GB1024245A - Testing of materials - Google Patents

Abstract

1,024,245. Testing strength of materials. NATIONAL RESEARCH DEVELOPMENT CORPORATION. Jan. 20, 1964 [Jan. 18, 1963], No. 2362/63. Heading G1S. In testing materials there is provided means for applying to a three dimensional specimen which is thin in one dimension relative to its other two dimensions, controllable loads in two directions at right angles to one another and to said one dimension of the specimen and an independent controlled pure shear load in the same plane as the direct loads. As shown in Fig. 1, axial tension is applied to the specimen e.g. a thin-walled member 29 of constant bore, by an hydraulic ram 18 two opposed pairs of cylinders 24-27 acting on a drum 22 to apply torque to the specimen. As shown in Fig. 1, the cylinders and rams are connected in pairs 24, 26 and 25, 27 by tapes 28 wound around the drum 22, and are arranged to apply torque in opposite directions. A tension cylinder 17 is provided having an upwardly projecting ram 18 carrying a cross-bar 19 connected by tie-bars 21 to the drum 22. Rotation of the cylinder 17 imparts a torque to the drum 22 which is balanced through torque cylinders 24-27. The oil pressure in the cylinder is controlled by valve means, shown in Fig. 5 and includes a spool 52 movable in a chamber 57 proportionate to the load. The end of the spool 52 abuts a pivoted lever 64 through a ball 65. A weight 66 is carried along an arm 67 of the lever through a lead screw 69, movement of the weight 66 being controlled by flow of oil through the valve. To measure the longitudinal strain, an extensometer is provided, and comprises rings 73, 74 situated on the specimen 29, ring 73 carrying a chequered grid 76 and the other a pointer 77 so that a direct reading may be obtained. The circumferential strain is measured by earthing the specimen 29 and enclosing it in a spaced electrode 78 (see Fig. 8) so that the variation in capacitance may be measured.