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This paper presents unified solutions for elastic–plastic expansion analysis of a cylindrical or spherical cavity in an infinite medium, adopting a flow theory of strain gradient plasticity. Previous cavity expansion analyses incorporating strain gradient effects have mostly focused on explaining the strain localization phenomenon and/or size effects during infinitesimal expansions. This paper is however concerned with the size-dependent behaviour of a cavity during finite quasi-static expansions. To account for the non-local influence of underlying microstructures to the macroscopic behaviour of granular materials, the conventional Mohr–Coulomb yield criterion is modified by including a second-order strain gradient. Thus the quasi-static cavity expansion problem is converted into a second-order ordinary differential equation system. In the continuous cavity expansion analysis, the resulting governing equations are solved numerically with Cauchy boundary conditions by simple iterations. Furthermore, a simplified method without iterations is proposed for calculating the size-dependent limit pressure of a cavity expanding to a given final radius. By neglecting the elastic strain increments in the plastic zone, approximate analytical size-dependent solutions are also derived. It is shown that the strain gradient effect mainly concentrates in a close vicinity of the inner cavity. Evident size-strengthening effects associated with the sand particle size and the cavity radius in the localized deformation zone is captured by the newly developed solutions presented in this paper. The strain gradient effect will vanish when the intrinsic material length is negligible compared to the instantaneous cavity size, and then the conventional elastic perfectly-plastic solutions can be recovered exactly. The present solutions can provide a theoretical method for modeling the size effect that is often observed in small-sized sand-structure interaction problems. [ABSTRACT FROM AUTHOR]

A possibility has been showed of obtaining nanocomposites with adjustable particle size, silver coating with polyvinylpyrrolidone powder (PVP) using technology electron beam deposition being an example. The influence of parameters such as time, concentration of silver and a molecular weight of PVP on the stability of colloidal systems nanocomposites dissolved in water. The structure of heterogeneous colloidal system PVP-Ag-H2O was examined using the electron microscopy and spectral (PCS and AES-ICP) methods. The sedimentation-stable colloid systems of ultrafine silver particles have been obtained. They are suitable for use in medicine and agriculture. [ABSTRACT FROM AUTHOR]

The examples of the effective use of simple mathematical statistics methods are offered in an industrial and build production. [ABSTRACT FROM AUTHOR]

This paper deals with ratios between the order of the system of linear algebraic equations for the amplitudes of oscillations in resonators and the number of accountable space harmonics that give the most precise solution of dispersion equation for open comb with combs of infinite thickness, using the method of partial areas. We also reveal the dependence between relative difference of the method of partial areas and the factorization method as well as phase shift of zero space harmonic at the period of the comb. [ABSTRACT FROM AUTHOR]

The present paper provides insights into experimental and theoretical research on the effect of low-carbon steels microstructure after quenching and tempering on the temperature of 100% brittleness of Charpy specimens. In addition, we obtain the conditions of metal fracture ahead of a notch at Charpy temperature. Using the results of Charpy tests, as well as low-temperature tensile tests of unnotched specimens, we show the value of effective overstress ahead of Charpy notch at the critical temperature. We conclude that susceptibility of Charpy temperature to the change in the carbide particle size depends on the value of yield stress and strain hardening exponent. [ABSTRACT FROM AUTHOR]

This paper deals with asymptotic properties of some Kalman-Bjusy filters. We also consider the conditions of convergence of dispersion matrices sequence of the estimation error and the properties of the limit matrix. [ABSTRACT FROM AUTHOR]

The study addresses the formation of graphite dispersed particles and thermographenite from the perspective of mechanical and physical-chemical dispersed methods. In particular, this new proposed method of the spherical shaped particles formation of thermographenite ensures pressing and items rolling without stratifications. [ABSTRACT FROM AUTHOR]