FIELD: physics.;SUBSTANCE: aligning wedge-shaped grooves are made in a specimen. Wedges are inserted into the grooves with a gap between the apex of the wedge and the bottom of the groove. The specimen is placed between press plates and compression force is applied to the wedges, the value of which determines strength of material of the specimen upon destruction of the specimen. Bottoms of the grooves have a cylindrical radius a, and the smaller base of the trapezoidal wedge is equal to 3a, where a is the maximum crack width set experimentally for any possible percentage of fibre reinforcement. The angle between planes of the wedge is equal to 2φ, where φ=arctg(f) is the angle of inclination of the transverse walls of the groove, and f is the coefficient of friction between surfaces of the specimen and the wedges.;EFFECT: more accurate testing.;3 dwg
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