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

46After the initial test loading was completed, the coupon was then tested untilfailure. This was done with the amount of stroke movement in the MTS machine beingcontrolled; in stroke control the rate of crosshead movement in the sample is controlledrather than the loading rate. The testing coupon was then loaded at a rate of 1/32 inch perminute until specimen yielding, and was then stretched 1/8 inch per minute in the plasticregion until failure. Similarly, as in the initial test, the readings from the strain gages,extensometer, load cell and stroke LVDT were recorded using Strain Smart Software.Once both tests were completed, the readings in Strain Smart were thentransferred into a spreadsheet so that the results could be plotted and evaluated. Themodulus of elasticity, yield stress, ultimate tensile stress, and strain hardening exponentand coefficient where then determined from these data. The markings from the originalmeasured eight inch gauge length were measured again and compared to the originallength to obtain the percent elongation.3.5.3 Type of Data Collected from Tensile Coupon TestingFor both coupon tests, the strain gage readings, extensometer, load cell andcrosshead stroke of the MTS machine, were recorded using the data acquisition unit.These recordings were then transferred into engineering units using Strain SmartSoftware. The values recorded from the strain gages were recorded in micro strains,which indicates that the actual strains in the specimens were 1x 10 -6 times the microstrainsreported. Strain is simply the amount of stretch in the specimen divided by theoriginal length; therefore it is a unit-less quantity.The extensometer recorded values in terms of inches. These values were thenconverted into micro strains to correlate with the strain gages. This was done in aspreadsheet after the Strain Smart software had transferred the data. The extensometerreadings were converted by dividing the actual recordings by the extensometer gage