FIELD: examination and testing materials. SUBSTANCE: specimen has cylindrical working part and two heads coaxial with it. Each head of specimen has surface for transmission of compressive force and circular flat area for transmission of tensile stress. Surface of compressive force transmission is made tapered, and specimen intermediate part is positioned between working part and each of heads is coaxial with the latter. Specimen intermediate part is limited by surface of revolution which generatrix is determined by dependence including half the initial length of specimen working part, initial radius of specimen working part, coordinates of generatrix arbitrary point determined in rectangular system of coordinates which axis coincides the specimen axis, and beginning is aligned with its working part middle. Maximum diameter of intermediate part is determined by inequality which includes initial diameter of working part and relative deformation in compression which must be attained during test. EFFECT: higher test results. 2 dwg
