| 摘要 |
<p>Shear strength of foundry sand mixts is determined across two planes vertical to the central axis of a cylindrical test-piece. The method results in the virtual elimination of any bending force in the applied stress, thus leading to more accurate measurements. The cylindrical test-piece is placed between two jaws, both of which have a semicircular face in contact with the test-piece, however, one jaw has a large slot in the centre of the semi-circular section so that this surface only contacts the end portions of the test-piece. Conversely, the other jaw is cut away at both ends leaving a centre section the same size as the slot in the mating jaw. If no test-piece was present, the jaws would mate but when a test is conducted, a shearing force is applied across the test piece in two planes. Keys and pegs ensure accurate location of the two jaws. Press. is applied by a hand-operated cylinder and the force measured with a manometer. Considerably higher shear test results are obtd.</p> |
