E.N. KHRUSTALEV(S METHOD OF DETERMINING STRENGTH AND STABILITY CRITICAL PRESSURE OF MATERIAL HALF-SPACE Russian patent published in 2015 - IPC E02D1/00 G01N33/24 

FIELD: physics.

SUBSTANCE: invention relates to material interaction physics when the hard flat body of a die comes into contact with the half-space of a deformable material medium in the initial phase of its strength and stability critical (breaking) state. The method includes, at a given mark of the material half-space at a depth h under a flat hard die, based on test results, determining physical characteristics of the compressible material with an unbroken structure: specific weight - γ_str, specific cohesion c=c_str, angle φ=φ_str of internal friction, gravitational (natural) pressure p_n, taking the value of atmospheric pressure as p_atm=1.033 kG/cm²; for approximated determination of the minimum breakdown pressure in the medium under the edge of the loaded die, using the N.P. Puzyrevsky′s scheme and the limit equilibrium condition of the medium; and to establish the value of the breakdown pressure under the centre of the foot of the die, considering the L. Prandtl - G. Reisner scheme. The minimum breakdown compression pressure of the medium under the edge of the foot of the die according to the N.P. Puzyrevsky′s scheme is approximated using the relationship $$p_{\mathrm{2,}comp}^{edf}\approx \frac{\pi {\gamma }_{str}h}{1+tg{\phi }_{str}\cdot \left({\phi }_{str}-\pi /2\right)}+\left(p_6+p_{atm}\right).$$

EFFECT: determining the boundaries of the phase critical (breakdown) stress-strain state of a body of an associated material medium under pressure of medium-sized a flat hard die at the moment of initial development of surface cracks.

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