Evaluation and Repair of Wrought Iron and - Purdue e-Pubs ...

17In this testing, wrought iron bars, plates and other shapes were purchased fromdifferent merchants and makers to be tested. The origins of the testing samples werecarefully recorded. The bars were then tested in the testing machine at the foundry whereKirkaldy worked. This testing machine consisted of a simple counter weight machineusing a lever arm and lighter weights to load the specimens, as seen in Figure 2.6.Specimens were loaded slowly and observations of the maximum breaking weight, andpercent elongation for the wrought iron bars were recorded during and after testing. Theobservations recorded did not include the yield stress of the wrought iron since at thattime the idea of yield stress was not yet fully understood and was difficult to obtain.Kirkaldy tested approximately 310 wrought iron bars while he was at RobertNapier’s Vulcan Foundry Works in Glasgow. The results of these test results wherecopied and recorded from the paper he published in 1862, and can be found in AppendixA. The results show the average ultimate tensile stress that Kirkaldy found for thewrought iron bars was 55,420 psi. The standard deviation was 7,533 psi which was13.6% of the mean. A plot of these results is shown in Figure 2.7.Along with testing wrought iron bars, Kirkaldy also tested wrought iron plate andangle iron. The average ultimate strength found for angle iron, bar and plate werecalculated and are shown in Table 2.1. As can be seen in this table, the bar had thehighest ultimate strength while the plate had the lowest. The tensile stress results of theplate, angle iron, and bar were plotted together to achieve an average value for theultimate tensile stress of 52,000 psi with a standard deviation of 7,240 psi. The standarddeviation was 14% of the average found. A plot of all these results can be seen in Figure2.8.Kirkaldy also recorded the percent elongations for several wrought iron bars. Tofind the percent elongations Kirkaldy recorded the length of the specimen before andafter testing and the compared these values to find the percent elongation. Figure 2.9 is a