METHOD AND APPARATUS FOR TESTING TUBULAR SPECIMENS FOR AXIAL COMPRESSION Russian patent published in 1994 - IPC

FIELD: test technology. SUBSTANCE: apparatus comprises two cups 1 having variable-length walls and support protrusions 2. Tubular specimen by its end-faces 3 is mounted on two washers 5 located on support protrusions 2 of each cup 1 at equal distances from one another. Each washer is made in the form of a plurality of rings elasticity modulus of which increases towards the cup support protrusions. The apparatus furthermore is provided with seat members 6 each of which is movably situated in corresponding pair of openings of the support protrusions and capable of axial movement, hinges 7 for transferring a load from a test machine onto cup 1. The member, thickness and material which the rings of washers 5 are made of and the distance between seat members 6 as well are selected from the condition to provide change in the shape of washers 5 under action of axial forces from seat members 6 and consequently to provide maximum contact with the end-faces on one hand and on the other hand to distribute lumped forces from seat members 6 onto the end-faces of specimen 3. The method involves the steps of: placing specimen 3 by end-faces on washers 5 located on side protrusions 2 of cups 1, applying load to the end-faces of specimen 3 which value is less than a destructive one, measuring the distribution of deformations in the middle portion of specimen 3, centering the specimen measuring the circumferential distribution of axial deformations along the specimen circumference and determination regions with its maximum values in the edge-effect presence area, and applying load to the end-faces of specimen in these regions through washers 5 till uniform distribution of axial deformations, then increasing load onto the specimen end-faces up to destructive one. EFFECT: enhanced reliability. 2 cl, 1 dwg