized. A high efficiency of using HFMP to increase the fatigue strength of metal structure welded joints at the stage of their manufacturing and operation is shown.

Neimitz A. Fracture toughness of structural elements: the influence of the in- and out-of-plane constraint on fracture toughness
Dietzel W., Pfuff M., and Juilfs G. G.Hydrogen permeation in plastically deformed steel membranes
Kurzydlowski K. J. Physical, chemical and mechanical properties of nanostructured materials
Carpinteri A. and Paggi M. Influence of the intermediate material on the singular stress field in tri-material junctions
Nazarchuk Z. T. Electromagnetic waves dispersion modelling by a thin dielectric coating on a cylinder

SUMMARY. Double-sided boundary conditions which contain only tangential components of diffracted field are used for mathematical modeling of electromagnetic scattering from an arbitrary cylinder with thin dielectric coating. The resulted boundary-value problem is reduced to the system of two second kind singular integral equations. The kernels of these equations are similar to the kernels of the first kind integral equations for a perfectly conducting screen. Numerical solution of the integral equations is obtained and the structure of diffracted field is investigated in the radio wave range for an elliptical cylinder with different dielectric coatings. The essential influence of the thin surface film on the cylinder scattering behaviour is established.

Novikov M. V., Maistrenko A. L., Kushch V. I., and Ivanov S. A. Assessment of quality rating of metal matrix–diamond composite by its thermal and electric conductivities

SUMMARY. An efficiency of the hot-pressed diamond-containing composite materials (DCM) for application in different tools is affected greatly by the microdefects, namely, residual porosity of metal matrix, damaged diamond grains and imperfect diamond-matrix interfaces. Experimental evaluation of these microdefects is rather difficult due to small size, non-standard shape and strong heterogeneity of specimens. Proposed here an alternate, non-destructive technique of DCM quality rating includes measurement of resistance and thermal conductivity of a diamond-containing composite and processing the obtained data by the composite mechanics methods. The numerical rating of quality is given in terms of two dimensionless parameters. The first one, 0 < K < 1, reflects quality of a sintered metal matrix whereas the second one, 0 < R < 1, is an aggregate measure of the diamond grains integrity and perfection degree of composite interfaces. A quite satisfactory agreement observed between the theory and experiment confirms efficiency of the technique and reliability of the reported data.

Firstov S. O., Rogul T. G., Sviechnikov V. L., and Dub S. M. Concept of “useful” admixtures and mechanical properties of nanostructurized chromium and molybdenum films

SUMMARY. Using the results of comparative analysis of structure, mechanical behaviour and nanohardness of chromium and molibdenum coatings obtained by magnetron spraying, the original mechanism of the very high hardness value of superfine grained chromium has been proposed. A concept of “useful” admixtures, the use of which allows to obtain (by grain boundaries engineering) nanostructural materials with the improved hardness (strength) has been developed.

Pluvinage G. Pipe defect assessment based on limit analysis, failure assessment diagram and subcritical crack growth
Morozov Ye. M. Calculation of the surface crack critical size

SUMMARY. The nomographic method for determination of the critical dimensions (depth and length) of a surface semi-elliptical crack in a plate under tension and bending has been proposed using the known stress intensity factor expressions.

Volodymyr Panasyuk (to the 80th birthday)

Revised: 28.02.2006