No. 76. TENSILE TEST, " STEEL PLATE. 54." x".372 Sheet stamped T. S., 60,000 pounds. Sectional area, 4.46 square inches. Gauged length, 20". Free length of specimen between holders, 32". Elongation of inch sections, ".14, ".14, ".14, ".14, ".15, ".15, ".16, "16, ".16, ".16, ".16, ".16, ".17, ".17, ".17, ".17, ".17, ".17, ".18, ".19, ".20, ".21, ".23, ".25, ".29, ".34, ".44, ".57, ".96, Minimum width at fracture, 10".06. ".38. Area at fracture, 1.91 square inches. Contraction of area, 57.2 %. Silky fracture. The specimen varied in thickness; the elastic limit was passed in the minimum section first. Fracture occurred at the smaller end, and the elongations show the greatest stretch at this end. When the "Cooper lines" were first developed some appeared at right angles to the axis of the specimen; others followed in diagonal lines from each edge, intersecting each other. The diagonal lines make an angle of 56° 20' with the axis of the speci men. The direction of fracture was diagonally across plate at an angle of 67° 10 with the axis of the specimen. When the fractured ends are brought together an opening at the middle remains about ".23 wide. SINGLE-RIVETED LAP JOINTS, " IRON PLATE. Punched holes: Punch, ".695 diameter; die, ".752 diameter. Failure occurred by tearing out upper plate at four rivets, as shown by the sketch, and by shearing one rivet, second from outside. The fracture first in sight appeared at the end of the plate at the calked side of the joint. Fractures also appeared at the end of the lap opposite the three middle rivets. In the under plate no fracture apparent at the holes. The sheared rivet had fracture started under the head. rivet was slightly fractured in the same manner. Another Square inches. 2.425 1.55 .c8 1.92 g" iron rivets, "Burden's best." Punched holes: Punch, ".695 diameter; die, ".752 diameter. Gross sectional area of plate Shearing area of rivets (".70 diameter) Joint failed by shearing four rivets, and tore out upper plate at one end rivet. Fractures started at end of lap in each plate and opposite each rivet but one. All the sheared rivets had fractures started under the heads. Elongation of holes from ".04 to ".08. Holes with the die-side in, stretching the most. Square inches. 2.52 1.63 .895 1.92 |