Experimental determination of the dependence of starch looseness on the concentration of the silicon dioxide nanopowder (tarcosil) in it

The looseness of starch powder is investigated, depending on the concentration of nanodimensional silicon dioxide powder (tarkosil) in it, by measuring the angle of the natural slope and the consumption of the flow of starch mixed with this powder through calibrated funnels with various diameters. It is found that adding small amounts of tarkosil substantially affects the angle of natural slope and increases the looseness of starch.     

Method of singular integrodifferential equations in plane dynamic problems of fracture mechanics

We develop a method for the solution of two-dimensional dynamic problems of the theory of elasticity for infinite bodies with smooth curvilinear cracks combining a modified method of finite differences in time with the method of singular integrodifferential equations in the space variables. Integral representations of the wave potentials are constructed and used to reduce the first boundary-value problem to the solution of systems of integrodifferential equations by the method of mechanical quadratures. The time dependences of the computed dynamic stress intensity factors at the tips of a rectilinear crack are analyzed for various impact and pulsed loads acting upon the crack lips.     

Optimization of the Shapes of Holes in a Quasiorthotropic Plate under Biaxial Tension

Materials Science - On the basis of solutions of the plane problems of the elasticity theory for a quasiorthotropic body with curvilinear hole, we propose an analytic-numerical algorithm for the...     

Calculation of the stress intensity factors and nominal stresses in the plane of a crack from the opening of its edges

A method is proposed for determination of the stress intensity factors and stress distribution in the plane of a defect under an arbitrary load. It includes measurement of the opening of the edges of a developing opening mode crack at several points at a distance from its tip. The theoretical basis of the method is the equation of the energy balance of the body with a crack and the Petroski-Achenbach approach of approximate calculation of the crack edge opening, making it possible to consider arbitrary configurations of the body and the crack. The results of solution of a series of method examples confirming the accuracy and effectiveness of the proposed approach are presented.Translated from Problemy Prochnosti, No. 6, pp. 27–34, June, 1990.