REMARKS ON THE BRAZILIAN RESEARCH TECHNIQUE FOR BRITTLE TENSION STRENGTH

Abstract

A plane deformation of a circular cylinder under different systems of statically equivalent loads is considered. The loading is done by the symmetrical constant-rate loads with respect to the centerline; the loads are applied to the cylinder side. Three load cases are analyzed: diametric forces along two generators (Hertz basic feasible solution), uniform normal loads, and uniform parallel forces. The comparison of equivalent stresses based on Mohr theory of strength with the tension intensity of the basic feasible solution in the failure plane is presented. Based on this comparison, the appropriateness of identifying the normal stress in the diametric plane under the specimen fracture, and of its tension stress limit is discussed. It is proved that the normal stress in the diametric plane of crushing the specimen in the Brazilian test technique is not a material tension limit; and it may be several times less than the specified stress limit for some brittle solids.