Failure took place immediately after the first warning that the rivets were yielding. Elongation of rivet holes from ".04 to ".06. 3" iron rivets, "Burden's best." Under plate, 10".04 x".495. Punched holes: Punch, 18" diameter; " diameter of die. 13// 16 Gross sectional area of under plate Bearing surface of rivets Shearing area of rivets (".2 diameter). 32 Square inches. 4.97 2.84 2.13 2.64 Punched holes: Punch, 1" diameter; die, 1" diameter. 16 Tore plate across four rivet holes, shearing one end rivet. The plate failed at the commencement of fracture by parting the middle sections, which showed a granular appearance. Metal not drawn down. Two sections between rivets have silky appearance, with seam through middle. Metal drawn down. Fractured end of upper plate, Joint No. 294, showing granular and silky appearance in same metal. No. 295.- STEEL PLATE. JOINT A. A . 15" iron rivets, "Burden's best." Punched holes: Punch, 1" diameter; die, 1" diameter. Broke suddenly across rivet holes; appearance of fracture granular; no contraction. 10.04 × 495 Square inches. 4.97 2.42 2.55 3.93 Photograph of fractured sections, upper plate, Joint No. 295. Granular fractures produced in the lap oint. Specimens cut out of fractured plate A A.. No. 295. Tested by direct tension. Sheet cut in two at middle. One-half prepared with milled grooves. One-half prepared with punched grooves. No. 316. MILLED SPECIMEN. Sectional area, ".982 × ".495 = .486 square inch. Ultimate strength, 32,850 pounds = 67,600 pounds per square inch. Area at fracture, ".88x".33 = .290 square inch. Contraction of area, 40.3 per cent. Silky fracture; spongy line through center. No. 317.-PUNCHED SPECIMEN. Sectional area, ".98 ×".501 = .49 square inch. Ultimate strength, 32,790 pounds = 66,920 pounds per square inch. Area at fracture, ".92x".36: = .33 square inch. Contraction of area, 32.7 per cent. Appearance of fracture, silky, with slight granular appearance at center. 18" iron rivets, "Burden's best." Punched holes: Punch, 1" diameter; die, 1" diameter. Fractured upper plate across line of rivet holes. Five of the fractured sections broke suddenly, with granular appearance and without contraction of area. The sixth end section had silky appearance, the metal drawing down before breaking. Square inches. 5.02 2.39 5.26 7.85 |