Fundamental Fracture Mechanics Equation of Material

On the basis of energy conservation law an without utilizing Linear Fracture Mechanics (LFM) postulates the equation of a real-structure material elastic-plastic fracture has been derived. With the help of this equation the force and energy criteria of Non-linear Fracture Mechanics (NLFM) have been found. These criteria constitute the basis of modern strength analysis of machineparts and structures made of real-structure materials. $K_{lc}$ dependence on ultimate strength limit, yield limit and impact toughness has been established and experimentally confirmed for a number of steelsComment: 8 pages, 3 figure

Cyclic Strength and Nonlinear Material Fracture Mechanics (by the example of steels)

It was shown that a material fatigue fracture diagram can be viewed as a locus of points with $\sigma$ and $\sqrt l$ coordinates' product equal to $K_{1c}/2$, and $\sigma$ and $l$ product -- to $G_{1c}/2$, where $K_{1c}$ and $G_{1c}$ are non-linear fracture mechanics force and energy criteria. It was established that the average number of interatomic bonds destroyed within one alternate stress $\nabla_{1cs}$ cycle is directly proportional to $\sigma$ that is twice as large as a peak value of $\sigma^a$. It was found that low-cycle fatigue is characterized by $\sigma >\sigma_{0.2}$ and $\sigma_{1cs}> 1$, high-cycle fatigue -- by $\sigma = \sigma_{0.2}$ and $\nabla_{1cs} = 1$, and giga-cycle fatigue -- by $\sigma < \sigma_{0.2}$ and $\nabla_{1cs} < 1$. An individual interatomic bond cannot be destroyed part by part but as a single unit. The latter means that in giga-cycle fatigue a single interatomic bond is destroyed within several cycles rather than within a single cycle. The factors $F$ (collapsibility) and $R$ (resistibility) were proposed and mentioned as essential material physical constants. The introduced notion $\nabla_{1cs}$ and the established linear nature of $\nabla_{1cs}$ relationship allow to: a) clarify the fatigue crack growth physical nature in low-, high- and giga-cycle fracture zones; b) determine the nature of a fatigue fracture diagram disruption; c) plot the fatigue fracture diagram using the results obtained in a single specimen cyclic strength test with a selected value of $\sigma \ge \sigma_{0.2}$. For giga-cycle fatigue it is important (with similar purpose in mind) to determine this dependence for $\sigma < \sigma_{0.2}$. It is recommended to use $G_{1c}$ criterion to find the $l_{cr}$ length value which in contrast to $K_{1c}$ has a clear physical nature.Comment: 10 pages, 6 figure

Possible Overionization of C II, N II, and O II Ions in the Atmospheres of Early B- and Late O-Type Stars

The reliability of C, N, and O abundances determined from the C II, N II, and O II lines in the main sequence (MS) early B- and late O-type stars is examined. This analysis is based on a fact of primary importance for this problem: the C II, N II, and O II ions in atmospheres of these stars are photoionized by radiation in the far UV. Observations show that the actual flux in this range for hot stars can be considerably higher than theoretical levels; thus, overionization of the C II, N II, and O II ions beyond the ionization calculated with the standard model atmospheres occurs in the actual atmospheres of these stars. Underestimates in the calculated ionization lead to reduced values of the C, N, and O abundances. This is confirmed by the observed dependence on the effective temperature Teff: the C, N and O abundances tend to be lower with increasing Teff. It is shown that overionization becomes significant for sufficiently hot stars, namely when Teff>18500 K for the C II lines and when Teff>26000 K for the N II and O II lines. The systematic difference in the C, N and O abundances between these relatively hot stars and the cooler B-type MS stars is about 0.2 dex. The relatively cool B-type MS stars (Teff<18100 K for C II and Teff<25000 K for N II and O II) yield the undistorted C, N and O abundances, and their average values agree very well with modern estimates for the Sun. It is noted that when an alternative method based on examining the ionization balance (e.g., He I-II, C II-III, Ne I-II, Si III-IV) is used to determine the parameters Teff and log g, the overionization problem essentially vanishes; however, this method leads to a systematic enhancement in Teff and log g. The overionization problem can be solved by shifting to the improved model atmospheres for early B- and late O-type stars that takes their sphericity into account and, possibly, stellar winds and magnetic fields

Soliton Organization of Thermal Field in a Chain at High Temperature

Thermal field soliton self-organization arising due to absorption of background atoms vibrations is observed in numerical experiment in nonlinear chain with Lennard-Jones potential at high temperature. At some stage intensive space-localized waves are formed and give additional peaks on high-energy tile of energy distribution unlike of Gibbs one.Comment: MikTex v.2.1, 7 pages, 2 EPS figure

Damage Thermodynamics of Quasibrittle Materials

The description of the early stage of microfracture growth in a quasibrittle solid with thermodynamic positions is considered. From the most general thermodynamic performances the "principle" of minimization of free energy is received. The account high (down to thirds) degrees in expansion of free energy concerning parameters of a mechanical field and average microcrack energy has allowed to write down the state equation for solids with microcracks, to find equilibrium and nonequilibrium values of their average energy. From positions of a developed formalism the reason of high stability of work developments on small depths and mechanism of loss of their stability on the large depths is explained. From the fact of presence of qualitatively various behaviour of a material on the large depths the additional estimated connection between parameters of the theory is established.Comment: MikTex v.2.1, 12 pages, 1 EPS figure

Conception of main local-strong-nonequilibriun state

A new conception of main local-strong-nonequilibrium state is proposed on the basis of development of the conception local equilibrium state. At list the conception is intended for description of evolution of internal defect structure in solids subjected severe external influences, for example, severe plastic deformation, radiation and so on, but can be developed on other closely related phenomena.Comment: 6 page

Vacancy theory of melting

The features of alternative approach of non-equilibrium evolution thermodynamics are shown on the example of theory of vacancies by opposed to the classic prototype of Landau theory. On this foundation a strict theory of the melting of metals, based on development of Frenkel ideas about the vacancy mechanism of such phenomena, is considered. The phenomenon of melting is able to be described as a discontinuous phase transition, while the traditional Frenkel's solution in the region of low-concentration of vacancies can describe such transition only as continuous one. The problem of limiting transition of shear modulus to zero values in the liquid state, as well as the problem of the influence of extended state of vacancies on their mobility, is discussed.Comment: 12 papges, 7 figure

Nonequilibrium evolution thermodynamics of vacancies

An alternative approach - nonequilibrium evolution thermodynamics, is compared with classical Landau approach. A statistical justification of the approach is carried out with help of probability distribution function on an example of a solid with vacancies. Two kinds of kinetic equations are deduced in terms of the internal energy and the modified free energy.Comment: 4 pages, 3 figure

Probability distribution function for a solid with vacancies

Expression for probability distribution is got taking into account a presence and removal of degeneracy on the microstates. Its application allows to describe the process of melting of solids, as saltatory phase transition of the first kind without bringing in of concept of the order parameter.Comment: 3 pages, 3 figures; budget topic 0109U006004 of NAS of Ukrain

Hubble's law and Superluminity Recession Velocities

The extension of the so-called "empty" (with gravity and antigravity that compensate each other in full or do not exist at all) universe and cosmological redshift in it are considered in this paper. Its flat space-time can be submitted not only as manifold with Friedman-Robertson-Walker metrics (FRW) of the general theory of relativity (GR) but also as space-time with usual Minkowski metrics (M-metrics) of the special theory of relativity (SR); the transfer of metrics can be done by suitable transformation of reference frame. Both below-mentioned statements are equally fair for such the universe. First: the distant galaxies can have superluminity recession velocities in FRW-space of GR; we have no right to use here the formula of relativistic Doppler effect. Secondly: the SR theory is fair in the M-space and, accordingly, recession velocities of the same galaxies here can aspire to the speed of light only. In this article it is shown that, despite opposite pictures in FRW-and M- spaces, in the careful account of all details both approaches yield results agreed among them. Thus, actually there are no contradictions between the interpretations of cosmological redshift, based on SR and GR.Comment: 7 pages, 3 figure